As filed with the Securities and Exchange Commission on July 1, 1998
                                                           Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                    FORM S-3
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------

                                   ENZON, INC.
             (Exact name of registrant as specified in its charter)

           DELAWARE                                          22-2372868
(State or other jurisdiction                             (I.R.S. Employer
of incorporation or organization)                        Identification No.)

                20 Kingsbridge Road, Piscataway, New Jersey 08854
                                 (732) 980-4500

(Address,  including zip code,  and telephone  number,  including  area code, of
registrant's principal executive offices)

                                 --------------
                                JOHN CARUSO, ESQ.
                      VICE PRESIDENT, BUSINESS DEVELOPMENT,
                          GENERAL COUNSEL AND SECRETARY
                                   ENZON, INC.
                20 Kingsbridge Road, Piscataway, New Jersey 08854
                                 (732) 980-4500

            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)
                                 --------------
                                   Copies to:
                             KEVIN T. COLLINS, ESQ.
                              DORSEY & WHITNEY LLP

                    250 Park Avenue, New York, New York 10177
                                 (212) 415-9200

     Approximate date of commencement of proposed sale to the public: As soon as
practicable after this Registration  Statement  becomes  effective.  If the only
securities  being registered on this Form are being offered pursuant to dividend
or interest reinvestment plans, please check the following box. [_]

     If any  securities  being  registered  on this Form are to be  offered on a
delayed or continuous  basis  pursuant to Rule 415 under the  Securities  Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, check the following box. [x]

     If this Form is filed to  register  additional  securities  for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list  the  Securities  Act  registration  statement  number  of the  earlier
effective registration statement for the same offering. [_]

     If this Form is a  post-effective  amendment  filed pursuant to Rule 462(c)
under the  Securities  Act,  check  the  following  box and list the  securities
registration  statement number of the earlier effective  registration  statement
for the same offering. [_]

     If delivery of the  prospectus is expected to be made pursuant to Rule 434,
please check the following box. [_]

                         CALCULATION OF REGISTRATION FEE

==================================================================================================================================== Title of Each Class Proposed Maximum Proposed Maximum Amount of of Securities to Amount to Offering Price Aggregate Registration be Registered be Registered per Share Offering Price Fee - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock $.01 par 3,983,000 shares $5.53(1) $22,025,990 $6,498 value per share ====================================================================================================================================
(1) Estimated solely for the purpose of computing the amount of the registration fee in accordance with Rule 457(c) under the Securities Act of 1933, as amended (the "Securities Act"), based on the average of the high and low sale price for the common stock, $.01 par value per share (the "Common Stock") as reported by the Nasdaq Stock Market on June 26, 1998. The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine. INFORMATION CONTAINED HEREIN IS SUBJECT TO COMPLETION OR AMENDMENT. A REGISTRATION STATEMENT RELATING TO THESE SECURITIES HAS BEEN FILED WITH THE SECURITIES AND EXCHANGE COMMISSION. THESE SECURITIES MAY NOT BE SOLD NOR MAY OFFERS TO BUY BE ACCEPTED PRIOR TO THE TIME THE REGISTRATION STATEMENT BECOMES EFFECTIVE. THIS PROSPECTUS SHALL NOT CONSTITUTE AN OFFER TO SELL OR THE SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE SECURITIES IN ANY STATE IN WHICH SUCH OFFER, SOLICITATION OR SALE WOULD BE UNLAWFUL PRIOR TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF ANY SUCH STATE. SUBJECT TO COMPLETION, DATED JULY 1, 1998 PROSPECTUS ENZON, INC. 3,983,000 Shares Common Stock ($.01 par value) ------------------------ This prospectus (the "Prospectus") relates to the offer and sale of up to 3,983,000 shares (the "Shares") of common stock, $.01 par value (the "Common Stock"), of Enzon, Inc. (the "Company" or "Enzon") by certain selling stockholders of the Company (each a "Selling Stockholders"). See "Selling Stockholders." The Company will not receive any of the proceeds from the sale of the Shares. The Selling Stockholders may sell the Shares from time to time in one or more transactions (which may involve block transactions) in the open market, in negotiated transactions, through the writing of options on the Shares (whether such options are listed on an options exchange or otherwise) or by a combination of these methods, at fixed prices that may be changed, at market prices at the time of sale, at prices related to market prices or at negotiated prices. The Selling Stockholders may effect these transactions by selling the Shares to or through broker-dealers, who may receive compensation in the form of discounts or commissions from the Selling Stockholders or from the purchasers of the Shares for whom the broker-dealers may act as agent or to whom they may sell as principal, or both in amounts to be negotiated immediately prior to the sale. The Selling Stockholders may also pledge the Shares as collateral for margin accounts or loans and the Shares could be resold pursuant to the terms of such accounts or loans. The Selling Stockholders, such brokers or dealers and any other participating brokers or dealers may be deemed to be "underwriters" within the meaning of the Securities Act of 1933, as amended (the "Securities Act") in connection with such sales. See "Plan of Distribution." In addition, any securities covered by this Prospectus which qualify for sale pursuant to Rule 144 under the Securities Act ("Rule 144") may be sold under Rule 144 rather than pursuant to this Prospectus. To the extent required, the specific shares of Common Stock to be sold, the name of any successor Selling Stockholders, the public offering price, the names of any such agent, dealer or underwriter, and any applicable commission or discount with respect to any particular offer will be set forth in an accompanying Prospectus Supplement. See "Selling Stockholders" and "Plan of Distribution." Neither the Company nor the Selling Stockholders can presently estimate the amount of commissions or discounts, if any, that will be paid by the Selling Stockholders on account of their sale of the Shares from time to time. The Company will bear all expenses in connection with the registration of the Shares herein, which expenses are estimated to be approximately $184,000. The Selling Stockholders will pay any brokerage compensation in connection with their sale of the Shares. See "Use of Proceeds." The Company's Common Stock is traded in the over-the-counter market and is quoted on The Nasdaq National Market, under the symbol "ENZN." On June 26, 1998 the last reported sale price of the Common Stock, as reported on The Nasdaq National Market was $5.5625 per share. AN INVESTMENT IN THE SECURITIES OFFERED HEREBY INVOLVES A HIGH DEGREE OF RISK. SEE "RISK FACTORS" COMMENCING ON PAGE 7. THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION, NOR HAS THE SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE. The date of this Prospectus is July __, 1998 TABLE OF CONTENTS Page ---- Available Information ................................................... 2 Incorporation of Certain Documents by Reference ......................... 2 Prospectus Summary ...................................................... 4 Risk Factors ............................................................ 7 Use of Proceeds ......................................................... 12 Selling Stockholders .................................................... 12 Plan of Distribution .................................................... 15 Legal Matters ........................................................... 16 Experts ................................................................. 16 No dealer, salesperson or other person has been authorized to give any not contained or incorporated by reference in this Prospectus in connection with this offering. Any information or representation not contained or incorporated by reference herein must not be relied on as having been authorized by the Company, the Selling Stockholders or their respective agents. This Prospectus does not constitute an offer to sell or the solicitation of an offer to buy the securities offered hereby in any state to any person to whom it is unlawful to make such offer or solicitation. Except where otherwise indicated, this Prospectus speaks as of its date and neither the delivery of this Prospectus nor any sale made hereunder shall, under any circumstances, create an implication that there has been no change in the affairs of the Company since the date hereof or that the information contained herein is correct as of any time subsequent to its date. AVAILABLE INFORMATION The Company is subject to the informational requirements of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and in accordance therewith files reports, proxy statements and other information with the Securities and Exchange Commission (the "Commission"). Such reports, proxy statements and other information filed by the Company can be inspected and copied at the public reference facilities maintained by the Commission at 450 Fifth Street, N.W., Washington, D.C. 20549, and at the following Regional Offices of the Commission: New York Regional Office, Seven World Trade Center, Suite 1300, New York, New York 10048; and Chicago Regional Office, Northwestern Atrium Center, 500 West Madison Street, Suite 1400, Chicago, Illinois 60661-2511. Copies of such material can be obtained from the Public Reference Section of the Commission at 450 Fifth Street, N.W., Washington, D.C. 20549 at prescribed rates. The Commission also maintains a Web site that contains reports, proxy and information regarding the Company at (http://www.sec.gov). The Company's Common Stock is listed on the Nasdaq National Market and reports, proxy and information statements and other information concerning the Company can be inspected at the National Association of Securities Dealers, 1735 K Street, N.W., 4th Floor, Washington, D.C. 20006-1506. The Company has filed with the Commission a Registration Statement on Form S-3 (referred to herein together with all amendments and exhibits thereto as the "Registration Statement") under the Securities Act, with respect to the shares of Common Stock offered hereby. This Prospectus which forms a part of the Registration Statement, does not contain all of the information set forth or incorporated by reference in the Registration Statement and the exhibits and schedules thereto, certain parts of which are omitted in accordance with the rules and regulations of the Commission. For further information with respect to the Company and the shares of Common Stock offered hereby, reference is hereby made to the Registration Statement, including the exhibits thereto. Copies of the Registration Statement, including the exhibits, may be obtained from the Public Reference Section of the Commission at the aforementioned address upon payment of the fee prescribed by the Commission. Copies of each document may also be obtained through the Commission's internet address at http://www.sec.gov. The summaries contained in this Prospectus of additional information included in the Registration Statement or any exhibit thereto are qualified in their entirety by reference to such information or exhibit. The following trademarks and service marks appear in or are incorporated by reference into, this Prospectus: ADAGEN(R) and ONCASPAR(R) are registered trademarks of the Company; PEGNOLOGY(R) is a registered service mark of the Company; SCA(R) is a registered trademark of Enzon Labs Inc., a wholly-owned subsidiary of the Company; Intron A(R) is a registered trademark of Schering Corporation. INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE The Company hereby incorporates by reference into this Prospectus (i) its Annual Report on Form 10-K for the Fiscal Year Ended June 30, 1997, which contains audited financial statements for the Company's latest fiscal year for which a Form 10-K was required to have been filed and incorporates by reference certain portions of the Company's definitive Proxy Statement for the Annual Meeting of Stockholders held December 2, 1997 (ii) all other reports filed by the Company pursuant to Section 13(a) or 15(d) of the Exchange Act since June 30, 1997, including but not limited to, the Quarterly Reports on Form 10-Q for the Quarters Ended September 30, 1997, December 31, 1997 and March 31, 1998 and the Current Report on Form 8-K filed on June 30, 1998 and (iii) the description of the Company's Common Stock, $.01 par value, as contained in its registration statement on Form 8-A, filed with the Commission on October 29, 1984, as amended by a Form 8 filed with the Commission on October 15, 1990. All documents filed by the Company pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, subsequent to the date hereof and prior to the filing of a post-effective amendment to the Registration Statement which indicates that all shares of Common Stock offered hereby have been sold or which deregisters all shares of Common Stock then remaining unsold, shall be deemed to be incorporated by reference into this Prospectus and to be a part hereof from the date of filing of such documents. 2 Any statement contained herein or in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this Prospectus to the extent that such statement is modified or superseded by a statement contained herein or in a subsequently filed document which also is or is deemed to be incorporated by reference herein. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Prospectus. The Company will provide, without charge, to each person (including any beneficial owner) to whom this Prospectus is delivered, upon written or oral request of such person, a copy of any and all of the information that has been incorporated by reference in this Prospectus (not including exhibits to such information unless such exhibits are specifically incorporated by reference into such information). Such requests should be directed to John Caruso, Vice President, Administration, General Counsel and Secretary, at the Company's principal executive offices at 20 Kingsbridge Road, Piscataway, New Jersey 08854, telephone (732) 980-4500. 3 PROSPECTUS SUMMARY The following summary is qualified in its entirety by the more detailed information and the Consolidated Financial Statements and the Notes thereto appearing elsewhere herein or incorporated by reference in this Prospectus. This Prospectus and such documents contain various "forward looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended (the "Securities Act"), which represent the Company's intentions, expectations or beliefs concerning future events, including, but not limited to, statements regarding management's expectations or beliefs concerning future events. These forward-looking statements are qualified by important factors that could cause actual results to differ materially from those in the forward-looking statements, including, without limitation, those discussed in "Risk Factors." See "Risk Factors." The Company Overview Enzon is a biopharmaceutical company that develops, manufactures and markets enhanced therapeutics for life-threatening diseases through the application of its two proprietary technologies: (i) polyethylene glycol ("PEG") modification and (ii) single-chain antigen-binding ("SCA") proteins. Enzon is focusing its research activities primarily in the area of oncology and is applying its proprietary technologies to compounds of known therapeutic efficacy in order to enhance the performance of these compounds. The Company is commercializing its proprietary technologies by developing products internally and in cooperation with strategic partners. To date, the Company and its partners have successfully commercialized two products, ONCASPAR and ADAGEN (described below). The Company currently has two products under development internally and has established more than 15 strategic alliances and license relationships for the development of products using the Company's proprietary technologies. The Company believes that its partners are dedicating substantial resources to the development of products which incorporate Enzon's proprietary technologies. These efforts include the development of PEG-Intron A, a PEG modified version of Schering-Plough Corporation's ("Schering-Plough") product, INTRON A (interferon alfa 2b), a genetically-engineered anticancer-antiviral drug, for which Schering-Plough is currently conducting Phase III clinical trials. PEG Technology The PEG process involves chemically attaching PEG, a relatively non-reactive and non-toxic polymer, to proteins, chemicals and certain other pharmaceuticals for the purpose of enhancing their therapeutic value (the "PEG Process"). The attachment of PEG helps to disguise the compound and reduce the recognition of the compound by the immune system, generally lowering potential immunogenicity and extending the life of such compounds in the circulatory system. The PEG Process also increases the solubility of the modified compound which enhances the delivery of the native compound. To date, Enzon's commercialized products are PEG modified proteins. Through enhancements, Enzon is seeking to apply its PEG technology to more traditional organic compounds. The Company has made significant improvements to the original PEG Process, collectively referred to as Second Generation PEG Technology, and has applied for and received certain patents covering some improvements. One of the components of the Second Generation PEG Technology is new linker chemistries; the chemical binding of PEG to unmodified proteins. These new linkers provide an enhanced binding of the PEG to the protein resulting in a more stable compound with increased circulation life and may result in more activity of the modified protein. The Company also has developed a Third Generation PEG Technology that is designed to enable the technology to be expanded to certain organic compounds and would give such PEG-modified compounds "Pro 4 Drug" attributes. This is accomplished by attaching PEG to a compound by means of a covalent bond that is designed to break down over time, thereby releasing the active ingredient in the proximity of various tissues. The Company believes that the "Pro Drug/Transport Technology" has much broader usefulness in that it can be applied to a wide range of small molecules, such as cancer chemotherapy agents, antibiotics, anti-fungals and immunosuppressants, as well as to proteins and peptides, including enzymes and growth factors, although there can be no assurance that such application will result in safe, effective, or commercially viable pharmaceutical products. Marketed PEG Products The Company has received marketing approval from the United States Food and Drug Administration ("FDA") for two first generation PEG technology products: (i) ONCASPAR, the PEG formulation of asparaginase, for the indication of acute lymphoblastic leukemia ("ALL") in patients who are hypersensitive to native forms of L-asparaginase and (ii) ADAGEN, the PEG formulation of adenosine deaminase, the first successful application of enzyme replacement therapy for an inherited disease to treat a rare form of Severe Combined Immunodeficiency Disease ("SCID"), commonly known as the "Bubble Boy Disease." ADAGEN is marketed by Enzon on a worldwide basis. ONCASPAR is marketed in the U.S. and Canada by Rhone-Poulenc Rorer Pharmaceuticals, Inc. and certain of its affiliated entities ("RPR") and in Europe by Medac GmbH ("Medac"). The Company has also granted exclusive licenses to RPR to sell ONCASPAR in the Pacific Rim and Mexico. The Company is entitled to royalties on the sales of ONCASPAR in North America by RPR, as well as manufacturing revenue from the production of ONCASPAR. The Company's agreements with RPR for the Pacific Rim and with Medac require the partners to purchase ONCASPAR from the Company at a set price which increases over the term of the agreements. In addition, the agreements provide for minimum purchase quantities. The Company manufactures both ADAGEN and ONCASPAR in its South Plainfield, New Jersey facility. PEG Products under Development The Company currently has three products created using its Second and Third Generation PEG Technology in clinical and preclinical trials. The first is PEG-Intron A, a PEG modified version of Schering-Plough's product, INTRON A (interferon alfa 2b), a genetically-engineered anticancer-antiviral drug, for which Schering-Plough is currently conducting Phase III clinical trials for use in the treatment of hepatitis C. The second product under development is PEG-hemoglobin, a proprietary bovine hemoglobin-based oxygen-carrier being developed for the radiosensitization of solid hypoxic tumors, for which the Company is currently conducting a Phase Ib clinical trial. The third product under development is PROTHECAN, a PEG-modified version of camptothecin, a potent topoisomerase-1 inhibitor, for use in certain cancers, which is currently in preclinical studies. PEG-Intron A. PEG-Intron A was developed by the Company in conjunction with Schering-Plough to have longer lasting activity and an enhanced safety profile compared to the currently marketed form of INTRON A. PEG-Intron A is currently in a large scale Phase III clinical trial in hepatitis C patients in the United States and Europe. Other indications being pursued include chronic myelogenous leukemia and solid tumors. It is expected that PEG-Intron A will be administered once a week, compared to the current regimen for unmodified INTRON A of three times a week. Moreover, it is anticipated that PEG-Intron A will provide a more convenient dosing schedule with an improved side effect profile and an improved therapeutic index for hepatitis C patients. Currently, some patients on INTRON A experience debilitating flu-like symptoms. Pursuant to an agreement with Schering-Plough, the Company will receive royalties on worldwide sales of PEG-Intron A, receive milestone payments, and has the option to be the exclusive manufacturer of PEG-Intron A for the U.S. market. Schering-Plough's sales of INTRON A were approximately $598 million in 1997 5 for all approved indications. The worldwide market for alpha interferon products is estimated to be in excess of $1 billion for all approved indications. The patents covering Schering-Plough's INTRON A will begin to expire in 2001. The Company's Second Generation PEG Technology patents that cover the modified product should afford Schering-Plough extended patent life for PEG Intron-A. SCA Technology The Company also has an extensive licensing program for its second proprietary technology, SCA protein technology. SCA proteins are genetically engineered proteins designed to overcome the problems hampering the diagnostic and therapeutic use of conventional monoclonal antibodies. Preclinical studies have shown that certain SCA proteins target and penetrate tumors more readily than conventional monoclonal antibodies. In addition to these advantages, because SCA proteins are developed at the gene level, they are better suited for targeted delivery of gene therapy vectors and fully-human SCA proteins can be isolated directly, with no need for costly "humanization" procedures. Also, many gene therapy methods require that proteins be produced in an active form inside cells. SCA proteins can be produced through intracellular expression (inside cells) more readily than monoclonal antibodies. Currently, there are nine SCA proteins in Phase I or II clinical trials by various corporations and institutions. Two of these corporations and institutions have existing licenses with the Company with respect to SCA proteins and others are expected to require similar licenses. Some of the areas being explored are cancer therapy, cardiovascular indications and AIDS. The Company has granted non-exclusive SCA licenses to more than a dozen companies, including Bristol-Myers Squibb Company, Baxter Healthcare Corporation, Eli Lilly & Co., Alexion Pharmaceuticals Inc., and the Gencell division of RPR. These licenses generally provide for upfront payments, milestone payments and royalties on sales of FDA approved products. The Company's principal executive office and mailing address is 20 Kingsbridge Road, Piscataway, New Jersey 08054, and its telephone number is (732) 980-4500. The Offering Securities Offered............ This Prospectus relates to an offering by the Selling Stockholders of up to 3,983,000 shares of Common Stock of the Company. Securities Outstanding(1) As of May 29, 1998 the Company had 31,331,081 shares of Common Stock outstanding. After giving effect to the completion of the private offering described in "Selling Stockholders," the Company would have 35,314,081 shares of Common Stock outstanding. Use of Proceeds .............. The Company will not receive any proceeds from the sale of the Shares offered herein by the Selling Stockholders. See "Use of Proceeds." Risk Factors ................. See "Risk Factors" for a discussion of certain risk factors that should be considered by prospective investors in connection with an investment in the shares of Common Stock offered hereby. - ---------- (1) Excludes 5,417,422 shares reserved for issuance upon exercise of options and warrants outstanding at May 29, 1998, at weighted average exercise prices of $4.03 and $4.17, respectively. 6 RISK FACTORS Information contained and incorporated by reference in this Prospectus contains "forward-looking statements" which can be identified by the use of forward-looking terminology such as "believes," "expects," "may," "will," "should," or "anticipates" or the negative thereof or other variations thereon or comparable terminology, or by discussions of strategy. No assurance can be given that the future results covered by the forward-looking statements will be achieved. The risk factors set forth below constitute cautionary statements identifying important factors with respect to such forward-looking statements, including certain risks and uncertainties, that could cause actual results to vary materially from the future results indicated in such forward-looking statements. Other factors could also cause actual results to vary materially from the future results indicated in such forward-looking statements. An investment in the Shares offered hereby involves a high degree of risk. Prospective investors should carefully consider the following risk factors in addition to the other information set forth and incorporated by reference in this Prospectus before making any decision to invest in the Shares. Accumulated Deficit and Uncertainty of Future Profitability. The Company was originally incorporated in 1981. To date, the Company's sources of cash have been the proceeds from the sale of its stock through public offerings and private placements, sales of its FDA approved products, ADAGEN(R) and ONCASPAR(R); sales of its products for research purposes; contract research and development fees; technology transfer and license fees; and royalty advances. At March 31, 1998, the Company had an accumulated deficit of approximately $114.5 million. The Company expects to incur operating losses for the foreseeable future. To date, ADAGEN and ONCASPAR are the only products of the Company which have been approved for marketing in the United States by the FDA, having been approved in March 1990 and February 1994, respectively. In addition, ONCASPAR has been approved for marketing in Canada, Germany and Russia. In order to achieve profitable operations on a continuing basis, the Company, either alone or through its partners, must successfully manufacture, market and sell its ADAGEN and ONCASPAR products and develop, manufacture and market the Company's products which are under development. These products are in various stages of development, and the period necessary to achieve regulatory approval and market acceptance of any individual product is uncertain and typically lengthy, if achievable at all. Potential investors should be aware of the difficulties a biopharmaceutical enterprise such as the Company encounters, especially in view of the intense competition in the pharmaceutical industry in which the Company competes. There can be no assurance that the Company's plans will either materialize or prove successful, that its products under development will be successfully developed or that its products will generate revenues sufficient to enable the Company to achieve profitability. Raw Materials and Dependence Upon Suppliers. Except for PEG-hemoglobin, the Company purchases the unmodified compounds utilized in its approved products and products under development from outside suppliers. There can be no assurance that the purified bovine hemoglobin used in the manufacture of PEG-hemoglobin can be produced by the Company in the amounts necessary to expand the current clinical trials. The Company may be required to enter into supply contracts with outside suppliers for certain unmodified compounds. The Company does not produce the unmodified adenosine deaminase used in the manufacture of ADAGEN, the unmodified forms of L-asparaginase used in the manufacture of ONCASPAR and the unmodified camptothecin used in the Company's PROTHECAN product which is under development and has a supply contract with an outside supplier for the supply of each of these unmodified compounds. Delays in obtaining or an inability to obtain any unmodified compound, including unmodified adenosine deaminase, unmodified L-asparaginase, unmodified bovine blood, or unmodified camptothecin on reasonable terms, or at all, could have a material adverse effect on the Company's business, financial condition and results of operations. In the event the Company is required to obtain an alternate source for an unmodified compound utilized in a product which is being sold commercially or which is in clinical development, the FDA and relevant foreign regulatory agencies 7 will likely require the Company to perform additional testing, which would cause delays and additional expenses, to demonstrate that the alternate material is biologically and chemically equivalent to the unmodified compound previously used. Such evaluations could include chemical, pre-clinical and clinical studies and could delay development of a product which is in clinical trials, limit commercial sales of an approved product and cause the Company to incur significant additional expenses. If such alternate material is not demonstrated to be chemically and biologically equivalent to the previously used unmodified compound, the Company will likely be required to repeat some or all of the pre-clinical and clinical trials conducted for such compound. The marketing of an FDA approved drug could be disrupted while such tests are conducted. Even if the alternate material is shown to be chemically and biologically equivalent to the previously used compound, the FDA or relevant foreign regulatory agency may require the Company to conduct additional clinical trials with such alternate material. Patents and Proprietary Technology. The Company has licensed, and been issued, a number of patents in the United States and other countries and has other patent applications pending to protect its proprietary technology. Although the Company believes that its patents provide certain protection from competition, there can be no assurance that such patents will be of substantial protection or commercial benefit to the Company, will afford the Company adequate protection from competing products, will not be challenged or declared invalid, or that additional United States patents or foreign patent equivalents will be issued to the Company. The scope of patent claims for biotechnological inventions is uncertain and the Company's patents and patent applications are subject to this uncertainty. The Company is aware of certain issued patents and patent applications belonging to third parties, and there may be other patents and patent applications, containing subject matter which the Company or its licensees or collaborators may require in order to research, develop or commercialize at least some of the Company's products. There can be no assurance that licenses under such patents and patent applications will be available on acceptable terms or at all. If the Company does not obtain such licenses, it or its partners could encounter delays in product market introductions while it attempts to design around such patents or could find that the development, manufacture or sale of products requiring such licenses could be foreclosed. If the Company does obtain such licenses it will in all likelihood be required to make royalty and other payments to the licensors, thus reducing the profits realized by the Company from the products covered by such licenses. The Company is aware that certain organizations are engaging in activities that infringe certain of the Company's PEG technology and SCA patents. There can be no assurance that the Company will be able to enforce its patent and other rights against such organizations. The Company expects that there may be significant litigation in the industry regarding patents and other proprietary rights and, if Enzon were to become involved in such litigation, it could consume a substantial amount of the Company's resources. In addition, the Company relies heavily on its proprietary technologies for which pending patent applications have been filed and on unpatented know-how developed by the Company. Insofar as the Company relies on trade secrets and unpatented know-how to maintain its competitive technological position, there can be no assurance that others may not independently develop the same or similar technologies. Although the Company has taken steps to protect its trade secrets and unpatented know-how, third-parties nonetheless may gain access to such information. The Company has two research and license agreements with The Green Cross Corporation ("Green Cross") regarding rHSA. The Company and Yoshitomi Pharmaceutical Industries, Ltd. ("Yoshitomi"), the successor to Green Cross' business, are currently in arbitration to resolve the amount of royalties that will be due the Company, if any. In April 1998, Yoshitomi filed documents in such arbitration seeking a declaratory judgment that under its agreement with the Company no royalties are payable. Any adverse decision from such an arbitration proceeding could result in a material adverse effect to the Company's future business, financial condition and results of operations. Research Corporation Technologies, Inc. ("Research Corporation") held the original patent upon which the PEG Process is based and had granted the Company a license under such patent. Research Corporation's patent for the PEG Process in the United States and its corresponding foreign patents have expired. Although the Company has obtained several improvement patents in connection with the PEG Process, there can be no assurance that any of these patents will enable the Company to prevent infringement or that competitors will not develop competitive products outside the protection that may be afforded by these patents. The Company is aware 8 that others have also filed patent applications and have been granted patents in the United States and other countries with respect to the application of PEG to proteins and other compounds. Based upon the expiration of the Research Corporation patent, other parties will be permitted to make, use, or sell products covered by the claims of the Research Corporation patent, subject to other patents, including those held by the Company. There can be no assurance that the expiration of the Research Corporation patent will not have a material adverse effect on the business, financial condition and results of operations of the Company. Limited Sales and Marketing Experience; Dependence on Marketing Partners. Other than ADAGEN, which the Company markets on a worldwide basis to a small patient population, the Company does not engage in the direct commercial marketing of any of its products and therefore does not have significant sales and marketing experience. For certain of its products, the Company has provided exclusive marketing rights to its corporate partners in return for royalties to be received on sales. With respect to ONCASPAR, the Company has granted exclusive marketing rights in North America and the Pacific Rim to RPR. The Company has also granted exclusive marketing rights in Europe and Russia to Medac Gmbh and in Israel to Tzamal Pharma Ltd.. The Company expects to retain marketing partners to market ONCASPAR in other foreign markets, principally South America, and is currently pursuing arrangements in this regard. There can be no assurance that such efforts will result in the Company concluding such arrangements. Regarding the marketing of certain of the Company's other future products, the Company expects to evaluate whether to create a sales force to market certain products in the United States or to continue to enter into license and marketing agreements with others for United States and foreign markets. These agreements generally provide that all or a significant portion of the marketing of these products will be conducted by the Company's licensees or marketing partners. In addition, under certain of these agreements, the Company's licensees or marketing partners may have all or a significant portion of the development and regulatory approval responsibilities. There can be no assurance that the Company will be able to control the amount and timing of resources that any licensee or marketing partner may devote to the Company's products or prevent any licensee or marketing partner from pursuing alternative technologies or products that could result in the development of products that compete with the Company's products and the withdrawal of support for the Company's products. Should the licensee or marketing partner fail to develop a marketable product (to the extent it is responsible for product development) or fail to market a product successfully, if it is developed, the Company's business, financial condition and results of operations may be adversely affected. There can be no assurance that the Company's marketing strategy will be successful. Under the Company's marketing and license agreements, the Company's marketing partners and licensees may have the right to terminate the agreements and abandon the applicable products at any time for any reason without significant payments. The Company is aware that certain of its marketing partners are pursuing parallel development of products on their own and with other collaborative partners which may compete with the licensed products and there can be no assurance that the Company's other current or future marketing partners will not also pursue such parallel courses. Reimbursement from Third-Party Payors. Sales of the Company's products will be dependent in part on the availability of reimbursement from third-party payors, such as governmental health administration authorities, private health insurers and other organizations. Government and other third-party payors are increasingly sensitive to the containment of health care costs and are limiting both coverage and levels of reimbursement for new therapeutic products approved for marketing, and are refusing, in some cases, to provide any coverage for indications for which the FDA and other national health regulatory authorities have not granted marketing approval. There can be no assurance that such third-party payor reimbursement will be available or will permit the Company to sell its products at price levels sufficient for it to realize an appropriate return on its investment in product development. Since patients who receive ADAGEN will be required to do so for their entire lives (unless a cure or another treatment is developed), lifetime limits on benefits which are included in most private health insurance policies could permit insurers to cease reimbursement for ADAGEN. Lack of or inadequate reimbursement by government and other third party payors for the Company's products would have a material adverse effect on the Company's business, financial condition and results of operations. 9 Government Regulation. The manufacturing and marketing of pharmaceutical products in the United States and abroad is subject to stringent governmental regulation and the sale of any of the Company's products for use in humans in the United States will require the prior approval of the FDA. Similar approvals by comparable agencies are required in most foreign countries. The FDA has established mandatory procedures and safety standards which apply to the clinical testing, manufacture and marketing of pharmaceutical products. Pharmaceutical manufacturing facilities are also regulated by state, local and other authorities. Obtaining FDA approval for a new therapeutic may take several years and involve substantial expenditures. ADAGEN was approved by the FDA in March 1990. ONCASPAR was approved by the FDA in February 1994, in Germany in November 1994 and in Canada in 1997 in each case for patients with acute lymphoblastic leukemia who are hypersensitive to native forms of L-asparaginase. ONCASPAR was approved in Russia for therapeutic use in a broad range of cancers. Except for these approvals, none of the Company's other products have been approved for sale and use in humans in the United States or elsewhere. There can be no assurance that the Company will be able to obtain FDA approval for any of its other products. In addition, any approved products are subject to continuing regulation, and noncompliance by the Company with applicable requirements can result in criminal penalties, civil penalties, fines, recall or seizure, injunctions requiring suspension of production, orders requiring ongoing supervision by the FDA or refusal by the government to approve marketing or export applications or to allow the Company to enter into supply contracts. Failure to obtain or maintain requisite governmental approvals or failure to obtain or maintain approvals of the scope requested, will delay or preclude the Company or its licensees or marketing partners from marketing their products, or limit the commercial use of the products, and thereby may have a material adverse affect on the Company's business, financial condition and results of operations. Intense Competition and Risk of Technological Obsolescence. Many established biotechnology and pharmaceutical companies with resources greater than those of the Company are engaged in activities that are competitive with the Company's and may develop products or technologies which compete with those of the Company. The Company is aware that other companies are engaged in utilizing PEG technology in developing drug products. There can be no assurance that the Company's competitors will not successfully develop, manufacture and market competing products utilizing PEG technology or otherwise. Other drugs or treatment modalities which are currently available or that may be developed in the future, and which treat the same diseases as those which the Company's products are designed to treat, may be competitive with the Company's products. There can be no assurance that the Company will be able to compete successfully against current or future competitors or that such competition will not have a material adverse effect on the Company's business, financial condition and results of operations. Rapid technological development by others may result in the Company's products becoming obsolete before the Company recovers a significant portion of the research, development and commercialization expenses incurred with respect to those products. The Company's success, in large part, depends upon developing and maintaining a competitive position in the development of products and technologies in its area of focus. There can be no assurance that the Company's competitors will not succeed in developing technologies or products that are more effective than any which are being sold or developed by the Company or which would render the Company's technologies or products obsolete or noncompetitive. The Company's failure to develop and maintain a competitive position with respect to its products and/or technologies would have a material adverse effect on its business, financial condition and results of operations. Uncertainty of Market Acceptance. The Company's products, ONCASPAR and ADAGEN, have been approved by the FDA to treat patients with acute lymphoblastic leukemia and a rare form of severe combined immunodeficiency disease, respectively. Neither product has become widely used due to the small patient population and limited indications approved by the FDA. The Company's current research and development efforts are directed towards developing new technologies to aid in drug delivery. Assuming that the Company is able to develop such technologies and secure the requisite FDA approvals, the market acceptance of any such products will depend upon the acceptance by the medical community of the use of such technologies. There can be no assurance that any additional products will be approved by the FDA or that, if approved, the medical 10 community will use them. In addition, the use of any such new products will depend upon the extent of third party medical reimbursement, increased awareness of the effectiveness of such technologies and sales efforts by the Company or any marketing partner. The Company's proprietary PEG technology has received only limited market acceptance to date. Failure of the Company to develop new FDA approved products and to achieve market acceptance for such products would have a material adverse effect on the Company's business, financial condition and results of operation. Potential Product Liability. The use of the Company's products during testing or after regulatory approval entails an inherent risk of adverse effects which could expose the Company to product liability claims. The Company maintains product liability insurance coverage in the total amount of $10 million for claims arising from the use of its products in clinical trials prior to FDA approval and for claims arising from the use of its products after FDA approval. There can be no assurance that the Company will be able to maintain its existing insurance coverage or obtain coverage for the use of its other products in the future. There can be no assurance that such insurance coverage and the resources of the Company would be sufficient to satisfy any liability resulting from product liability claims or that a product liability claim would not have a material adverse effect on the Company's business, financial condition or results of operations. Future Capital Needs; Uncertainty of Additional Financing. The Company's current sources of liquidity are its cash reserves, and interest earned on such cash reserves, sales of ADAGEN and ONCASPAR, sales of its products for research purposes, and license fees. There can be no assurance as to the level of sales of the Company's FDA approved products, ADAGEN and ONCASPAR, or the amount of royalties realized from the commercial sale of ONCASPAR pursuant to the Company's licensing agreements. Total cash reserves, including short term investments, as of March 31, 1998, were approximately $6.6 million, and after giving effect to the approximately $17,600,000 of net proceeds received by the Company from the private placement of the Shares offered herein, will be approximately 24,228,000. Based upon its currently planned research and development activities and related costs and its current sources of liquidity, the Company anticipates its current cash reserves will be sufficient to meet its capital and operational requirements for the foreseeable future. The Company's future needs and the adequacy of available funds will depend on numerous factors, including without limitation, the successful commercialization of its products, progress in its product development efforts, the magnitude and scope of such efforts, progress with preclinical studies and clinical trials, progress with regulatory affairs activities, the cost of filing, prosecuting, defending and enforcing patent claims and other intellectual property rights, competing technological and market developments, and the development of strategic alliances for the marketing of its products. There can be no assurance that the Company will not require additional financing for its currently planned capital and operational requirements. In addition, the Company may seek to acquire additional technology, enter into strategic alliances and engage in additional research and development programs, which may require additional financing. The Company does not have any committed sources of additional financing, and there can be no assurance that additional funding, if necessary, will be available on acceptable terms, if at all. To the extent the Company is unable to obtain financing, it may be required to curtail its activities or sell additional securities. There can be no assurance that any of the foregoing fund raising activities will successfully meet the Company's anticipated cash needs. If adequate funds are not available, the Company's business, financial condition and results of operations will be materially and adversely affected. Dividend Policy and Restrictions. The Company has paid no dividends on its Common Stock, since its inception and does not plan to pay dividends on its Common Stock in the foreseeable future. Except as may be utilized to pay the dividends payable on the Company's Series A Cumulative Convertible Preferred Stock (the "Series A Preferred Stock"), any earnings which the Company may realize will be retained to finance the growth of the Company. In addition, the terms of the Series A Preferred Stock restrict the payment of dividends on other classes and series of stock. 11 Possible Volatility of Stock Price. Historically, the market price of the Company's Common Stock has fluctuated over a wide range and it is likely that the price of the Common Stock will fluctuate in the future. Announcements regarding technical innovations, the development of new products, the status of corporate collaborations and supply arrangements, regulatory approvals, patent or proprietary rights or other developments by the Company or its competitors could have a significant impact on the market price of the Common Stock. In addition, due to one or more of the foregoing factors, in one or more future quarters, the Company's results of operations may fall below the expectations of securities analysts and investors. In that event, the market price of the Company's Common Stock could be materially and adversely affected. Shares Eligible for Future Sale. As of May 29, 1998, the Company had approximately 31,331,000 shares of Common Stock outstanding and after giving effect to the consummation of the private offering of 3,983,000 shares of Common Stock described in "Selling Stockholders" which are offered hereby, but assuming no additional shares are issued pursuant to outstanding options, warrants or convertible securities, would have had approximately 35,314,081 shares of Common Stock outstanding. The 3,983,000 shares of Common Stock offered hereby are "restricted securities," as that term is defined in Rule 144 under the Securities Act, which when sold pursuant to the Registration Statement will be freely transferrable without restrictions under the Securities Act, assuming such Shares are held by non-affiliates of the Company. Of the other shares of Common Stock outstanding, approximately 31,274,000 shares will be immediately available for sale without restriction in the public market and approximately 26,000 shares will be eligible for sale under Rule 144 of the Securities Act. In addition, the approximately 245,000 shares of Common Stock issuable upon conversion of the Series A Preferred Stock will be immediately available for sale without restriction in the public market when issued. Certain holders of the Company's securities are entitled to registration rights with respect to an aggregate of approximately 1,886,000 shares of Common Stock, including approximately 1,039,000 shares underlying outstanding warrants. Of such shares, approximately 989,000 shares are registered currently on Form S-3 registration statements. The approximately 4,378,000 shares of Common Stock underlying outstanding options which are held by employees, directors and consultants are registered on Form S-8 registration statements. Sales of substantial amounts of such shares in the public market or the prospect of such sales could adversely affect the market price of the Common Stock. Anti-takeover Considerations. The Company has the authority to issue up to 3,000,000 shares of Preferred Stock of the Company in one or more series and to fix the powers, designations, preferences and relative rights thereof without any further vote of shareholders. The issuance of such Preferred Stock could dilute the voting powers of holders of Common Stock and could have the effect of delaying, deferring or preventing a change in control of the Company. Certain provisions of the Company's Articles of Incorporation and By-laws, including those providing for a staggered Board of Directors, as well as Delaware law, may operate in a manner that could discourage or render more difficult a takeover of the Company or the removal of management or may limit the price certain investors may be willing to pay for shares of Common Stock. USE OF PROCEEDS The Company will not receive any proceeds from the sale of the Shares offered herein by the Selling Stockholders. Expenses expected to be incurred by the Company in connection with this offering are estimated to be $184,000. SELLING STOCKHOLDERS The Shares covered by this Prospectus were acquired from the Company in a private offering pursuant to Common Stock Purchase Agreements (the "Purchase Agreements") for an aggregate purchase price of $18,919,250 ($4.75 per share). The offer and sale by the Company of the Common Stock to the Selling Stockholders pursuant to the Purchase Agreements was made pursuant to an exemption from the registration 12 requirements of the Securities Act provided by Section 4(2) thereof. The Purchase Agreements contain representations and warranties as to each Selling Stockholder's status as an "accredited investor" as such term is defined in Rule 501 promulgated under the Securities Act. SBC Warburg Dillon Read & Co. Inc. ("Dillon Read"), the placement agent, was paid a fee of $900,000 or approximately 4.75% of the aggregate purchase price in connection with the sale of the Shares by the Company to the Selling Stockholders pursuant to the Purchase Agreements. In addition, the Company agreed to reimburse Dillon Read for its travel, legal and other out-of-pocket expenses incurred in connection with the sale of the Shares by the Company to the Selling Stockholders pursuant to the Purchase Agreements up to a maximum of $50,000. The Company paid Evolution Capital, a broker/dealer, a fee of $235,155 or approximately 1.25% of the aggregate purchase price in connection with the sale of the Shares by the Company to the Selling Stockholders pursuant to the Purchase Agreements. Pursuant to the Purchase Agreements, each Selling Stockholder has represented that he, she or it acquired the Shares for its own account as principal, for investment purposes only, and not with a present view to, or for, the resale distribution thereof, in whole or in part, within the meaning of the Securities Act or any state securities law. The Company agreed, in such Purchase Agreements, to use its best efforts to prepare and file a registration no later than 10 days after the effective date of the Purchase Agreements and to bear all expenses in connection with the offering, other than selling commissions, underwriting fees and stock transfer taxes applicable to the Shares and all fees and disbursements of counsel for any Selling Stockholder. Accordingly, in order to permit the Selling Stockholders to sell the Shares when each deems appropriate, the Company has filed with the Commission a Registration Statement on Form S-3, of which this Prospectus forms a part, with respect to the resale of the Shares from time to time as described herein and has agreed to prepare and file such amendments and supplements to the Registration Statement as may be necessary to keep the Registration Statement effective until all Shares offered hereby have been sold pursuant thereto or until such shares are no longer, by reason of Rule 144 or any other rule of similar effect, required to be registered for the sale thereof by the Selling Stockholders. Except as otherwise described in "Stock Ownership," prior to their acquisition of the Shares, none of the Selling Stockholders had a material relationship with the Company. In connection with the registration of the shares of Common Stock offered hereby, the Company will supply prospectuses to the Selling Stockholders. Stock Ownership The table below sets forth (i) the number of shares of Common Stock owned beneficially by the Selling Stockholders prior to the Offering; (ii) the number of shares of Common Stock being offered by the Selling Stockholders pursuant to this Prospectus; (iii) the number of shares of Common Stock to be owned beneficially by the Selling Stockholders after completion of the offering, assuming that all of the Shares offered hereby are sold; and (iv) the percentage of the outstanding shares of Common Stock to be owned beneficially by the Selling Stockholders after completion of the offering, assuming that all of the Shares offered hereby are sold. 13
Number of Percentage of Shares to be Outstanding Shares Number of Owned of Common Stock Shares Beneficially to be Owned Beneficially Number of After Beneficially After Owned Prior Shares Completion Completion Selling Stockholders to Offering Offered of Offering(1) of Offering(1) - -------------------- ----------- -------- -------------- ------------------ DCF Life Sciences Fund Ltd. 100,000 100,000 0 0 DCF Partners, L.P. 953,000 953,000 0 0 Oracle Partners, L.P. 315,789 315,789 0 0 Oracle Institutional Partners, L.P. 78,496 78,496 0 0 GSAM Oracle Fund, Inc. 168,721 168,721 0 0 Hausmann Holdings, N.V. 50,526 50,526 0 0 Oracle Offshore Ltd. 18,046 18,046 0 0 SBC Warburg Dillon Read, Inc. (2) 500,000 500,000 0 0 Caluceus Capital, L.P. 105,000 105,000 0 0 Caluceus Capital Ltd. 220,000 220,000 0 0 Marlin BioMed L.P. 21,053 21,053 0 0 Deutsche Vermogen Sbildungsgesell Shaft mbH 294,737 294,737 0 0 The Aries Trust 747,368 747,368 0 0 Aries Domestic Fund, L.P. 305,264 305,264 0 0 Wayne P. Rothbaum(3) 30,000 30,000 0 0 Mitchell D. Silber(3) 15,000 15,000 0 0 New Technologies Fund 60,000 60,000 0 0
14 (1) Based upon shares of Common Stock outstanding as of May 29, 1998. Assumes all Shares registered hereby are sold. Since the Selling Stockholders may sell all, some or none of their Shares, no actual determination can be made of the aggregate number of shares that each Selling Stockholder will own upon completion of the offering to which this Prospectus relates. (2) SBC Warburg Dillon Read Inc. acted as the placement agent in the private offering of the Shares to the Selling Stockholders and received a fee of $900,000 or approximately 4.75% of the aggregate purchase price and is entitled to reimbursement by the Company of travel, legal and other out-of-pocket expenses up to a maximum of $50,000. (3) Messrs. Rothbaum and Silber are principals with Evolution Capital, a registered broker-dealer which received a fee of $235,155 or approximately 1.25% of the aggregate purchase price in connection with the sale of the Shares to the Selling Stockholders. In February 1998, Evolution Capital was granted options to purchase 50,000 shares of the Company's Common Stock at an exercise price of $5.9375 per share pursuant to a one year advisory and consulting agreement which require Evolution Capital to provide institutional targeting, dossier reports, institutional surveillance and overall capital markets intelligence to the Company. In June 1996, The Carson Group Inc., an affiliate of Mr. Rothbaum, Mr. Silber and Evolution Capital, received $325,000 in cash and 50,000 five-year warrants to purchase Common Stock at an exercise price of $4.11 per share as a finder's fee in connection with the Company's private placement of Common Stock, preferred stock and warrants in January and March 1996. In addition, The Carson Group Inc. has received approximately $175,000 in consulting fees during the past two years for providing institutional targeting, dossier reports, institutional surveillance and overall capital markets intelligence to the Company. The Company has agreed to bear the expenses (other than broker discounts and commissions, if any, and expenses of counsel and other advisors to certain of the Selling Stockholders) incurred in connection with the registration of the Shares. PLAN OF DISTRIBUTION The Shares may be sold pursuant to this Prospectus by the Selling Stockholders. These sales may occur from time to time in one or more transactions (which may involve block transactions) in the open markets, in negotiated transactions, through the writing of options on the Shares (whether such options are listed on an options exchange or otherwise) or by a combination of such methods of sale, at fixed prices which may be changed, at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices. The Selling Stockholders may effect these transactions by selling the Shares to or through broker-dealers, who may receive compensation in the form of discounts or commissions from the Selling Stockholders or from the purchasers of the Shares for whom the broker-dealers may act as agent or to whom they may sell as principal, or both in amounts to be negotiated immediately prior to the sale. The Selling Stockholders may also pledge the Shares as collateral for margin accounts or loans and the Shares could be resold pursuant to the terms of such accounts or loans. There are currently no agreements, arrangements or understandings with respect to the sale of any of the Shares by the Selling Stockholders. The Shares are being registered to permit public secondary trading of the Shares, and the Selling Stockholders may offer the Shares for resale from time to time. In effecting sales, broker-dealers engaged by the Selling Stockholders may arrange for other broker-dealers to participate. Broker-dealers will receive commissions or discounts from the Selling Stockholders in amounts to be negotiated immediately prior to the sale. Neither the Company nor the Selling Stockholders can presently estimate the amount of commissions or discounts, if any, that will be paid by the Selling Stockholders on account of their sale of the Shares from time to time. In order to comply with the securities laws of certain states, if applicable, the Shares will be sold in such jurisdictions only through registered or licensed brokers or dealers. In addition, in certain states the Shares may not be sold unless they have been registered or qualified for sale in the applicable state or an exemption from the registration or qualification requirement is available and is complied with by the Company and the Selling Stockholders. 15 The Selling Stockholders and any broker-dealers who execute sales for the Selling Stockholders may be deemed to be "underwriters" within the meaning of the Securities Act by virtue of the number of shares of Common Stock to be sold or resold by such persons or entities or the manner of sale thereof, or both. If the Selling Stockholders, broker-dealers or other holders were determined to be underwriters, any discounts or commissions received by them or by brokers or dealers acting on their behalf and any profits received by them on the resale of their shares of Common Stock might be deemed underwriting compensation under the Securities Act. The Selling Stockholders have represented to the Company that any purchase or sale of the Common Stock by them will be in compliance with applicable rules and regulations of the Commission. In addition, any securities covered by this Prospectus which qualify for sale pursuant to Rule 144 under the Securities Act may be sold under Rule 144 rather than pursuant to this Prospectus. To the extent required, the specific shares of Common Stock to be sold, the name of any successor Selling Stockholders, the public offering price, the names of any such agent, dealer or underwriter, and any applicable commission or discount with respect to any particular offer will be set forth in an accompanying Prospectus Supplement. See "Selling Stockholders." Under applicable rules and regulations under the Exchange Act, any person engaged in the distribution of the Shares may not simultaneously engage in market making activities with respect to the Common Stock of the Company for a restricted period prior to the commencement of such distribution. In addition and without limiting the foregoing, the Selling Stockholders and any other person participating in a distribution will be subject to applicable provisions of the Exchange Act and the rules and regulations thereunder, including, without limitation, Regulation M, which provisions may limit the timing of purchases and sales of shares of the Company's Common Stock by the Selling Stockholders. The Company has agreed to indemnify the Selling Stockholders against certain liabilities, including liabilities under the Securities Act. The Selling Stockholders have agreed to indemnify the Company against certain liabilities, including liabilities under the Securities Act. There can be no assurance that the Selling Stockholders will sell all or any of the Shares offered hereby. LEGAL MATTERS The legality of the shares of Common Stock offered hereby has been passed on for the Company by Dorsey & Whitney LLP, New York, New York. EXPERTS The consolidated financial statements of Enzon, Inc. and subsidiaries as of June 30, 1997 and 1996 and for each of the years in the three-year period ended June 30, 1997, have been incorporated by reference herein and in the Registration Statement in reliance upon the report of KPMG Peat Marwick LLP, independent certified public accountants, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing. 16 PART II INFORMATION NOT REQUIRED IN PROSPECTUS Item 14. Other Expenses of Issuance and Distribution The following table sets forth an itemized estimate of fees and expenses (other than the Securities and Exchange Commission registration fee and Nasdaq filing fee) payable by the Registrant in connection with the issuance and distribution of the securities described in this registration statement, other than underwriting discounts and commissions. SEC registration fee ........................................ $ 6,500 Nasdaq filing fee ........................................... $ 17,500 Legal fees and expenses ..................................... $ 90,000 Accounting fees and expenses ................................ $ 10,000 Placement agent expense reimbursement ....................... $ 50,000 Miscellaneous ............................................... $ 10,000 Total .................................................. $184,000 ======== Item 15. Indemnification of Directors and Officers The General Corporation Law of the State of Delaware (the "DGCL") provides for indemnification as set forth in Section 145 thereof. The Registrant's By-laws, as amended provide for indemnification of the directors and officers of the Registrant against all costs, expenses and amounts of liability incurred by them in connection with any action, suit or proceeding in which they are involved by reason of their affiliation with the Registrant, to the fullest extent permitted by law. The Registrant's directors and officers also have indemnification agreements with the Registrant, which expand the indemnification protection provided to them under the Registrant's By-laws. The Company's Certificate of Incorporation provides that a director of the Company will not be personally liable for monetary damages to the Company or its stockholders for breach of fiduciary duty as a director, except for liability, (i) for any breach of the director's duty of loyalty to such corporation or its stockholders, (ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) for unlawful payments of dividends or unlawful stock repurchase or redemption as provided in Section 174 of the DGCL or (iv) for any transaction from which the director derived an improper personal benefit. Item 16. Exhibits -------- Page Number Exhibit or Incorporation Number Description By Reference - ------ ----------- ------------ 1.1 Form of Common Stock Purchase Agreement with Selling Stockholders E-1 4.1 Certificate of Incorporation, as amended * 4.2 Certificate of Amendment of Certificate of Incorporation filed with the Delaware Secretary of State on January 5, 1998 E-45 II-1 4.3 By-laws, as amended ** 5.1 Opinion of Dorsey & Whitney LLP regarding legality E-47 23.1 Consent of Dorsey & Whitney LLP (contained in opinion filed as Exhibit 5.1) 23.2 Consent of KPMG Peat Marwick LLP E-49 24.0 Power of Attorney (included on page II-4) * Previously filed as an exhibit to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 1996 and incorporated herein by reference thereto. ** Previously filed as an exhibit to the Company's Registration Statement on Form S-2 (File No. 33-34874) and incorporated herein by reference thereto. II-2 Item 17. Undertakings The undersigned Registrant hereby undertakes: (1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement: (i) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933; (ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in the volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective registration statement. (iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement: Provided, however, that paragraphs (1)(i) and (1)(ii) do not apply if the registration statement is on Form S-3, Form S-8 or Form F-3, and the information required to be included in a post-effective amendment by those paragraphs is contained in the periodic reports filed by the Registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement. (2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. (3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering. (4) That, for purposes of determining any liability under the Securities Act of 1933, each filing of the Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and where applicable, each filing of an employee benefit plan's annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in this Registration Statement shall be deemed to be a new Registration Statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. (5) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions or otherwise, the Registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director, officer or controlling person of the II-3 Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue. II-4 SIGNATURES Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized in the City of Piscataway, State of New Jersey, on June 30, 1998. ENZON, INC. By: /s/ Peter G. Tombros ---------------------- Peter G. Tombros, President and Chief Executive Officer POWER OF ATTORNEY Each person whose signature appears below hereby constitutes and appoints Peter G. Tombros and Kenneth J. Zuerblis, and each of them, severally, the true and lawful attorney-in-fact or attorneys-in fact, and agent or agents of the undersigned, with or without the other and with full power of substitution and resubstitution, for and in the name, place and stead of the undersigned, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, and hereby grants to such attorney-in-fact or attorneys-in-fact and agent or agents full power and authority to do and perform each and every act and thing requisite and necessary to be done in furtherance of the foregoing, as fully to all intents and purposes as the undersigned might or could do in person, hereby ratifying and confirming all that said attorney-in-fact or attorneys-in-fact and agent or agents, or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated. Signature Capacity Date /s/Peter G. Tombros President, Chief June 30, 1998 - ---------------------- Executive Officer and Director Peter G. Tombros (Principal Executive Officer) /s/ Randy H. Thurman Chairman of the Board June 30, 1998 - ---------------------- Randy H. Thurman II-5 /s/ Kenneth J. Zuerblis Vice President - Finance and June 30, 1998 - ------------------------- Chief Financial Officer Kenneth J. Zuerblis (Principal Financial Officer and Principal Accounting Officer) /s/ Rosina B. Dixon Director June 26, 1998 - ------------------------- Rosina B. Dixon /s/ Robert LeBuhn Director June 30, 1998 - ------------------------- Robert LeBuhn /s/ A.M. "Don" MacKinnon Director June 30, 1998 - ------------------------- A.M. "Don" MacKinnon /s/ Rolf A. Classon Director June 30, 1998 - ------------------------- Rolf A. Classon /s/ David Golde Director June 29, 1998 - ------------------------- David Golde II-6 ENZON, INC. EXHIBIT INDEX Exhibit No. Description 1.1 Form of Common Stock Purchase Agreement with Selling Stockholders 4.2 Certificate of Amendment of Certificate of Incorporation 5.1 Opinion of Dorsey & Whitney LLP regarding legality 23.1 Consent of Dorsey & Whitney LLP (contained in opinion filed as Exhibit 5.1) 23.2 Consent of KPMG Peat Marwick LLP II-7 ============================== SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 ___________________ EXHIBITS TO FORM S-3 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ___________________ ENZON, INC. (Exact name of Registrant as specified in its charter) ==============================


                         -------------------------------
                                   ENZON, INC.

                         COMMON STOCK PURCHASE AGREEMENT

                                  June 25, 1998
                          -------------------------------










                                TABLE OF CONTENTS

                                                                            Page
                                                                            ----
Section 1

           Authorization and Sale of Common Stock .........................    1
  1.1  Authorization ......................................................    1
  1.2  Sale of Common .....................................................    1

Section 2

           Closing Date: Delivery .........................................    1
  2.1  Closing Date .......................................................    1
  2.2  Delivery ...........................................................    1

Section 3

           Representations and Warranties of the Company ..................    2
  3.1  Organization and Standing ..........................................    2
  3.2  Corporate Power, Authorization .....................................    2
  3.3  Issuance and Delivery of the Shares ................................    2
  3.4  Private Placement Offering Memorandum: SEC Documents, Financial
       Statements .........................................................    2
  3.5  Governmental Consents ..............................................    3
  3.6  No Material Adverse Change .........................................    3
  3.7  Intellectual Property ..............................................    3
  3.8  Authorized Capital Stock ...........................................    4
  3.9  Litigation .........................................................    4
  3.10 Use of Proceeds ....................................................    4
  3.11 Accountants ........................................................    4
  3.12 Compliance With Other Instruments ..................................    5
  3.13 Permits ............................................................    5
  3.14 Investment Company .................................................    5
  3.15 Offering Materials .................................................    5

Section 4

           Representations, Warranties and Covenants of the Purchasers ....    5
  4.1  Power; Authorization ...............................................    5
  4.2  Investment Experience ..............................................    6
  4.3  Investment Intent ..................................................    6
  4.4  Registration or Exemption Requirements .............................    6



                                      E-1



                                TABLE OF CONTENTS
                                   (continued)


Section 5

           Conditions to Closing of Purchasers ............................    6
  5.1  Representations and Warranties .....................................    7
  5.2  Covenants ..........................................................    7
  5.3  Blue Sky ...........................................................    7
  5.4  Legal Opinion ......................................................    7
  5.5  Patent Opinion .....................................................    7
  5.6  Registration Statement .............................................    7
  5.7  Nasdaq Qualification ...............................................    7

Section 6

           Conditions to Closing of Company ...............................    7
  6.1  Representations and Warranties .....................................    8
  6.2  Covenants ..........................................................    8
  6.3  Blue Sky ...........................................................    8
  6.4  Registration Statement .............................................    8
  6.5  Nasdaq Qualification ...............................................    8

Section 7

           Affirmative Covenants of the Company ...........................    8
  7.1  Financial Information ..............................................    8
  7.2  Registration Requirements ..........................................    8
  7.3  Indemnification and Contribution ...................................   10

Section 8

           Restrictions on Transferability of Shares:
           Compliance with Securities Act .................................   12
  8.1  Restrictions on Transferability ....................................   13
  8.2  Restrictive Legend .................................................   13
  8.3  Transfer of Shares After Registration ..............................   13
  8.4  Purchaser Information ..............................................   13

Section 9

           Miscellaneous ..................................................   14
  9.1  Waivers and Amendments .............................................   14


                                      E-2



                                TABLE OF CONTENTS
                                   (continued)


  9.2  Placement Agent Fee ................................................  14
  9.3  Governing Law ......................................................  14
  9.4  Survival ...........................................................  14
  9.5  Successors and Assigns .............................................  14
  9.6  Entire Agreement ...................................................  14
  9.7  Notices, etc .......................................................  14
  9.8  Severability of this Agreement .....................................  15
  9.9  Counterparts .......................................................  15
  9.10 Further Assurances .................................................  15
  9.11 Termination ........................................................  15
  9.12 Expenses ...........................................................  15
  9.13 Currency ...........................................................  15
                                                                      
Exhibit A - Schedule of Purchasers
Exhibit B - Form of Purchaser's Questionnaire
Exhibit C - Opinion of Company  Counsel 
Exhibit D - Opinions of Patent  Counsel
Exhibit E - Form of Purchaser's Legend Removal Certificate
Exhibit F - Form of Purchaser's Certificate of Subsequent Sale
Exhibit G - Description of Capital Stock









                                      E-3


                                   ENZON, INC.


                         COMMON STOCK PURCHASE AGREEMENT

     This Common Stock Purchase  Agreement (the  "Agreement") is made as of June
25, 1998, by and among Enzon, Inc., a Delaware corporation (the "Company"), with
its principal office at 20 Kingsbridge  Road,  Piscataway,  New Jersey,  and the
persons  listed on the Schedule of Investors  attached  hereto as Exhibit A (the
"Purchasers").

                                    Section 1

                     Authorization and Sale of Common Stock

     1.1  Authorization.  The Company has  authorized  the sale and  issuance of
3,985,000  shares of its Common  Stock,  $0.01 par value per share (the  "Common
Stock") pursuant to this Agreement (the "Shares").

     1.2 Sale of Common.  Subject to the terms and conditions of this Agreement,
the  Company  agrees  to issue  and sell to each  Purchaser  and each  Purchaser
severally  agrees to  purchase  from the  Company the number of Shares set forth
opposite such Purchaser's name on Exhibit A for $4.75 per share.

                                    Section 2

                             Closing Date: Delivery

     2.1  Closing  Date.  The  closing  of the  purchase  and sale of the Shares
hereunder (the "Closing")  shall be held at the offices of Dorsey & Whitney LLP,
250 Park Avenue,  New York, NY 10177,  at or before 10:00 a.m. New York Time, on
that date that is two  business  days  after the date on which the  Registration
Statement  (as defined  herein) is declared  effective or at such time and place
upon which the Company and SBC Warburg Dillon Read Inc. (the "Placement  Agent")
shall agree. The date of the Closing is hereinafter  referred to as the "Closing
Date."

     2.2 Delivery.  At the Closing, the Company will deliver to each Purchaser a
certificate,  registered  in  the  Purchaser's  name  as  shown  on  Exhibit  A,
representing  the  number of  Shares  to be  purchased  by the  Purchaser.  Such
delivery  shall be  against  payment  of the  purchase  price  therefor  by wire
transfer to the Company's bank account in the amount set forth on Exhibit A.





                                      E-4




                                    Section 3

                  Representations and Warranties of the Company

     The Company  represents  and warrants to the  Purchasers  as of the Closing
Date as follows:

     3.1 Organization and Standing.  The Company is a corporation duly organized
and validly  existing under, and by virtue of, the laws of the State of Delaware
and is in good standing as a domestic  corporation  under the laws of said state
and has all requisite  corporate  power and authority to conduct its business as
currently conducted and disclosed in the Offering Memorandum (as defined below).

     3.2 Corporate Power, Authorization. The Company has all requisite legal and
corporate  power and has taken all  requisite  corporate  action to execute  and
deliver  this  Agreement,  to sell and  issue  the  Shares  and to carry out and
perform all of its obligations under this Agreement.  This Agreement constitutes
the  legal,  valid  and  binding  obligation  of  the  Company,  enforceable  in
accordance  with its terms,  except (i) as  limited  by  applicable  bankruptcy,
insolvency,  reorganization  or  similar  laws  relating  to  or  affecting  the
enforcement  of  creditors'  rights  generally  and (ii) as limited by equitable
principles generally. The execution and delivery of this Agreement does not, and
the performance of this Agreement and the compliance with the provisions  hereof
and the  issuance,  sale and  delivery  of the Shares by the  Company  will not,
conflict  with or result in a breach or  violation of the terms,  conditions  or
provisions  of, or  constitute  a default  under,  or result in the  creation or
imposition  of  any  lien  pursuant  to  the  terms  of,  the   Certificate   of
Incorporation  or Bylaws of the Company or any statute,  law, rule or regulation
or any state or federal order,  judgment or decree or any  indenture,  mortgage,
lease or other  agreement  or  instrument  to which  the  Company  or any of its
properties is subject.

     3.3  Issuance  and  Delivery  of the  Shares.  The  Shares,  when issued in
compliance with the provisions of this Agreement,  will be validly issued, fully
paid and  nonassessable.  The issuance and delivery of the Shares is not subject
to preemptive or any other similar rights of the  stockholders of the Company or
any liens or encumbrances.

     3.4  Private  Placement  Offering  Memorandum:  SEC  Documents,   Financial
Statements.  Each  complete or partial  statement,  report,  or proxy  statement
included within the Company's Private Placement  Offering  Memorandum dated June
4, 1998 (the  "Offering  Memorandum")  is a true and complete copy of or excerpt
from such  document as filed by the Company  with the  Securities  and  Exchange
Commission  (the "SEC").  The Company has filed in a timely manner all documents
that the Company was required to file with the SEC under  Sections 13, 14(a) and
15(d) of the Securities  Exchange Act of 1934, as amended (the "Exchange  Act"),
during the twelve (12) months preceding the date of this Agreement.  As of their
respective  filing dates,  all documents  filed by the Company with the SEC (the
"SEC Documents")  complied in all material respects with the requirements of the
Exchange Act or the



                                      E-5




Securities  Act of 1933,  as amended  (the  "Securities  Act"),  as  applicable.
Neither  the  Offering  Memorandum  nor any of the  SEC  Documents  as of  their
respective  dates contained any untrue  statement of material fact or omitted to
state a material  fact  required to be stated  therein or  necessary to make the
statements  made therein,  in light of the  circumstances  under which they were
made,  not  misleading.  As of their  respective  filing  dates,  the  financial
statements  of  the  Company  included  in the  SEC  Documents  (the  "Financial
Statements")  complied  as to  form in all  material  respects  with  applicable
accounting  requirements and with the published rules and regulations of the SEC
with respect thereto.  The Financial Statements have been prepared in accordance
with generally accepted accounting  principles  consistently  applied and fairly
present the consolidated  financial position of the Company and any subsidiaries
at the dates  thereof  and the  consolidated  results  of their  operations  and
consolidated cash flows for the periods then ended; provided,  however, that the
unaudited  Financial   Statements  are  subject  to  normal  recurring  year-end
adjustments  (which in any case will not be  material)  and do not  contain  all
footnotes required under generally accepted accounting principles.

     3.5 Governmental Consents. No consent, approval, order or authorization of,
or  registration,  qualification,  designation,  declaration or filing with, any
federal,  state, or local  governmental  authority on the part of the Company is
required in connection with the consummation of the transactions contemplated by
this Agreement  except for (a) compliance  with the securities and blue sky laws
in the states in which  Shares are offered  and/or  sold,  (b) the filing of the
Registration  Statement and all amendments  thereto with the SEC as contemplated
by Section 7.2 of this  Agreement  and (c) all required  filings with The Nasdaq
Stock Market necessary for the listing of the Shares.

     3.6 No  Material  Adverse  Change.  Except as  otherwise  disclosed  in the
Offering  Memorandum,  since March 31, 1998,  there have not been any changes in
the assets,  liabilities,  financial condition or operations of the Company from
those  reflected in the  Financial  Statements,  except  changes in the ordinary
course of business which have not been, either individually or in the aggregate,
materially adverse.

     3.7 Intellectual Property.  Except as disclosed in the Offering Memorandum,
the Company owns or  possesses  sufficient  rights to use all existing  patents,
patent rights,  inventions,  trade  secrets,  know-how,  proprietary  rights and
processes  that are  necessary  for the  conduct  and  proposed  conduct  of its
business as described in the Offering  Memorandum  (the  "Company's  Proprietary
Rights") without any conflict with or infringement of the rights of others which
would  result in a  material  adverse  effect  on the  condition  (financial  or
otherwise), earnings, operations, business or business prospects of the Company.
The Company believes that there are no third parties who have or will be able to
establish rights to any of the Company's  Proprietary Rights, except for (i) the
ownership  rights of the third  party  licensors  to the  Company's  Proprietary
Rights which are licensed to the Company by such third party  licensors and (ii)
the  third  party  licensees  of the  Company's  Proprietary  Rights.  Except as
disclosed in the Offering Memorandum,  to the knowledge of the Company, there is
no infringement by any third parties of any of the Company's Proprietary Rights.
Except as disclosed in the Offering Memorandum, the Company has not received any
notice of, and has



                                      E-6




no knowledge of any basis for, any  infringement  of or conflict  with  asserted
rights of others with  respect to any patent,  patent  right,  invention,  trade
secret,  know-how  or other  proprietary  rights  that,  individually  or in the
aggregate,  would have a material adverse effect on the condition  (financial or
otherwise), earnings, operations, business or business prospects of the Company.

     3.8 Authorized  Capital Stock.  All outstanding  shares of capital stock of
the Company have been duly  authorized and validly issued and are fully paid and
nonassessable,  have  been  issued  in  compliance  with all  federal  and state
securities  laws,  were not issued in violation of or subject to any  preemptive
rights  or  other  rights  to  subscribe  for or  purchase  securities,  and the
authorized  and  outstanding  capital stock of the Company  conforms,  as of the
dates for which such  information  is given,  in all  material  respects  to the
statements  relating thereto contained in Exhibit G hereto;  there is no capital
stock  outstanding as of such dates other than as described in Exhibit G hereto;
and all issued and outstanding  shares of capital stock of the Company have been
duly authorized and validly issued and are fully paid and nonassessable.  Except
as disclosed in or  contemplated  by the Offering  Memorandum  and the Financial
Statements and the related notes thereto included in the Offering  Memorandum or
in  Exhibit G hereto,  the  Company  does not have  outstanding  any  options to
purchase,  or any  preemptive  rights  or other  rights to  subscribe  for or to
purchase,  any securities or obligations  convertible  into, or any contracts or
commitments  to issue or sell,  shares of its capital stock or any such options,
rights, convertible securities or obligations.  Except as described in Exhibit G
hereto, no stockholder of the Company, other than the Purchasers,  has any right
(which  has not  been  waived  or has not  expired  by  reason  of lapse of time
following  notification  of  the  Company's  intent  to  file  the  Registration
Statement)  to require the Company to register  the sale of any shares  owned by
such stockholder under the Securities Act in the Registration Statement.

     3.9 Litigation.  Except as set forth in the Offering Memorandum,  there are
no actions, suits,  proceedings or investigations pending or, to the best of the
Company's  knowledge,  threatened  against the Company or any of its  properties
before  or by any  court or  arbitrator  or any  governmental  body,  agency  or
official in which there is the possibility of an adverse decision that (a) would
reasonably  be  expected  to have a  material  adverse  effect on the  Company's
properties  or assets or the business of the Company as  presently  conducted or
proposed  to be  conducted  or (b) would  reasonably  be  expected to impair the
ability of the Company to perform its obligations under this Agreement.

     3.10 Use of Proceeds. The Company will apply the net proceeds from the sale
of the Shares in the manner set forth under the caption "Use of Proceeds" in the
Offering Memorandum.

     3.11  Accountants.  KPMG Peat Marwick LLP, who have expressed their opinion
with respect to the audited financial  statements and schedules to be filed with
the SEC as a part of the Registration Statement and included in the Registration
Statement  and the  Prospectus  which  forms  a part  thereof,  are  independent
accountants  as required  by the  Securities  Act and the rules and  regulations
promulgated thereunder (the "Rules and Regulations").




                                      E-7




     3.12 Compliance With Other Instruments.  Except as to defaults,  violations
and breaches which individually or in the aggregate would not be material to the
Company,  the Company is not in  violation  or default of any  provision  of its
Articles  of  Incorporation  or  Bylaws,  each as  amended  to  date,  or of any
agreement, license, permit, instrument, judgment, order, writ or decree to which
it is a party or by which it is bound, or, to the best of its knowledge,  of any
provision of any federal or state statute,  rule or regulation applicable to the
Company.

     3.13 Permits. The Company has all franchises,  permits,  licenses,  and any
similar  authority  necessary  for the  conduct  of its  business  as now  being
conducted by it, the lack of which could  materially  and  adversely  affect the
business,  properties,  prospects,  or financial  condition of the Company.  The
Company is not in default in any material  respect under any of such franchises,
permits, licenses, or other similar authority.

     3.14 Investment Company.  The Company is not an "investment company" within
the meaning of the Investment Company Act of 1940, as amended.

     3.15  Offering  Materials.  The  Company has not  distributed  and will not
distribute  prior to the Closing Date any offering  material in connection  with
the offering and sale of the Shares other than the Offering Memorandum.

                                    Section 4

           Representations, Warranties and Covenants of the Purchasers

     Each  Purchaser  hereby  severally  represents and warrants to the Company,
effective as of the Closing Date, as follows:

     4.1 Power;  Authorization.  (i) Such Purchaser has all requisite  legal and
corporate or other power and capacity and has taken all  requisite  corporate or
other action to execute and deliver this Agreement, to purchase the Shares to be
purchased by it and to carry out and perform all of its  obligations  under this
Agreement;  and (ii) this  Agreement  constitutes  the legal,  valid and binding
obligation of such Purchaser,  enforceable in accordance with its terms,  except
(a) as limited by applicable bankruptcy, insolvency,  reorganization, or similar
laws relating to or affecting the enforcement of creditors' rights generally and
(b) as limited by equitable principles generally.

     4.2 Investment  Experience.  Such Purchaser is an "accredited  investor" as
defined in Rule 501(a) under the Securities Act. Such Purchaser has received and
reviewed the Offering Memorandum, is aware of the Company's business affairs and
financial   condition  and  has  had  access  to  and  has  acquired  sufficient
information about the Company to reach an informed and knowledgeable decision to
acquire the Shares.  Purchaser has such business and financial  experience as is
required  to permit it to  protect  its own  interests  in  connection  with the
purchase of the Shares.



                                      E-8





     4.3  Investment  Intent.  Such  Purchaser is  purchasing  the Shares in the
ordinary course of its business for its own account as principal, for investment
purposes only,  and not with a present view to, or for, the resale  distribution
thereof,  in whole or in part,  within the meaning of the  Securities Act or any
state securities laws. Purchaser  understands that its acquisition of the Shares
has not been  registered  under the  Securities  Act or  registered or qualified
under  any  state  law in  reliance  on  specific  exemptions  therefrom,  which
exemptions  may depend upon,  among other  things,  the bona fide nature of such
Purchaser's  investment intent as expressed herein. Such Purchaser has completed
or caused to be completed the Purchaser Questionnaire attached hereto as Exhibit
B for use in preparation of the Registration  Statement (as defined below),  and
the  responses  provided  therein  shall be true and correct as of the effective
date of the Registration Statement and as of the Closing Date. Purchaser has, in
connection  with its  decision  to  purchase  the  number of Shares set forth in
Exhibit A hereto,  relied solely upon the Offering  Memorandum and the documents
attached as appendices  thereto and the  representations  and  warranties of the
Company  contained  herein.  Such  Purchaser  will not,  directly or indirectly,
offer, sell, pledge,  transfer or otherwise dispose of (or solicit any offers to
buy, purchase or otherwise acquire or take a pledge of) any of the Shares except
in compliance with the Securities Act, and the rules and regulations promulgated
thereunder and applicable state securities laws.

     4.4  Registration  or  Exemption   Requirements.   Such  Purchaser  further
acknowledges,  understands  and  agrees  that the  Shares  may not be  resold or
otherwise  transferred  except in a transaction  registered under the Securities
Act or unless an exemption from such  registration is available.  Such Purchaser
understands that the certificate(s) evidencing the Shares will be imprinted with
a  legend  that  prohibits  the  transfer  of the  Shares  unless  (i)  they are
registered or such  registration  is not  required,  and (ii) if the transfer is
pursuant  to an  exemption  from  registration  other  than  Rule 144  under the
Securities  Act and, if the Company  shall so request in writing,  an opinion of
counsel  reasonably  satisfactory  to the Company is obtained to the effect that
the transaction is so exempt.

                                    Section 5

                       Conditions to Closing of Purchasers

     Each  Purchaser's  obligation  to purchase the Shares at the Closing is, at
the option of such  Purchaser,  subject to the  fulfillment  or waiver as of the
Closing Date of the following conditions:

     5.1 Representations and Warranties. The representations and warranties made
by the  Company in Section 3 hereof  shall be true and  correct in all  material
respects  when made,  and shall be true and correct in all material  respects on
the Closing  Date with the same force and effect as if they had been made on and
as of said date.




                                      E-9




     5.2 Covenants.  All covenants,  agreements and conditions contained in this
Agreement  to be  performed by the Company on or prior to the Closing Date shall
have been performed or complied with in all respects.

     5.3 Blue Sky. The Company shall have  obtained all  necessary  blue sky law
permits and  qualifications,  or secured exemptions  therefrom,  required by any
state or foreign or other jurisdiction for the offer and sale of the Shares.

     5.4 Legal Opinion.  The  Purchasers  shall have received a legal opinion of
Dorsey & Whitney LLP,  counsel to the  Company,  with respect to the matters set
forth on Exhibit C.

     5.5 Patent  Opinion.  The Purchasers  shall have received legal opinions of
patent  counsel to the Company  with respect to the matters set forth on Exhibit
D.

     5.6 Registration  Statement.  The Registration Statement (as defined below)
registering  the  resale of the Shares by the  Purchasers  shall have been filed
with  and  declared  effective  by the SEC,  and no stop  order  suspending  the
effectiveness thereof and no proceedings therefor shall be pending or threatened
by the SEC.

     5.7 Nasdaq  Qualification.  The Shares shall be duly authorized for listing
by the Nasdaq Stock Market.

                                    Section 6

                        Conditions to Closing of Company

     The Company's obligation to sell and issue the Shares at the Closing is, at
the option of the Company, subject to the fulfillment or waiver of the following
conditions:

     6.1  Representations  and  Warranties.  The  representations  made  by  the
Purchasers  in  Section  4  hereof  shall be true and  correct  in all  material
respects  when made,  and shall be true and correct in all material  respects on
the Closing  Date with the same force and effect as if they had been made on and
as of such date.

     6.2 Covenants.  All covenants,  agreements and conditions contained in this
Agreement  to be  performed  by the  Purchasers  on or prior to the Closing Date
shall have been performed or complied with in all material respects.

     6.3 Blue Sky. The Company shall have  obtained all  necessary  blue sky law
permits and  qualifications,  or secured exemptions  therefrom,  required by any
state for the offer and sale of the Shares.




                                      E-10




     6.4 Registration  Statement.  The Registration Statement (as defined below)
registering  the  resale of the Shares by the  Purchasers  shall have been filed
with  and  declared  effective  by the SEC,  and no stop  order  suspending  the
effectiveness thereof and no proceedings therefor shall be pending or threatened
by the SEC.

     6.5 Nasdaq  Qualification.  The Shares shall be duly authorized for listing
by the Nasdaq Stock Market.

                                    Section 7

                      Affirmative Covenants of the Company

     The Company hereby covenants and agrees as follows:

     7.1 Financial  Information.  The Company will mail the following reports to
each  Purchaser  until  such  Purchaser  transfers,  assigns or sells the Shares
purchased by such Purchaser pursuant to this Agreement:

          (a) Within one hundred (100) days after the end of each fiscal year, a
     copy of its Annual Report on Form 10-K.

          (b) Within fifty-five (55) days after the end of the first, second and
     third quarterly  accounting  periods of each fiscal year of the Company,  a
     copy of its Quarterly Report on Form 10-Q.

          (c) Within ten (10) days after the Company files any Current Report on
     Form 8-K with the SEC, such Current Report on Form 8-K

     7.2 Registration Requirements.

          (a) The  Company  shall use its best  efforts  to  prepare  and file a
     registration  statement  with the SEC under the  Securities Act to register
     the resale of the Shares by the Purchasers (the  "Registration  Statement")
     no later than ten (10) days after the date hereof.

          (b) The Company shall pay all Registration Expenses (as defined below)
     in connection with any registration, qualification or compliance hereunder,
     and each  Purchaser  shall pay all Selling  Expenses (as defined below) and
     other expenses that are not  Registration  Expenses  relating to the Shares
     resold by such  Purchaser.  Registration  Expenses shall mean all expenses,
     except for Selling Expenses,  incurred by the Company in complying with the
     registration  provisions herein described,  including,  without limitation,
     all registration,  qualification and filing fees, printing expenses, escrow
     fees, fees and disbursements of counsel for the Company,  blue sky fees and
     expenses,  and the expense of any special audits incident to or required by
     any such registration. Selling Expenses shall mean all selling commissions,



                                      E-11




     underwriting fees and stock transfer taxes applicable to the Shares and all
     fees and disbursements of counsel for any Purchaser.

          (c) In the case of the  registration  effected by the Company pursuant
     to these registration provisions,  the Company will use its reasonable best
     efforts to: (i) cause the Registration Statement to become effective within
     sixty (60) days of the date hereof,  (ii) keep such registration  effective
     until the earlier of (a) the second  anniversary  of the Closing Date,  (b)
     such date as all of the Shares have been resold by the original  Purchasers
     thereof,  or (c) such time as all of the Shares held by the  Purchasers can
     be sold  within a given  three-month  period  without  compliance  with the
     registration  requirements of the Securities Act pursuant to Rule 144 under
     the Securities Act; (iii) prepare and file with the SEC such amendments and
     supplements  to the  Registration  Statement  and  the  prospectus  used in
     connection  with the  Registration  Statement as may be necessary to comply
     with the provisions of the  Securities Act with respect to the  disposition
     of all securities covered by the Registration Statement;  (iv) furnish such
     number of prospectuses and other documents incident thereto,  including any
     amendment of or supplement to the  prospectus,  as a Purchaser from time to
     time may reasonably  request;  (v) cause all Shares registered as described
     herein  to be  listed  on  each  securities  exchange  and  quoted  on each
     quotation  service on which  similar  securities  issued by the Company are
     then listed or quoted;  (vi) provide a transfer agent and registrar for all
     Shares registered pursuant to the Registration Statement and a CUSIP number
     for all such Shares;  (vii)  otherwise  use its best efforts to comply with
     all  applicable  rules and  regulations  of the SEC;  and  (viii)  file the
     documents  required of the Company and  otherwise  use its best  efforts to
     maintain requisite blue sky clearance in (A) all jurisdictions in which any
     of the  Shares  are  originally  sold and (B) all other  states  reasonably
     specified  in writing by a Purchaser,  provided as to clause (B),  however,
     that in no event shall the Company be required to qualify to do business or
     consent  to  service  of  process  in any  state  in which it is not now so
     qualified or has not so consented.

          (d) The  Company  shall  furnish  to each  Purchaser  upon  request  a
     reasonable  number of copies of a  supplement  to or an  amendment  of such
     prospectus  as may be necessary in order to  facilitate  the public sale or
     other disposition of all or any of the Shares held by such Purchaser.

          (e) With a view to making  available to the Purchasers the benefits of
     Rule 144  promulgated  under the  Securities Act ("Rule 144") and any other
     rule or  regulation  of the SEC that may at any time permit a Purchaser  to
     sell  Shares  to  the  public  without   registration   or  pursuant  to  a
     registration on Form S-3, the Company covenants and agrees to: (i) make and
     keep  public  information  available,  as those  terms are  understood  and
     defined in Rule 144 under the Securities  Act, until the earlier of (A) the
     second  anniversary  of the  Closing  Date or (B)  such  date as all of the
     Shares shall have been resold by the original Purchasers thereof; (ii) file
     with the SEC in a timely manner all reports and other documents required of
     the  Company  under the  Securities  Act and the  Exchange  Act;  and (iii)
     furnish to any Purchaser  upon request,  as long as the Purchaser  owns any
     Shares,  (A) a written  statement by the Company that it has complied  with
     the reporting  requirements of the Securities Act and the Exchange Act, (B)
     a copy of the most recent annual or quarterly report of the Company, and



                                      E-12




     (C) such other information as may be reasonably requested in order to avail
     any Purchaser of any rule or regulation of the SEC that permits the selling
     of any such Shares without registration or pursuant to such Form S-3.

          (f) At any time the Company may refuse to permit a Purchaser to resell
     any Shares pursuant to the Registration Statement;  provided, however, that
     in order to exercise this right,  the Company must deliver a certificate in
     writing to the  Purchasers  and the  Placement  Agent to the effect  that a
     cessation  of  the  ability  to  sell  under,  or  a  withdrawal  of,  such
     Registration  Statement  is  necessary  because  a  sale  pursuant  to  the
     Registration   Statement  in  its  then-current  form  would  constitute  a
     violation of the federal  securities  laws.  In such an event,  the Company
     shall use its best efforts to promptly amend the Registration  Statement if
     necessary and take all other actions necessary to allow such sale under the
     federal  securities laws, and shall notify the Purchasers and the Placement
     Agent  promptly  after  it  has  determined   that  such  sale  has  become
     permissible  under  the  federal  securities  laws.   Notwithstanding   the
     foregoing,  the Company  shall not under any  circumstances  be entitled to
     exercise its right to withdraw the registration statement more then one (1)
     time in any twelve  (12) month  period,  and the period  during  which such
     Registration  Statement may be withdrawn  shall not exceed sixty (60) days.
     Each Purchaser hereby covenants and agrees that it will not sell any Shares
     pursuant to the Registration  Statement during the periods the Registration
     Statement is withdrawn  or the ability to sell  thereunder  is suspended as
     set forth in this Section 7.2(f).

     7.3 Indemnification and Contribution.

          (a) The Company  agrees to indemnify and hold harmless each  Purchaser
     from and against any losses,  claims, damages or liabilities (or actions or
     proceedings in respect  thereof) to which such Purchaser may become subject
     (under the  Securities  Act or otherwise)  insofar as such losses,  claims,
     damages or liabilities (or actions or proceedings in respect thereof) arise
     out of or are based upon, any untrue statement of a material fact contained
     in the Registration  Statement, on the effective date thereof, or arise out
     of any failure by the Company to fulfill  any  undertaking  included in the
     Registration Statement,  and the Company will, as incurred,  reimburse such
     Purchaser  for  any  legal  or  other  expenses   reasonably   incurred  in
     investigating, defending or preparing to defend any such action, proceeding
     or claim;  provided,  however,  that the Company shall not be liable in any
     such case to the extent that such loss,  claim,  damage or liability arises
     out of or is based upon (i) an untrue  statement made in such  Registration
     Statement  in reliance  upon and in  conformity  with  written  information
     furnished to the Company by or on behalf of such Purchaser specifically for
     use in preparation of the Registration Statement,  (ii) the failure of such
     Purchaser to comply with the covenants and agreements  contained in Section
     8.3  hereof,  or (iii)  any  untrue  statement  in any  Prospectus  that is
     corrected in any subsequent  Prospectus that was delivered to the Purchaser
     prior to the pertinent sale or sales by the Purchaser.

          (b) Each Purchaser, severally and not jointly, agrees to indemnify and
     hold harmless the Company from and against any losses,  claims,  damages or
     liabilities  (or actions or  proceedings  in respect  thereof) to which the
     Company may become subject (under the


                                      E-13



     Securities  Act or otherwise)  insofar as such losses,  claims,  damages or
     liabilities (or actions or proceedings in respect  thereof) arise out of or
     are based upon (i) an untrue statement made in such Registration  Statement
     in reliance upon and in conformity  with written  information  furnished to
     the  Company  by or on behalf  of such  Purchaser  specifically  for use in
     preparation  of the  Registration  Statement,  provided,  however,  that no
     Purchaser  shall be  liable  in any  such  case  for any  untrue  statement
     included in any Prospectus which statement has been corrected,  in writing,
     by such  Purchaser and delivered to the Company  before the sale from which
     such loss  occurred,  (ii) the failure of such Purchaser to comply with the
     covenants  and  agreements  contained  in Section 8.3 hereof,  or (iii) any
     untrue  statement in any  prospectus  that is  corrected in any  subsequent
     Prospectus  that was delivered to the Purchaser prior to the pertinent sale
     or sales by the Purchaser,  and each Purchaser,  severally and not jointly,
     will, as incurred,  reimburse  the Company for any legal or other  expenses
     reasonably incurred in investigating,  defending or preparing to defend any
     such action, proceeding or claim.

          (c) Promptly after receipt by any indemnified  person of a notice of a
     claim or the beginning of any action in respect of which indemnity is to be
     sought against an  indemnifying  person  pursuant to this Section 7.3, such
     indemnified person shall notify the indemnifying  person in writing of such
     claim or of the commencement of such action, and, subject to the provisions
     hereinafter  stated,  in case any such action  shall be brought  against an
     indemnified  person and the  indemnifying  person shall have been  notified
     thereof,  the indemnifying person shall be entitled to participate therein,
     and, to the extent that it shall wish, to assume the defense thereof,  with
     counsel  reasonably  satisfactory to the indemnified  person.  After notice
     from the indemnifying person to such indemnified person of the indemnifying
     person's  election to assume the defense thereof,  the indemnifying  person
     shall not be  liable  to such  indemnified  person  for any legal  expenses
     subsequently  incurred by such  indemnified  person in connection  with the
     defense thereof,  provided,  however, that if there exists or shall exist a
     conflict of interest  that would make it  inappropriate  in the  reasonable
     judgment of the  indemnified  person for the same counsel to represent both
     the  indemnified  person and such  indemnifying  person or any affiliate or
     associate  thereof,  the indemnified person shall be entitled to retain its
     own counsel at the expense of such indemnifying person.

          (d)  If  the  indemnification  provided  for in  this  Section  7.3 is
     unavailable to or insufficient to hold harmless an indemnified  party under
     subsection  (a) or (b) above in respect of any losses,  claims,  damages or
     liabilities  (or actions or  proceedings  in respect  thereof)  referred to
     therein,  then each indemnifying  party shall contribute to the amount paid
     or  payable by such  indemnified  party as result of such  losses,  claims,
     damages or liabilities  (or actions in respect  thereof) in such proportion
     as is  appropriate  to reflect the relative fault of the Company on the one
     hand and the  Purchasers on the other in connection  with the statements or
     omissions which resulted in such losses, claims, damages or liabilities (or
     actions  in  respect  thereof),  as well as any  other  relevant  equitable
     considerations.  The relative  fault shall be  determined  by reference to,
     among other  things,  whether the untrue or alleged  untrue  statement of a
     material fact or the omission or alleged  omission to state a material fact
     relates  to  information  supplied  by the  Company  on the  one  hand or a
     Purchaser on the other and the parties' relative intent, knowledge,  access
     to information and opportunity to correct or prevent such statement or



                                      E-14




     omission.  The Company and the  Purchasers  agree that it would not be just
     and  equitable  if  contribution  pursuant  to  this  subsection  (d)  were
     determined by pro rata  allocation  (even if the Purchasers were treated as
     one entity for such  purpose) or by any other  method of  allocation  which
     does not take account of the equitable  considerations referred to above in
     this subsection (d). The amount paid or payable by an indemnified  party as
     a result of the  losses,  claim,  damages,  or  liabilities  (or actions in
     respect  thereof)  referred to above in this subsection (d) shall be deemed
     to  include  any  legal  or  other  expenses  reasonably  incurred  by such
     indemnified  party in connection with  investigating  or defending any such
     action or claim.  Notwithstanding the provisions of this subsection (d), no
     Purchaser  shall be  required  to  contribute  any  amount in excess of the
     amount by which the net amount  received by the Purchaser  from the sale of
     the Shares to which such loss  relates  exceeds  the amount of any  damages
     which such  Purchaser has otherwise  been required to pay by reason of such
     untrue or alleged  untrue  statement  or omission or alleged  omission.  No
     person  guilty of  fraudulent  misrepresentation  (within  the  meaning  of
     Section 11(f) of the Securities Act) shall be entitled to contribution from
     any  person who was not guilty of such  fraudulent  misrepresentation.  The
     Purchasers' obligations in this subsection (d) to contribute are several in
     proportion to their  respective  sales of Shares to which such loss relates
     and not joint.

          (e) The  obligations  of the  Company  and the  Purchasers  under this
     Section 7.3 shall be in addition to any liability which the Company and the
     respective  Purchasers may otherwise  have and shall extend,  upon the same
     terms and conditions,  to each person,  if any, who controls the Company or
     any Purchaser within the meaning of the Act.

                                    Section 8

                   Restrictions on Transferability of Shares:
                          Compliance with Securities Act

     8.1 Restrictions on  Transferability.  The Shares shall not be transferable
in the  absence  of a  registration  under the  Securities  Act or an  exemption
therefrom or in the absence of compliance with any term of this  Agreement.  The
Company  shall be entitled to give stop  transfer  instructions  to its transfer
agent with respect to the Shares in order to enforce the foregoing restrictions.

     8.2 Restrictive  Legend.  Each certificate  representing  Shares shall bear
substantially  the following  legends (in addition to any legends required under
applicable securities laws):

               THE SHARES  REPRESENTED  BY THIS  CERTIFICATE
               HAVE BEEN  ACQUIRED FOR  INVESTMENT  PURPOSES
               ONLY AND HAVE NOT BEEN  REGISTERED  UNDER THE
               SECURITIES ACT OF 1933. THE SHARES MAY NOT BE
               SOLD OR  TRANSFERRED  IN THE  ABSENCE OF SUCH
               REGISTRATION OR AN EXEMPTION THEREFROM.



                                      E-15



               ADDITIONALLY   THE  TRANSFER  OF  THE  SHARES
               REPRESENTED BY THIS CERTIFICATE IS SUBJECT TO
               CERTAIN RESTRICTIONS  SPECIFIED IN THE COMMON
               STOCK PURCHASE  AGREEMENT DATED JUNE 25, 1998
               BETWEEN   THE   COMPANY   AND  THE   ORIGINAL
               PURCHASER, AND NO TRANSFER OF SHARES SHALL BE
               VALID OR  EFFECTIVE  ABSENT  COMPLIANCE  WITH
               SUCH RESTRICTIONS.  ALL SUBSEQUENT HOLDERS OF
               THIS CERTIFICATE WILL HAVE AGREED TO BE BOUND
               BY  CERTAIN  OF THE  TERMS OF THE  AGREEMENT,
               INCLUDING   SECTIONS   7.2  AND  8.3  OF  THE
               AGREEMENT.  COPIES  OF THE  AGREEMENT  MAY BE
               OBTAINED AT NO COST BY WRITTEN  REQUEST  MADE
               BY THE REGISTERED  HOLDER OF THIS CERTIFICATE
               TO THE SECRETARY OF THE COMPANY.

     The legend  contained in this Section 8.2 may be removed from a certificate
either in  accordance  with  Section  8.3 or  immediately  upon  receipt  by the
Transfer  Agent of a certificate  substantially  in the form attached  hereto as
Exhibit E.

     8.3 Transfer of Shares After Registration.  Each Purchaser hereby covenants
with the  Company  not to make  any  sale of the  Shares  except  either  (i) in
accordance with the Registration Statement, in which case Purchaser covenants to
comply with the  requirement  of  delivering  a current  prospectus,  or (ii) in
accordance with Rule 144, in which case Purchaser  covenants to comply with Rule
144.  Purchaser  further  acknowledges  and  agrees  that  such  Shares  are not
transferable on the books of the Company unless the certificate submitted to the
Company's  transfer  agent  evidencing  such Shares is accompanied by a separate
certificate  executed by an officer of, or other person duly  authorized by, the
Purchaser in the form attached hereto as Exhibit F.

     8.4 Purchaser  Information.  Each Purchaser covenants that it will promptly
notify  the  Company  of  any  changes  in  the  information  set  forth  in the
Registration  Statement  regarding such Purchaser or such  Purchaser's  "Plan of
Distribution."

                                    Section 9

                                  Miscellaneous

     9.1 Waivers and  Amendments.  With the  exception  of Sections  7.1 and 7.2
hereof,  the terms of this  Agreement  may be waived or amended with the written
consent of the Company and each Purchaser.  With respect to Sections 7.1 and 7.2
hereof,  with the written  consent of the Company and the record holders of more
than fifty percent (50%) of the Shares then  outstanding and held by Purchasers,
the terms of the Agreement may be waived or amended



                                      E-16




and any such  amendment  or waiver  shall be binding  upon the  Company  and all
holders of Shares.

     9.2  Placement  Agent Fee.  Each  Purchaser  acknowledges  that the Company
intends to pay a fee to SBC Warburg  Dillon Read Inc. and  Evolution  Capital in
respect of the sale of the Shares to the  Purchaser.  Each of the parties hereto
hereby  represents that, on the basis of any actions and agreements by it, there
are no other brokers or finders  entitled to compensation in connection with the
sale of the Shares to the Purchasers.

     9.3 Governing Law. This Agreement  shall be governed in all respects by and
construed  in  accordance  with the laws of the  State of New York  without  any
regard to conflicts of laws principles.

     9.4 Survival.  The  representations,  warranties,  covenants and agreements
made in this Agreement  shall survive any  investigation  made by the Company or
the Purchasers and the Closing.

     9.5  Successors  and  Assigns.  The  provisions  hereof  shall inure to the
benefit of, and be binding upon, the successors,  assigns,  heirs, executors and
administrators of the parties to this Agreement.  Notwithstanding the foregoing,
no Purchaser  shall assign this Agreement  without the prior written  consent of
the Company.

     9.6  Entire  Agreement.  This  Agreement  constitutes  the full and  entire
understanding  and  agreement  between the parties  with regard to the  subjects
thereof.

     9.7  Notices,  etc.  All  notices  and  other  communications  required  or
permitted  under this Agreement  shall be effective upon receipt and shall be in
writing and may be delivered in person, by telecopy,  overnight delivery service
or  registered or certified  United States mail  addressed to the Company or the
Purchasers,  as the case may be, at their respective  addresses set forth at the
beginning  of this  Agreement  or on Exhibit A or at such  other  address as the
Company or the  Purchasers  shall have  furnished to the other party in writing.
All  notices and other  communications  shall be  effective  upon the earlier of
actual  receipt  thereof by the person to whom  notice is directed or (i) in the
case of notices and  communications  sent by personal delivery or telecopy,  one
business  day after  such  notice or  communication  arrives  at the  applicable
address or was successfully sent to the applicable  telecopy number, (ii) in the
case of notices and communications  sent by overnight delivery service,  at noon
(local  time) on the  second  business  day  following  the day such  notice  or
communication was sent, and (iii) in the case of notices and communications sent
by United States mail seven days after such notice or  communication  shall have
been deposited in the United States mail.

     9.8  Severability  of this  Agreement.  If any provision of this  Agreement
shall be judicially  determined  to be invalid,  illegal or  unenforceable,  the
validity,  legality and enforceability of the remaining  provisions shall not in
any way be affected or impaired thereby.




                                      E-17




     9.9  Counterparts.  This  Agreement  may  be  executed  in  any  number  of
counterparts,  each of which  shall be an  original,  but all of which  together
shall constitute one instrument.

     9.10 Further Assurances.  Each party to this Agreement shall do and perform
or cause to be done and  performed  all such  further  acts and things and shall
execute and deliver all such other  agreements,  certificates,  instruments  and
documents as the other party hereto may reasonably request in order to carry out
the intent and accomplish the purposes of this Agreement and the consummation of
the transactions contemplated hereby.

     9.11 Termination.  In the event that the Closing shall not have occurred on
or before sixty (60) days from the date hereof,  the  Purchasers  shall have the
option to terminate this Agreement at the close of business on such date, and in
the event that the Closing shall not have occurred on or before ninety (90) days
from the date hereof, this Agreement shall terminate at the close of business on
such date.

     9.12  Expenses.  The  Company  and each such  Purchaser  shall bear its own
expenses  incurred  on its  behalf  with  respect  to  this  Agreement  and  the
transactions contemplated hereby, including fees of legal counsel.

     9.13 Currency.  All references to "dollars" or "$" in this Agreement  shall
be deemed to refer to United States dollars.



                                      E-18




     The  foregoing  agreement  is hereby  executed  as of the date first  above
written.


                                   "COMPANY"

                                   ENZON, INC.
                                   a Delaware corporation


                                   By:
                                      ------------------------------------------

                                   Title:
                                         ---------------------------------------


                                   "PURCHASERS"


                                   THE DCF LIFE SCIENCES FUND, LTD.



                                   By:
                                      ------------------------------------------

                                   Name:
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------



                                   DCF PARTNERS, L.P.



                                   By:
                                      ------------------------------------------

                                   Name:
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------









                                      E-19




                                   ARIES DOMESTIC FUND, L.P.



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------



                                   THE ARIES TRUST



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                         ---------------------------------------

                                   Title:
                                         ---------------------------------------



                                   HAUSMANN HOLDINGS, N.V.



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                         ---------------------------------------

                                   Title:
                                         ---------------------------------------














                                      E-20




                                   ORACLE OFFSHORE LTD.



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------



                                   ORACLE PARTNERS L.P.



                                   By:    
                                      ------------------------------------------

                                   Name:  
                                        ----------------------------------------

                                   Title: 
                                         ---------------------------------------



                                   ORACLE INSTITUTIONAL PARTNERS



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------














                                      E-21




                                   GSAM ORACLE FUND, INC.



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------



                                   SBC WARBURG DILLON READ, INC.



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------



                                   SBC WARBURG DILLON READ, INC.



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------














                                      E-22




                                   CACLUCEUS CAPITAL L.P.



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------



                                   CACLUCEUS CAPITAL LTD.



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------



                                   MERLIN BIOMED L.P.



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------













                                      E-23




                                   DEUTSCHE VERMOGEN SBILDUNGSGESELL
                                   SCHAFT MBH



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------



                                   WAYNE P. ROTHBAUM



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------



                                   MITCHELL D. SILBER



                                   By:   
                                      ------------------------------------------

                                   Name: 
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------













                                      E-24




                                   NEW TECHNOLOGIES FUND




                                   By:
                                      ------------------------------------------

                                   Name:
                                        ----------------------------------------

                                   Title:
                                         ---------------------------------------







                                      E-25


                                    Exhibit A
                                     to CSPA


Purchaser Shares Purchase Price --------- ------ -------------- DCF Life Sciences Fund Ltd. 100,000 $ 475,000 DCF Partners, L.P. 953,000 $ 4,526,750 C/O DCF Capital 660 Steamboat Road Greenwich, CT 06830 Attn: Mr. Doug Floren Facsimile: (203) 618-1495 Oracle Partners, L.P. 315,789 $ 1,499,997.75 Oracle Institutional Partners, L.P. 78,496 $ 372,856 GSAM Oracle Fund, Inc. 168,721 $ 801,424.75 Haussmann Holdings, N.V 50,526 $ 239,998.50 Oracle Offshore Ltd. 18,046 $ 85,718.50 C/O Oracle Partners, L.P. 712 Fifth Avenue, 45th Floor New York, NY 10019 Attn: Mr. Norman Schleffer Facsimile: (212) 459-0863 SBC Warburg Dillon Read, Inc. 500,000 $ 2,375,000 120 Wall Street, 6th Floor New York, NY 10005 Attn: Mr. James Del Medico Facsimile: (212) 554-5334 Cacluceus Capital L.P. 105,000 $ 498,750 Cacluceus Capital Ltd. 220,000 $ 1,045,000 C/O Orbimed Advisors LLC 767 Third Avenue, 6th Floor New York, NY 10017 Attn: Mr. Sven H. Borho Facsimile: (212) 789-2580 Merlin BioMed LP 21,053 $ 100,001.75 Deutsche Vermogen 294,737 $ 1,400,000.75 Sbildungsgesell Shaft mbH C/O Merlin Biomed 237 Park Avenue, Suite 801 New York, NY 10017 Attn: Ms. Jennifer Stoler The Aries Trust 747,368 3,549,998 Aries Domestic Fund, L.P. 305,264 1,450,004 C/O Paramount Capital Asset Management, Inc. 787 Seventh Avenue New York, NY 10019 Attn: Mr. David Tanen Facsimile: (212) 554-4355 Wayne P. Rothbaum 30,000 $ 142,500 Mitchell D. Silber 15,000 $ 71,250 C/O The Carson Group 156 West 56th Street 10th Floor New York, NY 10019 Attn: Mr. Wayne Rothbaum New Technologies Fund 60,000 $ 285,000 C/O Emerging Growth Management Co. One Embarcadero Center Suite 2410 San Francisco, CA 94111 Attn: Mr. Marc Pentopoulos Facsimile: (415) 782-9645 ---------- -------------- 3,983,000 $18,919,250 ========== ==============
E-26 Exhibit B INSTRUCTION SHEET FOR PURCHASER (to be read in conjunction with the entire Common Stock Purchase Agreement) A. Complete the following items in the Common Stock Purchase Agreement: 1. Provide the information regarding the Purchaser requested on the signature page. The Agreement must be executed by an individual authorized to bind the Purchaser. 2. Exhibit B-1 - Stock Certificate Questionnaire: Provide the information requested by the Stock Certificate Questionnaire; 3. Exhibit B-2 - Registration Statement Questionnaire: Provide the information requested by the Registration Statement Questionnaire. 4. Exhibit B-3 - Purchaser Certificate: Provide the information requested by the Certificate for Individual Purchasers or the Certificate for Corporate, Partnership, Trust, Foundation and Joint Purchasers, as applicable. 5. Return the signed Purchase Agreement including the properly completed Exhibit 4.2 to: Brobeck, Phleger & Harrison LLP 1633 Broadway, 47th Floor New York, New York 10019 Telephone: (212) 581-1600 Attn: Heather Willens, Esq. B. Instructions regarding the transfer of funds for the purchase of Shares will be telecopied to the Purchaser by the Placement Agent at a later date. C. Upon the resale of the Shares by the Purchaser after the Registration Statement covering the Shares is effective, as described in the Purchase Agreement, the Purchaser: (i) must deliver a current prospectus, and annual and quarterly reports of the Company to the buyer (prospectuses, and annual and quarterly reports may be obtained from the Company at the Purchaser's request); and (ii) must send a letter in the form of Exhibit D to the Company so that the Shares may be properly transferred. E-27 Exhibit B-1 ENZON, INC. STOCK CERTIFICATE QUESTIONNAIRE Pursuant to Section 4.3 of the Agreement, please provide us with the following information: 1. The exact name that the Shares are to be registered in (this is the name that will appear on the stock certificate(s)). You may use a nominee name if appropriate: _____________________________ 2. The relationship between the Purchaser of the Shares and the Registered Holder listed in response to item 1 above: _____________________________ 3. The mailing address of the Registered Holder listed in response to item 1 above: _____________________________ _____________________________ _____________________________ _____________________________ _____________________________ 4. The Tax Identification Number of the Registered Holder listed in response to item 1 above: _____________________________ E-28 Exhibit B-2 ENZON, INC. REGISTRATION STATEMENT QUESTIONNAIRE In connection with the preparation of the Registration Statement, please provide us with the following information regarding the Purchaser. 1. Please state your organization's name exactly as it should appear in the Registration Statement: 2. Have you or your organization had any position, office or other material relationship within the past three years with the Company or its affiliates other than as disclosed in the prospectus included in the Registration Statement? _____ Yes _____ No If yes, please indicate the nature of any such relationship below: - -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- E-29 Exhibit B-3 ENZON, INC. CERTIFICATE FOR INDIVIDUAL PURCHASERS If the investor is an individual Purchaser (or married couple) the Purchaser must complete, date and sign this Certificate. CERTIFICATE I certify that the representations and responses below are true and accurate: In order for the Company to offer and sell the Shares in conformance with state and federal securities laws, the following information must be obtained regarding your investor status. Please initial each category applicable to you as an investor in the Company. ___ (1) A natural person whose individual net worth, or joint net worth with that person's spouse, at the time of his purchase exceeds $1,000,000; ___ (2) A natural person who had an individual income in excess of $200,000 in each of the two most recent years, or joint income with that person's spouse in excess of $300,000, in each of those years, and has a reasonable expectation of reaching the same income level in the current year; ___ (3) An executive officer or director of the Company. Dated: __________________ ____________________________________________ Name(s) of Purchaser ____________________________________________ Signature ____________________________________________ Signature E-30 Exhibit B-4 ENZON, INC. CERTIFICATE FOR CORPORATE, PARTNERSHIP, TRUST, FOUNDATION AND JOINT PURCHASERS If the investor is a corporation, partnership, trust, pension plan, foundation, joint purchaser (other than a married couple) or other entity, an authorized officer, partner, or trustee must complete, date and sign this Certificate. CERTIFICATE The undersigned certifies that the representations and responses below are true and accurate: (a) The investor has been duly formed and is validly existing and has full power and authority to invest in the Company. The person signing on behalf of the undersigned has the authority to execute and deliver the Common Stock Purchase Agreement on behalf of the Purchaser and to take other actions with respect thereto. (b) Indicate the form of entity of the undersigned: ____ Limited Partnership ____ General Partnership ____ Corporation ____ Revocable Trust (identify each grantor and indicate under what circumstances the trust is revocable by the grantor): _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ ________. (Continue on a separate piece of paper, if necessary.) ____ Other type of Trust (indicate type of trust and, for trusts other than pension trusts, name the grantors and beneficiaries):_______ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ ________. (Continue on a separate piece of paper, if necessary.) E-31 ____ Other form of organization (indicate form of organization (____ _______________________________________________________________). (c) Indicate the approximate date the undersigned entity was formed: ______ ____________________. (d) In order for the Company to offer and sell the Shares in conformance with state and federal securities laws, the following information must be obtained regarding your investor status. Please initial each category applicable to you as an investor in the Company. ____ 1. A bank as defined in Section 3(a)(2) of the Securities Act, or any savings and loan association or other institution as defined in Section 3(a)(5)(A) of the Securities Act whether acting in its individual or fiduciary capacity; ____ 2. A broker or dealer registered pursuant to Section 15 of the Securities Exchange Act of 1934; ____ 3. An insurance company as defined in Section 2(13) of the Securities Act; ____ 4. An investment company registered under the Investment Company Act of 1940 or a business development company as defined in Section 2(a)(48) of that Act; ____ 5. A Small Business Investment Company licensed by the U.S. Small Business Administration under Section 301(c) or (d) of the Small Business Investment Act of 1958; ____ 6. A plan established and maintained by a state, its political subdivisions, or any agency or instrumentality of a state or its political subdivisions, for the benefit of its employees, if such plan has total assets in excess of $5,000,000; ____ 7. An employee benefit plan within the meaning of the Employee Retirement Income Security Act of 1974, if the investment decision is made by a plan fiduciary, as defined in Section 3(21) of such Act, which is either a bank, savings and loan association, insurance company, or registered investment advisor, or if the employee benefit plan has total assets in excess of $5,000,000 or, if a self-directed plan, with investment decisions made solely by persons that are accredited investors; ____ 8. A private business development company as defined in Section 202(a)(22) of the Investment Advisers Act of 1940; E-32 ____ 9. An organization described in Section 501(c)(3) of the Internal Revenue Code, corporation, Massachusetts or similar business trust, or partnership, not formed for the specific purpose of acquiring the Shares, with total assets in excess of $5,000,000; ____ 10. A trust, with total assets in excess of $5,000,000, not formed for the specific purpose of acquiring the Shares, whose purchase is directed by a sophisticated person as described in Rule 506(b)(2)(ii) of the Exchange Act; ____ 11. An entity in which all of the equity owners qualify under any of the above subparagraphs. If the undersigned belongs to this investor category only, list the equity owners of the undersigned, and the investor category which each such equity owner satisfies: _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ ________________________________________________________________. (Continue on a separate piece of paper, if necessary.) Dated: _________________________, 19__ ______________________________________ Name of investor _____________________________________________________________ Signature and title of authorized officer, partner or trustee E-33 Exhibit C Opinion of Company Counsel E-34 EXHIBIT C DRAFT [Closing Date], 1998 [ ] Re: Enzon, Inc. - Sale of Common Stock Ladies and Gentlemen: We have acted as counsel to Enzon, Inc. (the "Company") in connection with the sale by the Company of shares of common stock of the Company (the "Shares") pursuant to the Common Stock Purchase Agreement (the "Purchase Agreement"), dated as of June [ ], 1998, by and between the Company and the investors listed on Schedule A thereto (the "Purchasers"). This opinion is being delivered pursuant to Section 5.4 of the Purchase Agreement. All capitalized terms used herein and not defined herein have the meanings assigned to such terms in the Purchase Agreement. We have examined such documents and have reviewed such questions of law as we have considered necessary and appropriate for the purposes of our opinions set forth below. In rendering our opinions set forth below, we have assumed the authenticity of all documents submitted to us as originals, the genuineness of all signatures and the conformity to authentic originals of all documents submitted to us as copies. We have also assumed the legal capacity for all purposes relevant hereto of all natural persons and, with respect to all parties to agreements or instruments relevant hereto other than the Company, that such parties had the requisite power and authority (corporate or otherwise) to execute, deliver and perform such agreements or instruments, that such agreements or instruments have been duly authorized by all requisite action (corporate or otherwise) on the part of such parties and have been duly executed and delivered by such parties and that such agreements or instruments are the valid, binding and enforceable obligations of such parties. As to questions of fact material to our opinions, we have relied upon the representations made in the Purchase Agreement and upon certificates of officers of the Company and of public officials (including, without limitation, those certificates delivered to others at the Closing). E-35 Our opinions expressed below as to certain factual matters are qualified as being limited "to our knowledge" or by other words to the same or similar effect. Such words, as used herein, mean the information known to the attorneys in the firm who have principally represented the Company in connection with the transactions contemplated by the Purchase Agreement. In rendering such opinions, we have not conducted any independent investigation or consulted with other attorneys in our firm with respect to the matters covered thereby. No inference as to our knowledge with respect to such matters should be drawn from the fact of our representation of the Company. Based on the foregoing, we are of the opinion that: 1. The Company is a corporation duly incorporated, validly existing and in good standing under the laws of the State of Delaware. 2. The Company has the corporate power and authority to enter into the Purchase Agreement and to issue, sell and deliver to the Purchasers the Shares to be issued and sold by it thereunder. 3. The Purchase Agreement has been duly authorized by all necessary corporate action on the part of the Company and has been duly executed and delivered by the Company. 4. The performance by the Company of the Purchase Agreement and the consummation by the Company of the transactions therein contemplated will not (a) violate any provision of the Company's charter or bylaws or any applicable statute, rule or regulation, or (b) result in the material breach or violation of any of the terms and provisions, or constitute a default under, any indenture, mortgage, deed of trust, loan agreement, bond, debenture, note agreement or other evidence of indebtedness, or any lease, contract or other agreement or instrument known to us to which the Company is a party or by which its properties are bound, or, to our knowledge, any order, writ or decree of any court or governmental agency or body having jurisdiction over the Company, or over any of its properties or operations; provided, however, that we express no opinion herein regarding state or foreign securities or Blue Sky laws. 5. The Purchase Agreement constitutes a valid and binding obligation of the Company, enforceable against the Company according to its terms. E-36 6. The Shares to be issued by the Company pursuant to the terms of the Purchase Agreement will be, upon issuance and delivery against payment therefor in accordance with the terms thereof, duly authorized and validly issued and fully paid and nonassessable, and the stockholders of the Company have no preemptive or other rights to purchase any of the Shares. The opinions set forth above are subject to the following qualifications and exceptions: (a) Our opinions are subject to the effect of any applicable bankruptcy, insolvency, reorganization, moratorium or other similar law of general application affecting creditors' or secured creditors' rights, including (without limitation) applicable fraudulent transfer laws. (b) Our opinions are subject to the effect of general principles of equity, including (without limitation) concepts of materiality, reasonableness, good faith and fair dealing, and other similar doctrines affecting the enforceability of agreements generally (regardless of whether considered in a proceeding in equity or at law). (c) Our opinions are subject to possible judicial action giving effect to governmental actions or foreign laws affecting creditors' rights. (d) Our opinions, insofar as they relate to indemnification provisions, are subject to the effect of federal and state securities laws and public policy relating thereto. Our opinions expressed above are limited to the law of the State of New York, the Delaware General Corporation Law, and the federal laws of the United States of America. The foregoing opinions are being furnished to you solely for your benefit and may not be relied upon by, nor may copies be delivered to, any other person without our prior written consent. Very truly yours, E-37 Exhibit D OPINIONS OF PATENT COUNSEL E-38 Exhibit E PURCHASER'S LEGEND REMOVAL CERTIFICATE To: [Transfer agent name and address] Attention: ______________ The undersigned, the Purchaser or an officer of, or other person duly authorized by the Purchaser, hereby certifies that _____________________________ (fill in name of Purchaser) institution was the Purchaser of the Shares evidenced by the attached certificate, and in order to induce the Company to remove the legends contained on the certificates representing the Common Stock purchased by such Purchaser, Purchaser will sell such Shares (i) in accordance with the registration statement, file number in which case the Purchaser will satisfy the requirement of delivering a current prospectus in connection with such sale, or (ii) in accordance with Rule 144 under the Securities Act of 1933 ("Rule 144"), in which case the Purchaser certifies that it has complied with or will comply with the requirements of Rule 144. Print or type: Name of Purchaser: _______________________________________________________ Name of Individual representing Purchaser (if an Institution): _______________________________________________________ Title of Individual representing Purchaser (if an Institution): _______________________________________________________ Signature by: Purchaser or Individual representing Purchaser: _______________________________________________________ E-39 Exhibit F PURCHASER'S CERTIFICATE OF SUBSEQUENT SALE To: [Transfer agent name and address] Attention: _____________ The undersigned, the Purchaser or an officer of, or other person duly authorized by the Purchaser, hereby certifies that _____________________________ (fill in name of Purchaser) institution was the Purchaser of the Shares evidenced by the attached certificate, and as such, proposes to transfer such Shares on or about ______________________ either (i) in accordance with the registration statement, (date) file number _____________, in which case the Purchaser certifies that the requirement of delivering a current prospectus has been complied with or will be complied with in connection with such sale, or (ii) in accordance with Rule 144 under the Securities Act of 1933 ("Rule 144"), in which case the Purchaser certifies that it has complied with or will comply with the requirements of Rule 144. Print or type: Name of Purchaser: ___________________________________________________ Name of Individual representing Purchaser (if an Institution): ___________________________________________________ Title of Individual representing Purchaser (if an Institution): ___________________________________________________ Signature by: E-40 Exhibit G DESCRIPTION OF CAPITAL STOCK E-41 EXHIBIT G Description of Capital Stock Under its Certificate of Incorporation, the Company is authorized to issue 60,000,000 shares of Common Stock, par value $.01 per share, and 3,000,000 shares of preferred stock, par value $.01 per share. As of May 29, 1998, there were 31,331,081 shares of Common Stock, and 108,000 shares of preferred stock designated as Series A Preferred Stock, outstanding. Other than the Series A Preferred Stock, there are no other classes of preferred stock designated and no other shares of preferred stock outstanding. Holders of shares of Common Stock and Series A Preferred Stock are entitled to one vote per share on matters to be voted upon by the stockholders of the Company. There are no cumulative voting rights and, accordingly, the holders of a majority of the combined Common Stock and Series A Preferred Stock may elect all of the directors. The Common Stock and the Series A Preferred Stock shall be voted as one class, except (i) with respect to any action amending or repealing any of the powers, designations, preferences and rights of the Series A Preferred Stock, which requires the affirmative vote of holders of not less than two-thirds of the then outstanding Series A Preferred Stock and (ii) with respect to any action increasing or decreasing the authorized shares or the par value of the Common Stock or preferred stock or altering or changing adversely the powers, preferences, or special rights of such shares, which pursuant to Section 242 of the Delaware General Corporation Law requires the affirmative vote of a majority of the outstanding shares of the class so being affected, voting as a class and the affirmative vote of a majority of the combination of the outstanding Common Stock and Series A Preferred Stock, voting as one class. Common Stock Holders of shares of Common Stock will be entitled to receive dividends when, as and if declared by the Board of Directors and to share ratably in the assets of the Company legally available for distribution to its stockholders in the event of the liquidation, dissolution or winding up of the Company, in each case subject to the rights of the holders of the Series A Preferred Stock. Holders of Common Stock have no preemptive, subscription, redemption or conversion rights. All of the issued and outstanding shares of Common Stock are duly authorized, validly issued, fully-paid and non-assessable. The registrar and transfer agent for the Common Stock is Continental Stock Transfer and Trust Company, 2 Broadway, New York, New York 10004. The authorized but unissued preferred stock may be issued by the Board of Directors from time to time in one or more series with such preferences, terms and rights as the Board of Directors may determine without further action by the stockholders of the Company. Accordingly, the Board of Directors has the power to fix the dividend rate and to establish the provisions, if any, relating to voting rights, E-42 redemption rates, sinking fund, liquidation preferences and conversion rights for any series of preferred stock issued in the future. It is not possible to state the actual effect of the authorization of the preferred stock upon the rights of holders of the Common Stock until the Board of Directors determines the specific rights of the holders of a series of the preferred stock. The issuance of the preferred stock may have the effect of delaying, deferring or preventing a change in control of the Company without further action by the stockholders. Series A Preferred Stock The holders of the Series A Preferred Stock are entitled to an annual dividend of $2.00 per share, payable semi-annually but only when and if declared by the Board of Directors out of funds legally available therefor. Dividends on the Series A Preferred Stock are cumulative and accrue and accumulate. No dividends are to be paid or set apart for payment on the Common Stock, nor are any shares of Common Stock to be redeemed, retired or otherwise acquired for valuable consideration unless the Company has paid in full, or made appropriate provision for the payment in full of, all dividends which have then accumulated on the Series A Preferred Stock. Since the Company did not make cash dividend payments for eight semi-annual periods from the date of issuance of the Series A Preferred Stock, any holder of Series A Preferred Stock may elect, upon written notice to the Company, to be paid all or any part of such accrued and unpaid dividends, and any dividends which accrue but are not paid in cash within thirty days of the scheduled payment date thereafter, in shares of the Company's Common Stock. Accrued and unpaid dividends payable to holders of Series A Preferred Stock as of the date such holder elects to convert the Series A Preferred Stock into Common Stock may, at the Company's option, be paid by the Company's issuance of Common Stock to such holder. In all cases the number of shares of Common Stock to be received in lieu of accrued dividends shall be determined by dividing the aggregate amount of the accrued and unpaid dividends by the conversion rate of the Series A Preferred Stock in effect on the date of election. To date, the Company has paid no dividends on the Series A Preferred Stock, except for accrued dividends payable on Series A Preferred Stock which has been converted, all of which have been paid with Common Stock. The Company does not presently intend to pay cash dividends on the Series A Preferred Stock. There were 1,733,000 of accrued and unpaid dividends on the Series A Preferred Stock as of March 31, 1998. Dividends on the Series A Preferred Stock currently accrue at the rate of $216,000 per year. Each share of Series A Preferred Stock is convertible at any time prior to redemption. For purposes of conversion, each share of Series A Preferred Stock is deemed to have a value of $25.00. The Series A Preferred Stock is convertible into Common Stock at a conversion rate of $11.00 per share of Common Stock. The E-43 conversion rate will be adjusted upon the Company's payment of dividends on its Common Stock in Common Stock, the subdivision or reduction of the Company's outstanding Common Stock, the reclassification of the Common Stock or the merger or consolidation of the Company, provided, however, that no such adjustment to the conversion rate will be made unless the net effect on the conversion price per share of all such events is at least $.50 in the aggregate. The Company may at any time, redeem the whole or any part of the Series A Preferred Stock then outstanding at a redemption price of $25.00 per share, plus in each case a sum equal to all accumulated and unpaid dividends thereon through the date fixed for redemption. In case of redemption of only part of the Series A Preferred Stock at any time outstanding, the Company shall designate the amount of Series A Preferred Stock so to be redeemed and shall redeem such Series A Preferred Stock on a pro rata basis. Subject to certain limitations, the Board of Directors shall have the power and authority to prescribe the terms and conditions upon which the Series A Preferred Stock shall be redeemed from time to time. In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, the holders of Series A Preferred Stock will be entitled to receive in cash out of the assets of the Company, whether from capital or from earnings, available for distribution to its stockholders, before any amount shall be paid to the holders of the Common Stock, the sum of $25.00 per share of Series A Preferred Stock, plus an amount equal to all accumulated and unpaid dividends thereon through the date fixed for payment of such distributive amount. All shares of Common Stock are of junior rank to Series A Preferred Stock in respect of the preferences as to dividends, distributions and payments upon the liquidation, dissolution or winding up of the Company. The rights of the holders of the Common Stock are subject to the preferences and relative rights of the Series A Preferred Stock. The Company may authorize and issue additional or other Preferred Stock which is of equal rank with the Series A Preferred Stock in respect of the preferences as to dividends, distributions and payments upon the liquidation, dissolution or winding up of the Company; provided, however, that for so long as any Series A Preferred Stock remains outstanding, the Company shall not issue any capital stock which is more senior in rank than the Series A Preferred Stock in respect of the foregoing preferences or which shall have greater voting rights than the Series A Preferred Stock. In the event of a merger or consolidation of the Company with or into another corporation, the Series A Preferred Stock shall maintain its relative powers, designations and preferences. Common Stock Purchase Warrants As of May 29, 1998 the Company had outstanding warrants to purchase an aggregate of 1,038,686 shares of Common Stock at exercise prices ranging from $2.50 to $ 5.63 per share. E-44 Options to Purchase Common Stock As of May 29, 1998 the Company had outstanding options to purchase an aggregate of 4,378,736 shares of Common Stock at exercise prices ranging from $1.88 to $14.88 per share held by employees, directors and consultants under the Company's Non-Qualified Stock Option Plan. Independent Directors Stock Plan Under the terms of the Company's Independent Directors Stock Plan (approved by stockholders in December 1996) each independent director is granted shares of Common Stock equivalent to $2,500 per quarter, plus $500 for Board of Directors' meeting attended. The number of shares issued is based on the fair market value of the Common Stock on the last trading day of the applicable quarter. Registration Rights Schering Corporation has piggyback registration rights with respect to 847,489 shares of Common Stock. Such shares are eligible under Rule 144(k) of the Securities Act of 1933, as amended.

                                                                     Exhibit 4.2

                             CERTIFICATE OF AMENDENT

                                       OF

                          CERTIFICATE OF INCORPORATION

                                       OF

                                   ENZON, INC.

     Enzon,  Inc., a corporation  organized and existing  under and by virtue of
the General Corporation Law of the State of Delaware (the  "Corporation"),  DOES
HEREBY CERTIFY:

     FIRST: That the Board of Directors of said Corporation, at a meeting of its
members,  adopted  resolutions  proposing and declaring  advisable the following
amendments to the Certificate of Incorporation of said Corporation:

     RESOLVED,  that the  first  sentence  of  Article 4 of the  Certificate  of
     Incorporation be amended to read in its entirety as set forth below:

          "4.  Number if Shares.  The total  number of shares of  capital  stock
     which the Corporation shall have authority to issue is sixty-three  million
     (63,000,000)  shares, of which sixty million  (60,000,000)  shares shall be
     Common stock, par value $.01 per share."

     SECOND: That the remainder of Article 4 of the Certificate of Incorporation
of said Corporation shall remain unchanged.

     THRID:  That at the Annual Meeting of Stockholders of the Corporation,  the
holders of a majority of the outstanding stock entitled to vote thereon voted in
favor of said amendments in accordance with the provisions of Section 215 of the
General Corporation Law of the State of Delaware.

     FOURTH: That the aforesaid  amendments were duly adopted in accordance with
the applicable provisions of sections 242 and 216 of the General Corporation Law
of the State of Delaware.




                                      E-45





     IN WITNESS WHEREOF, Enzon, Inc. has caused this certificate to be signed by
Peter G. Tombros, its President and attested to by John A. Caruso,  Secretary of
the Corporation, this 18th of December, 1997.

                                                     By: /s/ Peter G. Tombros
                                                        ------------------------
                                                         Peter G. Tombros
                                                         President

ATTEST

By: /s/ John A. Caruso
    ----------------------
    John A. Caruso
    Secretary

                                      E-46



                                                                     EXHIBIT 5.1

                        [DORSEY & WHITNEY LLP LETTERHEAD]

                                  July 1, 1998

Enzon, Inc.
20 Kingsbridge Road

Piscataway, New Jersey 08854

     Re:  Registration Statement on Form S-3
          ----------------------------------

Ladies and Gentlemen:

          You have  requested  our opinion with respect to the  registration  by
     Enzon,  Inc. (the "Company")  pursuant to a Registration  Statement on Form
     S-3 (the  "Registration  Statement")  under the  Securities Act of 1933, as
     amended (the "Act"),  of an aggregate of 3,983,000 shares (the "Shares") of
     the Company's  Common Stock,  $.01 par value per share (the "Common Stock")
     which  may be sold  from  time to time by the  selling  stockholders  named
     therein (the "Selling Stockholders").  All Shares to be sold by the Selling
     Stockholders are issued and outstanding.

          In so acting,  we have  examined  originals  or copies,  certified  or
     otherwise  identified to our  satisfaction,  of such  documents,  corporate
     records,  certificates of public  officials and other  instruments and have
     conducted  such  other  investigations  of fact  and law as we have  deemed
     relevant  and  necessary  to form a  basis  for  the  opinions  hereinafter
     expressed.  In conducting  such  examination,  we have assumed (i) that all
     signatures are genuine,  (ii) that all documents and instruments  submitted
     to us as copies conform with the originals, and (iii) the due execution and
     delivery  of  all  documents   where  due  execution  and  delivery  are  a
     prerequisite to the effectiveness thereof. As to any facts material to this
     opinion, we have relied upon statements and representations of officers and
     other   representatives  of  the  Registrant  and  certificates  or  public
     officials and have not independently verified such facts.

          Based  solely upon the  foregoing,  it is our opinion  that the Shares
     constitute validly issued,  fully paid and non-assessable  shares of Common
     Stock of the Company.

          Our  opinions  expressed  above are limited to the law of the State of
     New York, the Delaware General Corporation Law, and the federal laws of the
     United States of America.



                                      E-47




          We hereby  consent to the filing of this  opinion as an exhibit to the
     Registration Statement,  and to the reference to our firm under the heading
     "Legal  Matters" in the Prospectus  constituting  part of the  Registration
     Statement relating to the registration of the Shares.

                                       Very truly yours,

                                       

                                       







                                      E-48



                                                                    EXHIBIT 23.2

                          INDEPENDENT AUDITORS' CONSENT

The Board of Directors
Enzon, Inc.

We consent to the use of our reports incorporated herein by reference and to the
reference to our firm under the heading "Experts" in the Prospectus.


                                                 /s/ KPMG Peat Marwick LLP
                                                 -------------------------
                                                 KPMG Peat Marwick LLP

Short Hills, New Jersey
June 29, 1998

                                      E-49