Page 6 of 6

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: June 12, 2003

                                                                       Exhibit 3


                    MUTUAL TERMINATION AND RELEASE AGREEMENT


         This MUTUAL TERMINATION AND RELEASE AGREEMENT (this "Agreement") is
made and entered into as of June 4, 2003 (the "Effective Date"), by and among
NPS Pharmaceuticals, Inc., a Delaware corporation ("NPS"), Enzon
Pharmaceuticals, Inc., a Delaware corporation ("Enzon"), Momentum Merger
Corporation, a Delaware corporation ("Momentum"), Newton Acquisition Corporation
a Delaware corporation ("Newton"), and Einstein Acquisition Corporation, a
Delaware corporation ("Einstein"). NPS, Enzon, Momentum, Newton, and Einstein
are collectively referred to herein as the "Parties" and each individually as a
"Party." Unless otherwise defined herein, capitalized terms used herein shall
have the meaning given them in the Merger Agreement (as defined below).

                                    RECITALS

         A.       NPS, Enzon, Momentum, Newton and Einstein are Parties to that
certain Agreement and Plan of Reorganization dated as of February 19, 2003, as
amended (the "Merger Agreement").

         B.       Contemporaneously with the execution of the Merger Agreement,
NPS, Enzon, Momentum, certain officers and directors of NPS and Enzon entered
into (i) those certain NPS Voting Agreements, (ii) those certain Enzon Voting
Agreements, (iii) those certain NPS Affiliate Agreements, and (iv) those certain
Enzon Affiliate Agreements (collectively, the "Ancillary Agreements").

         C.       Pursuant to the Merger Agreement, Enzon entered into that
certain Amended and Restated Employment Agreement with Arthur J. Higgins, as
amended (the "Higgins Employment Agreement").

         D.       NPS and Enzon in connection with the execution of this
Agreement shall enter into that certain Restricted Stock Purchase Agreement of
even date herewith and attached hereto as Exhibit A (the "Stock Purchase
Agreement") and the Registration Rights Agreement as described in the Stock
Purchase Agreement (the "Registration Rights Agreement").

         E.       The Board of Directors of each of NPS, Enzon, Momentum, Newton
and Einstein has determined to terminate the Merger Agreement and each of the
Ancillary Agreements and to effect certain other matters as provided herein.

                                    AGREEMENT

         NOW, THEREFORE, in consideration of the mutual covenants and agreements
set forth in this Agreement, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the Parties, intending
to be legally bound, agree as follows:




         1.       Termination of Merger Agreement. The Parties agree that,
effective at 5:30 p.m., Eastern Standard Time, on the Effective Date, and
subject to the terms and conditions of this Agreement, the Stock Purchase
Agreement and the Registration Rights Agreement, (i) the Merger Agreement is
hereby terminated and of no further force or effect pursuant to Section 7.1(a)
therein, and (ii) each of the Ancillary Agreements is each hereby terminated and
of no further force or effect. For the avoidance of doubt, it is the intention
of the Parties that no provision of the Merger Agreement, including without
limitation Section 7.2 (Notice of Termination; Effect of Termination) and 7.3
thereof (Fees and Expenses), shall survive the termination of the Merger
Agreement pursuant to the terms of this Agreement.

         2.       Issuance of NPS Shares. Subject to the terms and conditions of
this Agreement, the Stock Purchase Agreement and the Registration Rights
Agreement, NPS agrees to issue to Enzon, and Enzon agrees to purchase from NPS,
One Million Five Hundred Thousand (1,500,000) shares of NPS common stock, $0.001
par value per share (the "Shares").

         3.       Releases.

                  (a)      Each of the Parties on its behalf and on behalf of
its parents, affiliates, subsidiaries, segments or divisions, successors and
assigns, present and former stockholders, officers, directors, employees,
insurers, administrators, agents, representatives, attorneys and any persons
acting by, through, under or in concert with each of them or any of them, hereby
completely releases and forever discharges the other Parties, their parents,
affiliates, subsidiaries, segments or divisions, successors and assigns, present
and former stockholders, officers, directors, employees, insurers,
administrators, agents, representatives and attorneys (collectively, the
"Releasees") from any and all claims, rights, demands, actions, obligations,
liabilities and causes of action of any and every kind, nature and character
whatsoever, known or unknown, which such Party may now have, could have had or
may in the future have against the other Parties and the other Parties'
Releasees for or on account of any acts, omissions, events or matters relating
to or arising out of the Merger Agreement, the Ancillary Agreements, the Higgins
Employment Agreement and the transactions contemplated by any of such
agreements, including without limitation, claims of fraud, claims of willful or
intentional breach, or otherwise based on the termination thereof, and whether
based on tort, contract (express or implied), or any federal, state or local
law, statute or regulation (hereinafter, the "Released Matters"); provided,
however, that notwithstanding the foregoing, no Party releases any other Party
from any obligations, liabilities or claims arising under or in connection with
the performance of this Agreement, the Stock Purchase Agreement, the
Registration Rights Agreement or, after the date of this Agreement, the
Confidentiality Agreement. Each of the Parties shall refrain from asserting any
matter released or purported to be released hereby against the other Parties and
the other Parties' Releasees in any manner, including without limitation by way
of counterclaim, offset or defense.


                                      -2-


                  (b)      It is understood and agreed that the preceding
paragraph is a full and final release covering all known as well as unknown or
unanticipated debts, claims or damages of the Parties relating to or arising out
of the Merger Agreement, the Ancillary Agreements, the Higgins Employment
Agreement and the transactions contemplated by any of such agreements.
Therefore, each of the Parties expressly waives any rights it may have under
statute or common law principle under which a general release does not extend to
claims which such Party does not know or suspect to exist in its favor at the
time of executing the release, which if known by such Party must have affected
such Party's settlement with the other. In connection with such waiver and
relinquishment, the Parties acknowledge that they or their attorneys or agents
may hereafter discover claims or facts in addition to or different from those
which they now know or believe to exist with respect to the Released Matters,
but that it is their intention hereby fully, finally and forever to settle and
release all of the Released Matters. In furtherance of this intention, the
releases herein given shall be and remain in effect as full and complete mutual
releases with regard to the Released Matters notwithstanding the discovery or
existence of any such additional or different claim or fact.

         4.       Fees and Expenses. As was provided in Section 7.3(a) of the
Merger Agreement, NPS and Enzon shall share equally (i) all fees and expenses,
excluding attorneys' fees and expenses, which shall be paid for by the Party
incurring such expense but including accountants' fees and expenses, incurred in
relation to the printing and filing (with the SEC) of the Joint Proxy
Statement/Prospectus (including any preliminary materials related thereto) and
the Registration Statement (including financial statements and exhibits) and any
amendments or supplements thereto, (ii) the filing fee for the Notification and
Report Forms filed with the FTC and DOJ under the HSR Act, and pre-merger
notification and reports forms under similar applicable laws of other
jurisdictions, and (iii) reasonable attorneys' fees and expenses incurred in
connection with any foreign pre-merger filings. The Parties further acknowledge
that NPS and Enzon have each incurred additional expenses, including without
limitation attorneys' and accountants' fees and expenses, and fees and expenses
payable to their respective investment banks, which shall be paid for by the
Party incurring such expenses, in connection with the consummation of the
transactions contemplated by the Merger Agreement. In furtherance of the
foregoing with respect to fees and expenses that NPS and Enzon have agreed to
share, each of NPS and Enzon agree that (i) they shall accurately and completely
account to the other for all expenses that each of them has incurred for which
responsibility is to be shared pursuant to this Section 4 (a "Shared Expense"),
(ii) if either has paid or at any time pays more than fifty percent (50%) of any
Shared Expense, then such Party shall notify the other Party of such payment and
(iii) such other Party shall, within fifteen (15) days of its receipt of such
notice, reimburse to the notifying Party the appropriate amount so that both
Parties will have paid their share of each Shared Expense.

         5.       Confidentiality. The Parties acknowledge that Enzon and NPS
have previously executed a letter agreement effective December 18, 2002 (the
"Confidentiality Agreement"), which Confidentiality Agreement, including the
"Standstill" provisions in paragraph 7 therein (the "Standstill Provision"),
will continue in full force and effect in accordance with its terms and each of
NPS and Enzon will hold, and will cause its respective directors, officers,
Employees, agents and advisors (including attorneys, accountants, consultants,
bankers and financial advisors) to hold, any Evaluation Material (as defined in
the Confidentiality Agreement) confidential in accordance with the terms of the
Confidentiality Agreement. Notwithstanding the Standstill Provision, Enzon and
NPS acknowledge and agree that the negotiation and execution of this Agreement,
the Stock Purchase Agreement and the Registration Rights Agreement and NPS'
issuance of the Shares to Enzon pursuant to the Stock Purchase Agreement and the
completion of any other transactions contemplated by the Stock Purchase
Agreement and the Registration Rights Agreement and any transactions in which
Enzon may engage to hedge its position in the Shares it receives pursuant to the
Stock Purchase Agreement do not and will not cause a breach or violation of the
Standstill Provision by Enzon. In addition, as soon as practicable, but in no
event later than thirty (30) days from the date hereof, each of NPS and Enzon
shall (i) return to the other Party all copies of all Evaluation Material
received from such other Party and (ii) destroy all analyses, compilations,
summaries, studies and other materials prepared by it based in whole or in part
on, or otherwise containing or reflecting any of, the Evaluation Material
received from such other Party.


                                      -3-


         6.       Publicity. NPS and Enzon will issue a joint press release in
the form attached hereto as Exhibit B (the "Initial Release") upon the signing
of this Agreement with respect to this Agreement and the termination of the
Merger Agreement and the Ancillary Agreements. Except as required by law or
applicable listing agreement, no Party shall issue any other press release or
make any public announcement or statement relating to the termination of the
Merger Agreement or execution of this Agreement prior to the issuance of the
Initial Release or at any time thereafter that is inconsistent with the Initial
Release.

         7.       Further Assurances. Each Party agrees to cooperate fully with
the other Parties and to execute such further instruments, documents and
agreements and to give such further written assurances as may be reasonably
requested by any other Party to evidence and reflect the transactions described
in this Agreement and to carry into effect the intents and purposes of this
Agreement. Without limiting the foregoing, the Parties shall (a) cooperate with
each other and promptly prepare and file all necessary documentation to withdraw
all applications, including without limitation Momentum's listing application
with The NASDAQ National Market, notices, petitions and filings made with, and
shall use their reasonable efforts to terminate any proceedings before, any
Governmental Authority, including without limitation the SEC, in connection with
the Merger Agreement and (b) cooperate with each other to promptly wind up the
affairs of, and to dissolve under the laws of the State of Delaware, Momentum,
Einstein and Newton.

         8.       Representations and Warranties. Each of the Parties represents
and warrants to the other Parties that (a) such Party has all requisite legal
and corporate power and authority to execute, deliver and perform its
obligations under this Agreement; (b) all corporate action on the part of such
Party, its directors, officers and stockholders necessary for the authorization,
execution, delivery and performance of this Agreement by such Party has been
taken; and (c) this Agreement constitutes a valid and binding obligation of such
Party, enforceable against such Party in accordance with its terms, subject to
laws of general application relating to bankruptcy, insolvency and the relief of
debtors and rules of law governing specific performance, injunctive relief or
other equitable remedies.

         9.       Miscellaneous.

                  (a)      No Assignment; Binding Effect. Neither this Agreement
nor any right, interest or obligation hereunder may be assigned by any Party
hereto without the prior written consent of the other Parties hereto and any
attempt to do so shall be void, except for assignments and transfers by
operation of law. Subject to the preceding sentence, this Agreement is binding
upon, inures to the benefit of and is enforceable by and upon the Parties and
their respective successors and assigns.


                                      -4-


                  (b)      Amendment. This Agreement may be amended,
supplemented or modified by a written instrument duly executed by NPS and Enzon.
Any such amendment, supplement, or modification shall be binding upon all of the
Parties.

                  (c)      Notices. All notices and other communications
required or permitted hereunder shall between Enzon and NPS be in writing and
shall be mailed by registered or certified mail, postage prepaid by hand, by
messenger or by overnight courier, addressed:

                           (i)      if to Enzon, to:

                                    Enzon Pharmaceuticals, Inc.
                                    685 Route 202/206
                                    Bridgewater, New Jersey 08807
                                    Attention: Chief Executive Officer

                                    Or at such other address as Enzon shall have
furnished to NPS, with a copy to:

                                    Dorsey & Whitney LLP
                                    250 Park Avenue
                                    New York, New York 10177-1500
                                    Attention: Kevin T. Collins

                           (ii)     if to NPS, to:

                                    NPS Pharmaceuticals, Inc.
                                    420 Chipeta Way
                                    Salt Lake City, Utah 84108
                                    Attention: General Counsel

                                    Or as such address as NPS shall have
furnished to Enzon, with a copy to:

                                    Wilson Sonsini Goodrich & Rosati,
                                    Professional Corporation
                                    2795 East Cottonwood Parkway, Suite 300
                                    Salt Lake City, Utah 84121
                                    Attention: Robert G. O'Connor, Esq.

                           (iii)    Each such notice or other communication
shall for all purposes of this Agreement be treated as effective or having been
given when actually delivered as provided above, if delivered personally or by
messenger, or, on the day shown on the return receipt, if sent by mail or other
delivery service.


                                      -5-


                  (d)      Entire Agreement. This Agreement supercedes all prior
discussions, representations, warranties and agreements, both written and oral,
among the Parties with respect to the subject matter hereof, and contains the
sole and entire agreement among the Parties with respect to the subject matter
hereof, other than the Confidentiality Agreement.

                  (e)      Governing Law. This Agreement shall be governed by
and construed in accordance with the laws of the State of Delaware, regardless
of the laws that might otherwise govern under applicable principles of conflicts
of law thereof.

                  (f)      Remedies. In the event of any breach or default of
this Agreement, the non-breaching Party shall have all rights and remedies
provided by law and equity to enforce this Agreement, including, without
limitation, an action for damages and to obtain specific performance of the
terms of this Agreement.

                  (g)      Submission to Jurisdiction. Each of the Parties
irrevocably agrees that any legal action or proceeding with respect to this
Agreement or for recognition and enforcement of any judgment in respect hereof
brought by an other Party hereto or its successors or assigns may be brought and
determined in the Chancery or other Courts of the State of Delaware, and each of
the Parties hereby irrevocably submits with regard to any such action or
proceeding for itself and in respect to it property, generally and
unconditionally, to the nonexclusive jurisdiction of the aforesaid courts.

                  (h)      Severability. In the event that any provision of this
Agreement or the application thereof, becomes or is declared by a court of
competent jurisdiction to be illegal, void or unenforceable, the remainder of
this Agreement will continue in full force and effect and the application of
such provision to other persons or circumstances will be interpreted so as
reasonably to effect the intent of the Parties. The Parties further agree to
replace such void and unenforceable provision of this Agreement with a valid and
enforceable provision that will achieve, to the greatest extent possible, the
economic, business and other purposes of such void or unenforceable provision.

                  (i)      Rules of Construction. The Parties agree that they
have been represented by counsel during the negotiation and execution of this
Agreement and, therefore, waive the application of any Legal Requirement or rule
of construction providing that ambiguities in an agreement or other document
will be construed against the Party drafting such agreement or document.

                  (j)      Waiver of Jury Trial. EACH PARTY HEREBY IRREVOCABLY
WAIVES ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM
(WHETHER BASED ON CONTRACT, TORT OR OTHERWISE) ARISING OUT OF OR RELATING TO
THIS AGREEMENT OR THE ACTIONS OF MOMENTUM, NPS, ENZON, NEWTON, OR EINSTEIN IN
THE NEGOTIATION, ADMINISTRATION, PERFORMANCE AND ENFORCEMENT HEREOF.


                                      -6-


                  (k)      Counterparts. This Agreement may be executed in one
or more counterparts, all of which shall be considered one and the same
agreement and shall become effective when one or more counterparts have been
signed by each of the Parties and delivered to the other Parties, it being
understood that all Parties need not sign the same counterpart.

                  (l)      Third Party Beneficiaries. There are no third Party
beneficiaries to this Agreement except for the Parties' Releasees and the
Parties to the Ancillary Agreements that are not Parties to this Agreement



                           [Signature page follows.]


                                      -7-


         IN WITNESS WHEREOF, NPS, Enzon, Momentum, Newton and Einstein have
caused this Agreement to be duly executed as of the date first above written by
their respective officers duly authorized.

                                             NPS PHARMACEUTICALS, INC.


                                             By: /s/ Hunter Jackson
                                                 -------------------------------


                                             Name: Hunter Jackson
                                                   -----------------------------

                                             Its: President and CEO
                                                  ------------------------------


                                             ENZON PHARMACEUTICALS, INC.


                                             By: /s/ Arthur J. Higgins
                                                 -------------------------------


                                             Name: Arthur J. Higgins
                                                   -----------------------------

                                             Its: Chairman, President and CEO
                                                  ------------------------------


                                             MOMENTUM MERGER CORPORATION


                                             By: /s/ Hunter Jackson
                                                 -------------------------------


                                             Name: Hunter Jackson
                                                   -----------------------------

                                             Its: Executive Chairman
                                                  ------------------------------




          [Signature Page to Mutual Termination and Release Agreement]




                                             NEWTON ACQUISITION CORPORATION


                                             By: /s/ Hunter Jackson
                                                 -------------------------------


                                             Name: Hunter Jackson
                                                   -----------------------------

                                             Its: President and CEO
                                                  ------------------------------



                                             EINSTEIN ACQUISITION CORPORATION


                                             By: /s/ Arthur J. Higgins
                                                 -------------------------------


                                             Name: Arthur J. Higgins
                                                   -----------------------------

                                             Its: President and CEO
                                                  ------------------------------




          [Signature Page to Mutual Termination and Release Agreement]




                                   EXHIBIT A

                      Restricted Stock Purchase Agreement



                                   EXHIBIT B

                              Joint Press Release

                                                                       Exhibit 4


                           NPS PHARMACEUTICALS, INC.

                      RESTRICTED STOCK PURCHASE AGREEMENT


         This RESTRICTED STOCK PURCHASE AGREEMENT (this "Agreement") is made as
of June 4, 2003, by and between NPS Pharmaceuticals, Inc., a Delaware
corporation (the "Company"), and Enzon Pharmaceuticals, Inc., a Delaware
corporation (the "Purchaser").

                                    RECITALS

         A.       The Company and the Purchaser are parties to that certain
Mutual Termination and Release Agreement, dated of even date herewith (the
"Termination Agreement").

         B.       The obligations of the Company and the Purchaser under the
Termination Agreement are conditioned in part upon the execution and delivery of
this Agreement.

         C.       Pursuant to the Termination Agreement, the Company agreed to
issue shares of its common stock pursuant to the terms provided in this
Agreement.

         D.       Pursuant to the Termination Agreement, the Company has also
agreed to provide certain registration rights relating to such shares as
contained in that certain Registration Rights Agreement, to be executed and
delivered herewith, by and between the Company and the Purchaser (the
"Registration Rights Agreement").

                                    AGREEMENT

         NOW THEREFORE, in consideration of the Company and the Purchaser
entering into the Termination Agreement and the Registration Rights Agreement,
the mutual covenants and agreements set forth in this Agreement, and for other
good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the Company and the Purchaser, intending to be legally bound,
agree as follows:

         1.       Common Stock Purchase.

                  1.1      Purchase. Subject to the terms and conditions of this
Agreement, the Company will sell to the Purchaser, and the Purchaser will
purchase from the Company One Million Five Hundred Thousand (1,500,000) shares
(the "Shares") of the Company's Common Stock, par value $0.001 per share
("Common Stock"), in consideration of the Purchaser executing and delivering the
Termination Agreement and performing its obligations thereunder.

                  1.2      Closing Date. The purchase and sale of the Shares
shall be consummated at a closing (the "Closing") held at the offices of Wilson
Sonsini Goodrich & Rosati, Professional Corporation, 2795 East Cottonwood
Parkway, Suite 300, Salt Lake City, Utah, 84121 on June 4, 2003, at 3:30 p.m.,
local time, or at such other date, time and place upon which the Company and the
Purchaser shall agree (the "Closing Date").



                  1.3      Delivery. On the Closing Date, the Company shall
deliver to the Purchaser a certificate (or other electronic evidence)
representing the Shares (issued in the Purchaser's name) after receipt of the
Termination Agreement executed by the Purchaser.

         2.       Representations and Warranties of the Company. In connection
with the sale of the Shares, the Company represents and warrants to the
Purchaser that as of the date hereof:

                  2.1      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, under such laws. The
Company has requisite corporate power and authority to own and operate its
properties and assets and to carry on its business as presently conducted. The
Company is presently qualified to do business as a foreign corporation, and is
in good standing in those jurisdictions in which the nature of its business and
properties makes such qualification necessary and in which the failure to be so
qualified would have a material adverse effect on the business or financial
condition of the Company.

                  2.2      Corporate Power. The Company has all requisite legal
and corporate power and authority to execute, deliver and perform its
obligations under this Agreement and the Registration Rights Agreement and to
sell and issue the Shares hereunder.

                  2.3      Authorization. All corporate action on the part of
the Company, its directors and stockholders necessary for the authorization,
execution, delivery and performance of this Agreement and the Registration
Rights Agreement by the Company and the authorization, sale, issuance and
delivery of the Shares has been taken or will be taken prior to the Closing
Date. This Agreement and the Registration Rights Agreement constitutes valid and
binding obligations of the Company, enforceable in accordance with their terms,
subject to laws of general application relating to bankruptcy, insolvency and
the relief of debtors and rules of law governing specific performance,
injunctive relief or other equitable remedies. The Shares, when issued in
compliance with the provisions of this Agreement, will be validly issued, fully
paid and nonassessable, and the Shares will be free of any liens or encumbrances
other than any liens or encumbrances created by or imposed upon the holders;
provided, however, that the Shares may be subject to restrictions on transfer
under state or federal securities laws and restrictions set forth in the
Registration Rights Agreement.

                  2.4      Capitalization.

                           (a)      Immediately prior to the Closing, the
authorized capital stock of the Company consists of (i) 45,000,000 shares of
Common Stock and (ii) 5,000,000 shares of preferred stock, par value $0.001
("Preferred Stock") none of which are issued and outstanding. As of June 3,
2003, 35,196,259 shares of Common Stock were issued and outstanding (which
included 310,785 shares of NPS Allelix Inc., a wholly owned Canadian subsidiary
of the Company, which are exchangeable into shares of Common Stock). All of the
outstanding shares of capital stock of NPS are duly authorized and validly
issued, fully paid and nonassessable and not subject to any preemptive rights.


                                      -2-


                  2.5      Approvals. No authorization, approval or consent of
any court, governmental body, regulatory agency, self-regulatory organization,
or stock exchange or market or third party is required to be obtained by the
Company for the issuance and sale of the Shares to the Purchaser as contemplated
by this Agreement, except for notices and filings with the Nasdaq National
Market and such other authorizations, approvals and consents that have been
obtained.

                  2.6      Offering. Subject to the accuracy of the Purchaser's
representations in Section 3, the offer, sale and issuance of the Shares
constitutes a transaction exempt from the registration requirements of Section 5
of the Securities Act of 1933, as amended (the "Securities Act").

                  2.7      NASDAQ Listing Requirements. NPS is in compliance
with its listing agreement with The NASDAQ National Market, fully satisfies all
continued listing requirements of The NASDAQ National Market and is not aware of
any facts or circumstances that could reasonably be expected to result in a
violation of its listing agreement or such continued listing requirements and
has received no notice from The NASDAQ National Market of any such violation.

                  2.8      Non-Contravention. The execution and delivery of this
Agreement by NPS does not, and performance of this Agreement by NPS will not:
(i) conflict with or violate NPS' certificate of incorporation or bylaws or the
certificate of incorporation or bylaws of any subsidiary of NPS or (ii) conflict
with or violate any material order or decree of any court or governmental
authority.

                  2.9      Form S-3 Eligibility. NPS is currently eligible to
use Form S-3 to register the resale of the Shares. The Form S-3 Registration
Statement and the Prospectus (as such terms are defined in the Registration
Rights Agreement) will comply with the requirements of applicable law and will
not contain any untrue statement of a material fact or omit to state any
material fact required to be stated therein or necessary to make the statements
therein not misleading in light of the circumstances under which they are made.

                  2.10     Brokers' and Finders' Fees. With respect to or in
connection with the transactions contemplated in this Agreement, the Purchaser
will have no liability to any broker, finder or other third party acting on the
behalf of NPS.

         3.       Representations and Warranties of the Purchaser. In connection
with the acquisition of the Shares, the Purchaser represents and warrants to the
Company as of the date hereof:

                  3.1      Accredited Investor. It is an "accredited investor,"
as such term is defined in Section (2)(a)(15) of the Securities Act.

                  3.2      Preexisting Relationship with Company; Business and
Financial Experience. By reason of its business or financial experience or the
business or financial experience of its professional advisors who are
unaffiliated with the Company and who are not compensated by the Company, it has
the capacity to protect its own interests in connection with the purchase of the
Shares.


                                      -3-


                  3.3      Investment Intent; Blue Sky. It is acquiring the
Shares for investment for its own account, not as a nominee or agent, and not
with a view to, or for resale in connection with, any distribution thereof. It
understands that the issuance of the Shares has not been, and will not be,
registered under the Securities Act by reason of a specific exemption from the
registration provisions of the Securities Act, the availability of which depends
upon, among other things, the bona fide nature of the Purchaser's investment
intent and the accuracy of the Purchaser's representations as expressed herein.
The Purchaser's address set forth on the signature page attached hereto
represents the Purchaser's true and correct state of domicile, upon which the
Company may rely for the purpose of complying with applicable "blue sky" laws.

                  3.4      Rule 144. It acknowledges that the Shares must be
held indefinitely unless subsequently registered under the Securities Act or
unless an exemption from such registration is available. It is aware of the
provisions of Rule 144 promulgated under the Securities Act which permit limited
resale of shares purchased in a private placement subject to the satisfaction of
certain conditions, including, among other things, the existence of a public
market for the shares, the availability of certain current public information
about the Company, the resale occurring not less than one year after a party has
purchased and paid for the security to be sold, the sale being effected through
a "broker's transaction" or in a transaction directly with a "market maker," and
the number of shares being sold during any three-month period not exceeding
specified limitations.

                  3.5      Restrictions on Transfer; Restrictive Legends. It
understands that the transfer of the Shares is restricted by applicable state
and federal securities laws and by the provisions of the Registration Rights
Agreement, and that all certificates representing the Shares will be imprinted
with legends restricting transfer except in compliance therewith.

                  3.6      Authorization. All action on the part of the
Purchaser's board of directors and stockholders, as applicable, necessary for
the authorization, execution, delivery and performance of this Agreement and the
Registration Rights Agreement by the Purchaser, the purchase of and payment for
the Shares and the performance of all of the Purchaser's obligations under this
Agreement and the Registration Rights Agreement has been taken or will be taken
prior to the Closing Date. This Agreement and the Registration Rights Agreement,
when executed and delivered by the Purchaser, shall constitute valid and binding
obligations of the Purchaser, enforceable in accordance with their terms,
subject to laws of general application relating to bankruptcy, insolvency and
the relief of debtors and rules of law governing specific performance,
injunctive relief or other equitable remedies.

                  3.7      Risks. Purchaser understands that the purchase of the
Shares involves risk. Purchaser acknowledges that that it is able to fend for
itself in the transactions contemplated by this Agreement and has the ability to
bear the economic risks of its investment pursuant to this Agreement and has
such knowledge and experience in financial or business matters that it is
capable of evaluating the merits and risks of this investment in the Shares and
protecting its own interests in connection with this investment. Purchaser
acknowledges that in making its investment decision Purchaser has relied solely
on its review of the information contained in publicly available information,
including but not limited to the Company's filings with the Securities and
Exchange Commission and has not relied on any prior discussions or
correspondence between the Parties resulting from their pre-existing business
relationship. Purchaser further acknowledges that in making its investment
decision Purchaser is not using or relying upon any non-public or confidential
information of the Company.


                                      -4-


         4.       Conditions to Closing.

                  4.1      Purchaser's Conditions to Closing. The Purchaser's
obligation to purchase the Shares is, unless waived in writing by the Purchaser,
subject to the fulfillment of the following conditions:

                           (a)      Representations Correct. The representations
and warranties made by the Company in Section 2 hereof shall be true and correct
in all material respects.

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

                           (c)      Consents. No consent, approval order or
authorization of or registration, qualification, designation, declaration or
filing with any governmental authority shall be required in connection with the
sale or issuance of the Shares.

                           (d)      Registration Rights Agreement. The Company
shall have executed and delivered to the Purchaser the Registration Rights
Agreement substantially in the form attached hereto as Exhibit A.

                           (e)      Mutual Termination and Release Agreement.
The Company shall have executed and delivered to the Purchaser the Termination
Agreement.

                  4.2      Company's Conditions to Closing. The Company's
obligation to sell and issue the Shares is, unless waived in writing by the
Company, subject to the fulfillment of the following conditions:

                           (a)      Representations Correct. The representations
and warranties made by the Purchaser in Section 3 hereof shall be true and
correct in all material respects.

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

                           (c)      Consents. No consent, approval order or
authorization of or registration, qualification, designation, declaration or
filing with any governmental authority shall be required in connection with the
sale or issuance of the Shares to the Purchaser.

                           (d)      Registration Rights Agreement. The Purchaser
shall have executed and delivered to the Company the Registration Rights
Agreement.


                                      -5-


                           (e)      Mutual Termination and Release Agreement.
The Purchaser shall have executed and delivered to the Company the Termination
Agreement.

         5.       Miscellaneous.

                  5.1      Amendment. Except as otherwise provided above, any
provision of this Agreement may be amended or the observance thereof may be
waived (either generally or in a particular instance and either retroactively or
prospectively), only with the written consent of the Company and the Purchaser.

                  5.2      Governing Law. This Agreement shall be governed in
all respects by the laws of the State of Delaware, without regard to conflict of
laws provisions. Each of the parties hereto irrevocably agrees that any legal
action or proceeding with respect to this Agreement or for recognition and
enforcement of any judgment in respect hereof brought by any other party hereto
or its successors or assigns may be brought and determined in the Chancery or
other Courts of the State of Delaware, and each of the parties hereto hereby
irrevocably submits with regard to any such action or proceeding for itself and
in respect to its property, generally and unconditionally, to the non-exclusive
jurisdiction of the aforesaid courts.

                  5.3      Entire Agreement. This Agreement, the Registration
Rights Agreement, the letter agreement dated December 18, 2002 between the
Company and the Purchaser (the "Confidentiality Agreement") and the Termination
Agreement and the Annexes, Exhibits and Schedules attached hereto and thereto
and delivered in connection herewith and therewith, as the case may be,
constitute the full and entire understanding and agreement among the parties
regarding the matters set forth herein. The provisions hereof shall inure to the
benefit of, and be binding upon the successors, permitted assigns, heirs,
executors and administrators of the parties hereto.

                  5.4      Notices. All notices and other communications
required or permitted hereunder shall be in writing and shall be mailed by
registered or certified mail, postage prepaid, by hand, by messenger or by
overnight courier, addressed:

                           (a)      if to the Purchaser, to:

                                    Enzon Pharmaceuticals, Inc.
                                    685 Route 202/206
                                    Bridgewater, New Jersey  08807
                                    Attention:  Chief Executive Officer

                                    or at such other address as the Purchaser
shall have furnished to the Company, with a copy to:

                                    Dorsey & Whitney LLP
                                    250 Park Avenue
                                    New York, New York 10177-1500
                                    Attention: Kevin T. Collins


                                      -6-


                           (b)      if to the Company, to:

                                    NPS Pharmaceuticals, Inc.
                                    420 Chipeta Way
                                    Salt Lake City, UT  84108
                                    Attention:  General Counsel

                                    or at such other address as the Company
shall have furnished to the Purchaser, with a copy to:

                                    Wilson Sonsini Goodrich & Rosati,
                                    Professional Corporation
                                    2795 East Cottonwood Parkway
                                    Suite 300
                                    Salt Lake City, UT  84121
                                    Attn:  Robert G. O'Connor, Esq.

         Each such notice or other communication shall for all purposes of this
Agreement be treated as effective or having been given when actually delivered
as provided above, if delivered personally or by messenger, or, on the day shown
on the return receipt, if sent by mail or other delivery service.

                  5.5      Successors and Assigns. Each party's rights and
benefits of this Agreement shall inure to the benefit of, and be enforceable by,
such party's permitted successors and assigns. The rights and obligations of the
Purchaser under this Agreement may only be assigned with the prior written
consent of the Company. The rights and obligations of the Company under this
Agreement may only be assigned with the prior written consent of the Purchaser.

                  5.6      Further Actions. Both parties agree to execute any
additional documents and take such further action as may be reasonably necessary
to carry out the purposes of this Agreement.

                  5.7      Injunctive Relief. Each party hereto agrees that the
other party shall be entitled to a decree of specific performance of the terms
hereof or an injunction restraining violations of this Agreement, such right to
be in addition to any of the remedies of the Company. No remedy provided herein
is intended to be exclusive of any other remedy, and each and every remedy shall
be cumulative and shall be in addition to every other remedy given hereunder or
now or hereafter existing at law or in equity.

                  5.8      Severability. In the event that any provision of this
Agreement or the application thereof, becomes or is declared by a court of
competent jurisdiction to be illegal, void or unenforceable, the remainder of
this Agreement will continue in full force and effect and the application of
such provision to other persons or circumstances will be interpreted so as
reasonably to effect the intent of the parties hereto. The Parties further agree
to replace such void and unenforceable provision of this Agreement with a valid
and enforceable provision that will achieve, to the greatest extent possible,
the economic, business and other purposes of such void or unenforceable
provision.


                                      -7-


                  5.9      Expenses. Each party hereto shall pay its own
expenses incurred (including, without limitation, the fees of counsel) on its
behalf in connection with this Agreement or any transactions contemplated by
this Agreement.

                  5.10     Waivers. No waiver of any provision of this Agreement
or any rights or obligations of any party hereunder shall be effective, except
pursuant to a written instrument signed by the party or parties waiving
compliance, and any such waiver shall be effective only in the specific instance
and for the specific purpose stated in such writing.

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

                  5.12     "Standstill" Provisions in Confidentiality Agreement.
Notwithstanding the "standstill" provisions of Section 7 of the Confidentiality
Agreement, the Company and the Purchaser acknowledge and agree that the
negotiation and execution of the Termination Agreement, this Agreement and the
Registration Rights Agreement and the Company's issuance of the Shares to the
Purchaser pursuant to this Agreement and the completion of any other
transactions contemplated herein and in the Registration Rights Agreement and
any transactions in which the Purchaser may engage to hedge its position in the
Shares it receives pursuant to this Agreement do not and will not cause a breach
or violation of such standstill provisions by the Purchaser.



                 (Remainder of page intentionally left blank.)


                                      -8-


         IN WITNESS WHEREOF, the parties hereto have executed this Restricted
Stock Purchase Agreement as of the date first written above.



COMPANY:                                    PURCHASER:

NPS PHARMACEUTICALS, INC.                   ENZON PHARMACEUTICALS, INC.




By: /s/ Hunter Jackson                      By: /s/ Arthur J. Higgins
    -------------------------------             --------------------------------

Name: Hunter Jackson                        Name: Arthur J. Higgins
      -----------------------------               ------------------------------


Its: President and CEO                      Its: Chairman, President and CEO
     ------------------------------              -------------------------------




                                   Exhibit A

                         Registration Rights Agreement

                                                                       Exhibit 5


                           NPS PHARMACEUTICALS, INC.

                         REGISTRATION RIGHTS AGREEMENT

         This Registration Rights Agreement (this "Agreement") is made effective
as of June 4, 2003 (the "Closing Date") by and between NPS Pharmaceuticals,
Inc., a Delaware corporation (the "Company"), and Enzon Pharmaceuticals, Inc., a
Delaware corporation (the "Holder").

                                    RECITALS

         A.       The Company and the Holder have entered into a Restricted
Stock Purchase Agreement, dated as of the date hereof (the "Purchase
Agreement"), whereby the Holder will purchase shares of the Company's Common
Stock.

         B.       The Company is entering into this Agreement to provide
liquidity to Holder following Holder's acquisition of the shares of the
Company's Common Stock.

                                   AGREEMENT

         NOW, THEREFORE, in consideration of the mutual promises and covenants
contained herein, the receipt and sufficiency of which are hereby acknowledged,
the parties hereto agree as follows:

         1.       Certain Definitions. As used in this Agreement, the terms
below shall have the following respective meanings:

                  "Commission" means the Securities and Exchange Commission or
any other federal agency at the time administering the Securities Act.

                  "Exchange Act" means the Securities Exchange Act of 1934, as
amended, or any similar federal rule or statute and the rules and regulations of
the Commission thereunder, all as the same shall be in effect at the time.

                  "Form S-3 Registration Statement" means a registration
statement of the Company, on Form S-3 or any successor form filed by the Company
pursuant to this Agreement permitting registration of the Registrable Securities
for resale by the Holder (and in the event that pursuant to the Securities Act
the Company is unable to use Form S-3 (or any successor form), another
appropriate form permitting registration of the Registrable Securities for
resale by the Holder).

                  "Prospectus" means the prospectus included in a Form S-3
Registration Statement (including without limitation, a prospectus that
discloses information previously omitted from a prospectus filed as a part of an
effective Registration Statement in reliance upon Rule 430A promulgated under
the Securities Act), as amended or supplemented by amendment or prospectus
supplement, including post-effective amendments, and all materials incorporated
by reference or explicitly deemed to be incorporated by reference in such
prospectus.



                  "Registrable Securities" means the shares of the Company's
Common Stock purchased by Holder under the Purchase Agreement, or issuable in
respect thereof upon any conversion, stock split, stock dividend,
recapitalization, merger or other reorganization; provided, however, that
securities shall only be treated as Registrable Securities if and so long as
they have not been registered or sold to or through a broker or dealer or
underwriter in a public distribution or a public securities transaction.

                  "Register," "registered" and "registration" refer to a
registration effected by preparing and filing a registration statement in
compliance with the Securities Act, and the declaration or ordering of the
effectiveness of such registration statement.

                  "Registration Expenses" means all expenses, except Selling
Expenses, incurred by the Company in complying with Section 5 hereof, including
without limitation, all registration, qualification and filing fees, printing
expenses, reasonable fees and disbursements of counsel for the Company, blue sky
fees and expenses, the expense of any special audits incident to or required by
any such registration.

                  "Securities Act" means the Securities Act of 1933, as amended,
or any similar federal rule or statute and the rules and regulations of the
Commission thereunder, all as the same shall be in effect at the time.

                  "Selling Expenses" means (i) all underwriting discounts,
selling commissions and stock transfer taxes applicable to the securities
registered by the Holder and (ii) all fees and disbursements of counsel for the
Holder.

                  "Transfer" means a transfer or disposition, including but not
limited to by way of sale, assignment, encumberance, hypothecation, pledge,
conveyance, gift, or transfer.

         2.       Restrictions on Transferability.

                  (a)      The Registrable Securities shall not be Transferred,
except upon the conditions specified in this Agreement. The Holder will cause
any transferee who receives the Registrable Securities in a Transfer other than
a sale pursuant to (i) an effective registration statement under the Securities
Act or (ii) Rule 144 under the Securities Act to assume in writing the
obligations and restrictions of the Holder under this Agreement, including
without limitation the restrictions set forth in Section 4 (a "Permitted
Transferee").

                  (b)      Standstill. Each of the Company and the Holder hereby
acknowledge that the Company and the Holder have previously executed a letter
agreement, effective December 18, 2002 (the "Confidentiality Agreement"), under
which each of the Company and the Holder agreed to certain "standstill"
provisions in Section 7 therein regarding the acquisition of securities or
control of the other. Each of the Company and the Holder acknowledge that the
Confidentiality Agreement, including the "standstill" provisions under Section 7
therein, continues in full force and effect in accordance with its terms.
Notwithstanding the "standstill" provisions in the Confidentiality Agreement,
the Company and the Holder acknowledge and agree that the negotiation and
execution of the Mutual Termination and Release Agreement dated of even date
herewith between the Company and the Holder, the Purchase Agreement and this
Agreement and the Company's issuance of shares of its Common Stock to the Holder
pursuant to the Purchase Agreement and the completion of any other transactions
contemplated therein and in this Agreement and any transactions in which the
Holder may engage to hedge its position in the shares of Common Stock it
receives pursuant to the Purchase Agreement do not and will not cause a breach
or violation of such standstill provisions by the Holder.


                                      -2-


                  (c)      Volume Limitation on Sales. The Holder hereby agrees
and covenants that after the Form S-3 Registration Statement is declared
effective by the Commission (the "Effective Date") the Holder may Transfer no
more than 125,000 shares (as appropriately adjusted for stock splits, stock
dividends, combinations and similar events) of Registrable Securities in each
monthly period after the Effective Date, however, any shares of Registrable
Securities not Transferred in preceding monthly periods, which could have been
Transferred under the volume limits of this Section 2(c), may be accumulated and
Transferred subsequently provided, however, that in no instance may the Holder
Transfer more than 375,000 shares of Registrable Securities in any one (1) month
period. The Holder hereby acknowledges and agrees that the Company may place
stop transfer restrictions on the Registrable Securities where such Transfer
would exceed the volume limitations in the preceding sentence. In calculating
the volume limitations of this Section 2(c), Transfers by the Holder shall be
aggregated with any Transfers by Permitted Transferees. The limitations of this
Section 2(c) shall cease to be effective if the Company consummates a
Controlling Acquisition. For the purposes of this Section 2, the term
"Controlling Acquisition" means, with reference to the Company, any of the
following transactions: (i) a merger, consolidation, business combination,
recapitalization, liquidation, dissolution or similar transaction involving the
Company pursuant to which the stockholders of the Company immediately preceding
such transaction hold less than sixty percent (60%) of the aggregate equity
interests in the surviving or resulting entity of such transaction or any direct
or indirect parent thereof, (ii) a sale or other disposition by the Company of
assets representing in excess of forty percent (40%) of the aggregate fair
market value of the Company's business immediately prior to such sale, or (iii)
the acquisition by any Person or group (including by way of a tender offer or an
exchange offer or issuance by the Company or such Person or group), directly or
indirectly, of beneficial ownership or a right to acquire beneficial ownership
of shares representing in excess of forty percent (40%) of the voting power of
the then outstanding shares of capital stock of the Company.

         3.       Restrictive Legends. Each certificate representing the
Registrable Securities shall be stamped or otherwise imprinted with the
following or similar legends:

                  THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED
                  UNDER THE SECURITIES ACT OF 1933, AS AMENDED. SUCH SECURITIES
                  MAY NOT BE TRANSFERRED UNLESS A REGISTRATION STATEMENT UNDER
                  SAID ACT IS IN EFFECT AS TO SUCH TRANSFER OR, IN THE OPINION
                  OF COUNSEL SATISFACTORY TO THE ISSUER, SUCH TRANSFER MAY BE
                  MADE WITHOUT REGISTRATION UNDER SAID ACT.


                                      -3-


                  THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO
                  RESTRICTIONS SET FORTH IN A REGISTRATION RIGHTS AGREEMENT TO
                  WHICH THE ORIGINAL HOLDER OF THESE SHARES WAS A PARTY, A COPY
                  OF WHICH MAY BE OBTAINED AT THE PRINCIPAL OFFICE OF THE
                  COMPANY. SUCH RESTRICTIONS ARE BINDING ON TRANSFEREES OF THESE
                  SHARES.

The Holder consents to the making of a notation by the Company on its records
and giving instructions to any transfer agent of its capital stock in order to
implement the restrictions on transfer established in this Agreement.

         4.       Notice of Proposed Transfers. The Holder agrees to comply in
all respects with the provisions of this Agreement. Without in any way limiting
the immediately preceding sentence or the provisions of Section 2, no sale,
assignment, transfer or pledge (other than (i) a sale made pursuant to a
registration statement filed under the Securities Act and declared effective by
the Commission for which no stop order has been issued and is then existing or
(ii) a sale made in accordance with the applicable provisions of Rule 144) of
Registrable Securities shall be made by the Holder to any person unless such
person shall first agree in writing to be bound by the restrictions of this
Agreement, including without limitation this Section 4. Prior to any proposed
sale, assignment, transfer or pledge of any Registrable Securities, unless there
is in effect a registration statement under the Securities Act covering the
proposed transfer or such sale is made pursuant to Rule 144, the holder thereof
shall give written notice to the Company of such holder's intention to effect
such transfer, sale, assignment or pledge. Each such notice shall describe the
manner and circumstances of the proposed transfer, sale, assignment or pledge in
reasonable detail, and, if requested by the Company, the holder shall also
provide, at such holder's expense, a written opinion of legal counsel (who shall
be, and whose legal opinion shall be, reasonably satisfactory to the Company)
addressed to the Company, to the effect that the proposed transfer of the
Registrable Securities may be effected without registration under the Securities
Act and under applicable state securities laws and regulations. Upon delivery to
the Company of such notice and, if required, such opinion, the holder of such
Registrable Securities shall be entitled to transfer such Registrable Securities
in accordance with the terms of such notice. The Company agrees that it shall
not request such an opinion of counsel with respect to (i) a transfer not
involving a change in beneficial ownership or (ii) a transaction involving the
transfer without consideration of Registrable Securities by an individual holder
during such holder's lifetime by way of gift or on death by will or the laws of
descent and distribution. Each certificate evidencing the Registrable Securities
transferred as above provided shall bear, except if such transfer is made
pursuant to Rule 144 or pursuant to an effective registration statement, the
appropriate restrictive legend set forth in Section 3 above, except that such
certificate shall not bear such restrictive legend if, in the opinion of counsel
for such Holder and counsel for the Company, such legend is not required in
order to establish or ensure compliance with the provisions of the Securities
Act and this Agreement.


                                      -4-


         5.       Registration on Form S-3.

                  (a)      Registration. The Company shall use commercially
reasonable efforts to file with the Commission a Form S-3 Registration Statement
covering all Registrable Securities within thirty (30) days after the Closing
Date (the "Filing Deadline Date"). The Company shall use its commercially
reasonable efforts to cause such Form S-3 Registration Statement to be filed and
declared effective within ninety (90) days following the Closing Date (the
"Effectiveness Deadline Date"). The Company shall use its commercially
reasonable efforts to keep such Form S-3 Registration Statement effective until
the earlier of (i) the date all Registrable Securities then held by the Holder
represents less than one percent (1%) of the total issued and outstanding shares
of the Common Stock of the Company or (ii) the date all Registrable Securities
then held by the Holder may be sold pursuant to Rule 144(k) (the "Effective
Period").

                  (b)      Limitations on Registration and Sale of Registrable
Securities. Notwithstanding anything in this Agreement to the contrary, the
Company's obligations and the Holder's rights under this Section 5 are subject
to the limitations and qualifications set forth below, which may be waived in
writing by the Company.

                           (i)      The Company shall have no obligation to keep
effective a registration statement hereunder following the Effective Period.

                           (ii)     Upon (i) the issuance by the Commission of a
stop order suspending the effectiveness of the Form S-3 Registration Statement
or the initiation of proceedings with respect to the Form S-3 Registration
Statement, (ii) the occurrence of any event or the existence of any fact or
circumstance as a result of which the Form S-3 Registration Statement shall
contain any untrue statement of a material fact or omit to state any material
fact required to be stated therein or necessary to make the statements therein
not misleading, or any Prospectus shall contain any untrue statement of a
material fact or omit to state any material fact required to be stated therein
or necessary to make the statements therein, in the light of the circumstances
under which they were made, not misleading (a "Material Event"), or (iii) the
occurrence, existence or pendency of any corporate development that, in the
reasonable discretion of the Company, makes it detrimental to the Company for
the Form S-3 Registration Statement and the related Prospectus to be available
for a period of time, the Company shall (A) in the case of clause (ii) above,
subject to the next sentence, as promptly as practicable prepare and file, if
necessary pursuant to applicable law, a post-effective amendment to the Form S-3
Registration Statement or a supplement to the related Prospectus or any document
incorporated therein by reference or file any other required document that would
be incorporated by reference into the Form S-3 Registration Statement and
Prospectus so that the Form S-3 Registration Statement does not contain any
untrue statement of a material fact or omit to state any material fact required
to be stated therein or necessary to make the statements therein not misleading,
and such Prospectus does not contain any untrue statement of a material fact or
omit to state any material fact required to be stated therein or necessary to
make the statements therein, in the light of the circumstances under which they
were made, not misleading, as thereafter delivered to the purchasers of the
Registrable Securities being sold thereunder, and, in the case of a
post-effective amendment to a Registration Statement, subject to the next
sentence, use its commercially reasonable efforts to cause it to be declared
effective as promptly as is reasonably practicable, and (B) give notice to the
Holder, counsel for the Holder and underwriter, if any, that the availability of
the Form S-3 Registration Statement is suspended (a "Deferral Notice") and, upon
receipt of any Deferral Notice, the Holder agrees not to sell any Registrable
Securities pursuant to the Registration Statement until the Holder's receipt of
copies of the supplemented or amended Prospectus provided for in clause (A)
above, or until it is advised in writing by the Company that the Prospectus may
be used, and has received copies of any additional or supplemental filings that
are incorporated or deemed incorporated by reference in such Prospectus. The
Company will use its commercially reasonable efforts to ensure that the use of
the Prospectus may be resumed (x) in the case of clause (i) above, as promptly
as is reasonably practicable, (y) in the case of clause (ii) above, as soon as,
is reasonably practicable after the occurrence of the Material Event and (z) in
the case of clause (iii) above, as soon as in the reasonable discretion of the
Company, such suspension is no longer appropriate. The Company shall be entitled
to exercise its right under this Section 5(b)(ii) to suspend the availability of
the Form S-3 Registration Statement or any Prospectus no more than one (1) time
in any three-month period or two (2) times in any twelve-month period, and any
such period during which the availability of the Registration Statement and any
Prospectus is suspended (the "Deferral Period") shall not exceed 30 days;
provided, that the aggregate duration of any Deferral Periods shall not exceed
45 days in any three- month period (or 55 days in any three-month period in the
event of a Material Event pursuant to which the Company has delivered a second
notice as required below) or 60 days in any twelve-month period; provided, that
in the case of a Material Event relating to an acquisition or a probable
acquisition or financing, recapitalization, business combination or other
similar transaction, the Company may deliver to the Holder a second notice to
the effect set forth above, which shall have the effect of extending the
Deferral Period by up to an additional 10 days, or such shorter period of time
as is specified in such second notice.


                                      -5-


                  (c)      Registration Procedures. In connection with any
registration required under this Agreement, the Company shall take the actions
set forth below (subject to Section 5(b)(ii) below).

                           (i)      Prepare and file with the Commission and use
its commercially reasonable efforts to cause to become effective a Form S-3
Registration Statement with respect to the Registrable Securities in accordance
with the provisions of Section 5(a).

                           (ii)     Prepare and file with the Commission such
amendments and supplements to such Form S-3 Registration Statement and the
Prospectus as may be necessary to comply with the provisions of the Securities
Act with respect to the disposition of all securities covered by such Form S-3
Registration Statement.

                           (iii)    The Company shall permit a single firm of
counsel designated by the Holder to review the Form S-3 Registration Statement
and all amendments and supplements thereto a reasonable period of time prior to
the filing of the Form S-3 Registration Statement with the Commission.

                           (iv)     The Company shall notify the Holder of any
stop order issued or threatened by the Commission or other suspension of
effectiveness of the Form S-3 Registration Statement and will take all
reasonable actions necessary or appropriate to prevent the entry of such stop
order or to remove it if entered and will notify the Holder of the resolution of
such situation.


                                      -6-


                           (v)      The Company shall furnish to the Holder and
each underwriter, if any, of Registrable Securities covered by the Form S-3
Registration Statement filed pursuant to this Agreement (A) promptly after the
same is prepared and publicly distributed, filed with the Commission, or
received by the Company, one copy of the Form S-3 Registration Statement and any
amendment thereto, each Prospectus and each amendment or supplement thereto,
and, as promptly as practicable after the date of effectiveness of the Form S-3
Registration Statement or any amendment thereto, a notice stating that the Form
S-3 Registration Statement or amendment thereto has been declared effective, and
(B) such number of copies of such registration statement, each amendment and
supplement thereto (in each case including all exhibits thereto), and the
Prospectus included in such registration statement, in conformity with the
requirements of the Securities Act, and such other documents as the Holder may
reasonably request in order to facilitate the disposition of the Registrable
Securities owned by the Holder. Such delivery of documents pursuant to (B) above
shall be made by the Company within three (3) trading days of receipt of a
request therefor from the Holder.

                           (vi)     The Company shall use its commercially
reasonable efforts to register or qualify the Registrable Securities under the
securities or "blue sky" laws of each State of the United States of America as
any of the Holder or underwriters, if any, of the Registrable Securities covered
by a registration statement filed hereunder reasonably requests, and shall do
any and all other acts and things which may be reasonably necessary or advisable
to enable the Holder and each underwriter, if any, to consummate the disposition
in such States of the Registrable Securities owned by the Holder; provided that
the Company shall not be required to (A) qualify generally to do business in any
jurisdiction where it would not otherwise be required to qualify but for this
subsection (vi), (B) subject itself to taxation in any such jurisdiction or (C)
consent to general service of process in any such jurisdiction.

                           (vii)    As promptly as reasonably practicable give
notice to the Holder and counsel for the Holder, (i) when any Prospectus,
Prospectus supplement, Form S-3 Registration Statement or post-effective
amendment to the Form S-3 Registration Statement has been filed with the
Commission and, with respect to the Form S-3 Registration Statement or any
post-effective amendment, when the same has been declared effective, (ii) of any
written request, following the effectiveness of the Form S-3 Registration
Statement under the Securities Act, by the Commission or any other federal or
state governmental authority for amendments or supplements to any Form S-3
Registration Statement or related Prospectus or for additional information,
(iii) of the issuance by the Commission or any other federal or state
governmental authority of any stop order suspending the effectiveness of the
Form S-3 Registration Statement or the initiation or written threat of any
proceedings for that purpose, (iv) of the receipt by the Company of any
notification with respect to the suspension of the qualification or exemption
from qualification of any of the Registrable Securities for sale in any
jurisdiction or the initiation or the written threat of any proceeding for such
purpose, (v) of the occurrence of a Material Event (as defined below) (but not
the nature of or details concerning such Material Event) and (vi) of the
determination by the Company that a post-effective amendment to the Form S-3
Registration Statement will be filed with the Commission, which notice may, at
the discretion of the Company (or as required pursuant to Section 5(b)(ii)),
state that it constitutes a Deferral Notice (as defined below), in which event
the provisions of Section 5(b)(ii) shall apply.

                           (viii)   The Company shall enter into customary
agreements (including an underwriting agreement in customary form) and take all
such other reasonable and customary actions as the Holder or the underwriters,
if any, may reasonably request in order to expedite or facilitate the
disposition of the Registrable Securities in accordance with the terms of this
Agreement.


                                      -7-


                           (ix)     Make reasonably available for inspection
during normal business hours by a representative for the Holder, and any
broker-dealers, counsel for the Holder, accountants or underwriter, all relevant
financial and other records and pertinent corporate documents and properties of
the Company and its subsidiaries, and cause the appropriate officers, directors
and employees of the Company and its subsidiaries to make reasonably available
for inspection during normal business hours on reasonable notice all relevant
information reasonably requested by such representative for the Holder, or any
such broker-dealers, counsel for the Holder, accountants or underwriter in
connection with such disposition, in each case as is customary for similar "due
diligence" examinations; provided, however, that the Holder (and its agents and
representatives) shall hold in confidence and shall not make any disclosure of
any such information, unless (i) disclosure of such information is necessary to
comply with federal or state securities laws, (ii) disclosure of such
information is necessary to avoid or to correct a misstatement or omission in
the Form S-3 Registration Statement (and only for the purpose of correcting such
misstatement or omission in the Form S-3 Registration Statement), (iii) release
of such information is ordered pursuant to a subpoena or other order from a
court or government body of competent jurisdiction, (iv) such information has
been made generally available to the public other than by disclosure in
violation of this or any other agreement, or (v) the Company consents to any
such disclosure. The Holder agrees that it shall, upon learning that disclosure
of such information is sought in or by a court or governmental body of competent
jurisdiction or through other means, give prompt notice to the Company and allow
the Company, at its expense, to undertake appropriate action to prevent
disclosure of, or to obtain a protective order for, the information deemed
confidential. Nothing herein shall be deemed to limit the Holder's ability to
sell Registrable Securities in a manner which is otherwise consistent with
applicable laws and regulations.

                           (x)      The Company shall hold in confidence and not
make any disclosure of information concerning the Holder provided to the Company
pursuant to this Agreement unless (A) disclosure of such information is
necessary to comply with federal or state securities laws, provided that the
Holder shall be given reasonable notice of the proposed disclosure and that such
disclosure is limited to the maximum extent permitted under such securities
laws, (B) disclosure of such information is necessary to avoid or correct a
misstatement or omission in the Form S-3 Registration Statement, (C) release of
such information is ordered pursuant to a subpoena or other order from a court
or governmental body of competent jurisdiction, (D) such information has been
made generally available to the public other than by disclosure in violation of
this or any other agreement, or (E) the Holder consents to the form and content
of any such disclosure. The Company agrees that it shall, upon learning that
disclosure of such information concerning the Holder is sought in or by a court
or governmental body of competent jurisdiction or through other means, give
prompt notice to the Holder prior to making such disclosure, and allow the
Holder, at its expense, to undertake appropriate action to prevent disclosure
of, or to obtain a protective order for, such information.

                           (xi)     The Company shall cause all Registrable
Securities registered under this Agreement to be listed on the Nasdaq National
Market ("Nasdaq"), and shall pay any fees for the additional listing of the
shares of its common stock on Nasdaq as required by Nasdaq, or such other
principal market as the Company's Common Stock may then be listed or traded, and
take such other acts as may be necessary to secure such listing.


                                      -8-


         6.       Other Registration Rights. The Holder acknowledges that
certain other securityholders of the Company may now or hereafter have
registration rights, and that such other securityholders may be entitled to sell
their securities at the same time as the Holder hereunder.

         7.       Expenses of Registration. All Registration Expenses incurred
in connection with the Company's obligations hereunder shall be borne by the
Company. All Selling Expenses relating to securities proposed to be registered
hereunder and all other registration expenses shall be borne by the Holder.

         8.       Indemnification.

                  (a)      The Company will indemnify and hold harmless the
Holder, each of its officers and directors, employees, partners, advisors and
agents, and each person controlling the Holder within the meaning of Section 15
of the Securities Act, with respect to a registration that has been effected
pursuant to this Agreement, against all expenses, claims, losses, damages or
liabilities (or actions or proceedings in respect thereof), including reasonable
costs of investigation and reasonable legal fees and expenses and any of the
foregoing incurred in settlement of any litigation, commenced or threatened,
arising out of or based on (i) any untrue statement (or alleged untrue
statement) of a material fact contained in any registration statement,
preliminary Prospectus, Prospectus, offering circular or other document, or any
amendment or supplement thereto, incident to any such registration, or arising
out of or based on any omission (or alleged omission) to state therein a
material fact required to be stated therein or necessary to make the statements
therein, in light of the circumstances in which they were made, not misleading
or (ii) any violation or alleged violation by the Company of the Securities Act,
the Exchange Act, any other applicable securities law, including, without
limitation, any state securities law, or any rule or regulation thereunder or
under the Securities Act or the Exchange Act relating to the offer or sale of
the Registrable Securities and, in either case, the Company will reimburse each
Indemnified Party (as defined in Section 8(c)), for any legal and any other
expenses reasonably incurred in connection with investigating, preparing or
defending any such claim, loss, damage, liability or action, provided that the
Company will not be liable in any such case to the extent that any such claim,
loss, damage, liability or expense arises out of or is based on any untrue
statement or omission or alleged untrue statement or omission, made in reliance
upon and contained in written information furnished to the Company by the Holder
or controlling person or their authorized agent, specifically for use therein;
and provided, further, that the foregoing indemnity agreement is subject to the
condition that, insofar as it relates to any such untrue statement, alleged
untrue statement, omission or alleged omission made in a preliminary Prospectus,
such indemnity agreement shall not inure to the benefit of any person, if a copy
of the final Prospectus or an amended or supplemented Prospectus, as applicable,
was furnished to the Holder or an underwriter within the period of time required
by the Securities Act, and if the final Prospectus or the amended or
supplemented Prospectus, as applicable, would have cured the defect giving rise
to the loss, liability, claim or damage. In no event, however, shall the Company
have any indemnification obligation to the extent that the expenses, claims,
losses, damages or liabilities as to which indemnification is sought are in
connection with an offer or sale made by a person other than the Company during
a period in which the availability of the Form S-3 Registration Statement and
Prospectus are suspended pursuant to Section 5(b)(ii) hereof; provided a
Deferral Notice was delivered by the Company to the person making such sale
prior to the time such sale was effected (a "Violation"). The Company also
agrees to indemnify underwriters participating in the distribution, their
officers, directors, employees, partners and agents, and each person who
controls such underwriters (within the meaning of the Securities Act) to the
same extent as provided above, if so requested.


                                      -9-


                  (b)      The Holder will indemnify the Company, each of its
directors and officers, employees, partners, advisors and agents and each person
controlling the Company within the meaning of Section 15 of the Securities Act
against all claims, losses, damages and liabilities (or actions or proceedings
in respect thereof) arising out of or based on (i) a Violation by the Holder or
(ii) any untrue statement (or alleged untrue statement) of a material fact
contained in any such registration statement, Prospectus, offering circular or
other document, or any omission (or alleged omission) to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading, and will reimburse each Indemnified Party, for any legal
or any other expenses reasonably incurred in connection with investigating,
preparing or defending any such claim, loss, damage, liability or action, but,
in the case of clause (ii) above, only to the extent that such untrue statement
(or alleged untrue statement) or omission (or alleged omission) is made in
reliance upon and contained in written information furnished to the Company by
such Holder or controlling person or their agent specifically for use therein;
provided, however, that the foregoing indemnity is subject to the condition
that, insofar as it relates to any untrue statement, alleged untrue statement,
omission or alleged omission made in a preliminary Prospectus, such indemnity
agreement shall not inure to the benefit of any person, if a copy of the final
Prospectus or an amended or supplemented Prospectus, as applicable, was not
furnished by the Company to the Holder or underwriter within the time period
required by the Securities Act, and if the final Prospectus, as amended or
supplemented, as applicable, would have cured the defect giving rise to the
loss, liability, claim or damage; and provided further, however, that the Holder
shall be liable for only that amount as does not exceed the net proceeds
actually received by the Holder as a result of the offering of Registrable
Securities to which the loss, liability, claim or damage relates. The Holder
also agrees to indemnify underwriters participating in the distribution, their
officers, directors, employees, partners and agents, and each person who
controls such underwriters (within the meaning of the Securities Act) to the
same extent as provided above, if so requested.

                  (c)      Each party entitled to indemnification under this
Section 8 (the "Indemnified Party") shall give notice to the party required to
provide indemnification (the "Indemnifying Party") promptly after such
Indemnified Party has actual knowledge of any claim as to which indemnity may be
sought, and shall permit the Indemnifying Party to assume the defense of any
such claim or any litigation resulting therefrom, provided that (i) counsel for
the Indemnifying Party, who shall conduct the defense of such claim or
litigation, shall be approved by the Indemnified Party (whose approval shall not
unreasonably be withheld), and the Indemnified Party may participate in such
defense at such party's expense, (ii) that the failure of any Indemnified Party
to give notice as provided herein shall not relieve the Indemnifying Party of
its obligations under this Section 8 unless the failure to give such notice is
materially prejudicial to an Indemnifying Party's ability to defend such action,
and then only to the extent that such Indemnifying Party is materially
prejudiced, and (iii) that the Indemnifying Party shall not assume the defense
for matters as to which, in the reasonable opinion of counsel retained by the
Indemnified Party, there is a conflict of interest or there are separate and
different defenses. No Indemnifying Party, in the defense of any such claim or
litigation, shall, except with the consent of each Indemnified Party, consent to
entry of any judgment or enter into any settlement which (i) does not include as
an unconditional term thereof the giving by the claimant or plaintiff to such
Indemnified Party of a release from all liability in respect to such claim or
litigation and a covenant not to sue, (ii) includes admission of fault by the
Indemnified Party or (iii) commits the Indemnified Party to pay any money
damages. The indemnification required by this Section 8 shall be made by
periodic payments of the amount thereof during the course of the investigation
or defense, as such expense, loss, damage or liability is incurred and is due
and payable.


                                      -10-


         9.       Contribution. If the indemnification provided for in Section 8
is held by a court of competent jurisdiction to be unavailable to an Indemnified
Party or insufficient to hold it harmless as contemplated by Section 8, then the
Indemnifying Party, in lieu of indemnifying the Indemnified Party hereunder,
shall contribute to the amount paid or payable by the Indemnified Party as a
result of such loss, claim, damage or liability in such proportion as is
appropriate to reflect not only the relative benefits received by the
Indemnifying Party and the Indemnified Party, but also the relative fault of the
Indemnifying Party and the Indemnified Party in connection with the statements
or omissions that resulted in such loss, claim, damage or liability, as well as
any other relevant equitable considerations, provided that no Holder shall be
required to contribute an amount greater than the dollar amount of the net
proceeds received by such Holder with respect to the sale of the Registrable
Securities giving rise to such indemnification obligation. The relative fault of
any Indemnifying Party or of any Indemnified Party shall be determined by
reference to, among other things, whether the untrue or alleged untrue statement
of a material fact or omission or alleged omission to state a material fact
relates to information supplied by such Indemnifying Party or the Indemnified
Party or their affiliates or representatives, and the parties' relative intent,
knowledge, access to information and the opportunity to correct or prevent such
statement or omission. The parties hereto agree that it would not be just and
equitable if contribution pursuant to this Section 9 were determined by (i) pro
rata allocation (even if all Holders or any agents for the Holders or any
underwriters of the Registrable Securities, or all of them, were treated as one
entity for such purpose), or (ii) by any other method that does not take into
account the equitable considerations referred to in this Section 9. The amount
paid or payable by an Indemnified Party as a result of the losses, claims,
damages or liabilities (or actions or proceedings in respect thereof) referred
to above shall be deemed to include any legal or other fees or expenses
reasonably incurred by such Indemnified Party in connection with investigating
or defending any such action, proceeding or claim. 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.

         10.      Liquidated Damages.

                  (a)      If by the Effectiveness Deadline Date, the Form S-3
Registration Statement is not declared effective by the Commission (a
"Registration Default"), then the Company shall be required to pay a cash amount
equal to $20,000 per week (the "Liquidated Damages") to the Holder from and
including the day following such Registration Default until the time that the
Form S-3 Registration Statement is declared effective.

                  (b)      If the Form S-3 Registration Statement is declared
effective, and then for any reason ceases to be effective or becomes the subject
of a stop order or is otherwise unavailable to the Holder pursuant to the
restrictions contained herein for a period in excess of any Deferral Periods
allowed under Section 5(b)(ii) or any valid extensions thereof (an
"Effectiveness Default"), the Company will pay a cash amount of $20,000 per week
to the Holder from and including the day following such Effectiveness Default
until the time that the Form S-3 Registration Statement once again becomes
effective or such stop order is lifted.


                                      -11-


         11.      Information by Holder. The Holder shall furnish to the Company
such information regarding the Holder, the Registrable Securities held by it and
the distribution proposed by the Holder as the Company may reasonably request in
writing and as shall be required in connection with any registration referred to
in this Agreement. Notwithstanding anything contained herein to the contrary,
the Company shall have no obligation to effect any registration hereunder prior
to its receipt of such information.

         12.      Rule 144 Reporting. With a view to making available to the
Holder the benefits of certain rules and regulations of the Commission which may
permit the sale of the Registrable Securities to the public without registration
the Company agrees to use commercially reasonable efforts to:

                  (a)      Make and keep public information available, as those
terms are understood and defined in Rule 144 under the Securities Act;

                  (b)      File with the Commission in a timely manner all
reports and other documents required of the Company under the Securities Act and
the Exchange Act; and

                  (c)      Furnish to the Holder, so long as the Holder owns or
has the right to acquire any Registrable Securities, promptly after the Holder's
written request, a written statement by the Company as to its compliance with
the foregoing requirements and such other information as may be reasonably
requested in availing the Holder of any rule or regulation of the Commission
which permits the selling of any such securities without registration.

         13.      Transfer of Registration Rights. The rights to cause the
Company to register securities granted to the Holder by the Company pursuant to
Section 5 may be transferred or assigned by the Holder to a Permitted Transferee
who acquires no less than 500,000 shares of Registrable Securities, provided,
that, such transfer or assignment is in compliance with the terms of this
Agreement and the Company is provided with prior written notice of the
securities with respect to which such registration rights are being transferred
or assigned.

         14.      Amendment. Except as otherwise provided above, any provision
of this Agreement may be amended or the observance thereof may be waived (either
generally or in a particular instance and either retroactively or
prospectively), only with the written consent of the Company and the Holder.

         15.      Governing Law. This Agreement shall be governed in all
respects by the laws of the State of Delaware, without regard to conflict of
laws provisions.

         16.      Entire Agreement. This Agreement, the Purchase Agreement, the
Confidentiality Agreement and that certain Mutual Termination and Release
Agreement and the Annexes, Exhibits and Schedules attached hereto and thereto
and delivered in connection herewith and therewith, as the case may be,
constitute the full and entire understanding and agreement among the parties
regarding the matters set forth herein. Except as otherwise expressly provided
herein, all other agreements regarding the registration rights of the Holder
shall hereby expire. The provisions hereof shall inure to the benefit of, and be
binding upon the successors, permitted assigns, heirs, executors and
administrators of the parties hereto.


                                      -12-


         17.      Notices. All notices and other communications required or
permitted hereunder shall be in writing and shall be mailed by registered or
certified mail, postage prepaid, by hand, by messenger or by overnight courier,
addressed:

                  (a)      if to a Holder, to:

                           Enzon Pharmaceuticals, Inc.
                           685 Route 202/206
                           Bridgewater, New Jersey 08807
                           Attention:  Chief Executive Officer

                           or at such other address as such Holder shall have
furnished to the Company, with a copy to:

                           Dorsey & Whitney LLP
                           250 Park Avenue
                           New York, New York 10177-1500
                           Attention:  Kevin T. Collins

                  (b)      if to the Company, to:

                           NPS Pharmaceuticals, Inc.
                           420 Chipeta Way
                           Salt Lake City, Utah 84108
                           Attention:  General Counsel

                           or at such other address as the Company shall have
furnished to the Holder, with a copy to:

                           Wilson Sonsini Goodrich & Rosati, Professional
                           Corporation
                           2795 East Cottonwood Parkway, Suite 300
                           Salt Lake City, Utah 84121
                           Attn:  Robert G. O'Connor, Esq.

         Each such notice or other communication shall for all purposes of this
Agreement be treated as effective or having been given when actually delivered
as provided above, if delivered personally or by messenger, or, on the day shown
on the return receipt, if sent by mail or other delivery service.

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


                                      -13-


         IN WITNESS WHEREOF, the parties hereto have executed this Registration
Rights Agreement as of the date first written above.



COMPANY:                                    HOLDER:

NPS PHARMACEUTICALS, INC.                   ENZON PHARMACEUTICALS, INC.


By: /s/ Hunter Jackson                      By: /s/ Arthur J. Higgins
    -------------------------------             --------------------------------

Name: Hunter Jackson                        Name: Arthur J. Higgins
      -----------------------------               ------------------------------

Title: President and CEO                    Title: Chairman, President and CEO
       ----------------------------                -----------------------------


                                      -14-