------------------------------ OMB APPROVAL ------------------------------ OMB Number 3235-0287 Expires: September 30, 1998 Estimated average burden hours per response ....... 0.5 ------------------------------ U.S. SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 4 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(f) of the Investment Company Act of 1940 [_] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). (Print or Type Responses) ________________________________________________________________________________ 1. Name and Address of Reporting Person* MacKinnon A.M. "Don" - -------------------------------------------------------------------------------- (Last) (First) (Middle) c/o Enzon, Inc., 20 Kingsbridge Road - -------------------------------------------------------------------------------- (Street) Piscataway NJ 08854 - -------------------------------------------------------------------------------- (City) (State) (Zip) ________________________________________________________________________________ 2. Issuer Name and Ticker or Trading Symbol ENZON, INC. (ENZN) ________________________________________________________________________________ 3. IRS Identification Number of Reporting Person, if an Entity (Voluntary) ________________________________________________________________________________ 4. Statement for Month/Year August 1999 ________________________________________________________________________________ 5. If Amendment, Date of Original (Month/Year) ________________________________________________________________________________ 6. Relationship of Reporting Person(s) to Issuer (Check all applicable) [X] Director [_] 10% Owner [_] Officer (give title below) [_] Other (specify below) ________________________________________________________________________________ 7. Individual or Joint/Group Filing (Check applicable line) [X] Form filed by One Reporting Person [_] Form filed by More than One Reporting Person ________________________________________________________________________________ ================================================================================ Table I -- Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned ================================================================================ 6. 4. 5. Owner- Securities Acquired (A) or Amount of ship 3. Disposed of (D) Securities Form: 7. Transaction (Instr. 3, 4 and 5) Beneficially Direct Nature of 2. Code ------------------------------- Owned at End (D) or Indirect 1. Transaction (Instr. 8) (A) of Month Indirect Beneficial Title of Security Date ------------ Amount or Price (Instr. 3 (I) Ownership (Instr. 3) (mm/dd/yy) Code V (D) and 4) (Instr.4) (Instr. 4) - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 8/10/99 G(1) 1,000 D D - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 8/10/99 G(1) 1,000 D 71,624(3) D - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 8/10/99 G(2) 1,000 D I By wife - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 8/10/99 G(2) 1,000 D 59,800 I(4) By wife - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ ==================================================================================================================================== Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. * If the form is filed by more than one reporting person, see Instruction 4(b)(v). Potential Persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number. (Over) SEC 1474 (7-97)FORM 4 (continued) Table II -- Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities) ================================================================================ 10. 9. Owner- Number ship of Form 2. Deriv- of Conver- 5. 7. ative Deriv- 11. sion Number of Title and Amount Secur- ative Nature or Derivative 6. of Underlying 8. ities Secur- of Exer- 4. Securities Date Securities Price Bene- ity: In- cise 3. Trans- Acquired (A) Exercisable and (Instr. 3 and 4) of ficially Direct direct Price Trans- action or Disposed Expiration Date ---------------- Deriv- Owned (D) or Bene- 1. of action Code of(D) (Month/Day/Year) Amount ative at End In- ficial Title of Deriv- Date (Instr. (Instr. 3, ---------------- or Secur- of direct Owner- Derivative ative (Month/ 8) 4 and 5) Date Expira- Number ity Month (I) ship Security Secur- Day/ ------ ------------ Exer- tion of (Instr. (Instr. (Instr. (Instr. (Instr. 3) ity Year) Code V (A) (D) cisable Date Title Shares 5) 4) 4) 4) - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ ==================================================================================================================================== Explanation of Responses: (1) The reporting person gifted 1,000 shares each to two of his children. (2) The reporting person's wife gifted 1,000 shares each to two of her children. (3) The reporting person disclaims beneficial ownership of all securities held by his wife, and this report should not be deemed an admission that the reporting person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose. (4) This number includes shares granted under the Company's Independent Directors Stock Plan and qualified under Rule 16b-3. /s/ A.M. Don MacKinnon 9/9/99 - --------------------------------------------- ----------------------- **Signature of Reporting Person Date ** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a). Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure. Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number. Page 2 SEC 1474 (7-97)