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                                                                   EXHIBIT 10.45

                                  ATTACHMENT A

        As a supplement to the letter agreement dated April 24, 2002 between La
Jolla Pharmaceutical Company ("LJP") and Kenneth R. Heilbrunn, M.D.
("HEILBRUNN") related to Heilbrunn's employment by LJP, Heilbrunn and LJP hereby
agree as follows:

        In connection with Heilbrunn's employment with LJP, LJP's management
will recommend to LJP's Board of Directors that LJP grant to Heilbrunn an option
to purchase up to 90,000 shares of common stock of LJP. Such option, if granted,
shall be the "OPTION" for purposes hereof.

        If Heilbrunn's employment is terminated by LJP without cause (as defined
below), or if a Change in Control of LJP (as defined below) occurs and
Heilbrunn's employment with LJP or its successor "terminates in connection with"
(as defined below) that Change in Control and in the absence of any event or
circumstance constituting Cause, then:

               (i)    Heilbrunn will be entitled to receive from LJP a severance
                      payment equal to his then-current base salary for a period
                      of six full calendar months from the date of termination
                      and an additional three full calendar months if and when
                      after the first six months he has not found suitable
                      employment, payable consistent with LJP's normal payroll
                      practices, provided that such payment will be contingent
                      upon execution and delivery by Heilbrunn and LJP of a
                      mutual release, in form satisfactory to LJP, of all claims
                      arising in connection with Heilbrunn's employment with LJP
                      and termination thereof, and

               (ii)   Heilbrunn will be entitled to receive for a period of six
                      full calendar months from the date of termination and an
                      additional three full calendar months if and when after
                      the first six months he has not found suitable employment,
                      medical and dental benefits coverage for Heilbrunn and/or
                      his dependents through the Company's available plans at
                      the time and LJP will be responsible to continue payment
                      of all applicable deductions for premium costs. After the
                      Company's obligation to pay the premiums for health and
                      dental coverage Heilbrunn and/or his dependents will be
                      eligible to continue plan participation under COBRA.

               (iii)  Notwithstanding anything to the contrary in the option
                      plan (the "PLAN") pursuant to which all of Heilbrunn's
                      existing options were granted, the Options shall
                      automatically vest and become fully exercisable as of the
                      date of termination of Executive's employment (the
                      "TERMINATION DATE"), notwithstanding any vesting or
                      performance conditions applicable thereto, and shall
                      remain exercisable for a period of one year following the
                      Termination Date or such longer period as is provided by
                      the Plan or grant pursuant to which the Options were
                      granted. However, notwithstanding the foregoing, in no
                      case will the Options be exercisable beyond the duration
                      of the original term thereof, and if the Options qualify
                      as an incentive stock option under the Internal Revenue
                      Code and applicable regulations thereunder, the exercise
                      period thereof shall not be extended in such a manner as
                      to cause the Options to cease to qualify as an incentive
                      stock option unless Executive elects to forego incentive
                      stock option treatment and extend the exercise period
                      thereof as provided herein.

        For purposes hereof, "CHANGE IN CONTROL" of LJP has the meaning set
        forth in the Plan in its form as the date of grant of the Options.

        For purposes hereof, "CAUSE" means Heilbrunn has (i) engaged in serious
        criminal activity or other wrongful conduct that has an adverse impact
        on LJP, (ii) disregarded instructions given to him under the authority
        of LJP's Board of Directors, (iii) performed services for any person or
        entity other than LJP and appropriate civic organizations, or (iv)
        otherwise materially breached his employment or fiduciary
        responsibilities to LJP.

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        For purposes hereof, Heilbrunn's employment with LJP or its successor
        will be deemed to "TERMINATE IN CONNECTION WITH" a Change in Control if,
        within 180 days after the consummation of the Change of Control, (i)
        Heilbrunn is removed from Heilbrunn's employment by, or resigns his
        employment upon the request of, a person exercising practical voting
        control over LJP or its successor following the Change in Control or a
        person acting upon authority or at the instruction of such person; or
        (ii) Heilbrunn's position is eliminated as a result of a reduction in
        force made to reduce over-capacity or unnecessary duplication of
        personnel and Heilbrunn is not offered a replacement position with LJP
        or its successor as a Vice President with compensation and functional
        duties substantially similar to the compensation and duties in effect
        immediately before the Change in Control; or (iii) Heilbrunn resigns his
        employment with the Company or its successor rather than comply with a
        relocation of his primary work site more than 50 miles from LJP's
        headquarters.

               In Witness Whereof, LJP and Heilbrunn have entered into this
        agreement as of May 8, 2002.

        La Jolla Pharmaceutical Company

        By: /s/ Steven B. Engle              /s/ Kenneth R. Heilbrunn, M.D.
            ---------------------------      -----------------------------------
            Steven B. Engle                  Kenneth R. Heilbrunn, M.D.
            Chairman & CEO                   Vice President of Clinical
                                             Development

                                       2<PAGE>
     COMMON STOCK                                           COMMON STOCK
      GP NUMBER                                                SHARES
                                                         ___________________

INCORPORATED UNDER THE                                 SEE REVERSE FOR CERTAIN
   LAWS OF DELAWARE                                 DEFINITIONS AND RESTRICTIONS
                                     [LOGO]

                                                               CUSIP 36866T 10 3

THIS CERTIFIES THAT:

IS THE HOLDER OF

             FULLY PAID AND NON-ASSESSABLE SHARES OF COMMON STOCK,
                         $.0001 PAR VALUE PER SHARE, OF
    -------------------------GEN-PROBE INCORPORATED-------------------------

transferable on the books of the Corporation by the holder hereof in person or
by duly authorized attorney upon surrender of this Certificate properly
endorsed. This Certificate is not valid until countersigned by the Transfer
Agent and registered by the Registrar.

     WITNESS the facsimile seal of the Corporation and the facsimile signatures
of its duly authorized officers.

Dated:

/s/ HERM ROSENMAN                                 /s/ HENRY L. NORDHOFF
------------------------                          ------------------------
VICE PRESIDENT AND           [CORPORATE SEAL]     PRESIDENT AND
CHIEF FINANCIAL OFFICER                           CHIEF EXECUTIVE OFFICER

COUNTERSIGNED AND REGISTERED
                    MELLON INVESTOR SERVICES LLC  TRANSFER AGENT
                                                  AND REGISTRAR

                                                  AUTHORIZED SIGNATURE

     Keep this certificate in a safe place. If it is lost, stolen, or destroyed
the Corporation will require a bond of indemnity as a condition to the issuance
of a replacement certificate.

     A statement of the powers, designations, preferences and relative,
participating, optional or other special rights of each class of stock or series
thereof and the qualifications, limitations or restrictions of such preferences
and/or rights as established, from time to time, by the Certificate of
Incorporation of the Corporation and by any certificate of determination, and
the number of shares constituting each class and series and the designations
thereof, may be obtained by the holder hereof upon written request and without
charge from the Secretary of the Corporation at the principal office of the
Corporation.

     The following abbreviations, when sued in the inscription on the face of
this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

 TEN COM-  as tenants in common
 TEN ENT-  as tenants by the entireties
  JT TEN-  as joint tenants with
           right of survivorship and
           not as tenants in common
COM PROP-  as community property

UNIF GIFT MIN ACT-_____________________ CUSTODIAN___________________________
                         (CUST)                           (MINOR)

                         under Uniform Gifts to Minors

                         Act________________________________________________
                                        (State)

UNIF TRF MIN ACT-_______ Custodian (until age ____)
                 (Cust)

                 _______ under Uniform Transfer to Minors Act ___________
                 (Minor)                                        (State)
<PAGE>

Additional abbreviations may also be used though not in the above list.

FOR VALUE RECEIVED, _____________________ hereby sell, assign and transfer unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
IDENTIFY NUMBER OF ASSIGNEE

______________________________________

________________________________________________________________________________
(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________ Shares
of the common stock represented by the within Certificate, and do hereby
irrevocably constitute and appoint _____________________________________
Attorney to transfer the said stock on the books of the within named Corporation
with full power of substitution in the premises.

Dated: _________________      X ________________________________________________

                              X ________________________________________________
                                NOTICE: THE SIGNATURE(S) TO THE ASSIGNMENT MUST
                                CORRESPOND WITH THE NAME(S) AS WRITTEN UPON THE
                                FACE OF THE CERTIFICATE IN EVERY PARTICULAR,
                                WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE
                                WHATSOEVER.

Signature(s) Guaranteed:  By ___________________________________________________
                             THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN
                             ELIGIBLE GUARANTOR INSTITUTION (BANKS,
                             STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND
                             CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED
                             SIGNATURE GUARANTEE MEDALLION PROGRAM), PURSUANT
                             TO S.E.C. RULE 17Ad-15.

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