Document:

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PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT UNDER RULE 24b-2 OF THE SECURITIES EXCHANGE ACT OF
1934, AS AMENDED. THE OMITTED PORTIONS ARE MARKED "***" AND HAVE BEEN
SEPARATELY FILED WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                                                    EXHIBIT 10.1

                             COLLABORATION AGREEMENT

                  This Collaboration Agreement is made this August 25, 2000
("Effective Date") by and between Enchira Biotechnology Corporation, 4200
Research Forest Drive, The Woodlands, Texas 77381 (formerly Energy BioSystems
Corporation and hereinafter referred to as "ENBC") and Genencor International
Inc., 925 Page Mill Road, Palo Alto, California 94304 (hereinafter referred to
as "Genencor").

                                   WITNESSETH:

         WHEREAS, ENBC has developed and possesses expertise, know-how and
intellectual property rights relating to "chimeragenesis" of divergent genes
on transient templates and referred to as "ENBC's RACHITT Technology";

         WHEREAS, Genencor is engaged in the commercial manufacturing and
marketing of Industrial Proteins in certain uses and applications and ENBC and
Genencor have entered into that certain License Agreement dated effective as
of May 17, 2000 (the "License Agreement") pursuant to which ENBC has licensed
to Genencor certain rights to ENBC's RACHITT Technology for use by Genencor in
such efforts;

         WHEREAS, the License Agreement contemplates that ENBC and Genencor
shall enter into a definitive collaboration agreement setting forth the terms
and conditions under which Genencor will fund certain development activities
to be conducted by ENBC with respect to ENBC's RACHITT Technology; and

         WHEREAS, the parties intend for this Agreement to constitute the
definitive collaboration agreement as defined in, and contemplated by the
License Agreement.

         NOW, THEREFORE, ENBC and Genencor hereby agree as follows:

         1.       DEFINITIONS

                  The following definitions shall control the construction of
each of the following terms wherever they appear in this Agreement:

                  1.1   "AGREEMENT" shall mean this Collaboration Agreement.

                  1.2   "AGREEMENT QUARTER" shall mean each three (3) month
period during the Term as measured from the Initiation Date of work under the
Development Program.

                  1.3   "DEVELOPMENT FUNDS" shall have the meaning set forth
in Section 2.2(a).

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                  1.4   "DEVELOPMENT PROGRAM" shall mean the research and
development activities relating to the use of ENBC's RACHITT Technology for
development of Genencor targets to be conducted by ENBC in collaboration with
Genencor under this Agreement. A detailed Work Plan including objectives, R&D
plan, staffing, timelines, deliverables of the Development Program is set
forth on EXHIBIT A attached hereto and incorporated herein and may be amended
from time to time with the written consent of the Parties.

                  1.5   "INITIATION DATE" shall mean the date ENBC initiates
work under the Development Program.

                  1.6   "PARTY" shall mean either ENBC or Genencor, as
appropriate, whereas the term "Parties" shall mean ENBC and Genencor jointly.

                  1.7   "STEERING COMMITTEE" shall have the meaning set forth
in Section 2.4.

                  1.8   "BIOLOGICAL MATERIAL" shall mean material including
strains, genes, vectors, plasmids, and other DNA sequence or constructs,
libraries and the like, together with any progeny, mutants, derivatives or
replicated forms thereof, and any information relating thereto.

                  All other capitalized terms shall have the meaning set forth
in the License Agreement.

         2.       DEVELOPMENT COLLABORATION

                  2.1   SCOPE OF DEVELOPMENT COLLABORATION. The Parties hereby
undertake to jointly carry out the Development Program in accordance with the
Work Plan attached as EXHIBIT A hereto with the purpose of improving
Genencor's Industrial Proteins within the Licensed and/or Option Fields. The
Work Plan may be adjusted by the Parties from time to time as recommended by
the Steering Committee.

                  2.2   FUNDING OF COLLABORATION BY GENENCOR.

                  (a)   FUNDING. Subject to the terms and conditions set forth
herein, Genencor shall fund ENBC the amount of One Million Dollars
($1,000,000) (the "Development Funds") as payment for the activities to be
performed by ENBC under the Development Program, such amount to be paid in
accordance with the terms of Section 2.2(b).

                  (b)   PAYMENT. Genencor agrees to make quarterly
installments of One Hundred Twenty-Five Thousand Dollars ($125,000) to ENBC,
the first such installment being payable within ten (10) days of the
Initiation Date and the remaining installments being payable within 10 days of
the end of each Agreement Quarter until the payment in full of the Development
Funds.

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                  (c)   STAFFING. Staffing levels will be mutually agreed to
by the Parties through the operation of the Steering Committee and based on
the needs of the Development Program. It is expected that the overall annual
level of personnel allocated by ENBC will be an average of three (3.0) full
time equivalent (FTE) scientific personnel ("ENBC's Minimum Staffing"). ENBC
will, at the end of each Agreement Quarter, provide Genencor a report
confirming the man-months expended during the prior Agreement Quarter.

                  (d)   GENENCOR COSTS. Genencor will pay all its own expenses
for work on the Development Program, with no cost sharing by ENBC.

                  (e)   PERFORMANCE. Payment of the Development Funds shall be
a condition to ENBC's obligation to perform the work set out in the
Development Program, and shall be a basis for termination of this Agreement by
ENBC under Section 5.2 if such payments are not timely made. Adequate staffing
at or above the ENBC Minimum Staffing level shall be a condition to Genencor's
obligation to make payments pursuant to this Section 2.2, and shall be a basis
for termination of this Agreement by Genencor under Section 5.2 if staffing is
not adequately provided. Satisfactory performance of the work to be conducted
by ENBC and timely delivery of the deliverables set forth for ENBC in the Work
Plan shall be a condition to Genencor's obligation to make payments pursuant
to this Section 2.2, and shall be a basis for termination of this Agreement by
Genencor under Section 5.2.

                  2.3   PERFORMANCE OBLIGATIONS. The collaboration shall be
conducted at and/or coordinated from the facilities of each Party under the
direction and supervision of the Steering Committee. ENBC shall use reasonable
commercial efforts to diligently carry out and perform its tasks and duties
under the Development Program within the time periods set out in the Work
Plan. Each Party shall be responsible for the administrative management and,
subject to the funding obligations of Genencor under Section 2.2, fiscal
control and all other expenses incurred by it for tasks and duties assigned to
it in the Development Program. So long as the collaboration continues, ENBC
shall periodically (at least quarterly) provide to Genencor and the Steering
Committee progress reports summarizing the technical progress of ENBC's work.
Notwithstanding any other provision herein, provided ENBC shall have used
reasonable commercial efforts to perform its tasks and duties under the
Development Program as herein required, ENBC shall not be liable for any
failure to achieve its objectives described in the Work Plan on a timely basis
or at all.

                  2.4   STEERING COMMITTEE.

                  (a)   MEMBERSHIP. A committee (the "Steering Committee")
consisting of two (2) members appointed by ENBC and two (2) members appointed
by Genencor shall be established in order to monitor and coordinate the joint
collaboration efforts under this Agreement including the Development Program.
Each Party has one (1) vote total on any matter within the scope of the
Development Program coming before the Steering

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Committee. The Steering Committee may invite additional representatives from
both parties to participate in meetings as deemed necessary and appropriate.

                  (b)   RESPONSIBILITIES. The Steering Committee shall have
general responsibility, subject to the provisions of Section 2.4(d) below, for
directing the research efforts under the Development Program and for
monitoring the work done under the Development Program. The Steering Committee
shall in good faith discuss matters related, but not limited, to:

                        -      goals of the collaboration;
                               -    setting of priorities and time frames for
                                    the performance of certain activities and
                                    deliverables outlined in the Work Plan;
                               -    possible changes to, expansion of or
                                    abandonment of the Work Plan;
                        -      possible conflicts of interest;
                               -    inclusion of any third parties or any
                                    intellectual property rights or know-how
                                    belonging to third parties in the project;
                               -    personnel requirements for each goal or
                                    project within the Development Program; and
                               -    funding requirements for each goal or
                                    project within the Development Program
                                    subject to the funding obligations set forth
                                    in this Agreement.

                  (c)   MEETINGS. The Steering Committee shall hold meetings
at such times and places as shall be determined by a majority of the entire
membership of the Steering Committee, provided that in no event shall such
meetings be held less frequently than once every quarter. Such meetings may be
held in person or by telephone conference, provided that any decision made
during a telephone conference is evidenced by a confirmed writing signed by
one or more of the members of the Steering Committee from each Party.

                  (d)   VOTES. Actions to be taken by the Steering Committee
pursuant to the terms of this Agreement shall only be taken following the
unanimous vote of the Steering Committee. The Steering Committee shall attempt
to have all decisions approved by all members of the Steering Committee. If
the Steering Committee is unable to reach a unanimous decision, such matters
shall be referred to the management of each Party for consideration and
action. While the Steering Committee may take actions to coordinate the
efforts taken by each Party under the Development Program and to make
recommendations concerning the matters set forth in Section 2.4(b), the
Steering Committee shall not have any authority to enter into any contract or
to amend the terms and condition of this Agreement or the License Agreement or
incur any liability on behalf of either Party but shall be required to refer
any such matters to, and obtain authorization from, the respective management
of each Party. Notwithstanding the creation of the

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Steering Committee, each Party shall retain the rights, powers and discretion
granted to it under this Agreement and such Steering Committee shall not be
delegated with any such rights, powers or discretion unless the Parties
expressly agree in writing.

                  (e)   EXPENSES. Each Party shall bear all expenses of its
representatives related to the Steering Committee and the attendance at any
meetings of the Steering Committee.

                  2.5   OWNERSHIP OF INTELLECTUAL PROPERTY.

                  (a)   ENBC PATENTS AND KNOW-HOW. ENBC Patents and ENBC
Know-How are and shall continue to be the sole and exclusive property of ENBC,
subject to the licenses granted to Genencor pursuant to the License Agreement.

                  (b)   IMPROVEMENTS AND ENBC FUTURE PATENTS. Any Improvements
as defined in Section 1.12(ii) of the License Agreement and ENBC Future
Patents claiming such Improvements, shall be owned solely by ENBC, regardless
of the inventorship of such Improvements, subject to the licenses and options
granted to Genencor pursuant to the License Agreement. Genencor agrees that it
will, and does hereby, assign its rights to any such Improvements to ENBC and
further agrees to otherwise cooperate in all respects in providing such other
assistance to ENBC in the filing, prosecution, maintenance and/or enforcement
of any ENBC Future Patents. ENBC agrees to reimburse Genencor for its
reasonable expenses incurred in rendering such assistance.

                  (c)   OTHER INVENTIONS. Genencor shall own any invention,
discovery or development including any patent rights relating thereto
developed under the Development Program that relate to inventions, discoveries
or developments other than Improvements (Other Inventions), regardless of
inventorship, including but not limited to those rights relating to Industrial
Protein(s). ENBC agrees that it will, and does hereby, assign its rights to
any such Other Inventions relating thereto to Genencor and further agrees to
otherwise cooperate in all respects in providing such other assistance to
Genencor in the filing, prosecution, maintenance and/or enforcement of any
patents relating to such. Genencor agrees to reimburse ENBC for its reasonable
expenses incurred in rendering such assistance.

                  (d)   LICENSE TO CERTAIN OTHER INVENTIONS. Genencor will
upon request by ENBC grant ENBC a non-exclusive, sublicenseable, worldwide,
license under those Other Inventions (expressly excluding Industrial Protein
inventions) for the manufacture, use and sale of products or processes
developed or commercialized using RACHITT Technology for use and sale outside
of the Licensed Field and Option Field(s). This license shall be royalty free
for ENBC's internal research use of such Other Inventions and royalty bearing
for commercialization by ENBC or its sublicensee of any product or process
developed or commercialized using RACHITT Technology for use or sale outside
the Licensed Field or elected Option Field(s).

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                  2.6   PUBLICATION OF RESULTS. Neither Party shall be
entitled to publish the results obtained under the Development Program, to the
extent such results include a description of any technology rights or
confidential information owned by the other Party, without the prior written
approval of the other Party.

         3.       REPRESENTATIONS AND WARRANTIES

                  3.1   BY ENBC. ENBC represents and warrants to Genencor that:

                  (a)   it has the authority to enter into this Agreement;

                  (b)   it has duly informed Genencor, prior to the Effective
Date, of administrative or judicial proceedings, if any, contesting the
inventorship, ownership, validity or enforceability of any element of the ENBC
Patents and ENBC's RACHITT Technology; and

                  (c)   as of the Effective Date, ENBC has no third party
agreements which would be violated by the disclosure to Genencor of ENBC
Know-How.

                  3.2   BY GENENCOR. Genencor represents and warrants to ENBC
that it has the authority to enter into this Agreement and that this
Agreement, including the disclosure to ENBC by Genencor of any of its
proprietary and confidential information hereunder, does not conflict with the
terms of any other agreement to which it is subject.

         4.       PATENT PROSECUTION/ENFORCEMENT

                  4.1   PATENT PROSECUTION. Prosecution, filing and
maintenance of patents and patent applications relating to any Improvements
and ENBC Future Patents developed under this Agreement shall be handled in
accordance with the terms provided in Section 6.1 of the License Agreement.

                  4.2   PATENT ENFORCEMENT. In the event any Improvement
developed pursuant to this Agreement becomes subject to any claim of
infringement, the Parties shall comply with the terms of Sections 6.2, 6.3 and
6.4 of the License Agreement in such matters.

         5.       TERM AND TERMINATION

                  5.1   TERM. This Agreement shall become effective on the
Effective Date and, subject to the earlier termination hereof in accordance
with the provisions of this Section 5, continue for two (2) years.

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                  5.2   TERMINATION DUE TO MATERIAL BREACH.

                  (a)   If a Party to this Agreement commits a material breach
of any provision of this Agreement and fails to remedy such breach within
thirty (30) days after written notice thereof from the other Party stating the
intent to terminate, the Party not in default may, at its option, terminate
this Agreement by giving thirty (30) days prior written notice to the Party in
default.

                  (b)   If a Party to this Agreement terminates the License
Agreement as a result of the other Party's commission of a material breach
thereof and failure to cure same within the applicable terms of the License
Agreement, the Party so terminating the License Agreement shall be permitted
to terminate this Agreement.

                  5.3   GENENCOR TERMINATION OPTION. In the event Genencor
elects to terminate the License Agreement in accordance with the provisions of
Section 9.3 thereof, Genencor shall have the right to terminate this
Agreement. ENBC shall not be required to refund any previously paid
Development Funds upon any termination of this Agreement by Genencor pursuant
to this Section 5.3.

                  5.4   EFFECT OF TERMINATION.

                  (a)   If Genencor terminates this Agreement pursuant to
Section 5.2 or 5.3, Genencor shall pay to ENBC all installments of the
Development Funds due and payable as of the effective date of termination with
the Development Fund payment accruing for the Agreement Quarter in which such
termination occurs being paid on a pro rata basis through and including the
effective date of termination. Except as otherwise provided in the preceding
sentence, if Genencor terminates this Agreement pursuant to Section 5.2 or
5.3, Genencor shall have no further obligation to pay any additional
Development Funds under this Agreement.

                  (b)   If ENBC terminates this Agreement pursuant to Section
5.2, Genencor shall, in addition to any of the rights or remedies otherwise
available to ENBC, pay to ENBC all installments of the Development Funds due
and payable as of the effective date of termination with the Development Fund
payment accruing for the Agreement Quarter in which such termination occurs
being paid on a pro rata basis through and including the effective date of
termination.

                  (c)   Notwithstanding the expiration or sooner termination
of this Agreement, the provisions contained in Sections 2.5 and 2.6 and
Articles 6 and 7 of this Agreement shall continue to survive any such
expiration or sooner termination of this Agreement.

                  (d)   The termination or expiration of this Agreement for
any reason shall be without prejudice to any rights which shall have accrued
to the benefit of either Party prior to such termination or expiration,
including damages arising from any breach hereunder.

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         6.       CONFIDENTIALITY

                  6.1   In consideration of disclosure by either of the
Parties to the other Party of confidential information in written or oral form
or in the form of samples, the recipient and the recipient's Affiliates
undertake for a period of ten (10) years from the date of disclosure to treat
received information as strictly secret and therefore not to disclose it to
any third party (except reliable employees and Affiliates and sublicensees
under similar secrecy obligations), and to make no commercial use of it except
for the purposes of this Agreement or except as otherwise specifically
provided for herein. This obligation does not apply to:

                  (a)   information which, at the time of disclosure, is
already in the public domain;

                  (b)   information which, after disclosure, becomes a part of
the public domain by publication through no violation of this Agreement;

                  (c)   information which the recipient is able to prove by
competent written evidence to have been in the recipient's possession prior to
any disclosure by the disclosing Party including, without limitation, any
prior disclosure pursuant to the License Agreement;

                  (d)   information which is hereafter lawfully disclosed by a
third party to the recipient, which third party did not acquire the
information under a still effective obligation of confidentiality to the
disclosing Party;

                  I.    information which is independently developed by or for a
                        Party; and

                  (f)   information originally disclosed orally which is not
promptly confirmed in writing to the receiving party as being the confidential
information of the disclosing party.

                  6.2   PRESS RELEASE. Provided neither Party is precluded
from doing so, the Parties will endeavor to issue a joint press release after
execution of this Agreement. Neither Party shall issue any other public
statement concerning the existence or terms of this Agreement or any
activities related hereto without consulting and agreeing with the other
Party. However, each Party may disclose this Agreement or any activities
related hereto without the other Party's approval if such approval has been
requested but not received within forty-eight (48) hours and such party
concludes, after consulting with its legal advisors, that it is required by
law or regulatory or listing agency to disclose the transaction or part
thereof.

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         7.       INDEMNIFICATION

                  7.1   BY ENBC. ENBC shall defend, indemnify and hold
Genencor harmless against any liability, damage, loss, cost or expense,
including legal fees arising out of or resulting from: (i) ENBC's breach of a
material term of this Agreement; and (ii) ENBC's breach of any representation
or warranty set forth in Section 3.

                  7.2   BY GENENCOR. Genencor shall defend, indemnify and hold
ENBC harmless against any liability, damage, loss, cost or expense, including
legal fees arising out of or resulting from: (i) Genencor's breach of a
material term of this Agreement; and (ii) Genencor's breach of a
representation or warranty set forth in Section 3.

                  7.3   NOTICE AND COOPERATION. If either party hereunder
receives notice of any claim or of the commencement of any action,
administrative or legal proceeding, or investigation as to which the indemnity
provided for in Section 7 hereof may apply:

                        7.3.1   the party seeking indemnification shall notify
the indemnifying party of such fact within 14 days at the address noted in
Section 8.7; PROVIDED that the failure to so notify shall not release an
indemnifying party of its obligation hereunder unless such failure shall be
materially detrimental to the defense of any such action, proceeding or
investigation; and

                        7.3.2   the party seeking indemnification shall
cooperate with and assist the indemnifying party and its representatives in
the investigation and defense of any claim and/or suit for which
indemnification is provided.

                  7.4   DEFENSE AND SETTLEMENT. The indemnifying party shall
control the defense of any claim and/or suit for which indemnification is
provided under this Section 7. This agreement of indemnity shall not be valid
as to any settlement of a claim or suit or offer of settlement or compromise
without the prior written approval of the indemnifying party.

         8.       MISCELLANEOUS

                  8.1   FORCE MAJEURE. Each of the Parties hereto shall be
excused from the performance of its obligations hereunder and shall not be
liable for damages to the other in the event that such performance is
prevented by circumstances beyond its effective control. Such excuse from
performance shall continue for as long as the condition responsible for such
excuse continues and for a period of thirty (30) days thereafter, provided
that if such excuse continues for a period of one hundred and eighty (180)
days, the Party whose performance is not being prevented shall be entitled to
withdraw from this Agreement. For the purpose of this Agreement circumstances
beyond the effective control of the Party which excuse said Party from
performance shall include, without limitation, acts of God, enactments,
regulations or laws of any government, injunctions or judgment of any court,
war, civil commotion, destruction of facility or

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materials by fire, earthquake, storm or other casualty, labor disturbances and
failure of public utilities or common carrier.

                  8.2   INDEPENDENT CONTRACTORS. Nothing in this Agreement is
intended or shall be deemed to constitute a partnership, agency, employment or
joint venture relationship between the Parties. All activities by the Parties
hereunder shall be performed by the Parties as independent parties. Neither
Party shall incur any debts or make any commitment for or on behalf of the
other Party except to the extent, if at all, specifically provided herein or
subsequently agreed upon.

                  8.3   LIMITATION ON ASSIGNMENT. Except as provided herein,
ENBC may not assign this Agreement nor any interest or obligation hereunder
except with the prior written consent of Genencor, which consent shall not be
unreasonably or untimely withheld. Either Party may assign this Agreement in
connection with the sale or transfer of all or substantially all of its
business to which this Agreement relates. Any permitted assignee shall assume
all of the obligations of its assignor under this Agreement.

                  8.4   AMENDMENTS OF AGREEMENT. This Agreement may be amended
or modified or one or more provisions hereof waived only by a written
instrument signed by both Parties.

                  8.5   SEVERABILITY. In the event that any one or more of the
provisions of this Agreement should for any reason be held by any court or
authority having jurisdiction over this Agreement and the Parties to be
invalid, illegal or unenforceable, such provisions shall be deleted in such
jurisdiction; elsewhere this Agreement shall not be affected.

                  8.6   ARTICLE HEADINGS. The section headings contained in
this Agreement are for convenience only and are to be of no force or effect in
construing and interpreting this Agreement.

                  8.7   NOTICES. Any notice, report, request, approval,
payment, consent or other communication required or permitted to be given
under this Agreement shall be in writing and shall for all purposes be deemed
to be fully given and received, if delivered in person or sent by registered
mail, postage prepaid or by facsimile transmission to the respective parties
at the following addresses:

                  If to ENBC:        Enchira Biotechnology Corporation
                                     4200 Research Forest Drive
                                     The Woodlands, Texas 77381
                                     Telefax: (281) 364-6112
                                     Attention: Paul G. Brown, III

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                  If to Genencor:    Genencor International, Inc.
                                     925 Page Mill Road
                                     Palo Alto, CA 94304
                                     Attention:  Senior Vice President
                                     Commercial & Legal Affairs

                  Either Party may change its address for the purpose of this
Agreement by giving the other Party written notice of its new address.

                  8.8   NON-WAIVER FOR FAILURE TO ENFORCE COMPLIANCE. The
express or implied waiver by either Party of a breach of any provision of this
Agreement shall not constitute a continuing waiver of other breaches of the
same or other provisions of this Agreement.

                  8.9   APPLICABLE LAW. This Agreement shall be construed and
interpreted in accordance with the laws of the State of Texas.

                  8.10  AUTHORITY TO SIGN; COUNTERPARTS. Each person signing
below and each Party on whose behalf such person executes this Agreement
warrants that he, she or it as the case may be, has the authority to enter
into this Agreement. This Agreement may be executed in one or more
counterparts, each of which is an original but all of which, taken together,
shall constitute one and the same instrument.

         9.       PROVISION OF BIOLOGICAL MATERIALS

                  9.1   Biological Material made available to a party
("Receiving Party") by the other party ("Delivering Party") is made available
for research purposes within the Development Program only and shall not be
used for any other purpose without the prior written consent of the Delivering
Party. Biological Material provided hereunder will not be used for experiments
in which human beings are subjected to the Biological Material, nor for
research purposes other than the Development Program, for third parties, nor
will Biological Material be transferred to any party outside the Receiving
Party without the prior written consent of the Delivering Party. The Receiving
Party obtains no rights or license in the transferred Biological Material nor
may the Receiving Party file any patent applications claiming such Biological
Material. The Receiving Party will handle such Biological Material in
compliance with all laws, regulations and guidelines applicable to the
Biological Material and its use. The Biological Material is experimental in
nature, and is provided AS IS without any warranties with respect to
performance or fitness for particular purpose, or to completeness and accuracy
of information accompanying the Biological Material. The Receiving Party
acknowledges that the Biological Material is provided AS IS and without any
representation or warranty, express or implied unless otherwise agreed by the
Parties.

                  IN WITNESS WHEREOF, this Collaboration Agreement has been
entered into on the last date signed by the Parties below.

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                                        GENENCOR INTERNATIONAL, INC.

Date:                                   By:
     -----------------                     ------------------------------------
                                        Name:
                                             ----------------------------------
                                        Title:
                                              ---------------------------------

                                       ENCHIRA BIOTECHNOLOGY CORPORATION

Date:                                   By:
     -----------------                     ------------------------------------
                                        Name:
                                             ----------------------------------
                                        Title:
                                              ---------------------------------

                                      29

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                                    EXHIBIT A

                                      "***"

                                      30<PAGE>

                                                                   EXHIBIT 10.2

                                 August 30, 2000

David Carpi
53 Fremont St.
Somerset, NJ  08873

         Re:      Offer of Employment

Dear David:

         Enchira Biotechnology Corporation (the "Company") is pleased to offer
you the position of Vice President-Business Development on the terms provided
herein. You will report directly to and work closely with the President and
Chief Executive Officer of the Company. The purpose of this letter is to ensure
our mutual understanding and agreement on the details of your employment, which
are as follows:

EXECUTIVE POSITION & BASE SALARY

As Vice President-Business Development, you will be responsible for the
Company's strategic alliances, license agreements, collaborations, business
development and such other duties as may be assigned to you by me. You will be
entitled to an annual base salary of $170,000, paid in accordance with the
Company's normal payroll practices. The Compensation Committee of the Board of
Directors will review your base salary on an annual basis, and may authorize
merit increases in its sole discretion. You will be eligible for bonuses in the
discretion of the Board.

RELOCATION

         The Company will pay the reasonable, direct costs necessary to move
you, your family and your household goods from New Jersey to The Woodlands
area; however, we would ask that you coordinate such move with my office in
order to minimize such expenses. The Company will also pay the costs of
temporary housing and commuting expenses for you from New Jersey until 60 days
following the arbitrator's decision in the arbitration proceeding currently
pending between the Company and Maxygen (the "Targeted Relocation Date" or 60
days following the end of the New Jersey school year if necessary), provided
that all such arrangements are mutually agreeable, and will reimburse you for
usual costs incurred in selling your home in New Jersey. In addition, we will
pay for two house-hunting trips for you and your family to The Woodlands area.
All amounts paid in connection with your relocation will be grossed up for any
applicable taxes due thereon.

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EQUITY

         Upon joining the Company, you will receive an option to purchase
100,000 shares of the Company's Common Stock under the Company's Stock Option
Plan, subject to formal approval by the Board of Directors. This option will
entitle you to purchase the specified number of shares at a purchase price
which is equal to the fair market value of the Common Stock on the date your
employment commences and will contain vesting provisions as follows:

         -        25,000 shares vest as a bonus on closing of a mutually
                  agreeable strategic alliance with a biopharmaceutical company
                  within 12 months of employment; in the event that a strategic
                  alliance was not completed with a biopharmaceutical company in
                  the first 12 months of employment but is completed after 12
                  months of employment but prior to the expiration of 18 months,
                  then 25% of the 25,000 shares shall vest on completion of the
                  strategic alliance, and the remaining 75% thereof shall vest
                  on a monthly basis over a three year period of continued
                  employment thereafter.
         -        18,750 shares vest on the completion of 12 months of
                  employment with the Company, provided relocation has occurred
                  by this date.
         -        56,250 shares vest monthly over the following 36 months of
                  employment commencing on the completion of the first year of
                  employment provided relocation has occurred prior to the
                  Targeted Relocation Date.

         All shares vest in entirety upon a change of control.

EMPLOYEE BENEFITS AND VACATION

         You will be entitled to participate in all Company benefit programs in
effect from time to time on the same basis as other employees. Information
regarding such benefit programs will be sent to you under separate cover.
Please note that such policies and benefits may be changed by the Company from
time to time, subject to applicable laws.

SEVERANCE PAY

         In the event that your employment is terminated by the Company at any
time after the date hereof, except for "cause" as defined below, the Company
will continue to pay your then current salary and benefits for a period of nine
months following such termination. Such compensation will be contingent upon
your signing a waiver of rights releasing the Company from any and all further
liability or responsibility. The Company shall have no obligation to pay salary
or benefits in the event you terminate your employment or in the event the
Company terminates your employment for "Cause."

         "Cause" shall include your repeated failure, neglect or refusal, to
perform your duties and responsibilities, dishonesty affecting the Company,
excessive use of alcohol or use of illegal drugs, conviction of a felony or of
any crime involving moral turpitude, fraud or misrepresentation, or the
commission of any willful or intentional act which could reasonably be expected
to materially injure the reputation, business or business relationships of the
Company.

                                      32

<PAGE>

SECRECY AGREEMENT

         Consistent with Company policy, you will be required to execute the
Company's standard Confidentiality and Non-Competition Agreement prior to
commencement of employment. Such non-compete agreement shall provide that you
may not, for a three year period after termination of your employment for any
reason, be employed by or otherwise associated with a direct competitor of the
Company which is engaged in directed evolution technologies for the development
of gene-based products, such as Maxygen, Diversa, or Applied Molecular
Evolution, to name a few. A copy of such agreement will be sent to you under
separate cover.

         This offer is subject to your accepting this offer by August 31, 2000,
and starting employment by September 18, 2000, to completion of our final
reference checks, and to satisfactory completion of a pre-employment physical
examination at the Company's cost. A list of physicians in your area is
included in the enclosed benefit information.

         David, it was clear during your visit that we share a great deal of
enthusiasm and high expectations for the Company's future. We believe that you
can make a significant contribution to the success of the Company and are eager
to have you join us. Please call if there is any other information or
assistance we can provide. We look forward to hearing from you and to seeing
you on September 18, 2000.

                                   Sincerely,

                                   Peter P. Policastro
                                   President and CEO

         Except as provided above, this letter does not create an employment
contract and each party is free to terminate this relationship at any time.
Please indicate your acceptance of this offer which will remain in effect until
August 31, 2000, by signing and returning the enclosed copy.

Date:
                                   --------------------------
                                   David Carpi

                                      33

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