Document:

<PAGE>

                                                                    Exhibit 10.1

                                CONVERTIBLE NOTE
                           AND BONUS PAYMENT AGREEMENT

     This CONVERTIBLE NOTE AND BONUS PAYMENT AGREEMENT, dated as of February 28,
2002 (this "Agreement"), among (i) Essential Therapeutics, Inc., a Delaware
            ---------
corporation ("Parent"), (ii) those holders listed on Schedule 1 attached hereto
              ------                                 ----------
(the "Note Payees") of convertible promissory notes issued by Maret Corporation,
      -----------
a Delaware corporation (the "Company"), (iii) those directors, officers,
                             -------
employees and consultants of the Company who are listed on Schedule 2 attached
                                                           ----------
hereto and who execute and deliver this Agreement in the space provided for
their signatures (the "Management Payees"), (iv) the Company, and (v) and solely
                       -----------------
with respect to Section1.02(d)(i) hereof, Terence E. Winters, acting solely as
the Stockholder Representative referred to herein. Capitalized terms used herein
without definition shall have the meaning ascribed thereto in the Merger
Agreement.

     WHEREAS, the Company is to be acquired by Parent through the merger of MC
Merger Corp., a Delaware corporation and wholly owned subsidiary of Parent
("Subcorp"), with and into the Company, as a result of which the Company will be
  -------
the surviving corporation (the "Merger"), all in accordance with the General
                                ------
Corporation Law of the State of Delaware ("Delaware Law") and subject to the
                                           ------------
terms of that Agreement and Plan of Merger, of even date herewith, by and among
Parent, Subcorp, the Company and Terence E. Winters in his capacity as the
Stockholder Representative thereunder (the "Merger Agreement"); and
                                            ----------------

     WHEREAS, it is a condition to the willingness of the parties to enter into
the Merger Agreement that the parties hereto execute and deliver this Agreement
simultaneously with the execution and delivery of the Merger Agreement.

     NOW, THEREFORE, in consideration of the foregoing and the mutual covenants
and agreements herein contained and intending to be legally bound hereby, the
parties hereto hereby agree as follows:

                                    ARTICLE I
                                  THE PAYMENTS

     SECTION 1.01.  The Note Payments.
                    -----------------

          (a) Note Payment Shares. Immediately prior to, but subject to, the
              -------------------
consummation of the Merger, all outstanding principal and accrued but unpaid
interest owed by the Company to each Note Payee immediately prior to the
Effective Time (such principal and interest being hereinafter referred to, in
the case of such Note Payee, as the "Amount Due") under any promissory note,
                                     ----------
convertible promissory note or other instrument issued by the Company and then
held by such Note Payee (collectively, the "Notes" and each individually a
                                            -----
"Note") shall (automatically and without further action by such Note Payee, the
 ----
Company or Parent) be cancelled, and, in exchange and as full payment for such
Amount Due, Parent shall, subject to the remaining provisions of this Section
1.01, issue to such Note Payee the number of shares of Parent Common Stock set
forth opposite such Note Payee's name on Schedule 1 hereto
                                         ----------

<PAGE>

under the caption "Note Payment Shares". The aggregate number of shares of
Parent Common Stock that Parent is required to issue to all of the Note Payees
pursuant to this Section 1.01 shall be referred to as the "Note Payment Shares".
                                                           -------------------

          (b) Schedule 1. Schedule 1 hereto sets forth, opposite each Note
              ----------  ----------
Payee's name, the Note or Notes held by such Note Payee on the date of this
Agreement (each identified by the date of issue of each such Note and the
original principal amount thereof), and the number of Note Payment Shares to be
issued to such Note Payee. Each of the Company and the Note Payees hereby
represents and warrants to Parent and the Surviving Corporation that Schedule 1
                                                                     ----------
hereto is, and at the Closing will be, true, correct and complete, and that the
Company does not owe any amount to any of the Note Payees other than the amounts
set forth on Schedule 1 hereto. Parent and the Surviving Corporation shall be
             ----------
entitled to rely on Schedule 1 without any obligation to verify the same and
                    ----------
shall have no liability to any Note Payee or any other party as a result of such
reliance.

          (c) No Further Obligation. From and after the Effective Time, all of
              ---------------------
the Notes shall be terminated, canceled and of no further force or effect, and
none of Parent, Company or the Surviving Corporation shall have any liability or
obligation of any kind whatsoever to the Note Payees under the Notes.

          (d) Transfer of Title. Each Note Payee hereby covenants and agrees
              -----------------
that such Note Payee shall not transfer record or beneficial ownership of any of
the Notes at any time during the period commencing on the date hereof and ending
on the effective date of termination of this Agreement.

     SECTION 1.02. The Bonus Payments.
                   ------------------

          (a) Management Payment Shares.
              -------------------------

               (i) At Closing. Immediately prior to, but subject to, the
                   ----------
consummation of the Merger, all stay-bonus obligations owed by the Company to
each Management Payee immediately prior to the Effective Time (in the case of
each Management Payee, the "Management Stay-Bonus" and, collectively with the
                            ---------------------
Management Stay-Bonus owed to each other Management Payee, the "Management
                                                                ----------
Stay-Bonuses") shall (automatically and without further action by such
------------
Management Payee, the Company or Parent) be cancelled, and, in exchange and as
full payment for such Management Stay-Bonus, Parent shall, subject to the
remaining provisions of this Section 1.02, issue to such Management Payee the
number of shares of Parent Common Stock set forth opposite such Management
Payee's name on Schedule 2 hereto under the caption "Aggregate Management
                ----------
Payment Shares". The aggregate number of shares of Parent Common Stock that
Parent is required to issue to all of the Management Payees pursuant to this
Section 1.02 shall be 100,000 shares (subject to adjustment pursuant to the next
sentence). Any references in this Section 1.02 or in Schedule 2 hereto to any
                                                     ----------
number of shares of Parent Common Stock shall be equitably adjusted to reflect
fully the effect of any stock split, reverse split, stock combination, stock
dividend, reorganization, reclassification, recapitalization or other like
change with respect to Parent Common Stock after the date hereof and prior to
the Effective Time. The aggregate number of shares of Parent Common Stock that

                                       -2-

<PAGE>

Parent is required to issue to all of the Management Payees pursuant to this
Section 1.02 shall be referred to as the "Management Payment Shares".
                                          -------------------------

               (ii) Escrow. Notwithstanding any provisions of this Agreement to
                    ------
the contrary, ten percent (10%) of the shares that each Management Payee would
otherwise be entitled to receive pursuant to Section 1.02(a) above, resulting in
an aggregate of 10,000 of the Management Payment Shares (the "Management
                                                              ----------
Escrowed Shares"), shall be deposited with, and held by, the Escrow Agent
---------------
pursuant to the terms of the Escrow Agreement as Escrowed Property thereunder,
for the purpose of providing for the payment of any and all indemnification
claims made by Parent pursuant to Article IX of the Merger Agreement. By
executing this Agreement, each Management Payee agrees to be bound by the terms
and obligations of the Escrow Agreement. The aggregate number of shares of
Parent Common Stock that Parent is required to issue to all of the Management
Payees pursuant to this Section 1.02, less the Management Escrowed Shares, shall
be referred to as the "Management Closing Shares".
                       -------------------------

          (b) Schedule 2. Schedule 2 hereto sets forth, opposite each Management
              ----------  ----------
Payee's name, the Management Stay-Bonus owed by the Company to such Management
Payee, and the aggregate number of Management Payment Shares to which such
Management Payee would be entitled under this Section 1.02 if the Effective Time
were occurring on the date hereof, which aggregate number of Management Payment
Shares is allocated on Schedule 2 to reflect for each Management Payee such
                       ----------
Management Payee's portion of the Management Closing Shares and the Management
Escrowed Shares. Each of the Company and each Management Payee hereby represents
and warrants to Parent and the Surviving Corporation that Schedule 2 hereto is,
                                                          ----------
and at the Closing will be, true, correct and complete, and that the Company
does not owe any stay-bonus or other kind of bonus to any of the Management
Payees other than the Management Stay-Bonuses set forth on Schedule 2 hereto
                                                           ----------
(other than bonuses reserved for in the Company's unaudited financial statements
for the year ended December 31, 2001 owing to Gere Di Zerega and Kathleen
Rodgers in the aggregate amount of $28,400). Parent and the Surviving
Corporation shall be entitled to rely on Schedule 2 without any obligation to
                                         ----------
verify the same and shall have no liability to any Management Payee or any other
party as a result of such reliance.

          (c) No Further Obligation. From and after the Effective Time, all of
              ---------------------
the Management Stay-Bonuses shall be deemed to be paid in full, and none of
Parent, Company or the Surviving Corporation shall have any liability or
obligation of any kind whatsoever to the Management Payees with respect to the
Management Stay-Bonuses and all other bonuses owed by the Company to any of the
Management Payees (other than bonuses reserved for in the Company's unaudited
financial statements for the year ended December 31, 2001 owing to Gere Di
Zerega and Kathleen Rodgers in the aggregate amount of $28,400).

          (d) Additional Management Payee Agreements.
              --------------------------------------

               (i) Appointment of Stockholder Representative. By signing below,
                   -----------------------------------------
each Management Payee hereby agrees that the Stockholder Representative
appointed pursuant to the terms of the Merger Agreement, which appointee will
initially be, Terence E. Winters, shall

                                       -3-

<PAGE>

be his, her or its true and lawful agent and attorney-in-fact to enter into any
agreement in connection with the transactions contemplated by the Escrow
Agreement, to exercise all or any of the powers, authority and discretion
conferred on him under any such agreement, to give and receive notices on their
behalf and to be his, her or its exclusive representative with respect to any
matter, suit, claim, action or proceeding arising with respect to any
transaction contemplated by any such agreement, including, without limitation,
the defense, settlement or compromise of any claim, action or proceeding for
which Parent or the Surviving Corporation, may be entitled to indemnification
and, the Stockholder Representative agrees to act as, and to undertake the
duties and responsibilities of, such agent and attorney-in-fact. All actions,
decisions and instructions of the Stockholder Representative shall be conclusive
and binding upon all of the Management Payees and no Management Payee shall have
any cause of action against the Stockholder Representative for any action taken,
decision made or instruction given by the Stockholder Representative under this
Agreement or the Escrow Agreement (or for any failure to take such action, make
such decision or give such instruction).

               (ii) Release. Each Management Payee hereby agrees to release the
                    -------
Company, Parent and the Surviving Corporation and their respective affiliates
(as such term is defined in the Merger Agreement), and all of their respective
past and present directors, trustees, officers, shareholders, employees, agents,
successors and assigns, and all others connected with any of them, both
individually and in their official capacities, from any and all causes of
action, rights or claims that such Management Payee may have had in the past,
now have or might now have, in any way related to, connected with or arising out
of such Management Payee's relationship, in any capacity, with the Company,
including, without limitation, any claims pursuant to any other federal, state
or local law, regulation or other requirement, or pursuant to any written or
oral contract, agreement or understanding between such Management Payee and the
Company.

               (iii) Non-Disparagement. Further, each Management Payee hereby
                     -----------------
agrees that such Management Payee will continue to use such Management Payee's
best efforts to support and promote the interests and reputation of the Company,
Parent and/or the Surviving Corporation in the community; that such Management
Payee will not disparage the Company, Parent and/or the Surviving Corporation or
any of the people or organizations associated with it; and that Management Payee
will not otherwise do or say anything that is intended to injure the good morale
of the employees of the Company, Parent and/or the Surviving Corporation or
otherwise harm its business or reputation.

               (iv) Withholding. Each Management Payee agrees to pay to the
                    -----------
Company, the Surviving Corporation or Parent, as applicable, such amounts as any
of the foregoing is required to deduct and withhold under the Code, or any
provision of state, local or foreign tax law, with respect to the issuance of
the Management Payment Shares (the "Withholding Amount"). In the absence of
                                    ------------------
payment by any Management Payee of the Withholding Amount, each of the Company,
the Surviving Corporation and/or Parent shall be entitled to deduct and withhold
from any amounts due to any Management Payee the Withholding Amount. To the
extent that amounts are so withheld by Surviving Corporation or the Parent, as
the case may be, such withheld amounts shall be treated for all purposes of this

                                       -4-

<PAGE>

Agreement as having been paid to such holder in respect of which such deduction
and withholding was made by Surviving Corporation or the Parent, as the case may
be.

          (e) No Obligation. Notwithstanding any provision of this Agreement to
              -------------
the contrary, any person listed on Schedule 2 hereto that fails to execute and
deliver a signature page to this Agreement prior to the Closing contemplated by
the Merger Agreement (i) shall not be a Management Payee hereunder, (ii) shall
not be entitled to any Management Stay-Bonus, and (iii) shall not be entitled to
receive any Management Payment Shares.

     SECTION 1.03. Closing. Immediately prior to the Closing contemplated by the
                   -------
Merger Agreement, each Note Payee shall deliver the original Note held by it for
cancellation. Within a reasonable period of time after the Effective Time,
Parent will cause to be delivered: (i) to each Note Payee and Management Payee,
those materials that Parent or its transfer agent will require from the Note
Payees and the Management Payees, which materials may include any certifications
Parent may request with respect to compliance with any withholding obligations
of Parent or the Surviving Corporation under the Code, (ii) to each Note Payee
that has surrendered all original Notes held by such Note Payee and all required
originals (duly completed and executed by such Note Payee) of all materials
delivered to such Note Payee pursuant to the foregoing clause (i), a certificate
registered in the name of such Note Payee representing the number of Note
Payment Shares due to such Note Payee; and (ii) to each Management Payee that
has surrendered all required originals (duly completed and executed by such
Management Payee) of all materials delivered to such Note Payee pursuant to the
foregoing clause (i), a certificate registered in the name of such Management
Payee representing the number of Management Payment Shares due to such
Management Payee.

                                   ARTICLE II
                              ADDITIONAL AGREEMENTS

     SECTION 2.01. Termination of Securities. Each of the Management Payees and
                   -------------------------
Note Payees hereby agrees that any Company Option, Company Warrant or
Convertible Security held by such Management Payee or Note Payee, as the case
may be, immediately prior to the Closing contemplated by the Merger Agreement,
shall (automatically and without further action by such Management Payee or Note
Payee, as the case may be, the Company, the Surviving Corporation or Parent, and
notwithstanding any notice provisions provided for therein) be cancelled,
terminated and of no further force or effect immediately prior to such Closing.

     SECTION 2.02. Waiver of Appraisal Rights. Each of those Management Payees
                   --------------------------
and Note Payees that is also a Stockholder hereby agrees to waive all
dissenters' appraisal rights or similar rights or remedies to which he, she or
it may be entitled, available under Section 262 of the Delaware General
Corporation Law, or any other applicable law, in connection with the Merger and
the transactions contemplated thereby.

     SECTION 2.03. Registration Rights. Each of the Management Payees and the
                   -------------------
Note Payees hereby agrees to be subject to, and bound by, all of the provisions
of Section 6.06 of the

                                       -5-

<PAGE>

Merger Agreement to the same extent as if such Management Payee or Note Payee,
as the case may be, were a party to the Merger Agreement.

     SECTION 2.04. Stockholder Questionnaire. Each of the Management Payees and
                   -------------------------
the Note Payees is, simultaneously with the execution and delivery of this
Agreement, executing and delivering to Parent a properly completed Stockholder
Questionnaire.

                                   ARTICLE III
                        TERMINATION, AMENDMENT AND WAIVER

     SECTION 3.01. Termination. This Agreement shall terminate immediately upon,
                   -----------
and simultaneously with, the termination of the Merger Agreement for any reason
whatsoever. Additionally, this Agreement may be terminated and the transactions
contemplated hereby may be abandoned at any time prior to the Closing:

          (a) by mutual written agreement of all of the parties hereto;

          (b) by Parent, in the event of a material breach by the Company, any
Note Payee or any Management Payee of any representation, warranty, covenant,
obligation or agreement contained herein that has not been cured or is not
curable by the Closing Date; or

          (c) by Company, in the event of a material breach by Parent of any
representation, warranty, covenant, obligation or agreement contained herein
that has not been cured or is not curable by the Closing Date.

     SECTION 3.02. Effect of Termination. In the event of the termination of
                   ---------------------
this Agreement pursuant to Section 3.01, this Agreement shall forthwith become
void, there shall be no liability under this Agreement on the part of Parent,
the Company, any Management Payee or any Note Payee and all rights and
obligations hereunder of any party hereto shall cease; provided, however, that
                                                       -----------------
any such termination shall not affect, impair, release or terminate the rights
or liabilities of any party hereto that accrued prior to the effectiveness of
any such termination.

     SECTION 3.03. Amendment. This Agreement may not be amended except by an
                   ---------
instrument in writing signed by all of the parties hereto.

     SECTION 3.04. Waiver. At any time prior to the Closing, any party hereto
                   ------
may (a) extend the time for the performance of any obligation or other act of
any other party hereto and (b) waive compliance with any provision of this
Agreement. Any such extension or waiver shall be valid if set forth in an
instrument in writing signed by the party or parties to be bound thereby.

                                   ARTICLE IV
                               GENERAL PROVISIONS

     SECTION 4.01. Notices. All notices, requests, claims, demands and other
                   -------
communications hereunder shall be in writing, and shall be deemed to have been
duly given if

                                       -6-

<PAGE>

(a) delivered personally (effective upon delivery), (b) mailed by registered or
certified mail, return receipt requested, postage prepaid (effective five days
after dispatch), (c) sent via a reputable, established courier service that
guarantees next Business Day delivery (effective the next Business Day after
delivery to such courier) or (d) sent via telecopier (effective upon the
transmission of the telecopy in complete, readable form) addressed as set forth
below (or at such other address for a party as shall be specified in a notice
given in accordance with this Section 4.01):

     if to Parent:

               Essential Therapeutics, Inc.
               1365 Main Street
               Waltham, MA 02451
               Attention:  President
                                Facsimile:  781-647-4230

     with a copy to:

               Bingham Dana LLP
               150 Federal Street
               Boston, MA 02110
               Attention:  Julio E. Vega, Esq.
                                Facsimile:  617-951-8736

     if to the Company:

               Maret Corporation
               4041 MacArthur Blvd.
               Suite 375
               Newport Beach, CA  92660
               Attention:  President
                                Facsimile:  949-225-0006

     with a copy to:

               Stradling Yocca Carlson & Rauth
               660 Newport Center Drive
               Suite 1600
               Newport Beach, CA  92660
               Attention:  Lawrence B. Cohn, Esq.
                                Facsimile:  949-725-4100

if to any Note Payee or Management Payee, to the address for such Payee set
forth in the Company's books and records.

                                       -7-

<PAGE>

     SECTION 4.02. Entire Agreement; Assignment. This Agreement, including all
                   ----------------------------
exhibits, schedules and recitals hereto, together with the Merger Agreement, the
Voting Agreement, the Escrow Agreement and the Confidentiality Agreement,
constitutes the entire agreement among the parties with respect to the subject
matter hereof and supersedes all prior agreements and undertakings, both written
and oral, among the parties, or any of them, with respect to the subject matter
hereof. This Agreement shall not be assigned by operation of law or otherwise,
except that Parent may assign all or any of their rights and obligations
hereunder to any affiliate of Parent provided that no such assignment shall
relieve the assigning party of its obligations hereunder if such assignee does
not perform such obligations.

     SECTION 4.03. Governing Law; Venue. Except to the extent that Delaware Law
                   --------------------
is mandatorily applicable to the rights and obligations of parties to this
Agreement, this Agreement shall be governed by, and construed in accordance with
the laws of the Commonwealth of Massachusetts applicable to contracts executed
in and to be performed in that Commonwealth. Subject to the provisions of
Section 4.05 below, all actions and proceedings arising out of or relating to
this Agreement shall be heard and determined exclusively in any Massachusetts
state or federal court sitting in the City of Boston.

     SECTION 4.04. Waiver of Jury Trial. Each of Parent and the Company, and
                   --------------------
each Note Payee and Management Payee 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 Parent, the Company or any Note Payee or Management Payee in the
negotiation, administration, performance and enforcement thereof.

     Section 4.05. Dispute Resolution. Except to the extent otherwise
                   ------------------
specifically provided below in this Section 4.05, all claims, controversies,
differences or disputes between or among any of the parties hereto arising from
or relating to this Agreement and the transactions contemplated hereby shall be
determined solely and exclusively by arbitration in accordance with the rules of
commercial arbitration then in effect of the American Arbitration Association,
or any successors thereto ("AAA"), in Boston, Massachusetts, unless the parties
                            ---
otherwise agree in writing. Each of the parties consents to venue for such
arbitrations in Boston, Massachusetts and to service of process by certified or
registered mail. Upon commencement of any arbitration pursuant hereto, the
parties shall jointly select an arbitrator. In the event the parties fail to
agree upon an arbitrator within twenty (20) days, then each party shall select
an arbitrator and such arbitrators shall then select a third arbitrator to serve
as the sole arbitrator; provided that if either party, in such event, fails to
                        -------------
select an arbitrator within seven (7) days, such arbitrator shall be selected by
the AAA upon application of either party. Judgment upon the award of the agreed
upon arbitrator or the so chosen third arbitrator, as the case may be, shall be
binding and shall be entered by a court of competent jurisdiction. The parties
agree to abide by any decision rendered in any such arbitration as final and
binding and waive the right to submit the dispute to a public tribunal for a
jury or non-jury trial. The fees and expenses of the AAA in any such arbitration
shall be shared equally by the parties, unless otherwise ordered by the
arbitrator(s). Each party shall be responsible for all costs incurred by it in
preparing for and participating in the arbitration, unless the arbitrator(s)
order that a party shall be entitled to recover its actual out-of-pocket costs
and expenses, including without limitation reasonable attorneys' fees incurred
in connection with such arbitration. Notwithstanding

                                       -8-

<PAGE>

anything to the contrary in this Section 4.05, in no event, however, shall this
Section 4.05 be deemed to preclude a party hereto from instituting legal action
seeking relief in the nature of a restraining order, an injunction, a specific
performance order or the like in order to protect his or its rights pending the
outcome of an arbitration hereunder.

     SECTION 4.06. Headings. The descriptive headings contained in this
                   --------
Agreement are included for convenience of reference only and shall not affect in
any way the meaning or interpretation of this Agreement.

     SECTION 4.07. Counterparts. This Agreement may be executed and delivered
                   ------------
(including by facsimile transmission) in one or more counterparts, and by the
different parties hereto in separate counterparts, each of which when executed
and delivered shall be deemed to be an original but all of which taken together
shall constitute one and the same agreement.

            [The remainder of this page is intentionally left blank.
                            Signature page follows.]

                                       -9-

<PAGE>

     IN WITNESS WHEREOF, Parent, the Company and the undersigned Note Payees and
the Management Payees have caused this Agreement to be executed as an instrument
under deal as of the date first written.

                                   ESSENTIAL THERAPEUTICS, INC.

                                   By:      /s/ Mark Skaletsky
                                       ----------------------------------------
                                   Name: Mark Skaletsky
                                   Title: President and Chief Executive Officer

                                   MARET CORPORATION

                                   By:      /s/ Leonard R. Borrmann
                                       ----------------------------------------
                                   Name: Leonard R. Borrmann
                                   Title: President and Chief Executive Officer

                                   STOCKHOLDER REPRESENTATIVE:

                                       /s/ Terence E. Winters
                                   --------------------------------------------
                                   Terence E. Winters

            [The remainder of this page is intentionally left blank.
                            Signature page follows.]

<PAGE>

                                   NOTE PAYEES:
                                   -----------

                                   VALLEY VENTURES II, L.P.

                                   By: VV II MANAGEMENT, L.L.C.
                                   Its: General Partner

                                   By:      /s/ John M. Holbiman III
                                       ----------------------------------------

                                   Print Name: John M. Holbiman III
                                               --------------------------------
                                   Its: Manager

                                   NEW YORK LIFE INSURANCE COMPANY

                                   By:      /s/ Ray E. Newton, III
                                       ----------------------------------------

                                   Print Name: Ray E. Newton, III
                                               --------------------------------
                                   Its: Managing Director

            [The remainder of this page is intentionally left blank.
                            Signature page follows.]

<PAGE>

                                   COLUMBINE VENTURE FUND II, L.P.,
                                    a Delaware Limited Partnership

                                   By: Columbine Venture Management II,
                                        a Delaware Partnership
                                   Its: General Partner

                                   By:          /s/ Terence E. Winters
                                       ----------------------------------------
                                                Terence E. Winters
                                   Its: General Partner

                                   INNOCAL, L.P., a Delaware Limited Partnership

                                   By: Innocal Associates, L.P., a Delaware
                                        Limited Partnership
                                   Its: General Partner

                                   By:          /s/ John E. Houlihan
                                       ----------------------------------------

                                   Print Name: John E. Houlihan
                                               --------------------------------
                                   Its: General Partner

                                       /s/ John Patience
                                   --------------------------------------------
                                   John Patience

                                       /s/ Jack W. Schuler
                                   --------------------------------------------
                                   Jack W. Schuler

            [The remainder of this page is intentionally left blank.
                            Signature page follows.]

<PAGE>

                                   MANAGEMENT PAYEES:
                                   -----------------

                                       /s/ Gere di Zerega
                                   --------------------------------------------
                                   Gere di Zerega

                                       /s/ Kathleen Rodgers
                                   --------------------------------------------
                                   Kathleen Rodgers

                                       /s/ Helmer P.K. Agersborg
                                   --------------------------------------------
                                   Helmer P.K. Agersborg

                                       /s/ Leonard Borrmann
                                   --------------------------------------------
                                   Leonard Borrmann

                                       /s/ Gerald Messerschmidt
                                   --------------------------------------------
                                   Gerald Messerschmidt

                                       /s/ James Oliver
                                   --------------------------------------------
                                   James Oliver

                                       /s/ James Rock
                                   --------------------------------------------
                                   James Rock

                                       /s/ Catherine Oyler
                                   --------------------------------------------
                                   Catherine Oyler

                                       /s/ Randolph C. Steer
                                   --------------------------------------------
                                   Randolph C. Steer

                                       /s/ Leigh Thompson
                                   --------------------------------------------
                                   Leigh Thompson

                                       /s/ Terence E. Winters
                                   --------------------------------------------
                                   Terence E. Winters<PAGE>

                                                                    Exhibit 10.2

                                ESCROW AGREEMENT

     This ESCROW AGREEMENT (this "Agreement"), dated as of March 11, 2002, is
                                  ---------
among Essential Therapeutics, Inc., a Delaware corporation (the "Parent"),
                                                                 ------
Terence E. Winters in his capacity as representative (he or his successor, in
such capacity, being referred to as the "Stockholder Representative") for the
                                         ----------- --------------
stockholders listed on Schedule 1 hereof (each, a "Stockholder", and
                       -------- -                  -----------
collectively the "Stockholders") of Maret Corporation, a Delaware corporation
                  ------------
(the "Company"), the Management Payees (as defined below) listed on Schedule 1
      -------                                                       -------- -
hereto, and State Street Bank and Trust Company, a Massachusetts trust company,
as escrow agent (in such capacity, the "Escrow Agent"). Certain terms used in
                                        ------------
this Agreement not defined within the provisions in which they appear are
defined in Article 8 hereof. The Parent, the Company, the Management Payees and
the Stockholder Representative are sometimes referred to herein as the
"Interested Parties."
 ------------------

                                   WITNESSETH

     WHEREAS, the Parent, MC Merger Corp., a Delaware corporation and a wholly
owned subsidiary of the Parent (the "Merger Sub"), the Stockholder
                                     ----------
Representative and the Company have entered into an Agreement and Plan of
Merger, dated as of February 28, 2002 (the "Merger Agreement"), pursuant to
                                            ----------------
which the Parent has agreed to cause the Merger Sub to be merged with and into
the Company, with the Company being the surviving corporation (the "Surviving
                                                                    ---------
Corporation"), and in which the outstanding shares of capital stock of the
-----------
Company will be converted into the right to receive shares of the common stock
of the Parent, par value $0.001 per share ("Parent Common Stock") in accordance
                                            -------------------
with the terms of the Merger Agreement;

     WHEREAS, as a condition to, and concurrently with, the execution of the
Merger Agreement, certain directors, officers, employees and consultants of the
Company (collectively, the "Management Payees"), and all holders of convertible
                            ---------- ------
promissory notes issued by the Company (other than Parent) and outstanding on
the date of the Merger Agreement, Terence E. Winters in his capacity as the
Stockholder Representative therein, and Parent, have executed and delivered the
Convertible Note and Bonus Payment Agreement (the "Payment Agreement"), pursuant
                                                   ------- ---------
to which, among other things, Parent has agreed that, simultaneous with the
closing of the Merger contemplated by this Agreement, Parent shall issue 100,000
shares of Parent Common Stock to the Management Payees (the "Management Payment
                                                             ---------- -------
Shares"); and
------

     WHEREAS, pursuant to the Merger Agreement and the Payment Agreement, an
aggregate of two hundred thousand (200,000) shares of Parent Common Stock, of
which shares (i) one hundred ninety thousand (190,000) shares would be issuable
to the Stockholders on the Closing Date if shares of Parent Common Stock were
not to be issued into escrow pursuant to the Merger Agreement, and (ii) ten
thousand (10,000) shares would be issuable to the Management Payees on the
Closing Date if ten percent (10%) of the Management Payment Shares were not to
be issued into escrow pursuant to the Payment Agreement, shall be deposited in
escrow with the Escrow Agent, to be held and distributed by the Escrow Agent on
the terms and conditions set forth herein.

<PAGE>

                                       -2-

     NOW, THEREFORE, in consideration of the mutual covenants and agreements
contained herein, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties agree as follows:

                                    ARTICLE 1
                             ESTABLISHMENT OF ESCROW

     1.1 Escrowed Shares. On this date or promptly thereafter, Parent shall give
         ---------------
instructions to its transfer agent, Mellon Investor Services, to deliver a
single stock certificate representing 200,000 shares of Parent Common Stock (the
"Escrowed Shares") to the Escrow Agent, which stock certificate shall be
 ---------------
registered in the name of "Embassy & Co." as nominee for the Escrow Agent. The
Escrow Agent agrees to hold and disburse the Escrowed Shares (said Escrowed
Shares, together with any other property held in escrow hereunder, collectively,
the "Escrow Property") for the benefit of Parent, the Stockholders and/or the
     ---------------
Management Payees, as the case may be, in accordance with the provisions of this
Agreement. The Escrow Agent shall have no responsibility for the genuineness,
validity, market value, title or sufficiency for any intended purpose of the
Escrow Property.

     1.2 Stockholder and Management Payee Percentage Interests. Schedule 1
         -----------------------------------------------------------------
attached hereto shows for each Stockholder and Management Payee (i) the
respective percentage interest (the "Percentage Interest") of each such
                                     -------------------
Stockholder and Management Payee in the Escrowed Shares, and (ii) the
corresponding aggregate maximum number of shares of Parent Common Stock issuable
to each such Stockholder and Management Payee, assuming the release of all of
the Escrowed Shares to the Stockholders and Management Payees in accordance with
the provisions of this Agreement.

     1.3 Beneficial Interest. Unless and until any of the Escrow Property held
         -------------------
in escrow pursuant to this Agreement is released or required to be released to
Parent in accordance with the provisions of this Agreement, each Stockholder and
Management Payee shall have a beneficial interest in and to a portion of such
Escrow Property held in escrow equal to such Stockholder's and Management
Payee's Percentage Interest of such Escrow Property held in escrow.

                                    ARTICLE 2
                            DIVIDENDS, VOTING RIGHTS

     2.1 Dividends and Distributions. So long as any Escrowed Shares are held by
         ---------------------------
the Escrow Agent hereunder, all dividends and distributions paid or made in
respect of the Escrowed Shares and/or any other capital stock or securities held
in escrow by the Escrow Agent hereunder shall be added to and become part of the
Escrow Property, subject to the escrow covered by this Agreement, and shall be
held by the Escrow Agent in escrow for the benefit of Parent, the Management
Payees and/or the Stockholders, as the case may be, in accordance with the
provisions of this Agreement.

     2.2 Stock Splits; Stock Dividends. In the event of any stock split or stock
         -----------------------------
dividend with respect to Parent Common Stock or any other capital stock held in
escrow hereunder that

<PAGE>

                                       -3-

becomes effective at any time while any Escrowed Shares are held by the Escrow
Agent hereunder, the additional shares or securities so issued in connection
with such stock split or stock dividend shall be added to and become part of the
Escrow Property, subject to the escrow covered by this Agreement, and shall be
held by the Escrow Agent for the benefit of Parent, the Management Payees and/or
the Stockholders, as the case may be, in accordance with the provisions of this
Agreement.

     2.3 Voting Rights. Neither the Escrow Agent nor its nominee shall be under
         -------------
any duty to take any action to preserve, protect, exercise or enforce any rights
or remedies under or with respect to the Escrow Property (including without
limitation with respect to the exercise of any voting or consent rights,
conversion or exchange rights, defense of title, preservation of rights against
prior matters or otherwise). Notwithstanding the foregoing, if the Escrow Agent
is so requested in a written request of the Stockholder Representative received
by the Escrow Agent at least three (3) Business Days prior to the date on which
the Escrow Agent is requested therein to take such action (or such later date as
may be acceptable to the Escrow Agent), the Escrow Agent shall execute or cause
its nominee to execute, and deliver to the Stockholder Representative a proxy or
other instrument in the form supplied to it by the Stockholder Representative
for voting or otherwise exercising any right of consent with respect to any of
the Escrowed Shares held by it hereunder, to authorize therein the Stockholder
Representative to exercise such voting or consent authority in respect of the
Escrowed Shares (provided that the Escrow Agent shall not be obliged to execute
any such proxy or other instrument if, in its judgment, the terms thereof may
subject the Escrow Agent to any liabilities or obligations in its individual
capacity). The Escrow Agent shall not be under any duty or responsibility to
forward to any Interested Party, or to notify any Interested Party with respect
to, or to take any action with respect to, any notice, solicitation or other
document or information, written or otherwise, received from an issuer or other
person with respect to the Escrowed Shares, including but not limited to, proxy
material, tenders, options, the pendency of calls and maturities and expiration
of rights.

     2.4 Sale of Escrowed Shares. The Escrow Agent shall be under no obligation
         -----------------------
to sell any Escrowed Shares hereunder.

                                    ARTICLE 3
                          INVESTMENT OF ESCROW PROPERTY

         Until the termination of this Escrow Agreement and the release of the
Escrow Property held by the Escrow Agent pursuant hereto, the Escrow Agent
shall, at the written direction of the Stockholder Representative invest and
reinvest any portion of the Escrow Property held by the Escrow Agent hereunder
that consists of cash or cash equivalents solely in (a) marketable obligations
of, or obligations guaranteed by, the United States of America, or (b) Federal
Obligations (as defined below). In the event that the Stockholder
Representative, on behalf of the Stockholders, does not give written directions
to the Escrow Agent in a timely manner, the Escrow Agent shall have no
obligation or duty to invest (or otherwise pay interest on) any cash it may
receive as part of the Escrow Property from time to time; provided, however,
                                                          --------  -------
that the Escrow Agent is hereby authorized to invest any cash it may hold from
time to time hereunder in Goldman Sachs Financial Square Treasury Obligations
Fund #468. The Escrow Agent shall have no liability to the Stockholders or the
Parent arising, directly or indirectly, from any

<PAGE>

                                      -4-

investment made pursuant to this Article 3. Any earnings received on any
investment shall be added to and shall become part of the Escrow Property. As
used herein, the term "Federal Obligations" means obligations of, or obligations
                       -------------------
guaranteed by, the United States or any agency thereof and to agreements to
repurchase Federal Obligations that are at least one hundred percent (100%)
collateralized by Federal Obligations marked to market on a daily basis.

                                    ARTICLE 4
                                   TAX MATTERS

     4.1 Tax Reporting. For tax reporting purposes, all interest or other income
         -------------
earned from the investment of the Escrow Property in any tax year shall (i) to
the extent such interest or other income is distributed or required to be
distributed by the Escrow Agent to any pe rsons or entities pursuant to the
terms of this Agreement during such tax year, be allocated to such persons or
entities, and (ii) otherwise shall be allocated to the Stockholders and
Management Payees (in accordance with their percentage interest as set forth on
Schedule 1 attached hereto).

     4.2 Certification of Tax Identification Number. The Parent hereby agrees
         ------------------------------------------
to, and each Stockholder and Management Payee agrees to, provide the Escrow
Agent with a certified tax identification number by signing and returning a Form
W-9 (or Form W-8 BEN, in case of non-U.S. persons) to the Escrow Agent prior to
the date on which any income is earned on the investment of the Escrow Property.
In the event their tax identification numbers are not certified to the Escrow
Agent, the Internal Revenue Code, as amended from time to time, may require
withholding of a portion of any interest or other income earned on the
investment of the Escrow Property.

     4.3 Tax Indemnification. The Stockholder Representative and the Parent
         -------------------
agree to instruct the Escrow Agent in writing with respect to the Escrow Agent's
responsibility for withholding any other taxes, assessments or other
governmental charges, and to instruct the Escrow Agent with respect to any
certifications and governmental charges, and to instruct the Escrow Agent with
respect to any certifications that may be required under any laws or regulations
that may be applicable in connection with its acting as Escrow Agent under this
Agreement. Parent, the Management Payees and the Stockholders agree, jointly and
severally, to indemnify and hold the Escrow Agent harmless from any liability or
obligation on account of taxes, assessments, additions for late payment,
interest, penalties, costs, expenses (including reasonable legal fees and
expenses), interest and penalties and other governmental charges (including,
without limitation, (i) any liability for the withholding or deduction of, or
the failure to withhold or deduct, the same, and (ii) any liability for failure
to obtain proper certifications or to report properly to governmental
authorities in connection with this Agreement) that may be assessed or asserted
against the Escrow Agent in connection with or relating to any Escrow Property
distributed to Parent or any such Stockholder, as the case may be, or Escrow
Property in which Parent, any Management Payee or any such Stockholder, as the
case may be, may otherwise have a beneficial interest, except for (A) taxes paid
on income earned by the Escrow Agent, and (B) any taxes, assessments, additions
for late payment, interest penalties, expenses and other governmental charges
arising from the Escrow Agent's gross negligence or willful misconduct. The
foregoing indemnification and agreement to hold harmless shall survive the
termination of this Agreement. The sole recourse against any Stockholder or
Management

<PAGE>

                                      -5-

Payee for any such indemnification obligation or liability of such Stockholder
or Management Payee shall be to proceed against the escrow established
hereunder.

                                    ARTICLE 5
                                RELEASE OF ESCROW

     5.1  Indemnification Claims.
          ----------------------

          (a) From time to time prior to the first anniversary of the Effective
Time (as certified to the Escrow Agent by the Parent in writing) Parent may
deliver to the Escrow Agent and the Stockholder Representative a written notice
(a "Notice of Claim") (A) requesting distribution to the Parent of a number of
    ------ -- -----
Escrowed Shares having a value equal to the amount of Losses specified in such
notice for which Parent is seeking indemnification under Article IX of the
Merger Agreement, or (B) requesting that a number of Escrowed Shares having a
value equal to the amount of any such Losses remain in escrow until the amount
of such Losses and the validity of Parent's indemnification claim for such
Losses is finally determined. In addition, Parent shall deliver to the Escrow
Agent, immediately after receipt by Parent, a copy of a delivery receipt or
other appropriate proof of delivery to the Stockholder Representative of such
Notice of Claim (the "Delivery Receipt"). Subject to the provisions of this
                      -------- -------
Section 5.1(a), on the twentieth (20th) Business Day after the date of delivery
by Parent to the Stockholder Representative (as indicated in the Delivery
Receipt) of a Notice of Claim pursuant to the foregoing clause (A), Escrow Agent
shall release from the escrow hereunder and cause to be delivered to Parent, in
the manner provided in Section 5.5 below, a number of Escrowed Shares having a
value equal to the amount of Losses specified in such Notice of Claim.
Notwithstanding the foregoing, if Escrow Agent receives, within such twenty (20)
Business Day period (the "Objection Period"), a written objection from the
                          --------- ------
Stockholder Representative to all or any portion of the amount of Losses
specified by Parent in such Notice of Claim, then the Escrow Agent shall
withhold from the number of Escrowed Shares that would otherwise be released
pursuant to this Section 5.1(a) a number of Escrowed Shares (the "Clause A
                                                                  ------ -
Disputed Escrowed Shares") having a value equal to the amount of the Losses set
-------- -------- ------
forth in such Notice of Claim that the Stockholder Representative disputes in
such written objection until Escrow Agent shall have received either (I)
non-conflicting joint written instructions from the Stockholder Representative
and Parent as to the disposition of all or any number of the Clause A Disputed
Escrowed Shares, or (II) an order of an arbitrator or court having jurisdiction
over the matter, which is final and not subject to further court proceedings or
appeal, with respect to the appropriate disposition of the Clause A Disputed
Escrowed Shares. In the event that the Escrow Agent shall receive a Notice of
Claim delivered pursuant to clause (B) above, the Escrow Agent shall continue to
hold in escrow, a number of Escrowed Shares having a value equal to the amount
of the Losses set forth in such Notice of Claim (the "Clause B Disputed Escrowed
                                                      ------ - -----------------
Shares") until Escrow Agent shall have received either (I) non-conflicting joint
------
written instructions from the Stockholder Representative and Parent as to the
disposition of such Clause B Disputed Escrowed Shares, or (II) an order of an
arbitrator or court having jurisdiction over the matter, which is final and not
subject to further court proceedings or appeal, with respect to the appropriate
disposition of such Clause B Disputed Escrowed Shares. Upon receipt of any joint
written instructions from the Stockholder Representative and Parent or any such
order of an arbitrator or court, Escrow Agent shall release from the escrow
hereunder and cause to be delivered to Parent, the Management Payees and/or the

<PAGE>

                                       -6-

Stockholders, in the manner provided in Section 5.5 below, any and all Clause A
Disputed Escrowed Shares and/or Clause B Disputed Escrowed Shares subject to
such joint written instructions or order, all in accordance with such written
instructions or order. The foregoing provisions of this Section 5.1(a) shall not
apply to a claim made under Section 5.1(b) below.

          (b) Notwithstanding anything in Section 5.1(a) to the contrary, Parent
may deliver to the Escrow Agent (with a copy to the Stockholder Representative)
a written notice (a "Section 6.1 Notice of Claim") requesting distribution to
                     ------- --- ------ -- -----
the Parent of a number of Escrowed Shares having a value equal to the amount of
Losses specified in such notice for which Parent is seeking indemnification for
any liability or obligation of Parent to the Escrow Agent under Section 6.1 of
this Agreement. As soon as practicable after the date of delivery by Parent to
the Escrow Agent of a Section 6.1 Notice of Claim, the Escrow Agent shall
release from the escrow hereunder and cause to be delivered to Parent, in the
manner provided in Section 5.5 below, a number of Escrowed Shares having a value
equal to the amount of Losses specified in such Section 6.1 Notice of Claim. The
Stockholder Representative shall have no right to object to all or any portion
of the amount of Losses specified by Parent in such Section 6.1 Notice of Claim.

     5.2 Value of Escrowed Shares. For all purposes of this Agreement
         ------------------------
(including, without limitation, the provisions of Section 5.1 above), the value
of each of the Escrowed Shares shall be deemed to be the Reference Market Value.
In the event of any adjustment in the Reference Market Value of the Escrowed
Shares, the Parent shall notify the Escrow Agent in writing of such adjustment,
and in the absence of the receipt of such notice, as the case may be, the Escrow
Agent shall be entitled to assume the Reference Market Value is $3.54.

     5.3 Automatic Release. On the first anniversary of the Effective Time,
         -----------------
Escrow Agent shall release from the escrow hereunder and cause to be delivered
to the Stockholders and the Management Payees, in the manner provided in Section
5.5 below, all Escrowed Shares then held by Escrow Agent hereunder, other than
any and all Clause A Disputed Escrowed Shares and/or Clause B Disputed Escrowed
Shares. Any and all Clause A Disputed Escrowed Shares and/or Clause B Disputed
Escrowed Shares that are retained in escrow in accordance with this Section 5.3
shall be so retained until released in accordance with the provisions of Section
5.1(a) hereof.

     5.4 Release of Escrow Property. In the event of any release and delivery of
         --------------------------
Escrowed Shares to Parent, the Management Payees and/or the Stockholders
pursuant to, and in accordance with, the provisions of this Agreement, then,
together with any Escrowed Shares so released, the Escrow Agent shall release
and deliver to Parent, the Management Payees and/or the Stockholders, as the
case may be, the portion of any other Escrow Property then held in escrow
hereunder that is directly or indirectly attributable to any such Escrowed
Shares so released. Upon request by the Escrow Agent, Parent shall assist the
Escrow Agent in determining the amounts of other Escrow Property directly or
indirectly attributable to the Escrowed Shares to be released hereunder.

     5.5 Release Mechanics.
         -----------------

          (a) The Escrow Agent shall take such actions as directed by Parent in
writing (including, without limitation, giving instructions to third parties) to
cause Escrowed Shares,

<PAGE>

                                       -7-

Escrow Property and/or any other property held in escrow hereunder to be
released and delivered to Parent, the Management Payees and/or the Stockholders
whenever such release and delivery is required pursuant to the provisions of
this Agreement.

          (b) Without limiting the generality of the provisions of Section
5.5(a) above, in the event of any release and delivery of Escrowed Shares or any
other securities of Parent held in escrow hereunder to Parent, the Management
Payees and/or the Stockholders pursuant to this Agreement (collectively, the
"Released Securities"), the Escrow Agent shall deliver to Parent or Parent's
 -------- ----------
transfer agent the stock certificate or stock certificates representing the
Released Securities, together with appropriate stock powers or instruments of
transfer duly endorsed or executed and appropriate instructions to effect the
transfer of the record ownership of the Released Securities on the books and
records of Parent from the Escrow Agent to the Parent, the Management Payees
and/or the Stockholders, as the case may be. In the event that any stock
certificate delivered by the Escrow Agent to Parent or Parent's transfer agent
(a "Transfer Certificate") represents shares of Parent Common Stock or other
    -------- -----------
securities of Parent that are, in either case, greater in number than the number
of the Released Securities represented by such Transfer Certificate, then any
such transfer instructions delivered by the Escrow Agent shall instruct Parent
or Parent's transfer agent to deliver to the Escrow Agent, after effecting the
transfers of the Released Securities set forth in such instructions, a stock
certificate representing those shares of Parent Common Stock or other securities
of Parent that were represented by such Transfer Certificate and were not
Released Securities, whereupon such stock certificate so delivered by Parent or
Parent's transfer agent to the Escrow Agent pursuant to such instructions (and
the shares of Parent Common Stock or other securities of Parent represented by
such stock certificate) shall continue to be held in escrow pursuant to this
Agreement. Parent shall, and shall cause its transfer agent, if any, to effect
any and all transfers requested by the Escrow Agent, and otherwise to comply
with all other instructions given by the Escrow Agent, in each case pursuant to,
and in accordance with, the Escrow Agent's transfer instructions given pursuant
to this Section 5.5(a). The Escrow Agent shall have no liability for the actions
or omissions of, or any delay on the part of, Parent or the transfer agent in
connection with the foregoing.

     5.6 Allocation Among Stockholders and the Management Payees. In the event
         -------------------------------------------------------
of any release and delivery of any Escrow Property to the Stockholders and the
Management Payees pursuant to the provisions of this Agreement, such Escrow
Property shall be released to the various Stockholders and Management Payees on
a pro rata basis in accordance with their respective Percentage Interests as set
forth on Schedule 1 attached hereto. Subject to Section 4.3, in the event that,
         -------- -
at any time prior to any such release and delivery, the Escrow Agent shall have
made a claim against the escrow hereunder pursuant to Section 4.3 hereof on
account of the indemnification obligation or liability of any Stockholder or
Management Payee pursuant to Section 4.3 hereof (a "Section 4.3 Indemnitor"),
                                                    ------- --- ----------
then (A) the amount of any Escrow Property that would otherwise be released and
delivered to such Section 4.3 Indemnitor pursuant to the first sentence of this
Section 5.6 shall be reduced by the amount of such claim made by the Escrow
Agent pursuant to Section 4.3 (the "Reduction Amount"), and (B) the amount of
                                    --------- ------
any Escrow Property that would otherwise be released and delivered to the other
Stockholders and Management Payees pursuant to the first sentence of this
Section 5.6 shall be increased by an amount equal to such other Stockholders'
and Management Payees' pro rata portion of the amount of the Reduction Amount,
which pro rata portion shall be calculated based on the

<PAGE>

                                       -8-

Percentage Interests of such other Stockholders and Management Payees (i.e., not
including the Section 4.3 Indemnitor's Percentage Interest).

     5.7 Transfer of Beneficial Interest. In the event of any release and
         -------------------------------
delivery of any Escrow Property to Parent pursuant to, and in accordance with,
the provisions of this Agreement, each Stockholder's and each Management Payee's
beneficial interest in and to such Escrow Property shall terminate at that time
and the entire beneficial interest in and to such Escrow Property shall become
vested in Parent.

     5.8 Fractional Shares. Notwithstanding any provision in this Agreement to
         -----------------
the contrary, no fractional share interests of Parent capital stock shall be
released or delivered to Parent, the Management Payees and/or the Stockholders
upon any release or delivery of any Escrowed Shares or any other securities of
Parent held in escrow. In the event that the release or delivery of any Escrowed
Shares or any other securities of Parent held in escrow to Parent, the
Management Payees and/or the Stockholders would, without giving effect to the
provisions of this Section 5.8, result in Parent, any Management Payee or any
Stockholder receiving a fractional share interest of Parent capital stock, then
the number of shares of Parent capital stock to be released and delivered to
Parent, such Management Payee or such Stockholder, as the case may be, shall be
rounded down to the nearest whole number of shares by the Escrow Agent so that
only whole numbers of shares of Parent capital stock are released and delivered
to Parent, such Management Payee or such Stockholder, as the case may be. If, as
a result of the application of the provisions of this Section 5.8, any portion
of any Losses described in any Notice of Claim delivered by Parent is not
satisfied, then such unsatisfied portion of any such Losses shall be deemed
carried over until satisfied in full from one or more subsequent releases from
the escrow. In addition, if, as a result of the application of the provisions of
this Section 5.8, any Escrowed Shares or any other shares of Parent Common Stock
held in escrow that would otherwise have been released and distributed to the
Stockholders or Management Payees is not so released and distributed at the time
of the final release and distribution to Stockholders from the escrow hereunder,
then such Escrowed Shares or any other shares of Parent Common Stock held in
escrow shall be released and distributed to Parent and Parent shall deliver to
the Escrow Agent an amount (the "Final Fractional Share Escrow Payment") equal
                                 ----- ---------- ----- ------ -------
to the product of (A) the sum of such Escrowed Shares or any other shares of
Parent Common Stock, multiplied by (B) the Reference Market Value. Upon receipt
of the Final Fractional Share Escrow Payment, the Escrow Agent shall release and
distribute the Final Fractional Share Escrow Payment in accordance with the
provisions of Section 5.6 above.

                                    ARTICLE 6
                                THE ESCROW AGENT

     6.1 Liability. The Escrow Agent, in its capacity as such, or any successor
         ---------
escrow agent, shall be liable only to hold the Escrow Property in escrow
hereunder, to deliver the same to Parent, the Management Payees and/or the
Stockholders, as the case may be, in accordance with the provisions of this
Agreement and otherwise to perform the obligations expressly provided for the
Escrow Agent under this Agreement. The Escrow Agent shall not be responsible for
any of the agreements referred to or described herein (including without
limitation the Merger Agreement and Payment Agreement), or for determining or
compelling compliance therewith, and shall not otherwise be bound thereby. By
acceptance of this

<PAGE>

                                       -9-

Agreement, the Escrow Agent, in its capacity as such, or any successor escrow
agent, is acting in the capacity of a depositary only, and shall not be liable
or responsible for any damages, losses or expenses unless such damages, losses
or expenses shall be caused by its own gross negligence or willful misconduct.
In no event shall the Escrow Agent be liable for indirect, punitive, special or
consequential damage or loss (including but not limited to lost profits)
whatsoever, even if the Escrow Agent has been informed of the likelihood of such
loss or damage and regardless of the form of action. Neither the Escrow Agent,
in it capacity as such, nor any successor Escrow Agent, shall incur any
liability with respect to (i) any action taken or omitted in good faith upon the
advice of its counsel, including in-house counsel, with respect to any questions
relating to the duties and responsibilities of the Escrow Agent under this
Agreement, or (ii) any action taken or omitted in reliance upon any instrument,
including the written instructions provided for herein, not only as to the due
execution of such instrument, or the identity or authority of any person
executing such instrument, or the validity and effectiveness of such instrument,
but also as to the truth and assurance of any information contained therein,
provided that the Escrow Agent shall in good faith believe such instrument to be
-------- ----
genuine, to have been signed by a proper person or persons and to conform to the
provisions of this Agreement. The Escrow Agent shall not be obligated to take
any legal or other action hereunder which might in its judgment involve or cause
it to incur any expense or liability unless it shall have been furnished with
acceptable indemnification. In the event of any disagreement or the presentation
of adverse claims or demands in connection with or for any item affected hereby,
the Escrow Agent shall, at its option, be entitled to refuse to comply with any
such claims or demands during the continuance of such disagreement and may
refrain from delivering any Escrow Property affected hereby, and in so doing the
Escrow Agent shall not become liable to the parties, or to any other person, due
to its failure to comply with any such adverse claim or demand. The Escrow Agent
shall be entitled to continue, without liability, to refrain and refuse to act
until all of the rights of the adverse claimants have been either fully resolved
among themselves, arbitrated to a final award, or finally adjudicated by a court
having jurisdiction over the dispute with written notice thereof delivered to
Escrow Agent. The Escrow Agent may, but shall be under no duty whatsoever to,
institute or defend any legal proceedings that relate to the Escrow Property.
Except to the extent otherwise provided in Section 4.3 hereof, the Escrow Agent
(and its directors, officers and employees) shall be held harmless and
indemnified by Parent from and against any loss, liability, damage, cost and
expense of any nature incurred by the Escrow Agent arising out of or in
connection with this Agreement or with the administration of its duties
hereunder, including, but not limited to, attorney's fees and other costs and
expenses of defending or preparing to defend against any claim of liability and
expenses pursuant to the second sentence of Section 9.8, unless and except to
the extent such claims arise out of the gross negligence or willful misconduct
of the Escrow Agent. The foregoing indemnification and agreement to hold
harmless shall survive the termination of this Agreement. As between the
Interested Parties, the Stockholder Representative hereby acknowledges and
agrees that Parent shall be entitled to make a claim for indemnification under
Article IX of the Merger Agreement with respect to fifty percent (50%) of any
indemnification obligation or liability due to the Escrow Agent by Parent
pursuant to this Section 6.1. The Interested Parties acknowledge that (i) Parent
shall consult with the Stockholder Representative prior to satisfying any claim
for indemnification by the Escrow Agent hereunder, provided that Parent shall
                                                   -------- ----
have the absolute and sole discretion to satisfy any such claim, and (ii) Parent
shall be entitled to make a claim against the escrow hereunder (to the extent
available) pursuant to Section 5.1(b) hereof in order to satisfy such claim for

<PAGE>

                                      -10-

indemnification, notwithstanding any objection the Stockholder Representative
may have with respect thereto. Any action requested to be taken by the Escrow
Agent hereunder and not otherwise specifically set forth herein shall require
the agreement in writing of the Stockholder Representative, Escrow Agent and
Parent.

     6.2 Resignation of Escrow Agent, Successor. Escrow Agent may resign at any
         --------------------------------------
time, upon 30 days prior written notice to Parent and the Stockholder
Representative and shall deposit the Escrow Property with a successor escrow
agent to be jointly designated in writing by Parent and the Stockholder
Representative. Any such successor escrow agent must agree to be, and shall be,
bound by, and shall have all the rights, duties and responsibilities of the
Escrow Agent, under this Agreement. If, upon the effective date of such
resignation, no successor escrow agent shall have been designated, Escrow Agent
shall have the right to (i) apply to a court of competent jurisdiction for
appointment of a successor escrow agent or (ii) tender into the registry or
custody of any court of competent jurisdiction any part or all of the Escrow
Property hereunder, and shall be relieved of any further obligations under this
Agreement. Such resignation shall not deprive Escrow Agent of its compensation
earned prior thereto, and the provisions of Sections 4.3 and 6.1 hereof shall
survive any resignation by the Escrow Agent.

     6.3 Concerning the Escrow Agent.
         ---------------------------

          (a) The Escrow Agent shall have no more or less responsibility or
     liability on account of any action or omission of any book-entry
     depository, securities intermediary or other subescrow agent employed by
     the Escrow Agent than any such book-entry depository, securities
     intermediary or other subescrow agent has to the Escrow Agent, except to
     the extent that such action or omission of any book-entry depository,
     securities intermediary or other subescrow agent was caused by the Escrow
     Agent's own gross negligence or willful misconduct in breach of this
     Agreement.

     (b) The Escrow Agent is hereby authorized, in making or disposing of any
     investment permitted by this Agreement, or in carrying out any sale of the
     Escrow Property permitted by this Agreement, to deal with itself (in its
     individual capacity) or with any one or more of its affiliates, whether it
     or such affiliate is acting as a subagent of the Escrow Agent or for any
     third person or dealing as principal for its own account.

     (c) Notwithstanding any term appearing in this Agreement to the contrary,
     in no instance shall the Escrow Agent be required or obligated to
     distribute any Escrow Property (or take other action that may be called for
     hereunder to be taken by the Escrow Agent) sooner than two (2) Business
     Days after (i) it has received the applicable documents required under this
     Agreement in good form, or (ii) passage of the applicable time period (or
     both, as applicable under the terms of this Agreement), as the case may be.

<PAGE>

                                      -11-

                                    ARTICLE 7
                           STOCKHOLDER REPRESENTATIVE

     7.1 Power and Authority. The adoption of the Merger Agreement by the
         -------------------
Stockholders shall constitute ratification of this Escrow Agreement by each
Stockholder regardless of whether or not such Stockholder votes in favor of the
adoption of the Agreement and the approval of the Merger), and the execution by
each Management Payee of the Payment Agreement shall constitute ratification of
this Escrow Agreement by each Management Payee, and the Stockholder
Representative shall have full power and authority to represent the
Stockholders, the Management Payees and their successors with respect to all
matters arising under this Agreement, and all action taken by the Stockholder
Representative hereunder shall be binding upon such Stockholders, the Management
Payees and their successors as if expressly ratified and confirmed in writing by
each of them. Without limiting the generality of the foregoing, the Stockholder
Representative shall have full power and authority, on behalf of all the
Stockholders, the Management Payees and their successors, to interpret all the
terms and provisions of this Agreement, to dispute or fail to dispute any
Indemnification Claim, to negotiate and compromise any dispute which may arise
under this Agreement, to sign any releases or other documents with respect to
any such dispute, and to authorize payments to be made with respect thereto.

     7.2 Resignation; Successors. The Stockholder Representative, or any
         -----------------------
successor hereafter appointed, may resign and shall be discharged of his duties
hereunder upon the appointment of a successor Stockholder Representative as
hereinafter provided. The Stockholder Representative shall have power of
substitution to appoint a successor. In the event that the Stockholder
Representative dies, becomes unable to perform his duties or resigns, in each
case without having appointed a successor, then Stockholders holding,
immediately prior to the Effective Time, a majority of the combined voting power
of the Company's common stock, $0.0001 par value per share, and preferred stock,
$0.0001 par value per share, shall elect a successor Stockholder Representative.
Until notified in writing of the resignation or removal of the Stockholder
Representative, the Escrow Agent may rely conclusively and act upon the
directions, instructions and notices of the Stockholder Representative named
above, and thereafter, upon the directions, instructions and notices of any
successor named in a writing and filed with the Escrow Agent. As among the
Interested Parties, no Stockholder nor Management Payee shall have any cause of
action against the Stockholder Representative for any action taken, decision
made or instruction given by the Stockholder Representative under this Agreement
or the Merger Agreement or in connection with the transactions contemplated by
this Agreement.

                                    ARTICLE 8
                                   DEFINITIONS

     8.1. Certain Definitions. For purposes of this Agreement, the term:
          -------------------

     "Acquiror Covered Party" means, pursuant to the terms of Article IX of the
      -------- ------- -----
Merger Agreement, each of Parent and the Surviving Corporation and each of their
post-Closing officers, directors, employees and affiliates.

<PAGE>

                                      -12-

     "affiliate" of a specified person means a person who directly or indirectly
      ---------
through one or more intermediaries controls, is controlled by, or is under
common control with, such specified person.

     "Business Day" means any day on which the principal offices of the SEC in
      ------------
Washington, D.C. are open to accept filings, or, in the case of determining a
date when any payment is due, any day on which banks are not required or
authorized to close in the City of Boston, Massachusetts.

     "Closing Date" means, subject to the satisfaction or waiver of all the
      ------------
conditions contained in Article VII of the Merger Agreement, the actual date of
closing the transactions contemplated by the Merger Agreement.

     "Effective Time" means the date and time of the filing of the Certificate
      --------- ----
of Merger with the Secretary of State of the State of Delaware (or such later
time as may be agreed by each of the parties to the Merger Agreement and
specified in the Delaware Certificate of Merger) pursuant to the terms of the
Merger Agreement.

     "Indemnification Claim" shall mean (A) in the case of any Acquiror Covered
      --------------- -----
Party, any claim made by such Acquiror Covered Party, pursuant to the provisions
of Article IX of the Merger Agreement and this Escrow Agreement, for
indemnification of any Loss or Losses incurred by such Acquiror Covered Party,
and (B) in the case of any Target Covered Party, any claim made by Stockholder
Representative, for and on behalf of such Target Covered Party, pursuant to the
provisions of Article IX of the Merger Agreement, for indemnification of any
Loss or Losses incurred by such Target Covered Party.

     "Losses" means any and all liabilities, losses, damages, claims (whether
      ------
actual or threatened), charges, suits (whether actual or threatened), penalties,
costs and expenses (including, without limitation, court costs and attorneys'
fees and expenses incurred in investigating and preparing for any litigation or
proceeding, whether actual or threatened) sustained or incurred by any Acquiror
Covered Party, arising out of or as a result of the matters enumerated in
Article IX of the Merger Agreement.

     "Reference Market Value" means $3.54 (such price being subject to automatic
      --------- ------ -----
proportionate adjustment in the event of any stock dividend, stock split, stock
combination, recapitalization, or other similar event affecting the Parent
Common Stock).

     "subsidiary" or "subsidiaries" of any person means any corporation,
      ----------      ------------
partnership, joint venture or other legal entity of which such person (either
above or through or together with any other subsidiary), owns, directly or
indirectly, more than 50% of the stock or other equity interests the holders of
which are generally entitled to vote for the election of the board of directors
or other governing body of such corporation or other legal entity.

     "Target Covered Party" means, pursuant to the terms of Article IX of the
      ------ ------- -----
Merger Agreement, each Stockholder.

<PAGE>

                                      -13-

                                    ARTICLE 9
                                  MISCELLANEOUS

     9.1 Transferability. A Stockholder or Management Payee may not transfer any
         ---------------
interest in the Escrow Property or any other right under this Agreement to any
other party, except that upon written notice from the legal representative of
the estate of a deceased Stockholder or Management Payee to the Escrow Agent,
the Stockholder Representative and Parent, the rights of such Stockholder or
Management Payee under this Agreement shall be transferred to the estate of such
Stockholder or Management Payee, and subsequently to any beneficiary thereof, in
the event of the Stockholder's or Management Payee's death; provided, however,
                                                            --------  -------
that any such beneficiary or the legal representative of any such estate shall
be bound by the provisions of this Agreement without taking any further action.
The Escrow Agent, the Stockholder Representative or Parent, as the case may be,
shall be entitled to treat the legal representative of the estate of such
Stockholder or Management Payee, and subsequently any beneficiary thereof, as
the absolute owner of the rights of such Stockholder or Management Payee under
this Agreement in all respects and shall incur no liability for distributions
made in good faith to the legal representatives of such Stockholder, such
Management Payee, or such beneficiary in accordance with the terms of this
Agreement.

     9.2 Notices. All notices, requests, claims, demands and other
         -------
communications hereunder shall be in writing, and shall be deemed to have been
duly given if (a) delivered personally (effective upon delivery), (b) mailed by
registered or certified mail, return receipt requested, postage prepaid
(effective five days after dispatch), (c) sent via a reputable, established
courier service that guarantees next Business Day delivery (effective the next
Business Day after delivery to such courier) or (d) sent via telecopier
(effective upon the transmission of the telecopy in complete, readable form)
addressed as set forth below (or at such other address for a party as shall be
specified in a notice given in accordance with this Section 7.2); provided,
however, that no notice delivered to the Escrow Agent shall be deemed to have
been duly given until actually received by the Escrow Agent:

          (a)  If to Parent, to:

                  Essential Therapeutics, Inc.
                  1365 Main Street
                  Waltham, MA  02451-1624
                  Attention:  President
                  Facsimile:  781-647-4230

               copy to:

                  Bingham Dana LLP
                  150 Federal Street
                  Boston, MA 02110
                  Attention:  Julio E. Vega, Esq.
                  Facsimile:  617-951-8736

<PAGE>

                                      -14-

          (b)  If to Escrow Agent, to:

                  by first class mail, to:

                  State Street Bank and Trust Company
                  Global Investors Services Group
                  Corporate Trust
                  P.O. Box 778
                  Boston Massachusetts, 02102-0778
                  Attention: Essential Therapeutics/Maret Corporation Escrow
                  Facsimile: (617) 662-1463

                  If by hand, certified or registered mail or overnight courier
                  or delivery, to:

                  State Street Bank and Trust Company
                  Global Investors Services Group
                  Corporate Trust, 6th Floor
                  2 Avenue de Lafayette
                  Boston, Massachusetts 02111-1724
                  Attention: Essential Therapeutics/Maret Corporation Escrow
                  Facsimile: (617) 662-1463

          (c)  If to the Stockholder Representative, to:

                  Terence E. Winters
                  c/o Valley Ventures
                  6720 N. Scottsdale Road, #280
                  Scottsdale, AZ  85253
                  Facsimile: (480) 661-6262

               copy to:

                  Berenbaum, Weinshienk & Eason, P.C.
                  370 Seventeenth Street, Suite 2600
                  Denver, Colorado 80202
                  Attention:   Joseph S. Borus, Esq.
                             Facsimile: 303-629-7610

          9.3 Governing Law. This Agreement shall be governed by and construed
              --------------
in accordance with the laws of the Commonwealth of Massachusetts (without regard
to any laws applicable conflicts or choice of law).

          9.4 Binding Effect; No Third Party Beneficiaries. This Agreement shall
              --------------------------------------------
inure to the benefit of and be binding upon the respective heirs, executors,
administrators, successors and assigns of the parties hereto. Nothing herein
expressed or implied is intended or shall be construed to confer upon or to give
to any third party any rights or remedies by reason

<PAGE>

                                      -15-

of this Agreement. There are no intended third party beneficiaries under or by
reason of this Agreement.

          9.5 Separability. If any provision or section of this Agreement is
              ------------
determined to be void or otherwise unenforceable, it shall not affect the
validity or enforceability of any other provisions of this Agreement which shall
remain enforceable in accordance with their terms.

          9.6 Miscellaneous. The headings and subheadings contained in this
              -------------
Agreement are for reference only and for the benefit of the parties and shall
not be considered in the interpretation or construction of this Agreement. This
Agreement may be executed in any number of counterparts, each of which shall be
deemed to be an original, but all of which together shall constitute one and the
same instrument.

          9.7 Amendments. This Agreement may be amended from time to time but
              ----------
only by written agreement signed by all of the parties hereto. No course of
conduct shall constitute a waiver of any of the terms and conditions of this
Escrow Agreement, unless such waiver is specified in writing, and then only to
the extent so specified. A waiver of any of the terms and conditions of this
Escrow Agreement on one occasion shall not constitute a waiver of the other
terms of this Escrow Agreement, or of such terms and conditions on any other
occasion. Notwithstanding any other provision hereof, consent to an alteration
or modification of this Agreement may not be signed by means of an e-mail
address.

          9.8 Fees and Expenses of Escrow Agent. Subject to the provisions of
              ---------------------------------
Section 6.1 of this Agreement, the fees and expenses (including reasonable
attorneys' fees and costs) of the Escrow Agent for the services to be rendered
by the Escrow Agent hereunder as set forth on Schedule 2 hereof will be paid by
                                              -------- -
Parent. Parent and the Stockholders' Representative hereby acknowledge that all
fees and usual charges for services of the Escrow Agent hereunder shall be
considered compensation for ordinary services as contemplated by this Agreement.
Subject to the provisions of Section 6.1 of this Agreement, Parent also agrees
to reimburse the Escrow Agent on demand for all costs and expenses incurred in
connection with the administration of this Agreement or the escrow created
hereby or the performance or observance of its duties hereunder which are in
excess of its compensation for normal services hereunder, including without
limitation, payment of any legal fees and expenses incurred by the Escrow Agent
in connection with the resolution of any claim by any party hereunder.

          9.9 Consent to Jurisdiction and Service. Each of the Interested
              -----------------------------------
Parties hereby absolutely and irrevocably consents and submits to the
jurisdiction of the courts in the Commonwealth of Massachusetts and of any
Federal court located in said Commonwealth in connection with any actions or
proceedings brought against the Interested Parties (or any of them) by the
Escrow Agent arising out of or relating to this Escrow Agreement. In any such
action or proceeding, the Interested Parties each hereby absolutely and
irrevocably (i) waives any objection to jurisdiction or venue, (ii) waives
personal service of any summons, complaint, declaration or other process, and
(iii) agrees that the service thereof may be made by certified or registered
first-class mail directed to such party, as the case may be, at their respective
addresses in accordance with Section 9.2 hereof.

<PAGE>

                                      -16-

          9.10 Waiver of Jury Trial. THE ESCROW AGENT AND THE INTERESTED PARTIES
               --------------------
HEREBY WAIVE A TRIAL BY JURY OF ANY AND ALL ISSUES ARISING IN ANY ACTION OR
PROCEEDING BETWEEN THEM OR THEIR SUCCESSORS OR ASSIGNS, UNDER OR IN CONNECTION
WITH THIS AGREEMENT OR ANY OF ITS PROVISIONS OR ANY NEGOTIATIONS IN CONNECTION
HEREWITH.

          9.11 Force Majeure. The Escrow Agent shall not be responsible for
               -------------
delays or failures in performance resulting from acts beyond its control. Such
acts shall include but not be limited to acts of God, strikes, lockouts, riots,
acts of war, epidemics, governmental regulations superimposed after the fact,
fire, communication line failures, computer viruses, power failures, earthquakes
or other disasters.

          9.12 Reproduction of Documents. This Agreement and all documents
               -------------------------
relating thereto, including, without limitation, (a) consents, waivers and
modifications which may hereafter be executed, and (b) certificates and other
information previously or hereafter furnished, may be reproduced by any
photographic, photostatic, microfilm, optical disk, micro-card, miniature
photographic or other similar process. The parties agree that any such
reproduction shall be admissible in evidence as the original itself in any
judicial or administrative proceeding, whether or not the original is in
existence and whether or not such reproduction was made by a party in the
regular course of business, and that any enlargement, facsimile or further
reproduction of such reproduction shall likewise be admissible in evidence.

            [The remainder of this page is intentionally left blank.]

<PAGE>

     IN WITNESS WHEREOF, the undersigned have executed this Escrow Agreement
under seal as of the day and year first written above.

                          ESSENTIAL THERAPEUTICS, INC.

                          By: /s/ Paul J. Mellett
                              -----------------------------------
                                 Paul J. Mellett
                                 Chief Financial Officer

                          STOCKHOLDER REPRESENTATIVE:

Attest:

                             /s/ Terence E. Winters
-----------------         ---------------------------------------
                             Terence E. Winters

                          STATE STREET BANK AND TRUST
                          COMPANY, as Escrow Agent

Attest:

    /s/ Virginia Jones    By:/s/ Chi C. Ma
-----------------------      ------------------------------------
                          Name: Chi C. Ma
                          Title:  Vice President

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00035-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00035-of-00352.parquet"}]]