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                                                                   EXHIBIT 10.12

                           FIRST AMENDED AND RESTATED
                              EMPLOYMENT AGREEMENT
                              (Ganesh Venkataraman)

     This First Amended and Restated Employment Agreement dated as of April 10,
2002 (this "Agreement") is made by and between Mimeon, Inc., a Delaware
corporation (the "Company"), and Ganesh Venkataraman ("Employee").

     WHEREAS, the Company and Employee and parties to Employment Agreement dated
June 13, 2001 (the "Original Employment Agreement"); and

     WHEREAS, the Company and Employee desire to amend and restate the Original
Agreement to increase Employee's compensation, to change his title and
responsibilities and to effect the other modifications set forth herein;

     NOW, THEREFORE, in consideration of the premises and the mutual covenants
and agreements herein contained, the parties hereto agree as follows:

     1.   EMPLOYMENT. The Company hereby employs Employee to perform those
duties and services as the Company shall from time to time set forth, and
Employee accepts employment with the Company, upon the terms and conditions
hereinafter set forth. Employee shall serve as a Vice President of the Company
and shall report to the Chief Executive Officer of the Company. The Chief
Executive Officer shall have the right to review and change the responsibilities
of Employee and from time to time as he or she may deem necessary or appropriate
and the Chief Executive Officer may elect, at his or her discretion, to change
the reporting relationship for Employee.

     2.   BOARD OBSERVER RIGHTS. Employee may attend all meetings (whether in
person or telephonic) of the Board and the Compensation Committee of the Board
(the "Compensation Committee") in a non-voting, observer capacity. The Company
shall provide to Employee copies of all notices, minutes, consents, and other
materials that it provides to its directors; PROVIDED, however, that Employee
shall agree to act in a fiduciary manner with respect to all information so
provided; and, PROVIDED further, that the Company reserves the right to withhold
any information and to exclude Employee from any meeting or portion thereof (i)
if access to such information or attendance at such meeting could adversely
affect the attorney-client privilege between the Company and its counsel, or
(ii) if such information or meeting relates to Employee's employment or
compensation. Notwithstanding the foregoing, the Company may revoke Employee's
rights under this Section 2 if the Board of Directors determines, in its sole
discretion, that such revocation is in the best interests of the Company.

     3.   DUTY TO PERFORM SERVICES. Employee shall devote his full time during
normal business hours to rendering services to the Company hereunder, and shall
exert all reasonable efforts in the rendering of such services. Provided
Employee is in compliance with the immediately preceding sentence (and except to
the extent the restrictions contained in Section 9 may apply), nothing in this
Agreement shall prohibit Employee from (a) making and managing passive
investments and (b) engaging in religious, academic, charitable or other
community or

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non-profit activities, including continuing his part-time involvement in the
Consortium for Functional Glycomics.

     Employee agrees that in the rendering of all services to the Company and in
all aspects of employment hereunder, he shall comply in all material respects
with all directives, policies, standards and regulations from time to time
established by the Company, to the extent they are not in conflict with this
Agreement.

     4.   TERM OF AGREEMENT. There shall be no definite term of employment, and
Employee shall be an employee at will. The Company may terminate Employee's
employment with the Company at any time with or without Cause (as defined in
Section 18(e)).

     5.   COMPENSATION.

          (a)  BASE SALARY. Commencing as of January 1, 2002, and throughout the
term of this Agreement, the Company shall pay Employee a base salary, payable in
equal installments in accordance with the Company's standard schedule for salary
payments to its employees, at an annual rate equal to $140,000. Employee's base
salary shall be reviewed by the Company at least once every 12 months and may be
increased on or after each such review as mutually agreed upon by the Company
and Employee.

          (b)  REALLOCATION OF FOUNDERS STOCK. The Company and Employee shall
enter into Reallocation of Founder Shares Agreement, substantially in the form
of EXHIBIT A, which provides for the sale of 80,000 shares, in aggregate, of the
Company's outstanding common stock, $.0001 par value per share ("Common Stock"),
from Company founders Ram Sasisekharan and Robert Langer to Employee at a price
of $.0001 per share. These 80,000 shares shall be subject to vesting in
accordance with schedule set forth in Employee's Restricted Stock Purchase
Agreement dated as of June 13, 2001.

          (c)  BONUSES.

               (i)   SIGNING BONUS. Promptly after the Company and Employee sign
this Agreement, the Company shall pay Employee a signing bonus of $15,000 in
cash

               (ii)  YEAR-END BONUS. If the performance goals set forth in
SCHEDULE A (as the same may be modified from time to time in a writing signed by
the Employee and the Employee's supervisor, the "Performance Goals") are
achieved by December 31, 2002, then the Company shall pay Employee a bonus of
$30,000 in cash by March 1, 2003; PROVIDED, however, that the Company shall pay
Employee a bonus of less than $30,000 if only some of the Performance Goals have
been achieved or if some of the Performance Goals have been partially achieved;
and PROVIDED, further, however, that the amount of the bonus may be increased by
the Chief Executive Officer, after consultation with the Compensation Committee
of the Board of Directors if appropriate, based on other considerations deemed
relevant by the Chief Executive Officer at or about the time that the bonus is
to be awarded. The determination of whether or not a Performance Goal has been
achieved shall be made by the Chief Executive Officer in his or her sole
discretion.

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     6.   VACATIONS AND HOLIDAYS; BENEFITS.

          (a)  VACATION AND HOLIDAYS. Employee shall be entitled to 15 paid
vacation days annually and shall not be required to work but shall be paid for
all major U.S. holidays.

          (b)  BENEFITS. Employee and, to the extent applicable, Employee's
family, dependents and beneficiaries, shall be entitled to receive medical and
dental insurance coverage through the Company, and such other benefits,
including 401(k) plan, life insurance and disability insurance, as may be
provided by the Company to its other similarly situated senior executives from
time to time (collectively, the "Benefits").

     7.   EXPENSES. The Company shall pay or reimburse Employee for all
reasonable business expenses incurred by Employee in connection with his
employment by the Company in accordance with the Company's policies in effect
from time to time.

     8.   CONFIDENTIAL INFORMATION. While employed by the Company and
thereafter, Employee shall not, directly or indirectly, use any Confidential
Information (as defined below) other than pursuant to his employment by and for
the benefit of the Company, or disclose any Confidential Information to anyone
outside of the Company, whether by private communication, public address,
publication or otherwise, or disclose any Confidential Information to anyone
within the Company who has not been authorized to receive such information,
except as directed in writing by an authorized representative of the Company.
The term "Confidential Information" as used throughout this Agreement shall mean
all trade secrets, proprietary information, know-how, data, designs,
specifications, processes, customer lists and other technical or business
information (and any tangible evidence, record or representation thereof),
whether prepared, conceived or developed by a consultant or employee of the
Company (including Employee) or received by the Company from an outside source,
which is in the possession of the Company (whether or not the property of the
Company) and which is maintained in confidence by the Company. Without limiting
the generality of the foregoing, Confidential Information shall include:

          (a)  any idea, improvement, invention, innovation, development,
technical data, design, formula, device, pattern, sequence, concept, art,
method, process, machine, manufacturing method, composition of matter, computer
program, software, firmware, source code, object code, algorithm, subroutine,
object module, schematic, model, diagram, flow chart, chip masking
specification, user manual, training or service manual, product specification or
design, plan for a new or revised product, sample, compilation of information,
or work in process, and any and all revisions and improvements relating to any
of the foregoing (in each case whether or not reduced to tangible form); and

          (b)  the name of any employee, consultant, customer or prospective
customer, or any other customer or prospective customer information, any sales
plan, marketing material, plan or survey, business plan or opportunity, product
or development plan or specification, business proposal, financial record, or
business record or other record or information relating to the present or
proposed business of the Company or any customer.

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     Notwithstanding the foregoing, the term Confidential Information shall not
apply to information which the Company has voluntarily disclosed to the public
without restriction, or which has otherwise lawfully entered the public domain.

     Employee acknowledges that the Company from time to time has in its
possession information which is claimed by customers and others to be
proprietary and which the Company has agreed to keep confidential. Employee
agrees that all such information shall be Confidential Information for purposes
of this Agreement.

     9.   OWNERSHIP AND ASSIGNMENT OF INTELLECTUAL PROPERTY. Employee agrees
that all originals and all copies of all manuscripts, drawings, prints, manuals,
diagrams, letters, notes, notebooks, reports, models, records, files, memoranda,
plans, sketches and all other documents and materials containing, representing,
evidencing, recording, or constituting any Confidential Information (as defined
in Section 8 above), however and whenever produced (whether by Employee or
others) shall be the sole property of the Company.

     Employee agrees that all Confidential Information and all other
discoveries, inventions, ideas, specifications, designs, concepts, research and
other information, processes, products, methods and improvements, or parts
thereof conceived, developed, or otherwise made by him, alone or jointly with
others and in any way relating to the Company's present or proposed products,
programs or services or to tasks assigned to him during the course of his
employment, whether or not patentable or subject to copyright protection and
whether or not reduced to tangible form or reduced to practice, during the
period of his employment with the Company, whether or not made during my regular
working hours, and whether or not made on the Company's premises, and whether or
not disclosed by him to the Company (hereinafter referred to as "Intellectual
Property") together with all products or services which embody or emulate any
Intellectual Property shall be the sole property of the Company.

     Employee agrees to, and hereby does, assign to the Company all his right,
title and interest throughout the world in and to all Intellectual Property and
to anything tangible which evidences, incorporates, constitutes, represents or
records any Intellectual Property. Employee agrees that all Intellectual
Property shall constitute works made for hire under the copyright laws of the
United States and hereby assigns and, to the extent any such assignment cannot
be made at present, Employee hereby agrees to assign to the Company all
copyrights, patents and other proprietary rights Employee may have in any
Intellectual Property, together with the right to file for and/or own wholly
without restriction United States and foreign patents, trademarks, and
copyrights. Employee agrees to waive, and hereby waives, all moral rights or
proprietary rights in or to any Intellectual Property and, to the extent that
such rights may not be waived, agrees not to assert such rights against the
Company or its licensees, successors or assigns.

     Employee hereby certifies that SCHEDULE B sets forth any and all
confidential information and intellectual property that Employee claims as his
own or otherwise intends to exclude from this Agreement because it was developed
by him prior to the date of this Agreement. Employee understands that after
execution of this Agreement he shall have no right to exclude Confidential
Information or Intellectual Property from this Agreement.

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     10.  EMPLOYEE'S OBLIGATION TO KEEP RECORDS. Employee shall make and
maintain adequate and current written records of all Intellectual Property,
including notebooks and invention disclosures, which records shall be available
to and remain the property of the Company at all times. Employee shall disclose
all Intellectual Property promptly, fully and in writing to the Company
immediately upon production or development of the same and at any time upon
request.

     11.  EMPLOYEE'S OBLIGATION TO COOPERATE. Employee will, at any time during
his employment, or after it terminates, upon request of the Company, execute all
documents and perform all lawful acts which the Company considers necessary or
advisable to secure its rights hereunder and to carry out the intent of this
Agreement. Without limiting the generality of the foregoing, Employee will
assist the Company in any reasonable manner to obtain for its own benefit
patents or copyrights in any and all countries with respect to all Intellectual
Property assigned pursuant to Section 9, and Employee will execute, when
requested, patent and other applications and assignments thereof to the Company,
or Persons (as deemed in Section 18(f)) designated by it, and any other lawful
documents deemed necessary by the Company to carry out the purposes of this
Agreement, and Employee will further assist the Company in every way to enforce
any patents and copyrights obtained, including testifying in any suit or
proceeding involving any of said patents or copyrights or executing any
documents deemed necessary by the Company, all without further consideration
than provided for herein. It is understood that reasonable out-of-pocket
expenses of Employee's assistance incurred at the request of the Company under
this Section will be reimbursed by the Company.

     12.  NONCOMPETITION. Employee agrees that during the term of this Agreement
and for a period of 12 months after the termination of this Agreement (the
"Restricted Period"), Employee shall not directly or indirectly (i) provide any
services in the Field of Interest (as defined in Section 18(e)) to any Person
other than the Company, (ii) become an owner, partner, shareholder, consultant,
agent, employee or co-venturer of any Person that has committed, or intends to
commit, significant resources to the Field of Interest.

     13.  NONSOLICITATION. During the Restricted Period, Employee shall not (i)
solicit, encourage, or take any other action which is intended to induce any
employee of, or consultant to, the Company (or any other Person who may have
been employed by, or may have been a consultant to, the Company during the term
of Employee's employment) to terminate his or her employment or relationship
with the Company in order to become employed by or otherwise perform services
for any other Person or (ii) solicit, endeavor to entice away from the Company
or otherwise interfere with the relationship of the Company with any Person who
is, or was within the then-most recent 12 month period, a client or customer of
the Company.

     14.  RETURN OF PROPERTY. Upon termination of Employee's employment with the
Company, or at any other time upon request of the Company, Employee shall return
promptly any Confidential Information, including all customer or prospective
customer lists, other customer or prospective customer information or related
materials, computer programs, software, electronic data, specifications,
drawings, blueprints, medical devices, samples, reproductions, sketches, notes,
notebooks, memoranda, reports, records, proposals, business plans, or copies of
them, other documents or materials, tools, equipment, or other property
belonging to the Company or its customers which Employee may then possess or
have under his control.

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Employee further agrees that upon termination of his employment he shall not
take with him any documents or data in any form or of any description containing
or pertaining to Confidential Information or Intellectual Property.

     15.  OTHER OBLIGATIONS.

          (a)  Employee hereby represents, warrants and agrees (i) that Employee
has the full right to enter into this Agreement and perform the services
required of him hereunder, without any restriction whatsoever; (ii) that in the
course of performing services hereunder, Employee will not violate the terms or
conditions of any agreement between him and any third party or infringe or
wrongfully appropriate any patents, copyrights, trade secrets or other
intellectual property rights of any Person anywhere in the world; (iii) that
Employee has not and will not disclose or use during his employment by the
Company any confidential information that he acquired as a result of any
previous employment or consulting arrangement or under a previous obligation of
confidentiality; and (iv) that Employee has disclosed to the Company in writing
any and all continuing obligations to previous employers or others that require
him not to disclose any information to the Company.

          (b)  Employee acknowledges that the Company from time to time may have
agreements with other Persons, including the government of the United States or
other countries and agencies thereof, which impose obligations or restrictions
on the Company regarding inventions made during the course of work thereunder or
regarding the confidential nature of such work. Employee agrees to be bound by
all such obligations and restrictions and to take all action necessary to
discharge the obligations of the Company thereunder.

     16.  TERMINATION EVENT. The following events shall each be considered a
"Termination Event" and, upon the occurrence of any of them, shall have the
effect of immediately terminating the Company's obligations under this
Agreement, including its obligation to make any further payments hereunder but
excluding the payment of base salary and vacation benefits which are accrued at
the date of termination:

          (a)  Employee's death;

          (b)  Employee's Disability for such period of time and under
circumstances which would constitute a Long Term Disability;

          (c)  The termination of Employee's employment by the Company for Cause
(as defined in Section 18(e)). Termination pursuant to Section 16(c) shall be
without prejudice to any other right or remedy to which the Company may be
entitled, at law, in equity, under this Agreement or otherwise; or

          (d)  The termination of Employee's employment by Employee for any
reason.

     Notwithstanding Employee's termination of employment pursuant to Section
16(b), 16(c) or 16(d), Employee's covenants and obligations set forth in
Sections 8, 9, 10, 11, 12, 13 and 14 shall remain in effect and be fully
enforceable in accordance with the provisions thereof.

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     17.  TERMINATION WITHOUT CAUSE. In addition to the other termination rights
provided to the Company or Employee hereunder, the Company may terminate
Employee's employment without Cause at any time; PROVIDED, however, that:

          (a)  Employee's covenants and obligations set forth in Sections 8, 9,
10, 11, 12, 13 and 14 shall remain in effect and be fully enforceable in
accordance with the provisions thereunder; and

          (b)  in the event that Employee's employment is terminated by the
Company without Cause at any time after January 1, 2003, Employee shall be
entitled to receive (i) the installments of base salary set forth in Section
5(a) not yet paid to such Employee, payable when and as if Employee had
continued to be employed by the Company until the three month anniversary of the
date of such termination, and (ii) the benefits set forth in Section 6(b) for
such period of time.

     18.  MISCELLANEOUS.

          (a)  ENTIRE AGREEMENT. This Agreement constitutes the entire agreement
among the parties with respect to the subject matter hereof and supersede all
other prior agreements and understandings, both written and oral, between the
parties with respect to such subject matter, including the Original Agreement.

          (b)  ASSIGNABILITY, ETC. This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective successors and
permitted assigns. This Agreement is not intended to confer upon any Person
other than the parties hereto any rights or remedies hereunder, except as
otherwise expressly provided herein and shall not be assignable by operation of
law or otherwise.

          (c)  AMENDMENTS AND SUPPLEMENTS. This Agreement may not be altered,
changed or amended, except by an instrument in writing signed by the parties
hereto; PROVIDED, HOWEVER, that, except as provided in Section 5(c)(ii), no such
alteration, change or amendment may be binding on the Company unless approved by
the Board.

          (d)  NO WAIVER. The terms and conditions of this Agreement may be
waived only by a written instrument signed by the party waiving compliance. In
the case of the Company, no waiver shall be effective unless approved by the
Board. The failure of any party hereto to enforce at any time any of the
provisions of this Agreement shall in no way be construed to be a waiver of any
such provision, nor in any way to affect the validity of this Agreement or any
part hereof or the right of such party thereafter to enforce each and every such
provision. No waiver of any breach of or non-compliance with this Agreement
shall be held to be a waiver of any other or subsequent breach or
non-compliance.

          (e)  CERTAIN DEFINITIONS. For purposes of this Agreement, the
following terms shall have the meanings set forth below:

          "Cause" means:

               (i)   Employee's dishonesty with respect to the Company;

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               (ii)  Employee's misconduct which materially and adversely
reflects upon the business, affairs, operations, or reputation of the Company or
upon Employee's ability to perform his duties for the Company;

               (iii) Employee's failure (except by reason of Disability) to
perform his duties and responsibilities for the Company, which failure continues
for more than ten days after the Company gives written notice to Employee which
sets forth in reasonable detail the nature of such failure;

               (iv)  Employee's negligent performance of his duties, which
negligent performance continues for more than ten days after the Company gives
written notice to Employee which sets forth in reasonable detail the nature of
such negligence; or

               (v)   Employee's breach of any one or more of the material
provisions of this Agreement, which breach continues for more than ten days
after the Company gives written notice to Employee which sets forth in
reasonable detail the nature of such breach.

          "Disability" means the inability of Employee to substantially perform
his duties to the Company by reason of any medically determinable physical
impairment.

          "Field of Interest" means the field of sequencing, chemical, enzymatic
or biological synthesis, production or modification of linear and branched
sugars and glycoconjugates.

          "Long Term Disability" means a Disability which continues for at least
120 consecutive calendar days or 150 calendar days during any consecutive
twelve-month period, after its commencement, and is determined in good faith to
be total and permanent by the Board following consultation with reputable
medical or health experts selected by the Board.

          "Person" shall mean an individual, a corporation, an association, a
partnership, an estate, a trust and any other entity or organization.

          (f)  CONSTRUCTION OF AGREEMENT. A reference to a Section or Exhibit
shall mean a Section in or Exhibit to this Agreement unless otherwise expressly
stated. The titles and headings herein are for reference purposes only and shall
not in any manner limit the construction of this Agreement which shall be
considered as a whole. The words "include," "includes" and "including" when used
herein shall be deemed in each case to be followed by the words "without
limitation."

          (g)  NOTICE. All notices and other communications hereunder shall be
in writing and shall be deemed given if delivered by hand, sent by facsimile
transmission with confirmation of receipt, sent via a reputable overnight
courier service with confirmation of receipt requested, or mailed by registered
or certified mail (postage prepaid and return receipt requested) to the parties
at the following addresses (or at such other address for a party as shall be
specified by like notice), and shall be deemed given on the date on which
delivered by hand or otherwise on the date of receipt as confirmed:

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     To the Company:

          Mimeon, Inc.
          43 Moulton Street
          Cambridge, MA 02143
          Attention: President
          Fax: 617.491.9701

     To Employee:

          Ganesh Venkataraman
          215 Concord Road
          Bedford, MA 02451

          (h)  GOVERNING LAW. This Agreement shall be governed by, and construed
and enforced in accordance with, the substantive laws of The Commonwealth of
Massachusetts, without regard to its principles of conflicts of laws.

          (i)  REMEDIES. Employee recognizes that money damages alone would not
adequately compensate the Company in the event of breach by Employee of this
Agreement, and Employee therefore agrees that, in addition to all other remedies
available to the Company at law, in equity or otherwise, the Company shall be
entitled to injunctive relief for the enforcement hereof. All rights and
remedies hereunder are cumulative and are in addition to and not exclusive of
any other rights and remedies available at law, in equity, by agreement or
otherwise.

          (j)  SURVIVAL; VALIDITY. Except as expressly provided herein, the
provisions of this Agreement shall not survive termination of Employee's
employment by the Company for any reason. In the event that any provision of
this Agreement shall be determined to be unenforceable by reason of its
extension for too great a period of time or over too large a geographic area or
over too great a range of activities, it shall be interpreted to extend only
over the maximum period of time, geographic area or range of activities as to
which it may be enforceable. If, after application of the preceding sentence,
any provision of this Agreement shall be determined to be invalid, illegal or
otherwise unenforceable by a court of competent jurisdiction, the validity,
legality and enforceability of the other provisions of this Agreement shall not
be affected thereby. Except as otherwise provided in this Section 17, any
invalid, illegal or unenforceable provision of this Agreement shall be
severable, and after any such severance, all other provisions hereof shall
remain in full force and effect.

          (k)  COUNTERPARTS. This Agreement may be executed in one or more
counterparts, all of which together shall constitute one and the same Agreement.

                                    * * * * *

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     IN WITNESS WHEREOF, the parties have caused this Amended and Restated
Employment Agreement to be executed as an agreement under seal as of the date
first written above.

                                      MIMEON, INC.


                                      By:/s/ Alan L. Crane
                                         ---------------------------------------
                                         Alan L. Crane
                                         President and Chief Executive Officer


                                      /s/ Ganesh Venkataraman
                                      ------------------------------------------
                                      Ganesh Venkataraman

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