Exhibit 10.27


          The security represented by this certificate was originally
          issued on December 12, 1997, and has not been registered
          under the Securities Act of 1933, as amended.  The transfer
          of such security is subject to the conditions specified in
          the Warrant Agreement, dated as of December 12, 1997 (as
          amended and modified from time to time), between the issuer
          hereof (the "Company") and the initial holder hereof, and
          the Company reserves the right to refuse the transfer of
          such security until such conditions have been fulfilled with
          respect to such transfer.  Upon written request, a copy of
          such conditions shall be furnished by the Company to the
          holder hereof without charge.

                           SCRIPTGEN PHARMACEUTICALS, INC.

                                STOCK PURCHASE WARRANT


Date of Issuance:  December 12, 1997                         Certificate No. W-1


          FOR VALUE RECEIVED, SCRIPTGEN PHARMACEUTICALS, INC., a  Delaware
corporation (the "Company"), hereby grants to BIOCHEM PHARMA INC. or its
registered assigns (the "Registered Holder") the right to purchase from the
Company 1,428,258 shares of Warrant Stock at a price per share of US $4.38 (as
adjusted from time to time hereunder, the "Exercise Price").  This Warrant (the
"Warrant") in issued pursuant to the terms of the Warrant Agreement, dated as of
December 12, 1997 (the "Warrant Agreement"), between the Company and a certain
investor.  Certain capitalized terms used herein are defined in Section 5
hereof.  The amount and kind of securities obtainable pursuant to the rights
granted hereunder and the purchase price for such securities are subject to
adjustment pursuant to the provisions contained in this Warrant. 

          This Warrant is subject to the following provisions: 

          Section 1.  EXERCISE OF WARRANT.

          1A.  EXERCISE PERIOD.  The Registered Holder may exercise, in whole or
in part (but not as to a fractional share of Warrant Stock), the purchase rights
represented by this Warrant at any time and from time to time after the Date of
Issuance to and including 5 p.m., New York time on December 12, 2002 (the
"Exercise Period").


                                           


          1B.  EXERCISE PROCEDURE. 

          (i)  This Warrant shall be deemed to have been exercised when the
Company has received all of the following items (the "Exercise Time"): 

          (a)  a completed Exercise Agreement, as described in paragraph 1C
     below, executed by the Person exercising all or part of the purchase rights
     represented by this Warrant (the "Purchaser");

          (b)  this Warrant;

          (c)  if this Warrant is not registered in the name of the Purchaser,
     an Assignment or Assignments in the form set forth in EXHIBIT II hereto
     evidencing the assignment of this Warrant to the Purchaser, in which case
     the Registered Holder shall have complied with the provisions set forth in
     Section 7 hereof; and

          (d)  a check payable to the Company in an amount equal to the product
     of the Exercise Price multiplied by the number of shares of Warrant Stock
     being purchased upon such exercise (the "Aggregate Exercise Price").

          (ii) Certificates for shares of Warrant Stock purchased upon exercise
of this Warrant shall be delivered by the Company to the Purchaser within five
business days after the date of the Exercise Time.  Unless this Warrant has
expired or all of the purchase rights represented hereby have been exercised,
the Company shall prepare a new Warrant, substantially identical hereto,
representing the rights formerly represented by this Warrant which have not
expired or been exercised and shall, within such five-day period, deliver such
new Warrant to the Person designated for delivery in the Exercise Agreement. 

         (iii) The Warrant Stock issuable upon the exercise of this Warrant
shall be deemed to have been issued to the Purchaser at the Exercise Time, and
the Purchaser shall be deemed for all purposes to have become the record holder
of such Warrant Stock at the Exercise Time. 

          (iv) The issuance of certificates for shares of Warrant Stock upon
exercise of this Warrant shall be made without charge to the Registered Holder
or the Purchaser for any issuance tax in respect thereof or other cost incurred
by the Company in connection with such exercise and the related issuance of
shares of Warrant Stock.  Each share of Warrant Stock issuable upon exercise of
this Warrant shall, upon payment of the Exercise Price therefor, be fully paid
and nonassessable and free from all liens and charges 


                                         -2-


with respect to the issuance thereof. 

          (v)  The Company shall not close its books against the transfer of
this Warrant or of any share of Warrant Stock issued or issuable upon the
exercise of this Warrant in any manner which interferes with the timely exercise
of this Warrant.  The Company shall from time to time take all such action as
may be necessary to assure that the par value per share of the unissued Warrant
Stock acquirable upon exercise of this Warrant is at all times equal to or less
than the Exercise Price then in effect. 

          (vi) The Company shall assist and cooperate with any Registered Holder
or Purchaser required to make any governmental filings or obtain any
governmental approvals prior to or in connection with any exercise of this
Warrant (including, without limitation, making any filings required to be made
by the Company).

         (vii) Notwithstanding any other provision hereof, if an exercise of any
portion of this Warrant is to be made in connection with a registered public
offering or the sale of the Company, the exercise of any portion of this Warrant
may, at the election of the holder hereof, be conditioned upon the consummation
of the public offering or the sale of the Company in which case such exercise
shall not be deemed to be effective until the consummation of such transaction.

        (viii) The Company shall at all times reserve and keep available out of
its authorized but unissued shares of Warrant Stock solely for the purpose of
issuance upon the exercise of the Warrants, such number of shares of Warrant
Stock issuable upon the exercise of all outstanding Warrants.  The Company shall
take all such actions as may be necessary to assure that all such shares of
Warrant Stock may be so issued without violation of any applicable law or
governmental regulation or any requirements of any domestic securities exchange
upon which shares of Warrant Stock may be listed (except for official notice of
issuance which shall be immediately delivered by the Company upon each such
issuance and except that the Company shall not be required to register under the
Securities Act of 1933, as amended, any issuance of Warrant Stock, provided,
that nothing herein shall affect the rights of the Investor under the
Registration Rights Agreement dated of even date).  The Company shall not take
any action which would cause the number of authorized but unissued shares of
Warrant Stock to be less than the number of such shares required to be reserved
hereunder for issuance upon exercise of the Warrants.

          1C.  EXERCISE AGREEMENT.  Upon any exercise of this Warrant, the
Exercise Agreement shall be substantially in the form set forth in EXHIBIT I
hereto, except that if the shares of Warrant Stock are not to be issued in the
name of the Person in whose name 


                                         -3-


this Warrant is registered, the Exercise Agreement shall also state the name of
the Person to whom the certificates for the shares of Warrant Stock are to be
issued, and if the number of shares of Warrant Stock to be issued does not
include all the shares of Warrant Stock purchasable hereunder, it shall also
state the name of the Person to whom a new Warrant for the unexercised portion
of the rights hereunder is to be delivered.  Such Exercise Agreement shall be
dated the actual date of execution thereof. 

          1D.  FRACTIONAL SHARES.  If a fractional share of Warrant Stock would,
but for the provisions of paragraph 1A, be issuable upon exercise of the rights
represented by this Warrant, the Company shall, within five business days after
the date of the Exercise Time, deliver to the Purchaser a check payable to the
Purchaser in lieu of such fractional share in an amount equal to the difference
between the Market Price of such fractional share as of the date of the Exercise
Time and the Exercise Price of such fractional share. 

          Section 2.  ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF SHARES.  In
order to prevent dilution of the rights granted under this Warrant, the Exercise
Price shall be subject to adjustment from time to time as provided in this
Section 2, and the number of shares of Warrant Stock obtainable upon exercise of
this Warrant shall be subject to adjustment from time to time as provided in
this Section 2.  Capitalized terms not defined in this Section 2 shall have the
meanings ascribed to them in the Company's Restated Articles of Incorporation
(in the form attached as EXHIBIT C to the Stock Purchase Agreement dated of even
date).

          2A.  ADJUSTMENTS.  The initial Exercise Price above shall be subject
to adjustment from time to time and such exercise prices as adjusted shall
likewise be subject to further adjustment, all as hereinafter set forth.  The
term "Current Exercise Price" shall mean, as of any time, the Exercise Price in
case no adjustment shall have been required, or such conversion price as
adjusted pursuant to this Section 2A, as the case may be.

          (i)  If at any time after the date of issuance of the Warrant, the
Company shall issue (x) any shares of Common Stock other than (A) Excluded Stock
(as defined in (vi) below), (B) Common Stock issued or issuable upon conversion
of the Preferred Stock or exercise of this Warrant or (C) by way of dividend or
other distribution on shares of Common Stock referred to in the foregoing
clauses (A) and (B), or (y) any shares of a class or series convertible into
Common Stock, other than the Preferred Stock (collectively, with the Common
Stock, such "Securities"), for a consideration per share (the consideration in
each case to be determined in the manner provided in (E) and (F) below) less
than the Current Exercise Price in effect immediately 


                                         -4-


prior to the issuance of such Securities, the Current Exercise Price in effect
immediately prior to each such issuance shall forthwith (except as provided in
subparagraph (ii) below) be reduced to a Current Exercise Price obtained by
dividing an amount equal to the sum of

          (x)  the total number of shares of Common Stock outstanding (including
               the number of shares of Common Stock into which the Warrant and
               the outstanding shares of Preferred Stock and other securities
               convertible into Preferred Stock are then directly or indirectly
               convertible) immediately prior to such issuance multiplied by the
               Current Conversion Price in effect immediately prior to such
               issuance, plus

          (y)  the consideration received by the Company upon such issuance,

               by

          (z)  the total number of shares of Common Stock outstanding (including
               the number of shares of Common Stock into which the Warrant and
               the outstanding shares of Preferred Stock or other securities
               convertible into Preferred Stock are then directly or indirectly
               convertible) immediately after such issuance (including the
               number of shares of Common Stock into which such newly issued
               Securities are then convertible).

          (ii) For the purpose of any adjustment of the conversion price
pursuant to Subsection 2A(i) above, the following provisions shall be
applicable:

               (A)  In the case of the issuance of options or warrants to
                    purchase or rights to subscribe for Common Stock other than
                    Excluded Stock (collectively, "Rights"), the aggregate
                    maximum number of shares of Common Stock deliverable upon
                    exercise of such Rights shall be deemed to have been issued
                    at the time such Rights were issued, for a consideration
                    equal to the consideration (determined in the manner
                    provided in (E) and (F) below), if any, received by the
                    Company on the issuance of such Rights, plus the minimum
                    purchase price provided in such Rights for the Common Stock
                    covered thereby; provided that such shares of Common Stock
                    deliverable upon the exercise of 


                                         -5-


                    such Rights shall not be deemed to have been issued unless
                    such consideration per share would be less than the Current
                    Exercise Price in effect on the date of and immediately
                    prior to such issue.  No further adjustment of the Current
                    Exercise Price adjusted upon the issuance of such Rights
                    shall be made as a result of the actual issuance of shares
                    of Common Stock deliverable upon exercise of such Rights.

               (B)  In the case of the issuance of securities by their terms
                    convertible into or exchangeable for Common Stock other than
                    Excluded Stock (collectively, "Convertible Securities"), or
                    options or warrants to purchase or rights to subscribe for
                    securities by their terms convertible or exchangeable for
                    Common Stock other than Excluded Stock (collectively,
                    "Related Rights"), the aggregate maximum number of shares of
                    Common Stock deliverable upon conversion, exchange or
                    exercise of any such Convertible Securities or such Related
                    Rights shall be deemed to have been issued at the time such
                    Convertible Securities or such Related Rights were issued
                    and for a consideration equal to the consideration received
                    by the Company upon issuance of such Convertible Securities
                    or such Related Rights (excluding any cash received on
                    account of accrued interest or accrued dividends), plus the
                    additional consideration, if any, to be received by the
                    Company upon the conversion, exchange or exercise of such
                    Convertible Securities or Related Rights (the consideration
                    in each case to be determined in the manner provided in (E)
                    and (F) below); provided that such shares of Common Stock
                    deliverable upon such conversion, exchange or exercise of
                    such Convertible Securities or Related Rights shall not be
                    deemed to have been issued unless such consideration per
                    share would be less than the Current Exercise Price in
                    effect on the date of and immediately prior to such issue. 
                    No further adjustment of the Current Exercise Price adjusted
                    upon the issuance of such Related Rights shall be made as a
                    result of the actual issuance of such Convertible Securities
                    deliverable upon exercise of such Related Rights.


                                         -6-


               (C)  On any change in the number of shares of Common Stock
                    deliverable upon the exercise of such Rights or Related
                    Rights or upon the conversion, exchange or exercise of such
                    Convertible Securities or on any change in the minimum
                    purchase price of such Rights, Related Rights or Convertible
                    Securities other than a change resulting from the
                    anti-dilution provisions of such Rights, Related Rights or
                    Convertible Securities, the Exercise Price shall forthwith
                    be readjusted to such Current Exercise Price as would have
                    been obtained had the adjustment made upon the issuance of
                    such Rights, Related Rights or Convertible Securities not
                    converted exchanged or exercised prior to such change, been
                    made upon the basis of such change.

               (D)  On the expiration of any such Rights, Related Rights or
                    Convertible Securities, the Current Exercise Price shall
                    forthwith be readjusted to such Current Exercise Price as
                    would have obtained had the adjustment made upon the
                    issuance of such Rights or Related Rights or the conversion,
                    exchange or exercise of any such Convertible Securities been
                    made upon the basis of the issuance of only the number of
                    shares of Common Stock actually issued upon the exercise of
                    such Rights or Related Rights or the conversion, exchange or
                    exercise of any such Convertible Securities.

               (E)  In the case of the issuance of such Securities for cash, the
                    consideration shall be deemed to be the amount of cash paid
                    therefor (excluding amounts paid for accrued interest or
                    accrued dividends).

               (F)  In the case of the issuance of such Securities for a
                    consideration in whole or in part other than cash, the
                    consideration other than cash shall be deemed to be the fair
                    value thereof as determined in good faith by the Board of
                    Directors of the Company.

          (iii)If the Company declares a dividend or other distribution payable
in such Securities or subdivides its outstanding shares of Common Stock into a
larger number or combines its outstanding shares of Common Stock into a smaller
number, then the Current Exercise Price in effect immediately prior to such 


                                         -7-


dividend, other distribution, subdivision or combination, as the case may be,
shall forthwith be adjusted to that price determine by multiplying the Current
Conversion Price by a fraction (x) the numerator of which shall be the total
number of outstanding shares of such Securities immediately prior to such
dividend, other distribution, subdivision or combination and (y) the denominator
of which shall be the total number of outstanding shares of such Securities
immediately after such dividend, other distribution, subdivision or combination.

          (iv) In the event the Company shall declare a dividend or otherwise
distribute to the holders of its Common Stock shares of its capital stock (other
than such Securities), stock or other securities of other persons, evidences of
indebtedness issued by the Company or other persons, assets (excluding cash
dividends) or options, warrants or rights (excluding such Rights or Related
Rights), then, in each such case, immediately following the record date fixed
for the determination of the holders of Common Stock entitled to receive such
dividend or distribution, the Current Exercise Price in effect thereafter shall
be determined by multiplying the Current Exercise Price in effect immediately
prior to such record date by a fraction (A) the numerator of which shall be an
amount equal to the remainder of (x) the Current Market Price (as defined in
(viii) below) determined immediately prior to such distribution of one share of
Common Stock less (y) the fair value (as determined in good faith by the
Company's Board of Directors) of the stock, securities, evidences of
indebtedness, assets, options, warrants or rights so dividended or distributed
in respect of one share of Common Stock, as the case may be, and (B) the
denominator of which shall be the Current market Price of one share of Common
Stock determined immediately prior to such dividend or distribution.  Such
adjustment shall be made on the date such dividend or distribution is made, and
shall become effective at the opening of business on the business day following
the record date for the determination of stockholders entitled to such dividend
or distribution.

          (v)  Whenever the Current Exercise Price shall be adjusted as provided
in this Section 2A, the Company shall forthwith file, at the principal office of
the Company or at such other place as may be designated by the Company, a
statement, certified by the chief financial officer of the Company, show in
detail the facts requiring such adjustment and the Current Exercise Price that
shall be in effect after such adjustment.  The Company shall also cause a copy
of such statement to be sent by first class mail, postage prepaid, to the
Registered Holder at such holder's address as shown in the records of the
Company.

          (vi) "Excluded Stock" shall mean up to 4,850,000 shares (such amount
to be appropriately adjusted in the event of any stock 


                                         -8-


dividend, stock split or combination, or similar recapitalization affecting the
Common Stock) of Common Stock or options for the purchase thereof issued, sold
or granted, in the past or future, by the Company to its employees, directors or
consultants pursuant to bona fide employee stock purchase, option or similar
benefit plans or other incentive programs or compensation arrangements approved
by the Board of Directors of the Company.

          (vii)For the purpose of any computation pursuant to, subparagraph (iv)
above, the "Current Market Price" at any date of one share of Common Stock shall
be deemed to be the average of the daily closing prices for the 30 consecutive
business days ending 15 business days before the date in question (as adjusted
for any stock splits, stock dividends, combinations or recapitalization that
took effect during such 30 business-day period).  The closing price for each day
shall be the last reported sales price on such day on the principal national
securities exchange on which the Common Stock is listed or admitted to trading,
or if not listed or admitted to trading national securities exchange, the
average of the last reported bid and asked prices as reported by the National
Association of Securities Dealers Automated Quotation System, Inc., all as
adjusted for stock splits, stock dividends, combinations or similar
recapitalization that took effect during such 30 business-day period; PROVIDED,
HOWEVER, that if the Common Stock is not traded in such a manner that the
quotations referred to in this subparagraph (viii) are available for the period
required hereunder, the Current market Price shall be deemed to be the fair
value of such Common Stock ad determined in good faith by the Board of Directors
of the Company.

          (viii)If any event occurs of the type contemplated by the provisions
of this Section 2A but not expressly provided for by such provisions, then the
Board of Directors of the Company will make an appropriate adjustment in the
Current Exercise Price as to protect the rights of the holders of the Warrant;
provided that no such adjustment will increase the Current Exercise Price except
as otherwise permitted pursuant to subparagraph (iii) above or subparagraph
(c)(ii)(D) of this Section 2A or decrease the number of shares of Common Stock
issuable upon exercise of the Warrant.

          2B.  TREASURY SHARES.  The number of shares of Common Stock
outstanding at any given time does not include shares owned or held by or for
the account of the Company or any Subsidiary, and the disposition of any shares
so owned or held shall be considered an issue or sale of Common Stock. 

          2C.  RECORD DATE.  If the Company takes a record of the holders of
Common Stock for the purpose of entitling them (A) to receive a dividend or
other distribution payable in Common Stock, Rights or in Related Rights or (B)
to subscribe for or purchase 


                                         -9-


Common Stock, Rights or Related Rights, then such record date shall be deemed to
be the date of the issue or sale of the shares of Common Stock deemed to have
been issued or sold upon the declaration of such dividend or the making of such
other distribution or the date of the granting of such right of subscription or
purchase, as the case may be. 

          2D.  REORGANIZATION, RECLASSIFICATION, CONSOLIDATION, MERGER OR SALE. 
Any recapitalization, reorganization, reclassification, consolidation, merger,
sale of all or substantially all of the Company's assets or other transaction,
which in each case is effected in such a way that the holders of Common Stock
are entitled to receive (either directly or upon subsequent liquidation) stock,
securities or assets with respect to or in exchange for Common Stock is referred
to herein as "Organic Change."  Prior to the consummation of any Organic Change,
the Company shall make appropriate provision (in form and substance reasonably
satisfactory to the Registered Holder) to insure that each of the Registered
Holder the shares of Warrant Stock immediately theretofore acquirable and
receivable upon the exercise of such holder's Warrant, such shares of stock,
securities or assets as may be issued or payable with respect to or in exchange
for the number of shares of Warrant Stock immediately theretofore acquirable and
receivable upon exercise of such holder's Warrant had such Organic Change not
taken place.  In any such case, the Company shall make appropriate provision (in
form and substance reasonably satisfactory to the Registered Holders of the
Warrants representing a majority of the Warrant Stock obtainable upon exercise
of all Warrants then outstanding) with respect to such holder's rights and
interests to insure that the provisions of this Section 2 and Sections 3 and 4
hereof which are then in effect shall thereafter be applicable to the Warrant. 
The Company shall not effect any such consolidation, merger or sale, unless
prior to the consummation thereof, the successor entity (if other than the
Company) resulting from consolidation or merger or the entity purchasing such
assets assumes by written instrument (in form and substance reasonably
satisfactory to the Registered Holders of Warrants representing a majority of
the Warrant Stock obtainable upon exercise of all of the Warrants then
outstanding), the obligation to deliver to each such holder such shares of
stock, securities or assets as, in accordance with the foregoing provisions,
such holder may be entitled to acquire. 

          2E.  NOTICES.

          (i)  Immediately upon any adjustment of the Exercise Price, the
Company shall give written notice thereof to the Registered Holder, setting
forth in reasonable detail and certifying the calculation of such adjustment. 


                                         -10-


          (ii) The Company shall give written notice to the Registered Holder at
least 20 days prior to the date on which the Company closes its books or takes a
record (A) with respect to any dividend or distribution upon the Common Stock,
(B) with respect to any pro rata subscription offer to holders of Common Stock
or (C) for determining rights to vote with respect to any Organic Change,
dissolution or liquidation. 

         (iii) The Company shall also give written notice to the Registered
Holders at least 20 days prior to the date on which any Organic Change,
dissolution or liquidation shall take place. 

          2F.  TERMINATION.

          The provisions of Section 2A(i) and (ii), except to the extent
necessary to effectuate the other provisions of this Warrant, shall terminate
upon the closing of a Qualified Public Offering (as that term is defined in the
Stockholders' Agreement, dated of even date).  The provisions of Section 2A(i)
and (ii) shall not apply to any securities issued by the Company in the
Qualified Public Offering.

          Section 3.  LIQUIDATING DIVIDENDS.  If the Company declares a dividend
upon the Common Stock (except a dividend payable in shares of Common Stock
referred to in Section 2A(iii) payable otherwise than out of retained earnings,
the Current Exercise Price in effect immediately prior to the declaration of
such dividend shall be reduced (but not below par value) by an amount equal, in
the case of a dividend in cash, to the amount thereof payable per share of
Common Stock or, in the case of any other dividend, to the fair value thereof
per share of Common Stock as determined in good faith by the Board of Directors
of the Company.  For the purposes of the foregoing, a dividend payable other
than in cash shall be considered payable out of retained earnings only to the
extent that such retained earnings are charged an amount equal to the fair value
of such dividend as determined by the Board of Directors of the Company.  Such
reduction shall take effect as of the date on which a record is taken for the
purpose of such dividend or, if a record is not taken, the date as of which the
holders of the Common Stock of record entitled to such dividend are to be
determined.  Appropriate readjustment of the per share Exercise Price shall be
made in the event that any dividend referred to in this Section 3 shall be
lawfully abandoned.

          Section 4.  DEFINITIONS.  The following terms have meanings set forth
below:

          "COMMON STOCK" means, collectively, the Company's Common Stock and any
capital stock of any class of the Company hereafter authorized which is not
limited to a fixed sum or percentage of par 


                                         -11-


or stated value in respect to the rights of the holders thereof to participate
in dividends or in the distribution of assets upon any liquidation, dissolution
or winding up of the Company.

          "PERSON" means an individual, a partnership, a joint venture, a
corporation, a limited liability company, a trust, an unincorporated
organization and a government or any department or agency thereof.

          "WARRANT STOCK" means the Company's Common Stock, par value $.01 per
share; provided that if there is a change such that the securities issuable upon
exercise of the Warrants are issued by an entity other than the Company or there
is a change in the type or class of securities so issuable, then the term
"Warrant Stock" shall mean one share of the security issuable upon exercise of
the Warrants if such security is issuable in shares, or shall mean the smallest
unit in which such security is issuable if such security is not issuable in
shares.

          Other capitalized terms used in this Warrant but not defined herein
shall have the meanings set forth in the Purchase Agreement.

          Section 5.  NO VOTING RIGHTS; LIMITATIONS OF LIABILITY.  This Warrant
shall not entitle the holder hereof to any voting rights or other rights as a
stockholder of the Company.  No provision hereof, in the absence of affirmative
action by the Registered Holder to purchase Warrant Stock, and no enumeration
herein of the rights or privileges of the Registered Holder shall give rise to
any liability of such holder for the Exercise Price of Warrant Stock acquirable
by exercise hereof or as a stockholder of the Company.

          Section 6.  WARRANT TRANSFERABLE.  The Registered Holder, by
acceptance of this Warrant, agrees that this Warrant and the Warrant Stock
issued upon exercise of this Warrant are being acquired for investment and that
it will not offer, sell or otherwise dispose of this Warrant or any Warrant
Stock except under circumstances which will not result in a violation of the
Securities Act of 1933, as amended (the "Securities Act"). Upon exercise of this
Warrant, the Purchaser shall, if requested by the Company, confirm in writing,
in a form satisfactory to the Company, that the Warrant Stock is being acquired
for investment and not with a view toward distribution or resale. The
certificates representing the Warrant Stock (unless registered under the
Securities Act) shall be stamped or imprinted with a legend substantially in the
form enclosed herein.  Subject to the foregoing, this Warrant and all rights
hereunder are transferable, in whole or in part, without charge to the
Registered Holder, upon surrender of this Warrant with a properly executed
Assignment (in 


                                         -12-


the form of EXHIBIT II hereto) at the principal office of the Company.

          Section 7.  WARRANT EXCHANGEABLE FOR DIFFERENT DENOMINATIONS.  This
Warrant is exchangeable, upon the surrender hereof by the Registered Holder at
the principal office of the Company, for new Warrants of like tenor representing
in the aggregate the purchase rights hereunder, and each of such new Warrants
shall represent such portion of such rights as is designated by the Registered
Holder at the time of such surrender.  The date the Company initially issues
this Warrant shall be deemed to be the "Date of Issuance" hereof regardless of
the number of times new certificates representing the unexpired and unexercised
rights formerly represented by this Warrant shall be issued.  All Warrants
representing portions of the rights hereunder are referred to herein as the
"Warrants."

          Section 8.  REPLACEMENT.  Upon receipt of evidence reasonably
satisfactory to the Company (an affidavit of the Registered Holder shall be
reasonably satisfactory) of the ownership and the loss, theft, destruction or
mutilation of any certificate evidencing this Warrant, and in the case of any
such loss, theft or destruction, upon receipt of indemnity reasonably
satisfactory to the Company (provided that if the holder is a financial
institution or other institutional investor its own agreement shall be
satisfactory), or, in the case of any such mutilation upon surrender of such
certificate, the Company shall (at its expense) execute and deliver in lieu of
such certificate a new certificate of like kind representing the same rights
represented by such lost, stolen, destroyed or mutilated certificate and dated
the date of such lost, stolen, destroyed or mutilated certificate.

          Section 9.  NOTICES.  Except as otherwise expressly provided herein,
all notices referred to in this Warrant shall be in writing and shall be
delivered personally sent by reputable overnight courier service (charges
prepaid) and shall be deemed to have been given when so delivered or sent(i) to
the Company, at its principal executive offices and (ii) to the Registered
Holder of this Warrant, at such holder's address as it appears in the records of
the Company (unless otherwise indicated by any such holder).

          Section 10.  AMENDMENT AND WAIVER.  Except as otherwise provided
herein, the provisions of the Warrants may be amended and the Company may take
any action herein prohibited, or omit to perform any act herein required to be
performed by it, only if the Company has obtained the written consent of the
Registered Holders of Warrants representing a majority of the shares of Warrant
Stock obtainable upon exercise of the Warrants; provided that no such action may
change the Exercise Price of the Warrants or the number 


                                         -13-


of shares or class of stock obtainable upon exercise of each Warrant without the
written consent of the Registered Holders of Warrants representing at least 60%
of the shares of Warrant Stock obtainable upon exercise of the Warrants.

          Section 11.  DESCRIPTIVE HEADINGS; GOVERNING LAW.  The descriptive
headings of the several Sections and paragraphs of this Warrant are inserted for
convenience only and do not constitute a part of this Warrant.  The corporation
laws of the State of New York shall govern all issues concerning the relative
rights of the Company and its stockholders.  All other questions concerning the
construction, validity, enforcement and interpretation of this Warrant shall be
governed by the internal law of the State of New York, without giving effect to
any choice of law or conflict of law provision or rule (whether of the State of
New York or any other jurisdictions) that would cause the application of the
laws of any jurisdictions other than the State of New York.

          Section 12.  AMALGAMATION.  The Company acknowledges that Registered
Holder has advised it that it proposes to carry out a reorganization, including
an amalgamation, pursuant to which, among other things, a corporation named
BioChem Holdings Inc. (the "Successor") will own all of the assets and be liable
for all liabilities of Registered Holder (the "Amalgamation").  The Company
hereby agrees that, upon consummation of the Amalgamation, the Successor shall
have all of the rights and obligations of Registered Holder as if Successor had
executed this Agreement on the date hereof in lieu of Registered Holder, and
that neither Registered Holder nor Successor shall be required to send any
notice of any kind regarding the Amalgamation nor seek the consent of the
Company to such Amalgamation.













                                         -14-


          IN WITNESS WHEREOF, the Company has caused this Warrant to be signed
and attested by its duly authorized officers under its corporate seal and to be
dated the Date of Issuance hereof.


                                        SCRIPTGEN PHARMACEUTICALS, INC.


                                        By /s/ Mark T. Weedon
                                           ----------------------------
                                           Name:  Mark T. Weedon
                                           Title: President and Chief
                                                  Executive Officer


[Corporate Seal]

Attest:


/s/ Karen A. Hamlin
- ----------------------------
         Secretary

















                                         -15-


                                                                       EXHIBIT I

                                  EXERCISE AGREEMENT


To:                                                      Dated:  

          The undersigned, pursuant to the provisions set forth in the attached
Warrant (Certificate No. W-1), hereby agrees to subscribe for the purchase of
______ shares of the Warrant Stock covered by such Warrant and makes payment
herewith in full therefor at the price per share provided by such Warrant.


                                   Signature ____________________

                                   Address ______________________



                                                                      EXHIBIT II


                                     ASSIGNMENT 

          FOR VALUE RECEIVED, _________________________________ hereby sells,
assigns and transfers all of the rights of the undersigned under the attached
Warrant (Certificate No. W-1) with respect to the number of shares of the
Warrant Stock covered thereby set forth below, unto:

Names of Assignee                  Address                       No. Of Shares
- -----------------                  -------                       -------------




Dated:                             Signature _______________________

                                             _______________________

                                   Witness   _______________________