EXHIBIT 3.2

                                    AMENDED
              CERTIFICATE OF DESIGNATIONS, PREFERENCES AND RIGHTS
                                       OF
                          SERIES A PREFERRED STOCK OF
                                 MAXYGEN, INC.

     Maxygen, Inc., a Delaware corporation (the "Corporation"), organized and
existing under the laws of the State of Delaware, the Certificate of
Incorporation of which was filed in the office of the Secretary of State of
Delaware on May 7, 1996, does by its Secretary hereby certify as follows:

     FIRST:  that pursuant to the authority vested in the Board of Directors of
     -----
the Corporation in accordance with the provisions of its Certificate of
Incorporation and Section 151 of the DGCL, the Amended Certificate of
Designation, Preferences and Rights of the Series A Preferred Stock of the
Corporation shall be amended to read as follows:

     "A.  SERIES A PREFERRED STOCK
          ------------------------

     1.   Designation of Series.
          ---------------------

     2,800,000 shares of the Preferred Stock of the Corporation shall constitute
a series of Preferred Stock designated as Series A Preferred Stock ("Series A
Preferred"), the powers, preferences and relative and other rights and the
qualifications, limitations and restrictions of which are fixed and determined
in this Section A.

     2.   Dividends.
          ---------

     The holders of the then outstanding shares of Series A Preferred shall be
entitled to receive, when, as and if declared by the Board out of any funds
legally available therefor, noncumulative dividends at the rate of $0.16 per
share (as adjusted for any stock dividend, combination or split with respect to
such shares) per annum. No dividends shall be paid on any other series of
Preferred Stock of the Company unless dividends are paid ratably on the Series A
Preferred. No dividends (other than those payable solely in Common Stock) shall
be paid or declared on the Common Stock during any fiscal year of the
Corporation until dividends in the total amount of $0.16 per share (as adjusted
for any stock dividend, combination or split with respect to such shares) on the
Series A Preferred shall have been paid or declared and set apart during such
fiscal year.  So long as shares of Series A Preferred remain outstanding, no
dividends shall be paid or declared on the Common Stock at an annual rate in
excess of $0.16 per share (as adjusted for any stock dividend, combination or
split with respect to such shares).  No right shall accrue to holders of shares
of Series A Preferred by reason of the fact that dividends on such shares are
not declared, nor shall any undeclared or unpaid dividends bear or accrue
interest.


     3.   Liquidation Rights.
          ------------------

          (a)  In the event of any (i) merger or consolidation of the
Corporation in which the holders of the Common Stock and Preferred Stock of the
Corporation immediately preceding the merger or consolidation do not own 50% or
more of the capital stock of the entity surviving such merger or consolidation,
or if such capital stock is not entitled to elect a majority of the directors of
the surviving entity, (ii) sale, lease, assignment, license, transfer or other
conveyance of all or substantially all the assets of the Corporation or (iii)
liquidation, dissolution or winding up of the affairs of the Corporation,
whether voluntary or involuntary, (collectively, a "Liquidating Event"), after
payment or provision for payment of the debts and other liabilities and
obligations of the Corporation and subject to Section A(3)(c) below, the holders
of each share of Series A Preferred then outstanding shall be entitled to be
paid out of the net assets of the Corporation available for distribution to its
stockholders, before any payment or declaration and setting apart for payment of
any amount shall be made in respect of the Common Stock, an amount equal to
$2.00 per share or Series A Preferred (as adjusted for any stock dividend,
combination or split with respect to such shares), plus an amount equal to any
previously declared but unpaid dividends thereon (collectively, the "Series A
Liquidation Preference").  In the event insufficient funds are available to pay
the Series A Liquidation Preference, together with any liquidation preference
payable on any other series of Preferred Stock, the net assets of the Company
shall be paid ratably to the holders of Series A Preferred and any other series
of Preferred Stock.

          (b)  After payment in full of the Series A Liquidation Preference and
any liquidation preference payable on any other series of Preferred Stock, the
remaining net assets of the Corporation available for distribution shall be
distributed ratably to the holders of Common Stock.

          (c)  Upon the occurrence of a Liquidating Event described in clauses
(i) or (ii) of Section A(3)(a) above, the holders of a majority of the shares of
Series A Preferred then outstanding shall have the right to elect on behalf of
all of the holders of Series A Preferred the benefits of the provisions of
Section A(5)(i) below in lieu of receiving payment of the Series A Liquidation
Preference and other payments pursuant to this Section A(3).

     4.   Voting Rights.
          -------------

          Except as otherwise expressly provided herein or as required by law,
the holders of each share of Series A Preferred shall be entitled to vote on all
matters upon which holders of Common Stock have the right to vote and with
respect to such vote, shall be entitled to notice of any stockholders' meeting
in accordance with the Bylaws of the

                                      -2-


Corporation, and shall be entitled to a number of votes equal to the largest
number of full shares of Common Stock into which such shares of Series A
Preferred could be converted, pursuant to the provisions of Section A(5) below,
at the record date for the determination of stockholders entitled to vote on
such matters or, if no such record date is established, at the date such vote is
taken or any written consent of stockholders is solicited. Except as otherwise
expressly provided herein or to the extent class or series voting is otherwise
required by law or agreement, the holders of shares of Series A Preferred, the
holders of any other series of Preferred Stock that have such voting rights and
the holders of Common Stock shall vote together as a single class and not as
separate classes on all matters.

     5.   Conversion.
          ----------

     The holders of the Series A Preferred shall have the following conversion
rights (the "Conversion Rights"):

          (a)  Right to Convert.  Each share of Series A Preferred shall be
               ----------------
convertible, at the option of the holder thereof, at any time after the date of
issuance of such share but prior to the closing date for a Qualified Public
Offering (as that term is hereinafter defined), at the office of the Corporation
or any transfer agent, into fully paid and nonassessable shares of Common Stock,
at the Conversion Price (as that term is hereinafter defined) therefor in effect
at the time of conversion determined as provided in this Section A(5).  A
"Qualified Public Offering" shall mean an underwritten public offering of the
Corporation's Common Stock registered under the Securities Act of 1933, as
amended, the gross proceeds of which to the Corporation and/or selling
stockholders, if any, are at least $10 million (before deducting any
underwriting fees or selling commissions), provided that the public offering
price per share (before deducting any underwriting fees or selling commissions)
is at least $8.00 per share (as adjusted for any stock dividend, combination or
split with respect to such shares).

          (b)  Conversion Price.  Shares of Series A Preferred shall be
               ----------------
convertible into the number of shares of Common Stock that results from dividing
$2.00 by the Conversion Price per share in effect at the time of conversion for
each share of Series A Preferred being converted.  The Conversion Price per
share for the Series A Preferred at the date on which the first share of the
Series A Preferred is issued (the "Original Issue Date") shall be $2.00 and
shall be subject to adjustment from time to time thereafter as provided in this
Section A(5).

          (c)  Automatic Conversion.  Each share of Series A Preferred which
               --------------------
remains outstanding on the closing date for a Qualified Public Offering (the
"Registration Date") shall automatically, and without any action on the part of
the holder thereof or the Corporation, be converted on the same basis and at the
same Conversion Price as if each

                                      -3-


holder thereof had properly exercised his right to convert on the day next
preceding the Registration Date; provided that (i) such conversion shall be
effective immediately prior to the consummation of a Qualified Public Offering
and (ii) the Corporation shall have no obligation to issue and deliver to any
such holder of Series A Preferred on such date a certificate for the number of
shares of Common Stock to which he shall be entitled until such time as such
holder shall have surrendered his certificate or certificates for his Series A
Preferred, duly endorsed, at the office of the Corporation or any transfer agent
or the holder notifies the Corporation that such certificate or certificates
have been lost, stolen or destroyed and executes an agreement satisfactory to
the Corporation to indemnify the Corporation from any loss incurred by it in
connection therewith. All rights with respect to shares of Series A Preferred
outstanding on the Registration Date shall forthwith after the Registration Date
terminate, except only the right of the holders of such shares to receive Common
Stock upon surrender of their certificates for the Series A Preferred.

          (d)  Mechanics of Conversion; Unpaid Dividends.  Before any holder of
               -----------------------------------------
Series A Preferred shall be entitled to convert the same into shares of Common
Stock, he shall surrender the certificate or certificates therefor, duly
endorsed, at the office of the Corporation or of any transfer agent, and shall
give written notice by mail, postage prepaid, to the Corporation at such office
that he elects to convert the same and shall state therein the number of shares
of Series A Preferred being converted and the name or names in which the
certificate or certificates for shares of Common Stock are to be issued.
Thereupon the Corporation shall promptly issue and deliver at such office to
such holder of Series A Preferred or to the nominee or nominees of such holder a
certificate or certificates for the number of shares of Common Stock to which he
shall he entitled.

          Such conversion shall be deemed to have been made immediately prior to
the close of business on the date of such surrender of the shares of Series A
Preferred to be converted, and the person or persons entitled to receive the
shares of Common Stock issuable upon such conversion shall be treated for all
purposes as the record holder or holders of such shares of Common Stock on such
date.  Any dividends previously declared but unpaid on shares of Series A
Preferred surrendered for conversion shall be paid in cash contemporaneously
with the issuance of certificates evidencing shares of Common Stock upon the
conversion.

          (e)  Adjustment for Stock Splits and Combinations.  If the Corporation
               --------------------------------------------
shall at any time or from time to time after the Original Issue Date effect a
subdivision of the outstanding Common Stock, the Conversion Price then in effect
immediately before that subdivision shall be proportionately decreased;
conversely, if the Corporation shall at any time or from time to time after the
Original issue Date reduce the outstanding shares of Common Stock by combination
or otherwise, the Conversion Price then in effect immediately before the
combination shall be proportionately increased.  Any adjustment

                                      -4-


pursuant to this Section A(5)(e) shall become effective at the close of business
on the date the subdivision or combination becomes effective.

          (f)  Adjustment for Certain Dividends and Distributions.  In the event
               --------------------------------------------------
the Corporation at any time or from time to time after the Original Issue Date
shall make or issue, or fix a record date for the determination of holders of
Common Stock entitled to receive, a dividend or other distribution payable in
additional shares of Common Stock, then and in each such event the Conversion
Price for the Series A Preferred then in effect shall be decreased as of the
time of such issuance or, in the event such a record date shall have been fixed,
as of the close of business on such record date, by multiplying the Conversion
Price for the Series A Preferred then in effect by a fraction:

               (1)  the numerator of which shall be the total number of shares
          of Common Stock issued and outstanding immediately prior to the time
          of such issuance or the close of business on such record date; and

               (2)  the denominator of which shall be the total number of shares
          of Common Stock issued and outstanding immediately prior to the time
          of such issuance or the close of business on such record date, plus
          the number of shares of Common Stock issuable in payment of such
          dividend or distribution; provided, however, if such record date shall
          have been fixed and such dividend is not fully paid or if such
          distribution is not fully made on the date fixed therefor, the
          Conversion Price for the Series A Preferred shall be recomputed
          accordingly as of the close of business on such record date and
          thereafter the Conversion Price for the Series A Preferred shall be
          adjusted pursuant to this Section A(5)(f) as of the time of actual
          payment of such dividends or distributions.

          (g)  Adjustments to Dividends and Distributions.  In the event the
               ------------------------------------------
Corporation at any time or from time to time after the Original Issue Date shall
make or issue, or fix a record date for the determination of holders of Common
Stock entitled to receive, a dividend or other distribution payable in
securities of the Corporation other than shares of Common Stock, then and in
each such event provision shall be made so that the holders of Series A
Preferred shall receive upon conversion thereof in addition to the number of
shares of Common Stock receivable thereupon, the amount of securities of the
Corporation that they would have received had their Series A Preferred been
converted into Common Stock on the date of such event and had thereafter, during
the period from the date of such event to and including the conversion date,
retained such securities receivable by them as aforesaid during such period
giving application to all adjustments called for during such period under this
Section A(5) with respect to the rights of the holders of the Series A
Preferred.

                                      -5-


          (h)  Adjustment for Reclassification, Exchange or Substitution.  If
               ---------------------------------------------------------
the Common Stock issuable upon the conversion of the Series A Preferred shall be
changed into the same or a different number of shares of any class or classes of
stock, whether by capital reorganization, reclassification or otherwise (other
than a subdivision or combination of shares or stock dividend provided for in
Sections A(5)(f) and (g) above, or a reorganization, merger, consolidation or
sale of assets provided for in Section A(5)(i) below) then and in each such
event the holder of each share of Series A Preferred shall have the right
thereafter to convert such share into the kind and amounts of shares of stock
and other securities and property receivable upon such reorganization,
reclassification or other change, by holders of the numbers of shares of Common
Stock into which such shares of Series A Preferred might have been converted
immediately prior to such reorganization, reclassification or change, all
subject to further adjustment as provided in this Section A(5).

          (i)  Reorganization, Mergers, Consolidations or Sales of Assets.  If
               ----------------------------------------------------------
at any time or from time to time after the Original Issue Date there shall be a
capital reorganization of the Common Stock (other than a subdivision,
combination, reclassification or exchange of shares provided for elsewhere in
this Section A(5)) or a merger or consolidation of the Corporation in which the
holders of the Common Stock and Preferred Stock of the Corporation immediately
preceding the merger or consolidation do not own 50% or more of the capital
stock of the entity surviving such merger or consolidation or if such capital
stock is not entitled to elect a majority of the directors of the surviving
entity, or the sale, lease, assignment, license, transfer or other conveyance of
all or substantially all the Corporation's properties and assets to any other
person, and if as a part of such reorganization, merger, consolidation or sale,
the Series A Preferred is not canceled, exchanged, redeemed or otherwise
retired, then provision shall be made so that the holders of the Series A
Preferred shall thereafter be entitled to receive upon conversion of the Series
A Preferred, the number of shares of stock or other securities or property of
the Corporation, or of the successor corporation resulting from such merger or
consolidation or sale, to which a holder of that number of shares of Common
Stock deliverable upon conversion of the Series A Preferred would have been
entitled on such capital reorganization, merger, consolidation or sale.  In any
such case, appropriate adjustment shall be made in the application of the
provisions of this Section A(5) with respect to the rights of the holders of the
Series A Preferred after the reorganization, merger, consolidation or sale to
the end that the provisions of this Section A(5) (including adjustment of the
Conversion Price then in effect and the number of shares purchasable upon
conversion of the Series A Preferred) shall be applicable after that event as
nearly equivalent as may be practicable.  The holders of at least a majority of
the Series A Preferred upon the occurrence of a capital reorganization, merger
or consolidation of the Corporation or the sale of all or substantially all its
assets and properties as such events are more fully set forth in this Section
A(5)(i) shall have the option of electing on behalf of all of the holders of
Series A Preferred treatment of all

                                      -6-


shares of Series A Preferred under either this Section A(5)(i) or Section A(3)
hereof, notice of which election shall be submitted in writing to the
Corporation at its principal office no later than ten days before the effective
date of such event.

          (j)  Sale of Shares Below Conversion Price.
               -------------------------------------

               (1)  If at any time or from time to time after the Original Issue
          Date, the Corporation shall issue or sell Additional Shares of Common
          Stock (as hereinafter defined), other than as a dividend as provided
          in Section A(5)(f) above, and other than upon a subdivision or
          combination of shares of Common Stock as provided in Section A(5) (e)
          above, for a consideration per share less than the then existing
          Conversion Price for the Series A Preferred, then and in each such
          case the then existing Conversion Price for the Series A Preferred
          shall be reduced, as of the opening of business on the date of such
          issue or sale, to a price determined by multiplying such Conversion
          Price by a fraction:

                    (A)  the numerator of which shall be (i) the number of
               shares of Common Stock outstanding immediately prior to such
               issue or sale, plus (ii) the number of shares of Common Stock
               that the aggregate consideration received by the Corporation for
               the total number of Additional Shares of Common Stock so issued
               would purchase at such Conversion Price; and

                    (B)  the denominator of which shall be the number of shares
               of Common Stock outstanding immediately prior to such issue or
               sale plus the number of such Additional Shares of Common Stock so
               issued or sold.

               (2)  For the purpose of making any adjustment in the Conversion
          Price or number of shares of Common Stock purchasable on conversion of
          Series A Preferred as provided above, the consideration received by
          the Corporation for any issue or sale of securities shall:

                    (A)  to the extent it consists of cash, be computed at the
               net amount of cash received by the Corporation after deduction of
               any underwriting or similar commissions, concessions or
               compensation paid or allowed by the Corporation in connection
               with such issue or sale;

                    (B)  to the extent it consists of services or property other
               than cash, be computed at the fair market value of such services
               or property as determined in good faith by the Board; and

                                      -7-


                    (C)  if Additional Shares of Common Stock, Convertible
               Securities (as hereinafter defined), or rights or options to
               purchase either Additional shares of Common Stock or Convertible
               Securities are issued or sold together with other stock or
               securities or other assets of the Corporation for a consideration
               that covers both, be computed as the portion of the consideration
               so received that may be reasonably determined in good faith by
               the Board to be allocable to such Additional Shares of Common
               Stock, Convertible Securities or rights or options.

               (3)  For the purpose of the adjustment provided in Section
          A(5)(j)(1), if at any time or from time to time after the Original
          Issue Date the Corporation shall issue any rights or options for the
          purchase of, or stock or other securities convertible into, Additional
          Shares of Common Stock (such convertible stock or securities being
          hereinafter referred to as "Convertible Securities"), then, in each
          case, if the Effective Price (as hereinafter defined) of such rights,
          options or Convertible Securities shall be less than the then existing
          Conversion Price for the Series A Preferred, the Corporation shall be
          deemed to have issued at the time of the issuance of such rights or
          options or Convertible Securities the maximum number of Additional
          Shares of Common Stock, issuable upon exercise or conversion thereof
          and to have received as consideration for the issuance of such shares
          an amount equal to the total amount of the consideration, if any,
          received by the Corporation for the issuance of such rights or options
          or Convertible Securities, plus, in the case of such options or
          rights, the minimum amounts of consideration, if any, payable to the
          Corporation upon exercise or conversion of such options or rights.
          For purposes of the foregoing, "Effective Price" shall mean the
          quotient determined by dividing the total of all such consideration by
          such maximum number of Additional Shares of Common Stock.  No further
          adjustment of the Conversion Price adjusted upon the issuance of such
          rights, options or Convertible Securities shall be made as a result of
          the actual issuance of Additional Shares of Common Stock on the
          exercise of any such rights or options or the conversion of any such
          Convertible Securities.

               If any such rights or options or the conversion privilege
          represented by any such Convertible Securities shall expire without
          having been exercised, the Conversion Price adjusted upon the issuance
          of such rights, options or Convertible Securities shall be readjusted
          to the Conversion Price that would have been in effect had an
          adjustment been made on the basis that the only Additional Shares of
          Common Stock so issued were the Additional Shares of Common Stock, if
          any, actually issued or sold on the

                                      -8-


          exercise of such rights or options, or rights of conversion of such
          Convertible Securities, and such Additional Shares of Common Stock, if
          any, were issued or sold for the consideration actually received by
          the Corporation upon such exercise, plus the consideration, if any,
          actually received by the Corporation for the granting of all such
          rights and options, whether or not exercised, plus the consideration
          received for issuing or selling the Convertible Securities actually
          converted plus the consideration, if any, actually received by the
          Corporation on the conversion of such, Convertible Securities.

               (4)  For the purpose of the adjustment provided for in Section
          A(5)(j)(1), if at any time or from time to time after the Original
          Issue Date the Corporation shall issue any rights or options for the
          purchase of Convertible Securities, then in each such case, if the
          Effective Price thereof is less than the then existing Conversion
          Price, the Corporation shall be deemed to have issued at the time of
          the issuance of such rights or options the maximum number of
          Additional Shares of Common Stock issuable upon conversion of the
          total amount of Convertible Securities covered by such rights or
          options and to have received as consideration for the issuance of such
          Additional Shares of Common Stock an amount equal to the amount of
          consideration, if any, received by the Corporation for the issuance of
          such rights or options, plus the minimum amounts of consideration, if
          any, payable to the Corporation upon the exercise of such options or
          rights and upon the conversion of such Convertible Securities.  For
          the purposes of the foregoing, "Effective Price" shall mean the
          quotient determined by dividing the total amount of such consideration
          by such maximum number of Additional Shares of Common Stock.  No
          further adjustment of such Conversion Price adjusted upon the issuance
          of such rights or options shall be made as a result of the actual
          issuance of the Convertible Securities upon the exercise of such
          rights or options or upon the actual issuance of Additional Shares of
          Common Stock upon the conversion of such Convertible Securities.

               The provisions of Section A(5)(j)(3) above for the readjustment
          of such Conversion Price upon the expiration of rights or options or
          the rights of conversion of Convertible Securities, shall apply
          mutatis mutandis to the rights, options and Convertible Securities
          ------- --------
          referred to in this Section 13 (5)(j)(4).

          (k)  Definition.  The term "Additional Shares of Common Stock" as used
               ----------
herein shall mean all shares of Common Stock issued or deemed to be issued by
the Corporation after the Original Issue Date, whether or not subsequently
reacquired or

                                      -9-


retired by the Corporation, other than (1) shares of Common Stock issued upon
conversion of the Series A Preferred; (2) up to 6,000,000 shares of Common Stock
(as adjusted for any stock dividend, combination or split with respect to such
shares) issued to employees, officers, directors, consultants or other persons
performing services for the Corporation (if so issued solely because of any such
person's status as an officer, director, employee, consultant or other person
performing services for the Corporation and not as part of any offering of the
Corporation's securities) pursuant to any stock option plan, stock purchase
plan, management incentive plan, consulting agreement or arrangement or other
contract or undertaking approved by the Board; and (3) shares issued in
connection with equipment leasing or loan transactions approved by the Board.

          (l)  Accountants' Certificate of Adjustment.  In each case of an
               --------------------------------------
adjustment or readjustment of the Conversion Price for the number of shares of
Common Stock or other securities issuable upon conversion of the Series A
Preferred, the Corporation, at its expense, shall cause independent certified
public accountants of recognized standing selected by the Corporation (who may
be the independent certified public accountants then auditing the books of the
Corporation) to compute such adjustment or readjustment in accordance herewith
and prepare a certificate showing such adjustment or readjustment, and shall
mail such certificate, by first class mail, postage prepaid, to each registered
holder of the Series A Preferred at the holder's address as shown in the
Corporation's books.  The certificate shall set forth such adjustment or
readjustment, showing in detail the facts upon which such adjustment or
readjustment is based including a statement of (1) the consideration received or
to be received by the Corporation for any Additional Shares of Common Stock
issued or sold or deemed to have been issued or sold, (2) the Conversion Price
at that time in effect for the Series A Preferred, and (3) the number of
Additional Shares of Common Stock and the type and amount, if any, of other
property which at the time would be received upon conversion of the Series A
Preferred.

          (m)  Notices of Record Date.  In the event that the Corporation shall
               ----------------------
propose at any time, or from time to time, to (1) declare any dividend or
distribution upon its Common Stock or Preferred Stock, (2) effect any
reclassification or recapitalization of the Common Stock or Preferred Stock, (3)
merge or consolidate the Corporation with or into any other corporation, (4)
sell, lease, assign, license, transfer or otherwise convey all or substantially
all of the assets of the Corporation, (5) dissolve or wind up the affairs of the
Corporation, or (6) offer for sale to the public any shares of Common Stock, the
Corporation shall mail to each holder of Series A Preferred:

                    (A)  with respect to item (1) above, at least 30 days prior
               written notice of the date on which a record shall be taken for
               such dividend or distribution;

                                      -10-


                    (B)  with respect to items (2), (3), (4) and (5) above, at
               least 30 days prior written notice of the date on which a record
               shall be taken for determining the right to vote on such matter,
               and, in addition, the date on which the proposed transaction will
               be effective and the date on which the holders of shares of
               Common Stock and Preferred Stock shall be entitled to exchange
               their shares for securities or other property deliverable upon
               the occurrence of the proposed transaction; and

                    (C)  with respect to item (6), at least 30 days prior
               written notice of the date on which shares of Common Stock shall
               be offered to the public.

          (n)  Fractional Shares.  No fractional Common Stock shall be issued
               -----------------
upon conversion of Series A Preferred.  In lieu of any fractional shares to
which the holder would otherwise be entitled, the Corporation shall pay cash
equal to the product of such fraction multiplied by the fair market value of one
share of the Corporation's Common Stock on the date of conversion, as determined
in good faith by a unanimous vote of the Board.  Whether or not fractional
shares are issuable upon such conversion shall be determined on the basis of the
total number of shares of Series A Preferred the holder is at the time
converting into Common Stock and the number of shares of Common Stock issuable
upon such conversion.

          (o)  Reservation of Stock Issuable Upon Conversion.  The Corporation
               ---------------------------------------------
shall at all times reserve and keep available out of its authorized but unissued
shares of Common Stock, solely for the purpose of effecting the conversion of
the shares of the Series A Preferred, such number of its shares of Common Stock
as shall from time to time be sufficient to effect the conversion of all
outstanding shares of the Series A Preferred.  As a condition precedent to the
taking of any action which would cause an adjustment to the Conversion Price,
the Corporation will take such corporate action as may, in the opinion of its
counsel, be necessary to increase its authorized but unissued shares of Common
Stock to such number of shares as shall be sufficient to enable it to validly
and legally issue the shares of its Common Stock that are issuable based upon
such adjusted Conversion Price.

          (p)  Notices.  Any notice required by the provisions of this Section
               -------
A(5) to be given to the holder of shares of the Series A Preferred shall be
deemed given when received by such holder after the same has been sent by means
of certified mail, return receipt requested, postage prepaid, by a reputable
overnight courier or messenger for hand delivery and addressed to each holder of
record at his address appearing on the books of the Corporation.

                                      -11-


          (q)  Payment of Taxes.  The Corporation shall pay all taxes and other
               ----------------
governmental charges (other than taxes measured by the revenue or income of the
holders of the Series A Preferred) that may be imposed in respect of the issue
or delivery of shares of Common Stock upon conversion of the shares of the
Series A Preferred.

          (r)  No Dilution or Impairment.  The Corporation shall not amend this
               -------------------------
Certificate of Designation or participate in any reorganization,
recapitalization, transfer of assets, consolidation, merger, dissolution, issue
or sale of securities or any other voluntary action for the purpose of avoiding
or seeking to avoid the observance or performance of any of the terms to be
observed or performed under this Section A(5) by the Corporation, but will at
all times in good faith assist in carrying out all such action as may be
reasonably necessary or appropriate in order to protect the conversion rights of
the holders of the Series A Preferred against dilution or other impairment.

     6.   Restrictions and Limitations.
          ----------------------------

          (a)  So long as 1,750,000 shares of Preferred Stock remain
outstanding, the Corporation shall not, and shall not permit any corporation at
least 50% of whose outstanding voting stock shall at that time be owned directly
or indirectly by the Corporation (a "Subsidiary") to, without the vote or
written consent of the holders of a majority of the then outstanding shares of
Preferred Stock:

               (1)  effect any sale, lease, assignment, license, transfer or
          other conveyance of all or substantially all the assets of the
          Corporation or any of its Subsidiaries, or any consolidation or merger
          involving the Corporation or any of its Subsidiaries;

               (2)  effect any liquidation, dissolution or winding up of the
          affairs of the Corporation or any of its Subsidiaries, whether
          voluntary or involuntary, or file any voluntary petition in
          bankruptcy, or file any answer or other pleading seeking any
          reorganization, arrangement, composition, readjustment, liquidation or
          similar relief under any federal or state law relative to bankruptcy,
          insolvency or other relief of debtors, or seek, consent to or
          acquiesce in the appointment of any trustee, receiver, conservator or
          liquidator for any assets of the Corporation or any of its
          Subsidiaries, or any

                                      -12-


          reorganization or reclassification of any capital stock of the
          Corporation or any of its Subsidiaries; or

               (3)  amend the Restated Certificate of Incorporation or Bylaws of
          the Corporation.

     7.   No Reissuance of Preferred Stock.
          --------------------------------

     No share or shares of Series A Preferred acquired by the Corporation by
reason of redemption, purchase, conversion or otherwise shall be reissued, and
all such shares shall be canceled, retired and eliminated from the shares which
the Corporation shall be authorized to issue."

     SECOND:  That said amendment was duly adopted in accordance with the
     ------
provisions of Section 242 of the Delaware General Corporations Law.

     IN WITNESS WHEREOF, Maxygen, Inc. has caused this Amended Certificate of
Designations to be signed this 14th day of June, 1999.

                                   MAXYGEN, INC.



                                   By:  /s/ Julian N. Stern
                                      ------------------------------------
                                            Julian N. Stern, Secretary

                                      -13-