Technology Transfer Agreement - Affymax Technologies NV, Glaxo Group Ltd. and Maxygen Inc.


                 Affymax/Maxygen Technology Transfer Agreement
                  By and among Affymax Technologies N.V. and
      Glaxo Group Limited (collectively 'the Glaxo Wellcome Companies'),
                               and Maxygen, Inc.

1.0  INTRODUCTION

     1.1  The parties to this Agreement are:

           Affymax Technologies N.V.                      
           Glaxo Wellcome House, Berkeley Avenue          
           Greenford, Middlesex, United Kingdom UB6 ONN;  
           (hereinafter referred to as 'ATNV')            
           Glaxo Group Limited                            
                                                          
           Glaxo Wellcome House                           
           Berkeley House                                 
           Greenford, Middlesex, United Kingdom UA ONN;   
           (hereinafter referred to as 'GGL')             
                                                          
           collectively 'the Glaxo Wellcome Companies' and
                                                          
           Maxygen, Inc.                                  
           4001 Miranda Avenue                            
           Palo Alto, California 94304;                   
           (hereinafter referred to as 'Maxygen')          

     1.2  The effective date of this Agreement is February 1, 1997.

2.0  RECITALS

     The Glaxo Wellcome Companies and Maxygen have entered into a Registration
Rights Agreement, a Securities Purchase Agreement, and a Stockholder's Agreement
of even date (collectively, the 'Stock Agreements') which call for the issuance
of a total of 5,460,000 shares of Maxygen Common Stock to one or more of the
Glaxo Wellcome Companies at the closing of the transaction in exchange for the
assignment of or license to certain intellectual property from the Glaxo
Wellcome Companies to Maxygen. Maxygen acknowledges that the Glaxo Wellcome
Companies would not enter into this Agreement but for the Stock Agreements. This
Agreement is contingent upon closing of the Stock Agreements and shall become
effective only upon the closing of the last of the Stock Agreements.

________________
    
*    CERTAIN INFORMATION WITHIN THIS EXHIBIT HAS BEEN OMITTED AND THE NON-PUBLIC
     INFORMATION HAS BEEN FILED SEPARATELY WITH THE SEC. CONFIDENTIAL TREATMENT
     HAS BEEN REQUESTED WITH RESPECT TO THE OMITTED PORTIONS.    

 
     NOW, THEREFORE, in consideration of the premises, covenants, conditions and
Attachments set forth herein, the parties agree as follows:

3.0  ATTACHMENTS

     Schedules A and B are attached and form part of this Agreement.

4.0  DEFINITIONS

     4.1  'Affiliate' means any entity that directly or indirectly controls, is
controlled by or is under common control with a party to this Agreement. A
corporation or non-corporate business entity shall be regarded as in control of
another corporation if it owns or directly or indirectly controls at least sixty
percent (60%) of the voting stock of the other company, or (a) in the absence of
the ownership of at least sixty percent (60%) of the voting stock of a
corporation or (b) in the case of a non-corporate business entity, if it
possesses, directly or indirectly, the power to direct or cause the direction of
the management and policies of such corporation or non-corporate business
entity, as applicable.

Affiliates shall be entitled to exercise all rights of their respective party
under this Agreement provided that they agree in writing to be bound by the
corresponding obligations hereunder.

     4.2  'Agreement' means this Agreement, fully executed by the parties, to
include without limitation, all Attachments hereto.

     4.3  'Associated Technology' means a body of Confidential Information that
includes trade secrets, know-how, copyrights, and other technical information
reasonably related to the Patents and Applications set forth in Schedules A and
B, whether such information was developed by the named inventors or others.

     4.4  'Confidential Information' means that information which the Glaxo
Wellcome Companies and/or Maxygen desire to protect against unauthorized
disclosure or use and which the disclosing party designates as confidential (i)
in writing, or (ii) orally, prior to any oral disclosure of the Confidential
Information, and is reduced to tangible form and provided to the receiving party
pursuant to this Agreement. Confidential Information may include information of
third parties.

     4.5  'Derogatable Improvement' shall mean any modification of the
Derogatable Technology that is invented or developed by Maxygen prior to the
earlier of (i) five years from the closing of this transaction or (ii) upon the
closing of an underwritten public offering of shares of Maxygen under which not
less than $10 million in gross proceeds is provided to the Company and described
in a U.S. or foreign patent or patent application, provided that such
modification, if unlicensed, would infringe one or more of the claims of the
Licensed Patents and Applications.

 
     4.6  'Derogatable Technology' shall include all compositions, reagents, and
methods described in the Licensed Patents and Applications, excluding only
Licensed Technology and Designated Technology. Notwithstanding the foregoing,
'Derogatable Technology' shall not include any Derogated Technology. Derogatable
Technology includes, but is not limited to:

     (1)  gene therapy, including the optimization of vectors, such as HSV,
          HIV, retroviral, adenoviral, and adeno-associated vectors naked DNA
          vectors, and protein-coated vectors; and transgenes;    

     (2)  vaccines, including live, dead, and attenuated bacterial vaccines;
          live, dead, attenuated, subunit, and recombinant protein and peptide
          viral vaccines; DNA vaccines; and diverse vectors;    

     (3)  cell therapy, including cells expressing therapeutic transgenes, 
          protein, pharmaceuticals, and hormones;     

     (4)  protein pharmaceuticals, including enzymes, cytokines, growth 
          factors, hormones, novel agonists and novel antagonists; and     

     (5)  antibody pharmaceuticals, including whole IgGs and IgMs, Fabs, and 
          Fvs.     

     4.7  'Derogated Technology' shall mean any Derogatable Technology
specifically encompassed within a collaborative research project that Maxygen
has proposed to the Glaxo Wellcome Companies and upon which the Glaxo Wellcome
Companies has declined to pursue a collaborative research project with Maxygen
or upon which the parties have failed to negotiate a mutually satisfactory
agreement within the stipulated time period, provided, that Maxygen has entered
into a research collaboration with a third party on such Derogated Technology on
terms involving comparable scope and financial parameters as those proposed to
the Glaxo Wellcome Companies within twelve (12) months of Glaxo Wellcome
declining to participate in the project. 'Derogated Technology' shall also refer
to any Derogatable Technology specifically encompassed within a collaborative
research project between Maxygen and a third party, wherein the third party
initially proposed, in confidence, the collaboration to Maxygen.
    
     4.8 'Designated Technology' shall refer to the process of Shuffling as
practiced with mammalian or other eukaryotic cells using the compositions,
reagents, and methods described in the Licensed Patents and Applications in the
field of human pharmaceuticals; provided, however, that the proteins, RNAs, or
DNAs generated from such a process can be further manipulated, screened,
selected, or used in other hosts. Designated Technology shall include     

     (1)  the Shuffling of proteins for development of assays for drug discovery
          and optimization, such as proteins that can be used generically in
          various assay formats as well as proteins for use in specific assays
          with specific classes of targets, including modified ligands, modified
          receptors, and modified proteins in signal transduction; and      

     (2)  the Shuffling of proteins for validation of drug discovery targets,
          such as antibodies, proteins that interfere with a pathway or process,
          and other binding proteins.    

Designated Technology shall not include:

     (1)  the Shuffling of proteins, peptides, DNAs, and RNAs to be used as 
          human pharmaceuticals;     

 
     (2)  generic assay technology for screening and selection; as well as
          product-specific assay technology for screening and selection; and
              

     (3)  the Shuffling of viral sequences or mammalian plasmids or sequences 
          used for gene therapy or vaccines, or fragments or precursors thereof.
               

     4.9  'Dulbecco Patent' shall mean U.S. Patent No. 4,593,002.
    
     4.10 'Internal Research Purposes' shall mean that the Licensed Technology
and Licensed Improvements will not be used in specific research that is directly
subject to consulting or licensing obligations to a non-profit institution
(other than the United States Government) or to another for profit institution,
corporation or business entity unless written permission is obtained from the
owner of such Licensed Technology or Licensed Improvement, provided, however,
that the parties shall be free to use the Licensed Technology and Licensed
Improvements in furtherance of their own [*******] and the commercial marketing
of their products.     
    
     4.11 'Licensed Improvements' shall mean any modification of the Licensed
Technology related to the processes of generating molecular diversity within,
on, or secreted from [*******], provided (1) that such modification is invented
or developed by Maxygen or the Glaxo Wellcome Companies prior to the earlier of
(i) five years from the closing of this transaction or (ii) upon the closing of
an underwritten public offering of shares of Maxygen under which not less than
$10 million in gross proceeds is provided to the Company and described in a U.S.
or foreign patent or patent application and (2) that such modification, if
unlicensed, would infringe one or more of the claims of the Licensed Patents and
Applications.     

     4.12 'Licensed Technology' shall refer to the process of Shuffling of
proteins, RNAs, or DNAs as practiced in [*******] using the compositions,
reagents, and methods described in the Licensed Patents and Applications in the
field of [*******]; provided, however, that the proteins, RNAs, or DNAs
generated from such a process can be further manipulated, screened, selected, or
used in other hosts.

Licensed Technology includes but is not limited to:
    
     (1)  the Shuffling of proteins for [*******];     
         
     (2)  the Shuffling of proteins for [*******];     
    
     (3)  the Shuffling of [*******];      
    
     (4)  the Shuffling of proteins, RNAs, or DNAs [*******] and the subsequent
          screening and selection of the modified RNAs or DNAs in other cells
          for [*******] purposes; and     


 
     (5)  the Shuffling of proteins, DNAs, and RNAs for Internal Research
          Purposes only.

     Licensed Technology shall not include:
          
     (1)  the Shuffling of proteins, peptides, DNAs, and RNAs to be used as
         [*******];     
        
     (2)  generic assay technology for [*******], as well as product-specific
          assay technology for [*******]; and     
        
     (3)  the Shuffling of proteins, RNAs, or DNAs [*******] using the
          compositions, reagents, and methods described in the Licensed Patents
          and Applications.    

     4.13 Licensed Patents and Applications' are as defined in Schedule A.

     4.14 'Patent,' 'Patents,' 'Patent Applications' or 'Patents and
Applications' refer to issued U.S. Patents, pending and abandoned U.S. patent
applications, to any division, renewal, continuation in whole or in part,
substitution, conversions, reissue, prolongation or extension thereof, to all
foreign counterparts (including patent, utility model, and industrial designs),
and to any Letters Patent and Registrations which may hereafter be granted on
any of the foregoing in the United States and all countries throughout the
world.

     4.15 'Peptides-on-Plasmids Display Patents and Applications' refer to the
Patents and Applications set forth in the attached Schedule B.

     4.16 'Phage Display Patents and Applications' refer to the Patents and
Applications set forth in the attached Schedule B.

     4.17 'Polysome Display Patents and Applications' refer to the Patents and
Applications set forth in the attached Schedule B.

     4.18 'Receptor Immobilization Patent Application' refer to the Patents and
Applications set forth in the attached Schedule B.

     4.19 'Shuffling' shall mean the totality of the reiterative process of gene
fragmentation; reassembly; amplification, if necessary; transformation; and
screening or selection described in the Licensed Patents and Applications.

5.0  TRANSFERS

     5.1  ASSIGNMENT OF PATENTS AND ASSOCIATED TECHNOLOGY

 
          5.1.1  For good and valuable consideration, receipt of which is
acknowledged by the Glaxo Wellcome Companies, the Glaxo Wellcome Companies agree
to assign and hereby assign to Maxygen all right, title, and interest in and to
the Licensed Patents and Applications, including the right to claim the priority
from the Patents and Applications as provided by the Paris Convention, and to
the Associated Technology, subject to any outstanding licenses or other rights
provided to Affymetrix under the Affymax/Affymetrix Technology Transfer
Agreement by and among Affymax N.V., Affymax Technologies, N.V., Affymax
Research Institute, Glaxo Group Limited, and Affymetrix, Inc., effective date,
March 2, 1995 ('the Affymetrix Agreement'). The right, title and interest in and
to these Patents and Applications is to be held and enjoyed by Maxygen and
Maxygen's successors and assigns as fully and exclusively as it would have been
held and enjoyed by the Glaxo Wellcome Companies had this assignment not been
made, for the full term of any Letters Patent and Registrations which may be
granted thereon.

     5.2  LICENSE OF PATENTS

          5.2.1  The Glaxo Wellcome Companies hereby grant Maxygen, a perpetual,
worldwide, royalty-free, non-exclusive license without the right to sublicense,
to Peptides-on-Plasmids Display Patents and Applications, Polysome Display
Patents and Applications, Phage Display Patents and Applications, the Dulbecco
Patent, and Receptor Immobilization Patent Application. Maxygen agrees that use
of these patents and applications shall be restricted to [*******].

     5.3  LICENSED TECHNOLOGY AND LICENSED IMPROVEMENTS

          5.3.1  Grant to the Glaxo Wellcome Companies

                 5.3.1.1 Maxygen hereby grants and agrees to grant the Glaxo
Wellcome Companies a perpetual, worldwide, royalty-free, non-exclusive license,
with the right to sublicense Affiliates only, under the Licensed Patents and
Applications and Associated Technology to make, have made and use Licensed
Technology for Internal Research Purposes only.

                 5.3.1.2 Maxygen hereby grants and agrees to grant the Glaxo
Wellcome Companies a perpetual, worldwide, royalty-free, non-exclusive license,
with the right to sublicense Affiliates only, to make, have made, and use
Licensed Improvements for Internal Research Purposes only.

                 5.3.1.3 Notwithstanding the foregoing, if any Licensed
Improvement is derived from a collaboration between Maxygen and an independent
third party, whereby Maxygen does not have the right to license such Licensed
Improvement outside 

 
of the collaboration, then Maxygen shall have no obligation to license or
otherwise make available such Improvement to the Glaxo Wellcome Companies.
   
                 5.3.1.4 Maxygen hereby grants and agrees to grant the Glaxo
Wellcome Companies a perpetual, worldwide, royalty-free, non-exclusive license,
with the right to sublicense Affiliates only, under the Licensed Patents and
Applications, to make, have made, and use the [*******] for Internal Research
Purposes only.    

                 5.3.1.5 Upon the request of the Glaxo Wellcome Companies,
Maxygen shall grant a license to an Affiliate of the Glaxo Wellcome Companies
upon the terms set forth herein provided that the Glaxo Wellcome Companies shall
guarantee the performance of such licensee.

     
          5.4.1  Grant to Maxygen

                 5.4.1.1 The Glaxo Wellcome Companies hereby grant and agree to
grant the Maxygen a perpetual, worldwide, royalty-free, non-exclusive license,
without the right to sublicense, to make, have made and use Licensed
Improvements for Internal Research Purposes only.

                 5.4.1.2 Notwithstanding the foregoing, if any Licensed
Improvement is derived from a collaboration between any of the Glaxo Wellcome
Companies and an independent third party, whereby such Glaxo Wellcome Company
does not have the right to license such Licensed Improvement outside of the
collaboration, then the Glaxo Wellcome Companies shall have no obligation to
license or otherwise make available such Improvement to Maxygen.

     5.5  RIGHT OF FIRST NEGOTIATION FOR LICENSED TECHNOLOGY AND LICENSED
IMPROVEMENTS
   
          5.5.1 Maxygen grants and agrees to grant the Glaxo Wellcome Companies
a right of first negotiation for any collaborative project to develop Licensed
Technology and Licensed Improvements in the field of human pharmaceuticals.
Notwithstanding the foregoing, this right of first negotiation shall not extend
to collaborative projects proposed by third parties in confidence to Maxygen.
This right will terminate upon the earlier of five years from the closing of the
transaction or upon an underwritten public offering of shares of Maxygen under
which not less than $10 million in gross proceeds is provided to the Company.
This proposal for a collaborative research project shall include, at a minimum,
a description of the scope of the research, the financial parameters of the
project, and the required nonfinancial contributions of the collaborator.    

 
    
          5.5.2  If the Glaxo Wellcome Companies wish to pursue such a
collaborative project with Maxygen, then the Glaxo Wellcome Companies and
Maxygen agree that the parties will diligently and in good faith, negotiate the
terms and conditions of a collaborative research agreement and shall make a good
faith effort to conclude such license agreement within five months of
receipt of the Maxygen proposal by the Glaxo Wellcome Companies. If the Glaxo
Wellcome Companies decide not to pursue such a collaborative project, then they
shall promptly inform Maxygen of such a decision.    
   
          5.5.3  In the event that the Glaxo, Wellcome Companies decide not to
pursue a proposal of Maxygen as contemplated above or that the parties are
unable to negotiate a mutually satisfactory agreement within five months of
receipt of the Maxygen proposal by the Glaxo Wellcome Companies, Maxygen shall
be free to seek a third party sponsor of the project. If Maxygen enters into a
research collaboration with a third party on terms involving, comparable scope
and financial parameters as those proposed to the Glaxo Wellcome Companies
within twelve months of the Glaxo Wellcome Companies declining to participate
in the project or the failure of the parties to negotiate a mutually
satisfactory agreement within the stipulated time period, then the Glaxo
Wellcome Companies right to first negotiation for a collaborative project to
develop the Licensed Technology and Licensed Improvements specifically
encompassed within such proposal shall terminate.    
   
          5.5.4 If, however, Maxygen has not entered into a third party
collaboration on such project within twelve months of the Glaxo Wellcome
Companies declining to participate in the project or the failure of the parties
to negotiate a mutually satisfactory agreement within the stipulated time
period, then the Glaxo Wellcome Companies shall again have a right of first
negotiation for any collaborative project to develop the Licensed Technology and
Licensed Improvements encompassed within such proposal and Maxygen shall be
obligated to present any collaborative project to develop such Licensed
Technology and Licensed Improvements in the field of human pharmaceuticals to
the Glaxo Wellcome Companies prior to seeking a third party partner.    
   
          5.5.5 Notwithstanding the foregoing, in the event that Maxygen enters
into a research collaboration with a third party to Licensed Technology and
Licensed Improvements in the field of human pharmaceuticals, wherein the third
party initially proposed, in confidence, the collaboration to Maxygen, then the
Glaxo Wellcome Companies agree that the Glaxo Wellcome Companies right to first
negotiation for a collaborative project to develop the Licensed Technology and
Licensed Improvements specifically encompassed within such collaboration shall
terminate.    

     5.6  RIGHT OF FIRST NEGOTIATION FOR DESIGNATED TECHNOLOGY
   
          5.6.1 Maxygen will grant the Glaxo Wellcome Companies a right of first
negotiation for any collaborative project to develop Designated Technology in
the field of human pharmaceuticals. Notwithstanding the foregoing, this right of
first negotiation    

 
shall not extend to collaborative projects proposed by third parties in
confidence to Maxygen. This right will terminate upon the earlier of five years
from the closing of the transaction or upon an underwritten public offering of
shares of Maxygen under which not less than $10 million in gross proceeds is
provided to the Company. This proposal for a collaborative research project
shall include, at a minimum, a description of the scope of the research, the
financial parameters of the project, and the required non-financial
contributions of the collaborator.
    
          5.6.2  If the Glaxo Wellcome Companies wish to pursue such a
collaborative project with Maxygen, then the Glaxo Wellcome Companies and
Maxygen agree that the parties will diligently and in good faith, negotiate the
terms and conditions of a collaborative research agreement and shall make a good
faith effort to conclude such license agreement within five months of
receipt of the Maxygen proposal by the Glaxo Wellcome Companies. If the Glaxo
Wellcome Companies decide not to pursue such a collaborative project, then they
shall promptly inform Maxygen of such a decision.     
   
          5.6.3  In the event that the Glaxo Wellcome Companies decide not to
pursue a proposal of Maxygen as contemplated above or that the parties are
unable to negotiate a mutually satisfactory agreement within five months of
receipt of the Maxygen proposal by the Glaxo Wellcome Companies, Maxygen shall
be free to seek a third party sponsor of the project. If Maxygen enters into a
research collaboration with a third party on terms involving comparable scope
and financial parameters as those proposed to the Glaxo Wellcome Companies
within twelve months of the Glaxo Wellcome Companies declining to participate in
the project or the failure of the parties to negotiate a mutually satisfactory
agreement within the stipulated time period, then the Glaxo Wellcome Companies
right to first negotiation for a collaborative project to develop the Designated
Technology specifically encompassed within such proposal shall terminate.    
   
          5.6.4 If, however, Maxygen has not entered into a third party
collaboration on such project within twelve months of the Glaxo Wellcome
Companies declining to participate in the project or the failure of the parties
to negotiate a mutually satisfactory agreement within the stipulated time
period, then the Glaxo Wellcome Companies shall again have a right of first
negotiation for any collaborative project to develop the Designated Technology
encompassed within such proposal and Maxygen shall be obligated to present any
collaborative project to develop such Designated Technology in the field of
human pharmaceuticals to the Glaxo Wellcome Companies prior to seeking a third
party partner.    
   
          5.6.5 Notwithstanding the foregoing, in the event that Maxygen enters
into a research collaboration with a third party to Designated Technology in the
field of human pharmaceuticals wherein the third party initially proposed, in
confidence, the collaboration to Maxygen, then the Glaxo Wellcome Companies
agree that the Glaxo Wellcome Companies right to first negotiation for a
collaborative project to develop the     

 
Designated Technology specifically encompassed within such collaboration shall
terminate.

     5.7  RIGHT OF FIRST NEGOTIATION FOR DEROGATABLE TECHNOLOGY AND DEROGATABLE
          IMPROVEMENTS
   
          5.7.1 Maxygen will grant the Glaxo Wellcome Companies a right of first
negotiation for any collaborative project to develop Derogatable Technology or
Derogatable Improvements in the field of human pharmaceuticals. Notwithstanding
the foregoing, this right of first negotiation shall not extend to collaborative
projects proposed by third parties in confidence to Maxygen. This right will
terminate upon the earlier of five years from the closing of the transaction or
upon an underwritten public offering of shares of Maxygen under which not less
than $10 million in gross proceeds is provided to the Company. This proposal for
a collaborative research project shall include, at a minimum, a description of
the scope of the research, the financial parameters of the project, and the
required nonfinancial contributions of the collaborator.    
   
          5.7.2  If the Glaxo Wellcome Companies wish to pursue such a
collaborative project with Maxygen, then the Glaxo Wellcome Companies and
Maxygen agree that the parties will diligently and in good faith, negotiate the
terms and conditions of a collaborative research agreement and shall make a good
faith effort to conclude such license agreement within five months of receipt of
the Maxygen proposal by the Glaxo Wellcome Companies. If the Glaxo Wellcome
Companies decide not to pursue such a collaborative project, then they shall
promptly inform Maxygen of such a decision.    
   
          5.7.3  In the event that the Glaxo Wellcome Companies decide not to
pursue a proposal of Maxygen as contemplated above or that the parties are
unable to negotiate a mutually satisfactory agreement within five months of
receipt of the Maxygen proposal by the Glaxo Wellcome Companies, then Maxygen
shall be free to seek a third party sponsor of the project. If Maxygen enters
into a research collaboration with a third party on terms involving comparable
scope and financial parameters as those proposed to the Glaxo Wellcome Companies
within twelve months of the Glaxo Wellcome Companies declining to participate in
the project or the failure of the parties to negotiate a mutually satisfactory
agreement within the stipulated time period, then the Glaxo Wellcome Companies
right to first negotiation for a collaborative project to develop the
Derogatable Technology or Derogatable Improvements specifically encompassed
within such proposal shall terminate and the Derogatable Technology and
Derogatable Improvements specifically encompassed within such proposal shall be
deemed Derogated Technology and Derogated Improvements, respectively.    
   
          5.7.4  If, however, Maxygen has not entered into a third party
collaboration on such project within twelve months of the Glaxo Wellcome
Companies declining to participate in the project or the failure of the parties
to negotiate a mutually satisfactory agreement within the stipulated time
period, then such Derogated Technology or     

 
   
Derogated Improvements shall again be deemed Derogatable Technology or
Derogatable Improvements, respectively, and the Glaxo Wellcome Companies shall
again have a right of first negotiation as set forth above to such Derogatable
Technology and to such Derogatable Improvements and Maxygen shall be obligated
to present any collaborative project to develop such Derogatable Technology and
Derogatable Improvements in the field of human pharmaceuticals to the Glaxo
Wellcome Companies prior to seeking a third party for a collaborative partner
based on such Derogatable Technology and Derogatable Improvements in the field
of human pharmaceuticals.    
   
          5.7.5 Notwithstanding the foregoing, in the event that Maxygen enters
into a research collaboration with a third party to develop Derogatable
Technology or Derogatable Improvements in the field of human pharmaceuticals,
wherein the third party initially proposed, in confidence, the collaboration to
Maxygen, then the Glaxo Wellcome Companies agree that the Glaxo Wellcome
Companies right to first negotiation for a collaborative project to develop the
Derogatable Technology or Derogatable Improvements specifically encompassed
within such collaboration shall terminate and the Derogatable Technology and
Derogatable Improvements specifically encompassed within such collaboration
shall be deemed Derogated Technology and Derogated Improvements,
respectively.    

          5.7.6  The Glaxo Wellcome Companies shall have no rights to the
Derogatable Technology and Derogatable Improvements except as otherwise provided
in this section.

     5.8  ASSOCIATED TECHNOLOGY

     Each party agrees that the other party shall not be prevented from using
any Associated Technology of one party which Associated Technology was
rightfully acquired by the other party under this Technology Transfer Agreement,
provided that such use does not (1) result in improper disclosure or misuse of
Confidential Information or (2) make use of rights to Patents and Applications
which rights are not expressly provided by this Agreement. Each party further
agrees to maintain such Associated Technology as Confidential Information with
the same degree of care that it exercises with respect to its own information of
like import, but in no event less than reasonable care.


     5.9  TRADEMARKS

          5.9.1  For good and valuable consideration, receipt of which is hereby
acknowledged by the Glaxo Wellcome Companies, the Glaxo Wellcome Companies
hereby assigns to Maxygen all right, title, and interest to the marks MAXYGEN,
SHUFFLING, MOLECULAR BREEDING, and SEXUAL PCR, including all goodwill associated
therewith. Maxygen shall be responsible for any and all future expenses
associated with registration and/or prosecution of these marks. The rights of

 
Maxygen at common law and/or to the end of the term or terms of which
registration of the mark may be granted or renewed are to be enjoyed by Maxygen
for Maxygen's own use and enjoyment, and for the use and enjoyment of its
successors, assigns and other legal representatives, as fully and entirely as
the same would have been held and enjoyed by the Glaxo Wellcome Companies if
this assignment and sale had not been made; including all claims for royalties
for licensing of the marks provided in this section and damages by reason of
past infringement(s) of these marks, with the right to sue for and collect the
same for its own use and benefit, for the use, benefit and on behalf of its
successors, assigns and other legal representatives.

     5.10 Except as expressly provided herein, the licensing, assignment or
other conveyance of rights under this Agreement shall not be construed as
conferring any rights, license or title, express or implied, in or to any
Patents and Applications or Associated Technology.

6.0  TERM AND TERMINATION

     6.1  Term. The term of this Agreement shall commence on the Effective Date
and shall continue in force until terminated upon the expiration of the 
last-to-expire of the Licensed Patents and Applications unless terminated
earlier as set forth below.

     6.2  Termination for Material Breach. If either party fails to comply with
any of the material terms and conditions of this Agreement, the other party may
terminate this Agreement upon sixty (60) days' written notice to the defaulting
party specifying any such breach unless within the period of such notice, all
breaches specified therein shall have been remedied, or unless the breach is one
which, by its nature, cannot be fully remedied in sixty (60) days, but the
breaching party has undertaken reasonable, good faith efforts toward remedying
the breach within such sixty (60) days, and continues to use reasonable, good
faith, and diligent efforts to promptly remedy the breach.

          A material breach includes but is not limited to either party's
failure to comply with the provisions prohibiting disclosure or unauthorized use
of Confidential Information.

     6.3  Effect of Termination. Upon termination of the Agreement, as provided
in Section 6.2, all licenses granted by the nonbreaching party to the other
party under this Agreement shall terminate and all other rights granted by the
nonbreaching party to the other party shall revest in the nonbreaching party.

     6.4  Survival. The provisions of the following sections and paragraphs
shall survive expiration or termination of this Agreement: Section 4.0
('Definitions'); Paragraph 10.8 ('Notices'); Paragraph 6.3 ('Effect of
Termination'); Section 7.0 ('Confidential Information'); Section 8.0
('Warranties and Disclaimer of Warranties'); and Section 9.0 ('Limitations of
Liability').

 
7.0  CONFIDENTIAL INFORMATION

     7.1  Restrictions. Each party will hold in confidence any Confidential
Information received by it from the other and will protect the confidentiality
of such with the same degree of care that it exercises with respect to its own
information of like import, but in no event less than reasonable care.

     7.2  Exceptions. Notwithstanding any provisions herein concerning 
non-disclosure and non-use of the Confidential Information, the obligations of
the above Paragraph will not apply to any portion of the Confidential
Information which:

            (a) is now or which hereafter through no act or failure to act on
the part of the receiving party becomes generally known without restriction on
disclosure;

            (b) is hereafter furnished to the receiving party by a third party
as matter of right without restriction on disclosure;

            (c) is independently developed by the receiving party without the
use of the Confidential Information;

            (d) is disclosed to others by the party owning the Confidential
Information without restriction.

            (e) is required to be disclosed by the receiving party pursuant to a
legal, judicial, or administrative procedure, or is otherwise required by law;
providing the party required to disclose the Confidential Information gives the
party owning the Confidential Information notice of the proposed disclosure with
sufficient time to seek relief and that such disclosure, if made, is made in a
fashion as to maximize the protection of the information from further
disclosure;

            (f) is already known to the receiving party without restriction on
disclosure; or

            (g) is approved for release or use without restriction by written
authorization of an officer of the party owning the Confidential Information.

     7.3  Advising Employees and Suspected Violations. Each party will inform
its employees having access to the Confidential Information of such party's
limitations, duties, and obligations regarding non-disclosure and copying of the
Confidential Information and will obtain their agreement, whether by means of
existing or new agreements, to comply with those limitations, duties, and
obligations. Each party will provide notice to the other party immediately after
learning of, or having reason to suspect, a breach of any of the confidential
restrictions set forth in this section.

 
     7.4  Independent Development. Each party understands that the other party
may develop information internally, or receive information from third parties,
that may be similar to Confidential Information. Accordingly, nothing in this
Agreement will be construed as a representation or inference that each party
will not develop or acquire products, for itself or others, that compete with
the products, systems, or methods contemplated by the other party's Confidential
Information, provided that the party has not done so in breach of this
Agreement.

8.0  WARRANTIES AND DISCLAIMER OF WARRANTY

     8.1  Right to Enter into Agreement. The parties warrant that they have the
right and power to enter into this Agreement and to convey the rights granted
herein.

     8.2  DISCLAIMER OF WARRANTY. EXCEPT AS PROVIDED IN THIS SECTION, NEITHER
PARTY MAKES ANY EXPRESS OR IMPLIED WARRANTIES. WARRANTIES DISCLAIMED INCLUDE,
BUT ARE NOT LIMITED TO, THE WARRANTIES OF DESIGN, MERCHANTABILITY, OR FITNESS
FOR A PARTICULAR PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE, OR TRADE
PRACTICE. NO REPRESENTATION OR STATEMENT NOT EXPRESSLY CONTAINED IN THIS
AGREEMENT WILL BE BINDING UPON EITHER PARTY AS A WARRANTY OR OTHERWISE.

     8.3  Nothing in this Agreement shall be construed as:

           (i)   a warranty or representation by either Party as to the
validity or scope of any Licensed Patent; or

           (ii)  a warranty or representation that anything made, use, sold or
otherwise disposed of under any license granted in this Agreement is or will be
free from infringement of patents of third parties; or

           (iii) a requirement that either Party shall file any patent
application, secure any patent, or maintain any patent in force; or

           (iv)  an obligation to bring or prosecute actions or suits against
third parties for infringement; or

           (v)   an obligation to furnish any manufacturing or technical
information or training; or

           (vi)  conferring a right to use in advertising, publicity, or
otherwise any trademark or tradename of either Party

 
9.0  LIMITATIONS OF LIABILITY

     9.1  IN NO EVENT WILL EITHER PARTY BE LIABLE TO THE OTHER FOR ANY LOST
REVENUES OR PROFITS OR OTHER INCIDENTAL, SPECIAL, INDIRECT, OR CONSEQUENTIAL
DAMAGES ARISING OUT OF THIS AGREEMENT, EVEN IF THAT PARTY HAS BEEN ADVISED OF
THE POSSIBILITY OF SUCH DAMAGES.

10.0 MISCELLANEOUS

     10.1 Force Majeure. Neither party will be deemed in default of this
Agreement to the extent that performance of its obligations or attempts to cure
any breach are delayed or prevented by reason of any act of god, fire, natural
disaster, accident, act of government, or any other cause beyond the control of
such party ('Force Majeure'), provided that such party gives the other party
written notice thereof, and uses good faith efforts to so perform or cure. In
the event of such a Force Majeure, the time for performance or cure will be
extended for a period equal to the Force Majeure, but in no event more than six
(6) months.

     10.2 Governing Law. This Agreement is deemed entered into in the state of
California and will be governed and construed in all respects according to the
laws of California as such laws are applied to agreements between California
residents entered into and entirely performed within California (except that
body of law controlling conflict of laws). Any litigation or other dispute
resolution between the parties, relating to this Agreement will take place in
Santa Clara County, California. By executing this Agreement, the parties consent
to personal jurisdiction of, and venue within the state and federal courts
within that country.

     10.3 Arbitration of Disputes. Any controversy or claim arising out of or
relating to this Agreement, or the breach thereof, will be settled by
arbitration before a single arbitrator, and judgment upon the award rendered by
the arbitrator may be entered in any court having jurisdiction thereof. The
arbitration will take place in Palo Alto, California. The arbitration will be
conducted in the English language, and each party will bear its own expenses and
attorneys fees connected with the arbitration regardless of the outcome.

          If the parties cannot agree on a single arbitrator, each party will
appoint an arbitrator, and the two appointed arbitrators will appoint a third
neutral arbitrator, whereupon the arbitration will take place before the three
arbitrators, so appointed.

     10.4 Severability. If any provision of this Agreement, or the application
thereof, will for any reason and to any extent be determined by a court of
competent jurisdiction to be invalid or unenforceable under applicable law, the
remaining provisions of this Agreement will be interpreted so as best to
reasonably effect the intent of the parties. The

 
parties further agree to replace any such invalid or unenforceable provisions
with valid and enforceable provisions designed to achieve, to the extent
possible. The business purposes and intent of such invalid and unenforceable
provisions.

     10.5 Relationship to the Parties. No employees, consultants, contractors,
or agents of one party are agents, employees, franchisees, or joint ventures of
the other party, nor do they have any authority to bind the other party by
contract or otherwise to any obligation. They will not represent to the
contrary, either expressly, implicitly, or otherwise.

     10.6 Assignment. Neither party will assign this Agreement to a third party
without the other party's prior written approval, except to a third party
pursuant to a merger, sale of all or substantially all of the business of which
this Agreement is a part, or other corporate reorganization.

     10.7 Successors and Assigns. This Agreement will be binding upon and inure
to the benefit of the parties hereto and to their respective successors and
assigns, subject to the provisions of Paragraph 10.6.

     10.8 Notices. All notices required hereunder must be in writing and
delivered either in person or by a means evidenced by a delivery receipt, to the
address specified in this Agreement or as otherwise notified in writing. Such
notice will be effective upon receipt.

          Notices to the Glaxo Wellcome Companies will be to the attention of:


Affymax N.V. and Affymax Technologies N.V.   Via Facsimile 011-44-181-966-8838
c/o Dr. Alan Hesketh                            Confirmation by DHL Courier
Manager, Intellectual Property Department
Glaxo Wellcome plc
Glaxo House, Berkeley Avenue
Greenford, Middlesex, United Kingdom UB6 ONN
 
Dr. Gordon Ringold                              Via Facsimile (415) 424-0832
Chief Executive Officer                      Confirmation by Registered Mail
Affymax Research Institute
4001 Miranda Avenue
Palo Alto, CA 94304

          Notices to Maxygen will be to the attention of:

Dr. Alejandro Zaffaroni                      Via Facsimile (415) 424-0832
Chief Executive Officer                      Confirmation by Registered Mail
Maxygen, Inc.

 
4001 Miranda Avenue
Palo Alto, CA 94304
 
     10.9  No Waiver. Failure by either party to enforce any provision of this
Agreement will not be deemed a waiver of future enforcement of that or any other
provision.

     10.10 No Rights in Third Parties. This Agreement is made for the benefit of
the parties, and not for the benefit of any third parties unless otherwise
agreed to by the parties.

     10.11 Headings. The headings and captions used in this Agreement are used
for convenience only and are not to be considered in construing or interpreting
this Agreement.

     10.12 Construction. This Agreement has been negotiated by the parties and
by their respective counsel. This Agreement will be fairly interpreted in
accordance with its terms and without any strict construction in favor of or
against either party.

     10.13 Entire Agreement. This Agreement, including all Attachments hereto,
represents the entire understanding and agreement of the parties with respect to
the subject matter of the Agreement, and supersedes all prior or contemporaneous
understandings and agreements, whether written or oral, except as specifically
provided in this Agreement. Unless otherwise provided herein, this Agreement may
not be modified, amended, rescinded, or waived, in whole or part except by a
written instrument signed by the duly authorized representatives of both
parties.

 
11.0 EXECUTION BY THE PARTIES

          IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed by their duly authorized representatives. This Agreement may be
executed in one or more counterparts, each of which will be deemed an original,
but all of which will constitute but one and the same instrument.


Affymax Technologies N.V.

By: /s/ Adrian Hennah
Name:   Adrian Hennah
Title:  Director
Date:   March 12, 1997


Glaxo Group Limited

By: /s/ Stephen J. Cowden
Name:   Stephen J. Cowden
Title:  Company Secretary
Date:   March 12, 1997

Maxygen, Inc.

By: /s/ Alejandro Zaffaroni
Name:   Alejandro Zaffaroni
Title:  President
Date:

 
                                  SCHEDULE A

For the purposes of this term sheet, 'Licensed Patents and Applications' shall
be defined as the following patents and applications:

   
1.    U.S. Serial No. 08/198,431        filed February 17, 1994
2.    U.S. Serial No. 08/537,874        filed October 30, 1995
3.    U.S. Serial No. 08/564,955        filed November 30, 1995
4.    U.S. Serial No. 08/621,859        filed March 25, 1996
5.    U.S. Serial No. 08/621,430        filed March 25, 1996
6.    U.S. Serial No. 08/650,400        filed May 20, 1996
7.    PCT/US95/02126                    filed February 17, 1995 and    
     
      National Phase counterparts:     
    
      a)    Australia Appln. No. 29714/95;
      b)    Canada Appln. No. 2,182,393;
      c)    China Appln. No. 95191679.3;
      d)    Europe Appln. No. 95911826.6;
      e)    Japan Appln. No. 7-521977;
      f)    Korea Appln. No. 96-704465;
      g)    Russia Appln. No. 96118426     
    
8.    U.S. Serial No. 08/721,824        filed September 27, 1996
9.    U.S. Serial No. 08/722,660        filed September 27, 1996
10.   Townsend & Townsend file          filed December 2, 1996
      No. 16528J-014613PCT, entitled 'Methods for generating
      polynucleotides having desired characteristics by iterative selection and
      recombination'                   
    
11.   Townsend & Townsend file filed December 18, 1996
      No. 16528J-0202500, entitled 'Methods and compositions for polypeptide 
      engineering'     
    
12.   U.S. Serial No. 08/425,684        filed April 18, 1995
13.   U.S. Serial No. 08/675,502        filed July 3, 1996
14.   PCT/US96/05480                    filed April 18, 1996     
    
15.   Provisional Application           filed January    , 1997    
      Townsend & Townsend file No. 018907-0207-OOUS, entitled 'Recursive 
      sequence recombination between libraries of fragments and cellular genomes
      of evolving whole cells and organisms'    
    
16.   All rights of Glaxo Wellcome Companies relating to Shuffling Patents and 
      Applications under the Affymax/Affymetrix Technology Transfer 
      Agreement; effective date, March 2, 1995.    

 
                                  SCHEDULE B

For the purposes of this term sheet, the patents and patent applications related
to various peptide display technologies shall be defined as the following
patents and applications:

    
Peptides-on-Plasmids Display-Patents and Applications     
----------------------------------------------------
    
1.  U.S. Patent No. 5,270,170
2.  U.S. Patent No. 5,338,665
3.  European Patent Application No. 93908777.1
4.  U.S. Patent No. 5,498,530
5.  U.S. Serial No. 08/548,540     filed October 26, 1995
6.  PCT Patent Application No. US96/09809     
    
Polysome Display Patents and Applications     
-----------------------------------------
    
1.  U.S. Serial No. 08/300,262     filed September 2, 1994     
    
2.  U.S. Serial No. 08/586,176     filed January 17, 1996      
    
Phage Display Patents and Applications     
--------------------------------------
    
1.  U.S. Patent No. 5,427,908
2.  European Patent Application No. 91908963.1
3.  Japan Patent Application No. 3-508896
4.  U.S. Serial No. 08/376,326     filed January 20, 1995
5.  U.S. Serial No. 08/450,754     filed May 25, 1995
6.  U.S. Serial No. 07/541,108     filed June 20, 1990
7.  U.S. Patent No. 5,432,018
8.  European Patent Application No. 91913221.7
9.  Japan Patent Application No. 3-512623
10. Australian Patent No. 663,055
11. Canada Patent No. 2,084,411
12. U.S. Serial No. 08/465,295    filed June 5, 1995
13. U.S. Serial No. 08/463,390    filed June 5, 1995
14. U.S. Serial No. 08/465,484    filed June 5, 1995
15. U.S. Serial No. 08/466,653    filed June 6, 1995     
    
Dulbecco Patent     
---------------
    
1.  U.S. Patent No. 4,593,002     
    
Receptor Immobilization Patent Application     
-----------------------------------------
    
1.  U.S. Serial No. 08/309,345    filed September 19, 1994 as a file wrapper 
    continuation of U.S. Serial No. 07/947,339, filed September 18, 
    1992     

 
                                MODIFICATION TO
                          AFFYMAX/MAXYGEN TECHNOLOGY
                              TRANSFER AGREEMENT

     This modification to the Affymax/Maxygen Technology Transfer Agreement (the
Agreement), is made by and between Affymax Technologies N.V. and Glaxo Group
Limited, each of which is a corporation having a registered address at Glaxo
Wellcome House, Berkeley Avenue, Greenford, Middlesex, United Kingdom
(collectively referred to as 'the Glaxo Wellcome Companies') and Maxygen, Inc.,
a Delaware corporation having an address at 3410 Central Expressway, Santa
Clara, CA 95051 (referred to as 'Maxygen') and shall have an effective date of
March 1, 1998.

1.0      Definitions
         -----------
         
     'Antibodies on Phage Patents and Applications'' refer to the following
     Patents and Applications: US Patent No. 5,427,908; European Patent
     Application No. 91908963.1; and Japan Patent Application No. 3-508896     

     'Modification Agreement' shall refer to this agreement.

2.0      Modification of Article 5.2
         ---------------------------

     Article 5.2 of the Agreement is hereby modified in its entirety to read as
     follows:
         
     5.2.1   The Glaxo Wellcome Companies hereby grant Maxygen a perpetual,
             worldwide, royalty-free, non-exclusive license, without the right
             to sublicense, to Peptides-on-Plasmids Display Patents and
             Applications, Polysome Display Patents and Applications, Phage
             Display Patents and Applications, the Dulbecco Patent, and Receptor
             Immobilization Patent Application. Maxygen agrees that use of these
             patents and applications shall be [*******]. Maxygen further agrees
             that Maxygen shall not enter into a research collaboration with a
             third party, or conduct research on behalf of a third party, for
             the purpose of developing reagents for commercial use in the
             Diagnostic Field and using antibodies on phage technology as
             claimed in the Antibody on Phage Patents and Applications.
             Notwithstanding the foregoing, such restriction shall apply only in
             those countries in which the Antibody on Phage Patents have
             issued.     
        
     5.2.2   For purposes of this Modification Agreement, 'Diagnostic Field'
             shall mean the [*******].    

3.0  Miscellaneous
     -------------

     The terms of the Agreement not specifically modified by this Modification
Agreement shall continue in effect.


 
4.0    Execution by the Parties
       ------------------------

     IN WITNESS WHEREOF, the parties have caused this Modification Agreement to
be executed by their duly authorized representatives. This Modification
Agreement may be executed in one or more counterparts, each of which will be
deemed an original, but all of which will constitute but one and the same
instrument.

Affymax Technologies N.V.

By: /s/ Alan Baxter
Name:   Alan Baxter
Title:  Managing Director
Date:   November 13, 1998


Glaxo Group Limited

By: /s/ S M Bicknell
Name:   S M Bicknell
Title:  Assistant Secretary
Date:   May 11, 1998

Maxygen, Inc.

By: /s/ Russell J. Howard
Name:   Russell J. Howard
Title:  President & CEO
Date:   October 7, 1998