EXHIBIT 10.7

                                                                  EXECUTION COPY
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                                 LOAN AGREEMENT

         THIS LOAN  AGREEMENT (this "AGREEMENT"),  is entered  into as of May 6,
1999, between INFORMAX,  INC., a Delaware corporation (the "BORROWER"),  and PNC
BANK,  NATIONAL  ASSOCIATION  (the "BANK").  The Borrower and the Bank, with the
intent to be legally bound, agree as follows:

1.   LOAN. The following loan and credit facilities (collectively referred to as
     the "FACILITY"), shall be subject to and governed by this Agreement:

     $800,000 Secured Revolving Credit ("REVOLVING CREDIT")

     $200,000 Equipment Line of Credit ("EQUIPMENT LINE")

The maximum  available amount of the Facility shall be $1,000,000.  The proceeds
of the Revolving Credit shall be used for general  corporate and working capital
purposes.  The  proceeds  of the  Equipment  Line  shall  be used  only  for the
acquisition of computer and telecommunications equipment.

2.   TERMS  AND  CONDITIONS.  Subject  to the terms and  conditions  hereof  and
     relying upon the  representations and warranties herein set forth, the Bank
     agrees to make  advances  under the  Facility  (each an  "ADVANCE")  to the
     Borrower  at any time or from time to time on or after  the date  hereof in
     accordance with the terms of this Agreement.

     The Facility  shall consist of the components set forth in Section 1 hereof
     in accordance with the following terms:

     2.1    EXPIRATION DATE.

            (a) Revolving  Credit:  Three hundred sixty four (364) days from the
            date of the closing of this Agreement  ("CLOSING  DATE"), or on such
            subsequent anniversary of the Closing Date as the parties hereto may
            agree (the "REVOLVING CREDIT EXPIRATION DATE").

            (b) Equipment  Line:  All advances  under the Equipment Line must be
            requested  and made  within the three  hundred  sixty four (364) day
            period  immediately  following the Closing Date (the "EQUIPMENT LINE
            EXPIRATION DATE"). Six months from the Closing Date (the "FIRST TERM
            LOAN CONVERSION  DATE") all Equipment Line advances then outstanding
            will  convert  into a term  loan (the  "FIRST  TERM  LOAN").  On the
            Equipment  Line  Expiration  Date,  all Equipment Line advances made
            since the First Term Loan Conversion Date shall be converted into
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            a second term loan (the "SECOND TERM LOAN").  Each of the First Term
            Loan and the  Second  Term  Loan  shall  provide  for  repayment  of
            principal   and   interest  in  twenty   four  (24)  equal   monthly
            installments.

     2.2    INTEREST RATES.

            (a) Revolving Credit:  the Prime Rate (as defined  hereinafter) plus
            1.50% per annum;  the "PRIME RATE" shall be the rate of interest per
            annum  announced by the Bank from time to time as its "PRIME  RATE;"
            it is a base rate upon  which  other  rates  charged by the Bank are
            based, and is not necessarily the best rate offered by the Bank.

            (b) Equipment Line: the Prime Rate plus 1.75% per annum

     2.3    FACILITY FEE. The Borrower shall pay to the Bank a one-time facility
            fee in an amount equal to .75% of the maximum amount of the Facility
            ($7,500), payable on the Closing Date.

     2.4    BORROWING BASE/AVAILABILITY.

            (a) Revolving  Credit:  the  Revolving  Credit shall be available in
            amounts  determined in accordance  with the Borrowing  Base Rider in
            the form attached hereto as Exhibit A.

            (b) Equipment  Line.  (i) no Advances  shall be available  under the
            Equipment  Line  until the  earlier of (A) the  consummation  by the
            Borrower  of a new round of equity  financing  which  results in net
            proceeds  to  the   Borrower   of  at  least  One  Million   Dollars
            ($1,000,000);  and (B)  certification  by the  Borrower  that it has
            attained a Tangible Net Worth,  calculated in accordance  with GAAP,
            consistently applied, of at least Two Hundred Fifty Thousand Dollars
            ($250,000);

            (ii) Advances  under the  Equipment  Line shall be limited to 80% of
            the face amount of equipment invoices (excluding taxes, shipping and
            installation)  submitted with any Advance Request (as provided below
            in Section 2.5), not to exceed $200,000 in the aggregate.

     2.5    REQUESTS. Except as otherwise provided herein, the Borrower may from
            time to time prior to the Revolving  Credit  Expiration Date, or the
            Equipment Line Expiration  Date, as applicable,  request the Bank to
            make an advance  under the  Revolving  Credit or  Equipment  Line by
            delivering to the Bank, not later than 12:00 Noon,  Eastern Standard
            time, a request by telephone by the Chief  Executive  Officer of the
            Borrower  immediately  confirmed in writing by letter,  facsimile or
            telex from the Chief Executive  Officer of the Borrower (an "ADVANCE
            REQUEST"),  it  being  understood  that  the  Bank  may  rely on the
            authority of such officer making

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            such a telephonic  request  without the necessity of receipt of such
            written confirmation.  Each Advance Request shall be irrevocable and
            shall specify (a) the proposed borrowing date; and (b) the aggregate
            amount of the proposed borrowing  hereunder.  If the Advance Request
            is made under the Revolving  Credit,  it shall be accompanied by the
            most recent Borrowing Base Certificate prepared by the Borrower.  If
            the Advance  Request is made under the  Equipment  Line, it shall be
            accompanied by invoices for equipment acquisitions.

     2.6    PROMISSORY  NOTES.  The  obligation  of the  Borrower  to repay  the
            aggregate unpaid principal amount of the Revolving Credit,  together
            with interest  thereon,  shall be evidenced by a promissory  note of
            the Borrower  ("REVOLVING  CREDIT NOTE") payable to the order of the
            Bank in a face amount equal to the maximum  amount of the  Revolving
            Credit. The obligation of the Borrower to repay the aggregate unpaid
            principal  amount of the  Equipment  Line,  together  with  interest
            thereon,  shall be evidenced  by a  promissory  note of the Borrower
            ("TERM  NOTE")  payable  to the  order of the Bank in a face  amount
            equal to the maximum  amount of the  Equipment  Line.  The Revolving
            Credit Note and the Term Note shall be  referred to together  herein
            as the "NOTES."

     2.7    LOCKBOX. If an Event of Default (as hereinafter defined) occurs, and
            the same is not cured  subject to any  applicable  cure period,  the
            Bank may require,  in its sole  discretion,  the  establishment of a
            lockbox at the Bank to which account  debtors of the Borrower  would
            submit  all   payments  in  respect  of  the   Borrower's   accounts
            receivable.

3.   SECURITY.  The security for repayment of the Facility shall include but not
     be limited to the collateral,  guaranties and other  documents  heretofore,
     contemporaneously  or  hereafter  executed  and  delivered to the Bank (the
     "SECURITY  DOCUMENTS"),  which shall secure repayment of the Facility,  the
     Notes and all  other  loans,  advances,  debts,  liabilities,  obligations,
     covenants  and  duties  owing  by the  Borrower  to the Bank of any kind or
     nature,  present or future,  whether or not evidenced by any note, guaranty
     or other  instrument,  whether  arising under any agreement,  instrument or
     document,  whether  or not for the  payment  of money,  whether  arising by
     reason of an  extension of credit,  opening of a letter of credit,  loan or
     guarantee or in any other  manner,  whether  arising out of  overdrafts  on
     deposit or other accounts or electronic  funds transfers  (whether  through
     automatic clearing houses or otherwise) or out of the Bank's non-receipt of
     or  inability  to  collect  funds or  otherwise  not  being  made  whole in
     connection  with depository  transfer check or other similar  arrangements,
     whether  direct or indirect  (including  those  acquired by  assignment  or
     participation),  absolute or contingent, joint or several, due or to become
     due, now existing or hereafter  arising,  and any  amendments,  extensions,
     renewals or increases  and all costs and  expenses of the Bank  incurred in
     the documentation,  negotiation,  modification,  enforcement, collection or
     otherwise  in  connection  with  any of the  foregoing,  including  but not
     limited to reasonable attorneys' fees and expenses (hereinafter referred to
     collectively as the "OBLIGATIONS"). Unless expressly provided to

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     the  contrary  in  documentation  for any other  loan or  loans,  it is the
     express intent of the Bank and the Borrower that all Obligations  including
     those included in the Facility be cross-collateralized and cross-defaulted,
     such that collateral securing any of the Obligations shall secure repayment
     of all  Obligations  and a default under any Obligation  shall be a default
     under all Obligations.  This Agreement (including the Addendum),  the Notes
     and the  Security  Documents  are  collectively  referred  to as the  "LOAN
     DOCUMENTS".

4.   REPRESENTATIONS  AND  WARRANTIES.  The Borrower  hereby makes the following
     representations  and warranties,  which shall be true and correct as of the
     date of this Agreement and the date of the making of an Advance,  and which
     shall be true and correct  except as  otherwise  set forth on the  Addendum
     attached hereto and incorporated herein by reference (the "ADDENDUM").

     4.1.   EXISTENCE,  POWER AND  AUTHORITY.  The  Borrower is duly  organized,
            validly existing and in good standing under the laws of Delaware and
            has the corporate  power and authority to own and operate its assets
            and to conduct  its  business  as now or  currently  proposed  to be
            carried on, and is duly qualified,  licensed and in good standing to
            do business in all jurisdictions  where its ownership of property or
            the nature of its business requires such qualification or licensing,
            except where the failure to be so  qualified  or licensed  would not
            have a  material  adverse  effect on (a) the  business,  operations,
            property,  condition  (financial  or  otherwise) or prospects of the
            Borrower or (b) the validity or  enforceability of this Agreement or
            any of the other Loan  Documents  or the rights or  remedies  of the
            Bank  hereunder or thereunder  (a "MATERIAL  ADVERSE  EFFECT").  The
            Borrower  is  duly  authorized  to  execute  and  deliver  the  Loan
            Documents,  its Board of Directors has taken all necessary action to
            authorize the execution and delivery of the Loan Documents,  and the
            Borrower is and will continue to be duly  authorized to borrow under
            this  Agreement and to perform all of the other terms and provisions
            of the Loan Documents.

     4.2.   FINANCIAL  STATEMENTS.  The Borrower  has  delivered or caused to be
            delivered its most recent balance sheet and income statement for the
            fiscal  year ended  December  31,  1998 (the  "HISTORICAL  FINANCIAL
            STATEMENTS"). The Historical Financial Statements are true, complete
            and  accurate  in all  material  respects  and  fairly  present  the
            financial  condition,  assets  and  liabilities,   whether  accrued,
            absolute,  contingent or otherwise and the result of the  Borrower's
            operations  for  the  period  specified   therein.   The  Historical
            Financial Statements have been prepared in accordance with generally
            accepted accounting  principles ("GAAP")  consistently  applied from
            period to period subject in the case of interim statements to normal
            year-end  adjustments  and to  items  that  would  be  disclosed  in
            footnotes to audited statements.

     4.3.   NO  MATERIAL  ADVERSE  CHANGE.  Since  the  date  of the  Historical
            Financial  Statements,  the  Borrower  has not suffered any material
            damage  to,  destruction  or loss of,  its  assets,  and no event or
            condition has occurred or exists, which has

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            resulted or, to Borrower's  knowledge,  could reasonably be expected
            to result in a  material  adverse  change in its  business,  assets,
            operations, financial condition or result of operation.

     4.4.   BINDING OBLIGATIONS. The Loan Documents, when executed and delivered
            by the  Borrower,  will  constitute  the  legal,  valid and  binding
            obligations  of the Borrower  enforceable  in accordance  with their
            terms  except  as  enforceability   may  be  limited  by  applicable
            bankruptcy,  reorganization,  moratorium  and  other  laws,  now  or
            hereafter in effect,  affecting the enforcement of creditor's rights
            generally  and  that   enforceability  may  be  limited  by  general
            principles of equity.

     4.5.   NO DEFAULTS OR VIOLATIONS. There does not exist any Event of Default
            under this  Agreement  or any  material  default or violation by the
            Borrower of or under any of the terms, conditions or obligations of:
            (i) its certificate of  incorporation  or bylaws;  (ii) any material
            indenture,  mortgage,  deed of trust, franchise,  permit,  contract,
            agreement, or other instrument to which it is a party or by which it
            is bound; or (iii) any law, regulation,  ruling, order,  injunction,
            decree,   condition  or  other  requirement  of  a  material  nature
            applicable  to or imposed  upon it by any law,  or the action by any
            court or any  governmental  authority or agency against the Borrower
            or its assets.  The  consummation of the  transactions  set forth in
            this Agreement will not result in any such default or violation.

     4.6.   TITLE  TO  ASSETS.  The  Borrower  has  valid  title  to the  assets
            reflected on the Historical Financial Statements,  free and clear of
            all  liens  and  encumbrances,  except  for (i)  current  taxes  and
            assessments not yet due and payable, (ii) liens and encumbrances, if
            any,  reflected  or noted in the  Historical  Financial  Statements,
            (iii) assets  disposed of by the Borrower in the ordinary  course of
            business since the date of the Historical Financial Statements, (iv)
            those liens or encumbrances specified on the Addendum, (v) liens and
            encumbrances   permitted   by   Section   6.2  and  (vi)  liens  and
            encumbrances under the Loan Documents.

     4.7.   LITIGATION. There are no actions, suits, proceedings or governmental
            investigations  pending or, to the best of the Borrower's knowledge,
            threatened against the Borrower,  which could reasonably be expected
            to result in a  material  adverse  change in its  business,  assets,
            operations,  financial  condition or results of operations and there
            is no basis known to the Borrower for any action, suit,  proceedings
            or governmental  investigation which could reasonably be expected to
            result in such a material adverse change.  All pending or threatened
            litigation  against the Borrower of which  Borrower has knowledge is
            listed on the Addendum.

     4.8.   TAX RETURNS. The Borrower has filed all returns and reports that are
            required to be filed by it in connection with any federal,  state or
            local tax, duty or charge levied, assessed or imposed upon it or its
            property or withheld by it, including

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            unemployment,  social  security and similar  taxes,  and all of such
            taxes have been either paid or adequate  reserve or other  provision
            has been made.

     4.9.   EMPLOYEE  BENEFIT PLANS.  Each employee benefit plan as to which the
            Borrower may have any  liability  complies in all material  respects
            with all  applicable  provisions of the Employee  Retirement  Income
            Security  Act  of  1974   ("ERISA"),   including   minimum   funding
            requirements,  and (i) no Prohibited  Transaction  (as defined under
            ERISA)  has  occurred  with  respect  to  any  such  plan,  (ii)  no
            Reportable  Event (as  defined  under  Section  4043 of  ERISA)  has
            occurred with respect to any such plan which would cause the Pension
            Benefit Guaranty Corporation to institute  proceedings under Section
            4042 of ERISA,  (iii) the Borrower has not  withdrawn  from any such
            plan or initiated  steps to do so, and (iv) no steps have been taken
            to terminate any such plan.

     4.10.  ENVIRONMENTAL  MATTERS.  The  Borrower  is  in  compliance,  in  all
            material respects,  with all Environmental Laws, including,  without
            limitation,  all  Environmental  Laws in  jurisdictions in which the
            Borrower owns or operates,  or has owned or operated,  a facility or
            site,  stores  Collateral,  arranges or has arranged for disposal or
            treatment  of  hazardous  substances,  solid  waste or other  waste,
            accepts or has  accepted for  transport  any  hazardous  substances,
            solid  waste or other  wastes or holds or has held any  interest  in
            real  property or  otherwise.  Except as otherwise  disclosed on the
            Addendum,  no litigation or proceeding arising under, relating to or
            in  connection  with any  Environmental  Law is  pending  or, to the
            Borrower's  knowledge,  threatened  against the  Borrower,  any real
            property  which the  Borrower  holds or has held an  interest or any
            past  or  present  operation  of the  Borrower.  To  the  Borrower's
            knowledge,  no release,  threatened release or disposal of hazardous
            waste,  solid waste or other wastes is  occurring,  or has occurred,
            on, under or to any real  property in which the  Borrower  holds any
            interest or performs any of its operations, in material violation of
            any  Environmental  Law.  As used in this  Section,  "LITIGATION  OR
            PROCEEDING"  means any demand,  claim notice,  suit, suit in equity,
            action,  administrative  action,  investigation  or inquiry  whether
            brought  by  a   governmental   authority  or  other   person,   and
            "ENVIRONMENTAL   LAWS"  means  all  provisions  of  laws,  statutes,
            ordinances, rules, regulations, permits, licenses, judgments, writs,
            injunctions,  decrees,  orders,  awards and standards promulgated by
            any governmental  authority concerning health, safety and protection
            of,  or  regulation  of  the  discharge  of  substances   into,  the
            environment.

     4.11.  INTELLECTUAL PROPERTY. The Borrower owns or has the right to use all
            patents, patent rights, and to the information, knowledge and belief
            of  the  Borrower,  Borrower  owns  or has  the  right  to  use  all
            trademarks,  trade names,  service marks,  copyrights,  intellectual
            property,  technology,  know-how  and  processes  necessary  for the
            conduct of its business as currently  conducted that are material to
            the condition  (financial or  otherwise),  business or operations of
            the Borrower.

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     4.12.  YEAR 2000.  The  Borrower has reviewed the areas within its business
            and  operations  which  could  be  adversely  affected  by,  and has
            developed  or is  developing  a program to address on a timely basis
            the risk that certain computer applications used by the Borrower may
            be unable to recognize and perform properly date-sensitive functions
            involving dates prior to and after December 31, 1999 (the "YEAR 2000
            PROBLEM").  The  Year  2000  Problem  will  not  have,  and  is  not
            reasonably expected to have, a Material Adverse Effect.

     4.13.  REGULATORY MATTERS. No part of the proceeds of the Loan will be used
            for  "PURCHASING"  or  "CARRYING"  any  "MARGIN  STOCK"  within  the
            respective  meanings of each of the quoted terms under  Regulation U
            of the Board of Governors of the Federal  Reserve  System as now and
            from time to time in effect or for any purpose  which  violates  the
            provisions of the Regulations of such Board of Governors.

     4.14.  SOLVENCY.  As of the date  hereof  and  after  giving  effect to the
            transactions  contemplated by the Loan Documents,  the Borrower will
            have  sufficient  cash  flow to  enable  it to pay its debts as they
            mature.

     4.15.  DISCLOSURE. None of the Loan Documents contains any untrue statement
            of  material  fact or omits to state a material  fact  necessary  in
            order to make the statements contained in this Agreement or the Loan
            Documents  not  misleading.  There is no fact known to the  Borrower
            which materially  adversely  affects or, might materially  adversely
            affect, the business,  assets,  operations,  financial  condition or
            results of operation  of the  Borrower  and which has not  otherwise
            been fully set forth in this Agreement or in the Loan Documents.

5.   AFFIRMATIVE COVENANTS.  The Borrower agrees that from the date of execution
     of this  Agreement  until  all  Obligations  have been  fully  paid and any
     commitments of the Bank to the Borrower have been terminated,  the Borrower
     will:

     5.1.   BOOKS AND RECORDS.  Maintain  books and records in  accordance  with
            GAAP and give  representatives  of the Bank  access  thereto  at all
            reasonable  times  following   reasonable   notice  from  the  Bank,
            including  permission to examine,  copy (at the Bank's  expense) and
            make  abstracts  from any of such books and  records  and such other
            information  as the Bank may from time to time  reasonably  request,
            and the Borrower  will make  available  to the Bank for  examination
            copies of any reports,  statements or returns which the Borrower may
            make to or file with any governmental department,  bureau or agency,
            federal  or  state.   The  Bank  shall  treat  as  confidential  all
            non-public   information   contained  in  such  books  and  records;
            provided, however, that if Bank is required to disclose confidential
            information pursuant to a court order,  subpoena or similar process,
            prior to disclosure Bank shall: (i) promptly provide Borrower with a
            copy of the court order or subpoena; (ii) cooperate with Borrower at
            Borrower's  expense in obtaining a protective or similar order;  and
            (iii) in any event, disclose only such confidential information as

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            Bank, with the advice of its counsel, shall deem necessary to comply
            with such court order or subpoena.

     5.2.   INTERIM FINANCIAL  STATEMENTS;  CERTIFICATE OF NO DEFAULT;  ACCOUNTS
            RECEIVABLE.

            (a) Monthly  Reporting.  Furnish  the Bank  within  twenty (20) days
            after the end of each month:

                 (i) a detailed  report on its sales and accounts  receivable in
            such  reasonable  detail  consistent with the form currently used by
            the Borrower's management;

                 (ii) an income  statement  and balance  sheet for such  period,
            each in reasonable detail, certified by an authorized officer of the
            Borrower and prepared in accordance with GAAP applied from period to
            period;

                 (iii)  a  certificate  as to  its  compliance  with  applicable
            financial  covenants for the period then ended and whether any Event
            of Default exists, and, if so, the nature thereof and the corrective
            measures the Borrower proposes to take; and

                 (iv)  a  completed  Borrowing  Base  Certificate  in  the  form
            attached to the Borrowing Base Rider.

            (b) Quarterly Reporting. Furnish the Borrower's Financial Statements
            to the Bank  within  twenty  (20)  days of the end of each  calendar
            quarter.  "FINANCIAL  STATEMENTS" means the Borrower's  consolidated
            and, if required by the Bank in its sole  discretion,  consolidating
            balance sheets,  income  statements and statements of cash flows for
            the  year  or  quarter  together  with   year-to-date   figures  and
            comparative figures for the corresponding periods of the prior year.

     5.3.   ANNUAL  FINANCIAL  STATEMENTS.   Furnish  the  Borrower's  Financial
            Statements to the Bank within ninety (90) days after the end of each
            fiscal  year.  Those  Financial   Statements  will  be  prepared  in
            accordance with GAAP and audited by an independent  certified public
            accountant  selected by the Borrower and reasonably  satisfactory to
            the Bank. Audited Financial Statements shall contain the unqualified
            opinion  of an  independent  certified  public  accountant  and  its
            examination   shall   have  been  made  in   accordance   with  GAAP
            consistently  applied from period to period.  The Borrower will also
            provide  filings made with any  regulatory  authority and such other
            information reasonably requested by the Bank from time to time.

     5.4.   PAYMENT OF TAXES AND OTHER  CHARGES.  Pay and discharge when due all
            indebtedness and all taxes,  assessments,  charges, levies and other
            liabilities imposed upon the Borrower, its income, profits, property
            or business, except those

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            which  currently  are being  contested in good faith by  appropriate
            proceedings and for which the Borrower shall have set aside adequate
            reserves in accordance  with GAAP or made other  adequate  provision
            with  respect  thereto  acceptable  to the  Bank  in its  reasonable
            discretion.

     5.5.   MAINTENANCE  OF  EXISTENCE,  OPERATION  AND  ASSETS.  Do all  things
            necessary to  maintain,  renew and keep in full force and effect its
            organizational  existence  and all rights,  permits  and  franchises
            necessary  to  enable  it to  continue  its  business;  continue  in
            operation in substantially  the same manner as at present;  keep its
            properties in good operating condition and repair, ordinary wear and
            tear and  obsolescence  excepted;  and make all necessary and proper
            repairs, renewals, replacements, additions and improvements thereto.

     5.6.   INSURANCE.  Maintain with financially sound and reputable  insurers,
            insurance  with respect to its  property  and business  against such
            casualties and  contingencies,  of such types and in such amounts as
            is  customary  for  established  companies  engaged  in the  same or
            similar business and similarly situated.  In the event of a conflict
            between the provisions of this Section and the terms of any Security
            Documents  relating to  insurance,  the  provisions  in the Security
            Documents will control.

     5.7.   COMPLIANCE WITH LAWS.  Comply in all material respects with all laws
            applicable  to the  Borrower  and to the  operation  of its business
            (including  any statute,  rule or regulation  relating to employment
            practices and pension benefits or to environmental, occupational and
            health standards and controls).

     5.8.   BANK  ACCOUNTS.  Establish  and  maintain  at  the  Bank  all of the
            Borrower's primary depository accounts.

     5.9.   FINANCIAL  COVENANTS.  Comply  with all of the  financial  and other
            covenants,  if  any,  set  forth  on the  Addendum,  subject  to all
            applicable cure periods set forth herein.

     5.10.  ADDITIONAL REPORTS. Provide prompt written notice to the Bank of the
            occurrence  of any of the  following of which the  Borrower  obtains
            knowledge  (together  with a  description  of the  action  which the
            Borrower  proposes to take with respect  thereto):  (i) any Event of
            Default,  (ii)  any  material  litigation  filed by or  against  the
            Borrower,  (iii) any Reportable Event or Prohibited Transaction with
            respect to any  Employee  Benefit  Plan(s)  (as defined in ERISA) or
            (iv) any event  which  might  reasonably  be expected to result in a
            material  adverse  change  in  the  business,   assets,  operations,
            financial condition or results of operation of the Borrower.

6.   NEGATIVE COVENANTS. The Borrower covenants and agrees that from the date of
     execution of this Agreement until all Obligations  have been fully paid and
     any

                                       9
<PAGE>

     commitments of the Bank to the Borrower have been terminated,  the Borrower
     will not,  except as set forth in the  Addendum,  without the Bank's  prior
     written consent:

     6.1.   INDEBTEDNESS.  Incur, assume or permit to exist any indebtedness for
            borrowed money other than: (i)  indebtedness  under the Facility and
            any subsequent  indebtedness to the Bank; (ii) existing indebtedness
            disclosed on the Borrower's Historical Financial Statements referred
            to in Section 4.2;  (iii)  capital lease  obligations  not to exceed
            $100,000  in the  aggregate  over the term of the Loan;  (iv)  trade
            payables  incurred in the ordinary course of business;  (v) guaranty
            obligations  permitted  pursuant  to  Section  6.3  below;  or  (vi)
            indebtedness  specifically disclosed by the Borrower on the Addendum
            and any renewal or refinance of thereof  which does not increase the
            principal thereof.

     6.2.   LIENS AND  ENCUMBRANCES.  Except as provided in Section 4.6, create,
            assume or permit to exist any mortgage, pledge, encumbrance or other
            security  interest  or lien upon any assets  now owned or  hereafter
            acquired  or  enter  into  any  lease  or any  arrangement  for  the
            acquisition of property subject to any conditional  sales agreement,
            other  than (i)  leasehold  interests  related to  operating  leases
            entered  into by the  Borrower in the  ordinary  course of business,
            (ii) liens for taxes,  assessments  or charges  due and  payable and
            subject to interest or penalty, provided that the Borrower maintains
            such reserves or other  appropriate  provisions as shall be required
            by GAAP and pays all such taxes,  assessments  or charges  forthwith
            upon the  commencement  of  proceedings  to foreclose any such lien,
            (iii)  liens of  mechanics,  materialmen,  warehousemen,  repairmen,
            carriers,  or other statutory  nonconsensual liens,  provided,  that
            such  liens do not  materially  affect  the  Collateral  or,  in the
            aggregate,  materially impair the ability of the Borrower to perform
            its Obligations  hereunder or under the other Loan  Documents,  (iv)
            liens  consisting  of  zoning   restrictions,   easements  or  other
            restrictions on the use of real property,  none of which  materially
            impairs the use of such property or the value  thereof,  and none of
            which is  violated in any  material  respect by existing or proposed
            structures  or land use,  and (v)  pledges or  deposits  made in the
            ordinary   course  of  business  to  secure   payment  of  workmen's
            compensation,  or to  participate  in any  fund in  connection  with
            workmen's compensation,  unemployment insurance, old-age pensions or
            other social security programs.

     6.3.   GUARANTEES.  Guarantee,  endorse or voluntarily become  contingently
            liable  for the  obligations  of any  person,  firm or  corporation,
            except in connection  with the  endorsement and deposit of checks in
            the ordinary course of business for collection.

     6.4.   LOANS OR ADVANCES;  INVESTMENTS.  Purchase or hold  beneficially any
            stock, other securities or evidences of indebtedness of any loans or
            advances  to,  or  make  any  investment  or  acquire  any  interest
            whatsoever  in, any other person,  firm or  corporation in excess of
            $10,000 in the aggregate during the term of the Facility, except (i)
            investments   disclosed  on  the  Borrower's   Historical  Financial
            Statements

                                       10
<PAGE>

            or acceptable  to the Bank in its  reasonable  discretion,  and (ii)
            advances to employees to meet expenses incurred by such employees in
            the ordinary course of business.

     6.5.   MERGER OR TRANSFER OF ASSETS.  Merge or consolidate with or into any
            person,  firm or corporation or lease,  sell,  transfer or otherwise
            dispose of property or assets  (excluding  the sale of  inventory in
            the ordinary  course of business)  having an aggregate book value in
            excess of One Hundred Thousand Dollars  ($100,000) whether now owned
            or  hereafter  acquired  other than such  merger,  consolidation  or
            disposition approved by the Bank.

     6.6.   CHANGE IN  BUSINESS,  MANAGEMENT  OR  OWNERSHIP.  Make or permit any
            material  change in the nature of its  business  as carried on as of
            the  date  hereof,  in  the  composition  of its  current  executive
            management,  or in its equity  ownership other than (i) transfers to
            heirs  and  beneficiaries  of a  stockholder  upon  the  death  of a
            stockholder,  (ii) in connection  with an initial public offering of
            the capital  stock of the Borrower,  (iii) private  offerings of the
            equity  securities of the Borrower  approved by the Borrower's Board
            of Directors,  (iv)  issuances of shares  pursuant to the Borrower's
            employee stock option plan in effect as of the date hereof or (v) in
            connection with the repurchase of shares acquired through retirement
            plans or employee  stock option plans or pursuant to the exercise of
            contractual  rights  of  first  refusal  to  purchase  such  shares;
            provided that the Bank shall not unreasonably  withhold or delay its
            consent to a change in the Borrower's executive management which has
            been approved by the Borrower's Board of Directors.


     6.7.   DIVIDENDS.  Declare or pay any dividends on or make any distribution
            with  respect to any class of its equity or ownership  interest,  or
            purchase,  redeem,  retire or  otherwise  acquire  any of its equity
            other than (a) recessions and/or reissuance of the equity securities
            of the  Borrower  to  address  Blue Sky  matters  and (b)  purchase,
            redemption, retirement or other acquisitions of equity securities of
            the Borrower (not covered by clause (a) above) not to exceed $25,000
            in the aggregate during of the term of the Facility.

7.   EVENTS OF DEFAULT. The occurrence of any of the following will be deemed to
     be an "EVENT OF DEFAULT":

     7.1.   PAYMENT  DEFAULT.  The  Borrower  shall  fail to pay any  payment of
            principal  when  due or any  payment  of  interest  within  five (5)
            business  days  following  the date  when  due,  in  respect  of the
            Obligations.

     7.2.   MATERIAL ADVERSE CHANGE. There shall be a material adverse change in
            the business,  operations, assets, financial condition or results of
            operations of Borrower.
                                       11
<PAGE>

     7.3.   COVENANT DEFAULT.  The Borrower shall default in the performance of,
            or violate any of, the  covenants  or  agreements  contained in this
            Agreement  (other  than  with  respect  to  payment  as set forth in
            Section 7.1), which default shall not have been cured within fifteen
            (15) business days after the occurrence thereof.

     7.4.   BREACH  OF  WARRANTY.   Any  Financial  Statement,   representation,
            warranty or  certificate  made or  furnished  by the Borrower to the
            Bank in connection with this Agreement shall be false,  incorrect or
            incomplete in any material respect when made.

     7.5.   BANKRUPTCY OR INSOLVENCY. A proceeding shall have been instituted in
            a court having  jurisdiction  over the Borrower  seeking a decree or
            order for relief in respect of Borrower in an involuntary case under
            any  applicable  bankruptcy,   insolvency  reorganization  or  other
            similar law and such  involuntary  case shall remain  undismissed or
            unstayed and in effect for a period of sixty (60) consecutive  days,
            or Borrower  shall  commence a voluntary  case under any such law or
            consent to the  appointment  of a  receiver,  liquidator,  assignee,
            custodian,  trustee,  sequestrator,  conservator  (or other  similar
            official).

     7.6.   OTHER  DEFAULT.  The occurrence of an Event of Default as defined in
            the Notes or any of the Security  Documents.


Upon the  occurrence  of an Event of Default,  the Bank will have all rights and
remedies  specified in the Notes and the Security  Documents  and all rights and
remedies (which are cumulative and not exclusive) available under applicable law
or in equity.

8.   CONDITIONS. The Bank's obligation to make any Advance under the Facility is
     subject to the conditions that as of the date of the Advance:

     8.1.   FUNDING  OF  INITIAL  ADVANCE  UNDER THE  REVOLVING  CREDIT.  On the
            Closing Date:

            (a) No Event of Default. No Event of Default or event which with the
            passage of time,  provision  of notice or both would  constitute  an
            Event of Default shall have occurred and be continuing.

            (b)  Authorization  Documents.  The Borrower shall have furnished to
            the Bank  certified  copies of resolutions of the board of directors
            authorizing the execution of this Agreement, the Notes or any of the
            Security  Documents,  or  other  proof of  authorization  reasonably
            satisfactory to the Bank.

            (c) Receipt of Loan Documents.  The Borrower shall have executed and
            delivered to the Bank the Loan Documents and such other  instruments
            and documents  which the Bank may  reasonably  request in connection
            with the transactions provided for in this Agreement.

                                       12
<PAGE>

            (d)   Representations   and  Warranties.   The  representations  and
            warranties  of the Borrower to the Bank shall be true and correct in
            all respects.

            (e) Opening Balance Sheet.  The Borrower shall furnish the Bank with
            its Opening Balance Sheet. "OPENING BALANCE SHEET" means the balance
            sheet of the Borrower dated March 31, 1999.

            (f)  Opinion  of  Counsel.  Counsel  for  the  Borrower  shall  have
            delivered to the Bank, a written opinion, dated the Closing Date and
            in form and substance  reasonably  satisfactory  to the Bank and its
            counsel.

     8.2.   ADDITIONAL  ADVANCES.  At the time of making any additional Advances
            under the Revolving  Credit or the  Equipment  Line and after giving
            effect   to  any   such   proposed   extensions   of   credit:   the
            representations and warranties of the Borrower contained in the Loan
            Documents  shall  be true on and as of the date of such  funding  or
            Advance  with the same  effect as though  such  representations  and
            warranties   had  been  made  on  and  as  of  such   date   (except
            representations  and warranties  which expressly relate solely to an
            earlier date or time, which  representations and warranties shall be
            true and correct on and as of the specific  dates or times  referred
            to therein) and the Borrower  shall have performed and complied with
            all  covenants  and  conditions  hereof;  no Event of Default or any
            event  specified  in  Section 7,  which,  with the giving of notice,
            lapse of time or both, would become an Event of Default,  shall have
            occurred and be continuing or shall exist;  the advancement of funds
            under  the  Facility  shall  not   materially   contravene  any  law
            applicable  to the  Borrower  or the Bank,  as  applicable;  and the
            Borrower  shall  have  delivered  to the  Bank a duly  executed  and
            completed Advance Request.

9.   EXPENSES.  The  Borrower  agrees to pay the Bank,  upon the closing of this
     Agreement,  and  otherwise  on demand,  all  reasonable  costs and expenses
     incurred by the Bank in connection  with the (i)  preparation,  negotiation
     and  delivery  of this  Agreement  and the other  Loan  Documents,  and any
     modifications  thereto,  including reasonable fees and expenses of counsel,
     expenses for auditors, lien searches,  recording and filing fees and taxes,
     and (ii)  collection of the Loan or instituting,  maintaining,  preserving,
     enforcing and  foreclosing  the security  interest in any of the collateral
     securing the Facility,  whether through judicial  proceedings or otherwise,
     or in defending or prosecuting any actions or proceedings arising out of or
     relating to this Agreement.

10.  INCREASED COSTS. Within thirty (30) days following written demand, together
     with the  written  evidence of the  justification  therefor,  the  Borrower
     agrees to pay the Bank, all direct costs  incurred and any losses  suffered
     or payments made by the Bank as a  consequence  of making any Advance under
     the  Facility  by  reason  of  any  change  in  law  or  regulation  or its
     interpretation  imposing any  reserve,  deposit,  allocation  of capital or
     similar  requirement  (including  without  limitation,  Regulation D of the
     Board of Governors of the Federal  Reserve System) on the Bank, its holding
     company or any of their respective assets.

                                       13
<PAGE>

11. MISCELLANEOUS.

     11.1.  NOTICES. All notices,  demands,  requests,  consents,  approvals and
            other  communications  required or  permitted  hereunder  must be in
            writing and will be effective  upon receipt if delivered  personally
            to  such  party,   or  if  sent  by  facsimile   transmission   with
            confirmation  of delivery,  or by  nationally  recognized  overnight
            courier  service,  to the  address  set forth below or to such other
            address  as any  party  may give to the  other in  writing  for such
            purpose:


To the Bank:                                To the Borrower:

PNC Bank, National Association              InforMax, Inc.
1401 Eye Street, N.W.                       6110 Executive Boulevard
Suite 200                                   N. Bethesda, MD 20852
Washington, DC 20005                        Attention: Joseph Lehnen
Attention: Katherine S. Kappler             Facsimile No.: 301-984-8306
Facsimile No.: 202-393-1545


     11.2.  PRESERVATION OF RIGHTS. No delay or omission on the part of the Bank
            to exercise  any right or power  arising  hereunder  will impair any
            such right or power or be  considered  a waiver of any such right or
            power or any acquiescence  therein,  nor will the action or inaction
            of the Bank impair any right or power arising hereunder.  The Bank's
            rights and remedies  hereunder are  cumulative  and not exclusive of
            any other  rights or  remedies  which the Bank may have under  other
            agreements, at law or in equity.

     11.3.  ILLEGALITY.  In case any one or more of the provisions  contained in
            this Agreement  should be invalid,  illegal or  unenforceable in any
            respect, the validity,  legality and enforceability of the remaining
            provisions  contained  herein  shall not in any way be  affected  or
            impaired thereby.

     11.4.  CHANGES IN  WRITING.  No  modification,  amendment  or waiver of any
            provision  of this  Agreement  nor consent to any  departure  by the
            Borrower  therefrom,  will in any event be effective unless the same
            is in  writing  and  signed  by the Bank,  and then  such  waiver or
            consent shall be effective only in the specific instance and for the
            purpose for which  given.  No notice to or demand on the Borrower in
            any case will entitle the Borrower to any other or further notice or
            demand in the same, similar or other circumstance.

     11.5.  ENTIRE  AGREEMENT.  This  Agreement  (including  the  documents  and
            instruments referred to herein) constitutes the entire agreement and
            supersedes all other prior

                                       14
<PAGE>

            agreements and  understandings,  both written and oral,  between the
            parties  with   respect  to  the  subject   matter   hereof.

     11.6.  COUNTERPARTS.  This  Agreement  may  be  signed  in  any  number  of
            counterpart   copies  and  by  the   parties   hereto  on   separate
            counterparts,  but all such copies shall constitute one and the same
            instrument.

     11.7.  SUCCESSORS  AND  ASSIGNS.  This  Agreement  will be binding upon and
            inure  to the  benefit  of the  Borrower  and  the  Bank  and  their
            respective,  successors  and assigns;  provided,  however,  that the
            Borrower  may not assign this  Agreement in whole or in part without
            the prior  written  consent of the Bank and the Bank at any time may
            assign this Agreement in whole or in part, upon prior written notice
            to Borrower.

     11.8.  INTERPRETATION.  In this Agreement, unless the Bank and the Borrower
            otherwise agree in writing, the singular includes the plural and the
            plural the singular;  words  importing any gender  include the other
            genders; references to statutes are to be construed as including all
            statutory  provisions  consolidating,   amending  or  replacing  the
            statute  referred  to;  the word "or"  shall be  deemed  to  include
            "and/or",  the words "including",  "includes" and "include" shall be
            deemed to be followed by the words "without limitation";  references
            to articles,  sections (or subdivisions of sections) or exhibits are
            to  those  of  this  Agreement  unless  otherwise   indicated;   and
            references to agreements and other contractual  instruments shall be
            deemed to include all subsequent  amendments and other modifications
            to such  instruments,  but only to the extent  such  amendments  and
            other  modifications  are  not  prohibited  by  the  terms  of  this
            Agreement.  Section  headings in this  Agreement  are  included  for
            convenience  of  reference  only and shall not  constitute a part of
            this Agreement for any other purpose.  Unless otherwise specified in
            this  Agreement,  all accounting  terms shall be interpreted and all
            accounting determinations shall be made in accordance with GAAP.

     11.9.  INDEMNITY.  The Borrower  agrees to indemnify  each of the Bank, its
            directors,  officers and employees  and each legal  entity,  if any,
            which controls the Bank (the "INDEMNIFIED PARTIES") and to hold each
            Indemnified  Party  harmless  from and  against  any and all claims,
            damages,  losses,  liabilities  and  expenses  (including,   without
            limitation,  reasonable  fees of counsel  with whom any  Indemnified
            Party may  consult and all  reasonable  expenses  of  litigation  or
            preparation therefor) which any Indemnified Party may incur or which
            may be asserted against any Indemnified  Party in connection with or
            arising out of the matters  referred to in this  Agreement or in the
            other Loan  Documents by any third  person,  entity or  governmental
            authority  (including any person or entity claiming  derivatively on
            behalf of the  Borrower),  whether (a)  arising  from or incurred in
            connection with any breach of a representation, warranty or covenant
            by the Borrower,  or (b) arising out of or resulting  from any suit,
            action, claim, proceeding or governmental investigation,  pending or
            threatened,  whether based on statute, regulation or order, or tort,
            or contract or otherwise, before any court or

                                       15
<PAGE>

            governmental  authority,  which  arises  out of or  relates  to this
            Agreement,  any other Loan  Document,  or the use of the proceeds of
            the  Facility.  The  indemnity  agreement  contained in this Section
            shall  survive the  termination  of this  Agreement,  payment of any
            Advance and  assignment  of any rights  hereunder.  The Borrower may
            participate  at its  expense in the  defense  of any such  action or
            claim.

     11.10. ASSIGNMENTS  AND  PARTICIPATION.  At any time,  upon  prior  written
            notice  to the  Borrower,  the  Bank  may  sell,  assign,  transfer,
            negotiate,  grant  participation  in, or otherwise dispose of all or
            any part of the Bank's  interest  in the Loan.  Upon  prior  written
            notice  to the  Borrower,  the  Bank  may  provide  any  information
            concerning  the Borrower,  including  information  pertaining to the
            Borrower's  financial  condition,  business  operations  or  general
            creditworthiness,  to any person or entity  which may  succeed to or
            participate  in all or  any  part  of  the  Bank's  interest  in the
            Facility, provided that such person or entity agrees to maintain the
            confidentiality of such information.

     11.11. GOVERNING LAW AND JURISDICTION. This Agreement has been delivered to
            and  accepted  by the  Bank  and  will be  deemed  to be made in the
            Commonwealth of Pennsylvania. THIS AGREEMENT WILL BE INTERPRETED AND
            THE RIGHTS AND  LIABILITIES  OF THE  PARTIES  HERETO  DETERMINED  IN
            ACCORDANCE  WITH  THE  LAWS  OF THE  COMMONWEALTH  OF  PENNSYLVANIA,
            EXCLUDING   ITS  CONFLICT  OF  LAWS  RULES.   The  Borrower   hereby
            irrevocably  consents to the exclusive  jurisdiction of any state or
            federal court seated in Allegheny County, Pennsylvania, and consents
            that  all  service  of  process  be  sent by  nationally  recognized
            overnight courier service directed to the Borrower at the Borrower's
            address  set forth  herein and  service so made will be deemed to be
            completed  on the  business  day after  deposit  with such  courier;
            provided that nothing  contained in this  Agreement will prevent the
            Bank from  bringing any action,  enforcing  any award or judgment or
            exercising any rights against the Borrower individually, against any
            security or against any  property of the  Borrower  within any other
            county,  state or other foreign or domestic  jurisdiction.  The Bank
            and the  Borrower  agree that the venue  provided  above is the most
            convenient  forum for both the Bank and the  Borrower.  The Borrower
            waives  any  objection  to venue and any  objection  based on a more
            convenient forum in any action instituted under this Agreement.

     11.12. WAIVER OF JURY TRIAL.  EACH OF THE BORROWER AND THE BANK IRREVOCABLY
            WAIVES  ANY  AND ALL  RIGHT  IT MAY  HAVE TO A TRIAL  BY JURY IN ANY
            ACTION,   PROCEEDING  OR  CLAIM  OF  ANY  NATURE  RELATING  TO  THIS
            AGREEMENT,  ANY DOCUMENTS EXECUTED IN CONNECTION WITH THIS AGREEMENT
            OR  ANY  TRANSACTION  CONTEMPLATED  IN ANY OF  SUCH  DOCUMENTS.  THE
            BORROWER  AND THE BANK  ACKNOWLEDGE  THAT THE  FOREGOING  WAIVER  IS
            KNOWING AND VOLUNTARY.

                                       16
<PAGE>

The Borrower  acknowledges that it has read and understood all the provisions of
this  Agreement,  including  the waiver of jury trial,  and has been  advised by
counsel as  necessary  or  appropriate.

         WITNESS the due  execution of this Loan  Agreement as a document  under
seal, as of the date first written above.


ATTEST:                                 INFORMAX, INC.


By: /s/ Joseph E. Lehnen                By: /s/ Alex Titomirov         (SEAL)
------------------------------             -----------------------------

Print Name: Joseph E. Lehnen            Print Name: Alex Titomirov
           -------------------                     ---------------------

Title:  CFO                             Title: Chief Executive Officer
      ------------------------

                                        PNC BANK, NATIONAL
                                        ASSOCIATION


                                        By: /s/ Katharine Kappler      (SEAL)
                                           -----------------------------

                                        Print Name: Katherine Kappler
                                                   ---------------------

                                        Title: Vice President
                                              --------------------------








                                       17
<PAGE>

ADDENDUM to that certain Loan  Agreement  dated May ___, 1999 between  InforMax,
Inc.,  as the  Borrower,  and PNC  BANK,  NATIONAL  ASSOCIATION  , as the  Bank.
Capitalized terms used in this Addendum and not otherwise defined shall have the
meanings given them in such Loan Agreement.

                             I. FINANCIAL COVENANTS

1.   The  Borrower  will not permit its  Modified  Tangible Net Worth to be less
     than the  following  amounts  by the end of the fiscal  quarters  specified
     below:


     Quarter Ending                               Tangible Net Worth
     --------------                               ------------------
     June 30, 1999                                    $  424,000
     September 30, 1999                               $  503,000
     December 31, 1999                                $  622,000
     March 31, 2000                                   $  889,000
     June 30, 2000                                    $  957,000
     September 30, 2000                               $1,338,000
     December 31, 2000                                $2,144,000
     March 31, 2001                                   $2,845,000
     June 30, 2001                                    $3,602,000
     September 30, 2001                               $4,798,000
     December 31, 2001                                $5,999,000

2.   The  Borrower  shall  have a minimum  ratio of  Current  Assets to  Current
     Liabilities as follows (measured each month at month end).

                                                       Ratio of Current Assets
     Period                                            to Current Liabilities
     ------                                            ----------------------

     Closing through November 30, 1999                 1.10 to 1.00
     December 1, 1999 through April 30, 2000           1.15 to 1.00

3.   The  Borrower  shall  maintain a minimum  Cash  Balance  during each of the
     periods specified below (measured each month at month end).

     Quarter Ending                              Cash Balance
     --------------                              ------------

     June 30, 1999                                 $  108,000
     September 30, 1999                            $  129,000
     December 31, 1999                             $  139,000
     March 31, 2000                                $  172,000
     June 30, 2000                                 $  155,000
     September 30, 2000                            $  211,000
     December 31, 2000                             $  614,000
     March 31, 2001                                $1,052,000
     June 30, 2001                                 $1,513,000
     September 30, 2001                            $2,219,000
     December 31, 2001                             $2,997,000

                                      A-1
<PAGE>

DEFINITIONS:
------------

     "CASH BALANCE" means the sum of cash and marketable securities.

     "CURRENT ASSETS" means the sum of cash,  accounts receivable and marketable
     securities.

     "CURRENT  LIABILITIES"  means the sum of (a) all current  liabilities other
     than  deferred  revenue plus (b) amounts  outstanding  under the  Revolving
     Credit not classified as current liabilities.

     "MODIFIED TANGIBLE NET WORTH" means Tangible Net Worth plus 75% of deferred
     revenues (calculated in accordance with GAAP).

     "TANGIBLE  NET WORTH" means  shareholders'  equity less  intangible  assets
     (calculated in accordance with generally accepted  accounting  principles),
     plus all equity or subordinated and/or convertible debt investments created
     after the date of this Agreement.






                                      A-2


<PAGE>

                                II. DISCLOSURES
                                ---------------

4.6  TITLE TO ASSETS.
     ----------------

     See Attached Disclosure

4.7  AND 4.10 LITIGATION AND PROCEEDINGS.
              ---------------------------

     See Attached Disclosure

6.1 INDEBTEDNESS
    ------------

     None















                                      A-3

<PAGE>
                                                      EXECUTION COPY

                                 AMENDMENT NO. 1
                                       TO
                                 LOAN AGREEMENT


     THIS AMENDMENT NO. 1 TO LOAN AGREEMENT (this "AMENDMENT"),  is entered into
as of August 6,  1999,  between  INFORMAX,  INC., a Delaware  corporation  (the
"BORROWER"), and PNC BANK, NATIONAL ASSOCIATION (the "BANK").

                                   WITNESSETH:

     WHEREAS,  the Borrower and the Bank entered into a Loan Agreement  dated as
of May 6, 1999 (the "LOAN AGREEMENT")  wherein the Bank agreed to extend certain
credit facilities to the Borrower, including a $200,000 Equipment Line of Credit
(the  "EQUIPMENT  LINE"),  subject to the terms and conditions of the Agreement;
and

     WHEREAS,  the Borrower has requested that the Bank amend the Loan Agreement
to increase the maximum availability under the Equipment Line to $600,000 and to
extend the  amortization  period for each of the First Term Loan and Second Term
Loan (as each is defined in the Agreement) from twenty four to thirty months.

     NOW, THEREFORE,  in consideration of the premises herein and other good and
valuable consideration, the Borrower and the Bank, with the intent to be legally
bound hereby, agree as follows:

     1. DEFINED TERMS.  Capitalized  terms used in this Amendment shall have the
meanings  provided  in the Loan  Agreement  unless  a  different  definition  is
provided herein.

     2.  EQUIPMENT  LINE  AVAILABILITY.   The  maximum  availability  under  the
Equipment Line is hereby increased to $600,000. All Advances under the Equipment
Line  shall  continue  to be  limited  to 80% of the face  amount  of  equipment
invoices (excluding taxes, shipping and installation) submitted with any Advance
Request.

     3.  EXTENSION OF EQUIPMENT  LINE TERM.  Each of the First Term Loan and the
Second Term Loan shall provide for repayment of principal and interest in thirty
(30) equal monthly installments.

     4.  AMENDED  AND  RESTATED  LINE OF CREDIT  NOTE.  Simultaneously  with the
execution and delivery of this Amendment, the Borrower shall execute and deliver
to the Bank an Amended and Restated  Line of Credit Note (the  "AMENDED  NOTE").
Upon receipt of the

<PAGE>

Amended  Note,  the Bank shall  return to the  Borrower  the Line of Credit Note
dated May 6, 1999.

     5.  SECURITY/COLLATERAL.  All  obligations of the Borrowers,  or any one of
them,  to the Bank under the Equipment  Line,  as amended,  and the Amended Note
shall  constitute  Obligations  as  defined  in the  Loan  Agreement  and in the
Security Agreement dated as of May 6, 1999 by and between Borrower and the Bank,
and  shall  be  entitled  to the  benefits  of and be  secured  by the  Security
Documents.

     6.  FACILITY  FEE.  The  Borrower  shall pay to the Bank a facility  fee of
$3,000  (.75% of the  increased  amount of the  Equipment  Line),  payable  upon
execution of this Amendment.

     7.  REPRESENTATIONS  AND  WARRANTIES.  The Borrower  hereby  represents and
warrants to the Bank as follows:

         (a) all representations,  warranties and covenants made by the Borrower
to the Bank that are contained in the Loan Agreement,  as modified  hereby,  the
Amended Note,  and each of the other Loan  Documents are true and correct on and
as of the date  hereof  with the same  effect  as though  such  representations,
warranties  and  covenants  had been made on and as of the date  hereof  (except
representations  and warranties which expressly relate solely to an earlier date
or time, which  representations  and warranties shall be true and correct on and
as of the specific dates or times referred to therein);

         (b) to the Borrower's knowledge,  no event or condition has occurred or
exists which,  with the giving of notice or the passage of time, or both,  would
constitute an Event of Default under any of the Loan Documents;

         (c) the  Borrower has  delivered  copies of its most  recently  amended
Certificate of Incorporation and Bylaws to the Bank together with this Amendment
No. 1, and such amended  Certificate and Bylaws have not been amended,  revised,
supplemented,  restated  or changed in any way since their  respective  dates of
adoption and are still in full force and effect; and

         (d)  the  execution  and  delivery  of  this  Amendment  No.  1 and the
consummation  of the  transactions  contemplated  hereby and by the Note and any
other documents executed by the Borrower required to be delivered to the Bank in
connection  with this  Amendment No. 1 have been duly and validly  authorized by
the Borrower and all such documents  together  constitute  the legal,  valid and
binding  agreement  of  the  Borrower,   enforceable  against  the  Borrower  in
accordance with their respective terms.

     8.  REIMBURSEMENT OF EXPENSES.  The Borrower shall reimburse the Bank, upon
the execution of this  Amendment,  and otherwise on demand,  all  reasonable and
necessary  costs  and  expenses  incurred  by the  Bank in  connection  with the
preparation,  negotiation  and delivery of this  Amendment No. 1 and the Amended
Note and any modifications thereto. The obligations of


                                       2
<PAGE>

the Borrower to pay expenses  hereunder  are in addition to, and not in lieu of,
any similar obligations set forth in the Loan Agreement.

     9.  COUNTERPARTS.  This  Amendment  No.  1 may be  executed  in one or more
counterparts by any party hereto in separate counterparts, each of which when so
executed and delivered to the other party shall be deemed an original.  All such
counterparts together shall constitute one and the same instrument.

     10. WAIVERS.  This Amendment No. 1 shall not, except as expressly set forth
above,  serve to waive,  supplement  or amend  the Loan  Agreement,  which  Loan
Agreement shall remain in full force and effect as amended hereby.


                           [Signature Page to Follow]
















                                       3
<PAGE>

     WITNESS the due execution of this  Amendment  No. 1 to Loan  Agreement as a
document under seal, as of the date first written above.

ATTEST:                                     INFORMAX, INC.



By:  /s/ Brigitta Lipsky                    By: /s/ Joseph E. Lehnen
   _________________________                    _________________________ (SEAL)

Print Name: Brigitta Lipsky                 Print Name: Joseph E. Lehnen
            ________________                            _________________

Title:  Controller                          Title:  Chief Financial Officer
      ______________________                       __________________________


                                            PNC BANK,
                                            NATIONAL ASSOCIATION


                                            By: /s/ Katharine Kappler
                                                _________________________ (SEAL)

                                            Print Name: Katharine Kappler
                                                        _________________

                                            Title: Vice President
                                                   ________________________















                                       4
<PAGE>
                                                                  EXECUTION COPY

                                 AMENDMENT NO. 2
                                       TO
                                 LOAN AGREEMENT


     THIS AMENDMENT NO. 2 TO LOAN AGREEMENT ("AMENDMENT NO. 2"), is entered into
as of November  30, 1999 (the  "AMENDMENT  DATE"),  between  INFORMAX,  INC.,  a
Delaware  corporation (the "BORROWER"),  and PNC BANK, NATIONAL ASSOCIATION (the
"BANK").

                                   WITNESSETH:

     WHEREAS,  the Borrower and the Bank entered into a Loan Agreement  dated as
of May 6, 1999 (the "ORIGINAL LOAN AGREEMENT") wherein the Bank agreed to extend
certain  credit  facilities  to the  Borrower,  including  an  $800,000  Secured
Revolving  Credit (the  "REVOLVING  CREDIT")  and a $200,000  Equipment  Line of
Credit  (the  "EQUIPMENT  LINE"),  subject  to the terms and  conditions  of the
Original Loan Agreement; and

     WHEREAS,  the Borrower and the Bank entered into an Amendment No. 1 to Loan
Agreement, dated as of August 6, 1999 ("AMENDMENT NO. 1"), pursuant to which the
parties  agreed to  increase  the  Equipment  Line to  $600,000  and  extend the
amortization  term for each of the  First  Term Loan and  Second  Term Loan (the
Original Loan  Agreement as amended by Amendment No. 1, is referred to herein as
the "LOAN AGREEMENT"); and

     WHEREAS,  the Borrower has  requested  that the Bank further amend the Loan
Agreement to (i) increase the maximum  availability  under each of the Revolving
Credit and the  Equipment  Line to  $1,000,000,  (ii) adjust the interest  rates
applicable  to each of the  Revolving  Credit and the  Equipment  Line and (iii)
modify certain covenants of the Borrower as described in this Second Amendment.

     NOW, THEREFORE,  in consideration of the premises herein and other good and
valuable consideration, the Borrower and the Bank, with the intent to be legally
bound hereby, agree as follows:

     1. DEFINED TERMS. Capitalized terms used in this Amendment No. 2 shall have
the meanings  provided in the Loan  Agreement  unless a different  definition is
provided herein.

     2. AVAILABILITY.

         (a) The  maximum  availability  under  the  Revolving  Credit is hereby
increased  to  $1,000,000  as of the  Amendment  Date.  All  Advances  under the
Revolving  Credit  shall  continue  to be  subject  to  the  limitations  of the
Borrowing Base Rider attached to the Loan Agreement as

<PAGE>

Exhibit A.

         (b) Equipment Line. The maximum  availability  under the Equipment Line
is hereby  increased to $1,000,000 as of the Amendment  Date. All Advances under
the  Equipment  Line shall be limited  to 100% of the face  amount of  equipment
invoices (excluding taxes, shipping and installation) submitted with any Advance
Request.

     3.  ADJUSTMENT  OF INTEREST  RATES.  Effective  as of the  Amendment  Date,
interest shall accrue at a rate of

         (a) Prime plus  1.00% per annum on all  amounts  outstanding  under the
Revolving Credit; and

         (b) Prime plus  1.25% per annum on all  amounts  outstanding  under the
Equipment Line.

The foregoing  interest rates shall apply to all amounts  outstanding  under the
Revolving  Credit and  Equipment  Line as of the Amendment  Date,  respectively,
without regard to whether Advances under such Revolving Credit or Equipment Line
were made before or after the Amendment Date.

     4. MODIFICATION OF CERTAIN COVENANTS.

         (a)  Monthly  Reporting  Requirements.   Section  5.2(a)  of  the  Loan
Agreement is hereby  amended to provide that the Borrower  shall satisfy each of
the reporting obligations under Section 5.2(a) within thirty (30) days after the
end of each month.

         (b)  Financial  Covenants.  Section  I of  the  Addendum  to  the  Loan
Agreement is hereby amended and restated in its entirety as follows:

                             I. FINANCIAL COVENANTS

1.   The  Borrower  will not permit its  Modified  Tangible Net Worth to be less
     than the  following  amounts  by the end of the fiscal  quarters  specified
     below:

     Quarter Ending                          Tangible Net Worth
     --------------                          ------------------
     June 30, 1999                           $  424,000
     September 30, 1999                      $  503,000
     December 31, 1999                       $2,794,000
     March 31, 2000                          $3,174,000
     June 30, 2000                           $3,097,000
     September 30, 2000                      $2,846,000

     Beginning with the quarter ending December 31, 2000, the Borrower shall not
     experience two consecutive quarters of Negative Net Operating Income.


                                       2
<PAGE>

2.   The  Borrower  shall  have a minimum  ratio of  Current  Assets to  Current
     Liabilities as follows (measured each month at month end).

                                                 Ratio of Current Assets
     Period                                      to Current Liabilities
     ------                                      --------------------------
     Closing through November 30, 1999           1.10 to 1.00
     December 1, 1999 through April 30, 2000     1.15 to 1.00

3.   The  Borrower  shall  maintain a minimum  Cash  Balance  during each of the
     periods specified below (measured each month at month end).

     Quarter Ending                         Cash Balance
     --------------                         ------------
     June 30, 1999                          $  108,000
     September 30, 1999                     $  129,000
     December 31, 1999                      $  750,000
     March 31, 2000                         $  750,000
     June 30, 2000                          $  750,000
     September 30, 2000                     $  750,000
     December 31, 2000                      $  750,000
     March 31, 2001                         $1,052,000
     June 30, 2001                          $1,513,000
     September 30, 2001                     $2,219,000
     December 31, 2001                      $2,997,000

DEFINITIONS:

     "CASH BALANCE" means the sum of cash and marketable securities.

     "CURRENT ASSETS" means the sum of cash,  accounts receivable and marketable
     securities.

     "CURRENT  LIABILITIES"  means the sum of (a) all current  liabilities other
     than  deferred  revenue plus (b) amounts  outstanding  under the  Revolving
     Credit not classified as current liabilities.

     "MODIFIED TANGIBLE NET WORTH" means Tangible Net Worth plus 75% of deferred
     revenues (calculated in accordance with GAAP).

     "NEGATIVE NET OPERATING  INCOME" means  earnings  before  interest,  taxes,
     depreciation and amortization  less than zero calculated in accordance with
     generally accepted accounting principles.


                                       3
<PAGE>

     "TANGIBLE  NET WORTH" means  shareholders'  equity less  intangible  assets
     (calculated in accordance with generally accepted  accounting  principles),
     plus all equity or subordinated and/or convertible debt investments created
     after the date of this Agreement.

     5. AMENDED  NOTES.  Simultaneously  with the execution and delivery of this
Amendment  No. 2, the Borrower  shall execute and deliver to the Bank an Amended
and Restated  Line of Credit Note and a Second  Amended and  Restated  Equipment
Line Note (the "AMENDED NOTES").

     6.  SECURITY/COLLATERAL.  All  obligations of the Borrowers,  or any one of
them, to the Bank under the Revolving Credit and the Equipment Line, as amended,
and the  Amended  Notes  shall  constitute  Obligations  as  defined in the Loan
Agreement and in the Security  Agreement  dated as of May 6, 1999 by and between
Borrower  and the Bank,  and shall be entitled to the benefits of and be secured
by the Security Documents.

     7. FACILITY  FEE. The Borrower  shall pay to the Bank (a) a facility fee of
$4,500 (.75% of the increased amount of the Facility),  and (b) an amendment fee
of $2,500 (.125% of the aggregate amount of the Facility,  each such fee payable
upon execution of this Amendment No. 2.

     8.  REPRESENTATIONS  AND  WARRANTIES.  The Borrower  hereby  represents and
warrants to the Bank as follows:

         (a) all representations,  warranties and covenants made by the Borrower
to the Bank that are contained in the Loan Agreement,  as modified  hereby,  the
Amended Notes,  and each of the other Loan Documents are true and correct on and
as of the date  hereof  with the same  effect  as though  such  representations,
warranties  and  covenants  had been made on and as of the date  hereof  (except
representations  and warranties which expressly relate solely to an earlier date
or time, which  representations  and warranties shall be true and correct on and
as of the specific dates or times referred to therein);

         (b) to the Borrower's knowledge,  no event or condition has occurred or
exists which,  with the giving of notice or the passage of time, or both,  would
constitute an Event of Default under any of the Loan Documents;

         (c) the  Borrower has  delivered  copies of its most  recently  amended
Certificate of Incorporation and Bylaws to the Bank together with this Amendment
No. 2, and such amended  Certificate and Bylaws have not been amended,  revised,
supplemented,  restated  or changed in any way since their  respective  dates of
adoption and are still in full force and effect; and


                                       4
<PAGE>

         (d)  the  execution  and  delivery  of  this  Amendment  No.  2 and the
consummation of the  transactions  contemplated  hereby and by the Amended Notes
and any other documents executed by the Borrower required to be delivered to the
Bank in  connection  with  this  Amendment  No. 2 have  been  duly  and  validly
authorized by the Borrower and all such documents together constitute the legal,
valid and binding agreement of the Borrower, enforceable against the Borrower in
accordance with their respective terms.

     9.  REIMBURSEMENT OF EXPENSES.  The Borrower shall reimburse the Bank, upon
the execution of this  Amendment,  and otherwise on demand,  all  reasonable and
necessary  costs  and  expenses  incurred  by the  Bank in  connection  with the
preparation,  negotiation  and delivery of this  Amendment No. 2 and the Amended
Notes and any  modifications  thereto.  The  obligations  of the Borrower to pay
expenses  hereunder  are in  addition  to,  and  not in  lieu  of,  any  similar
obligations set forth in the Loan Agreement.

     10. NOTICES. The addresses for notices provided in Section 11.1 of the Loan
Agreement are hereby amended and restated as follows:

To the Bank:                                To the Borrower:

PNC Bank, National Association              InforMax, Inc.
Venture Bank @ PNC                          6010 Executive Boulevard
11600 Sunrise Valley Drive                  N. Bethesda, MD  20852
Reston, VA  20191                           Attention:  Joseph Lehnen
Attention:  Katharine S. Kappler            Facsimile No.:  240-223-0025
Facsimile No.:  703-391-9734

     11.  COUNTERPARTS.  This  Amendment  No. 2 may be  executed  in one or more
counterparts by any party hereto in separate counterparts, each of which when so
executed and delivered to the other party shall be deemed an original.  All such
counterparts together shall constitute one and the same instrument.

     12. WAIVERS.  This Amendment No. 2 shall not, except as expressly set forth
above,  serve to waive,  supplement  or amend  the Loan  Agreement,  which  Loan
Agreement shall remain in full force and effect as amended hereby.





                           [Signature Page to Follow]

                                       5
<PAGE>

     WITNESS the due execution of this  Amendment  No. 2 to Loan  Agreement as a
document under seal, as of the date first written above.

ATTEST:                                     INFORMAX, INC.



By: /s/ Joseph E. Lehnen                     By: /s/ Alex Titomirov
    ________________________                   _________________________ (SEAL)

Print Name: Joseph E. Lehnen                Print Name: Alex Titomirov
            ________________                            _________________

Title: Chief Financial Officer              Title: President/CEO
      ________________________                     ______________


                                            PNC BANK,
                                            NATIONAL ASSOCIATION


                                            By: /s/ Katherine Kappler
                                              _________________________ (SEAL)

                                            Print Name: Katherine Kappler
                                                        _________________

                                            Title: Vice President
                                                  __________________________















                                       6
<PAGE>

                                                                  EXECUTION COPY

                                 AMENDMENT NO. 3
                                       TO
                                 LOAN AGREEMENT


     THIS AMENDMENT NO. 3 TO LOAN AGREEMENT ("AMENDMENT NO. 3"), is entered into
as of February 7 2000 (the "AMENDMENT DATE"), between INFORMAX, INC., a Delaware
corporation (the "BORROWER"), and PNC BANK, NATIONAL ASSOCIATION (the "BANK").

                                   WITNESSETH:

         WHEREAS,  the Borrower and the Bank entered into a Loan Agreement dated
as of May 6, 1999 (the  "ORIGINAL  LOAN  AGREEMENT")  wherein the Bank agreed to
extend certain credit facilities to the Borrower,  including an $800,000 Secured
Revolving  Credit (the  "REVOLVING  CREDIT")  and a $200,000  Equipment  Line of
Credit  (the  "EQUIPMENT  LINE"),  subject  to the terms and  conditions  of the
Original Loan Agreement; and

     WHEREAS,  the Borrower and the Bank entered into an Amendment No. 1 to Loan
Agreement, dated as of August 6, 1999 ("AMENDMENT NO. 1"), pursuant to which the
parties  agreed to  increase  the  Equipment  Line to  $600,000  and  extend the
amortization term for each of the First Term Loan and Second Term Loan; and

     WHEREAS,  the Borrower and the Bank entered into an Amendment No. 2 to Loan
Agreement,  dated as of November 30, 1999 ("AMENDMENT NO. 2"), pursuant to which
the parties  agreed to (i) increase the maximum  availability  under each of the
Revolving Credit and the Equipment Line to $1,000,000,  (ii) adjust the interest
rates  applicable  to each of the Revolving  Credit and the  Equipment  Line and
(iii) modify  certain  covenants of the Borrower as described in Amendment No. 2
(the Original Loan  Agreement as amended by Amendment No. 1 and Amendment No. 2,
is referred to herein as the "LOAN AGREEMENT"); and

     WHEREAS,  the Borrower has  requested  that the Bank further amend the Loan
Agreement to (i) increase the maximum  availability  under each of the Revolving
Credit and the Equipment Line to $3,000,000, (ii) extend the expiration date for
the  Revolving  Credit,  and (iii) modify  certain  covenants of the Borrower as
described in this Amendment No. 3.

     NOW, THEREFORE,  in consideration of the premises herein and other good and
valuable consideration, the Borrower and the Bank, with the intent to be legally
bound hereby, agree as follows:

<PAGE>

     1. DEFINED TERMS. Capitalized terms used in this Amendment No. 3 shall have
the meanings  provided in the Loan  Agreement  unless a different  definition is
provided herein.

     2. EXPIRATION  DATE. The "REVOLVING  CREDIT  EXPIRATION  DATE" shall be the
date three hundred sixty four (364) days after the Amendment Date.

     3. AVAILABILITY.

         (a)  Revolving  Credit.  The maximum  availability  under the Revolving
Credit is hereby  increased to $3,000,000 as of the Amendment Date. All Advances
under the Revolving  Credit shall  continue to be subject to the  limitations of
the Borrowing Base Rider attached to the Loan Agreement as Exhibit A.

         (b) Equipment Line. The maximum  availability  under the Equipment Line
is hereby  increased to $3,000,000 as of the Amendment  Date. All Advances under
the  Equipment  Line shall be limited  to 100% of the face  amount of  equipment
invoices (excluding taxes, shipping and installation) submitted with any Advance
Request.

     4.  ADJUSTMENT  OF INTEREST  RATES.  Effective  as of the  Amendment  Date,
interest shall accrue at a rate of

         (a) Prime plus  1.00% per annum on all  amounts  outstanding  under the
Revolving Credit; and

         (b) Prime plus  1.25% per annum on all  amounts  outstanding  under the
Equipment Line.

The foregoing  interest rates shall apply to all amounts  outstanding  under the
Revolving  Credit and  Equipment  Line as of the Amendment  Date,  respectively,
without regard to whether Advances under such Revolving Credit or Equipment Line
were made before or after the Amendment Date.

     5. MODIFICATION OF CERTAIN COVENANTS. Section I of the Addendum to the Loan
Agreement is hereby amended and restated in its entirety as follows:

                             I. FINANCIAL COVENANTS

1.   The  Borrower  will not permit its  Modified  Tangible Net Worth to be less
     than the  following  amounts  by the end of the fiscal  quarters  specified
     below:

     Quarter Ending                         Tangible Net Worth
     --------------                         ------------------
     March 31, 2000                         $2,900,000
     June 30, 2000                          $2,900,000
     September 30, 2000                     $2,300,000
     December 31, 2000                      $3,100,000

<PAGE>

     Beginning with the quarter ending December 31, 2000, the Borrower shall not
     experience two consecutive quarters of Negative Net Operating Income.

2.   The Borrower  shall at all times during the term of this  Agreement  have a
     minimum  ratio of  Current  Assets to Current  Liabilities  of 1.50 to 1.00
     (measured each month at month end).

3.   The Borrower shall at all times during the term of this Agreement  maintain
     a minimum Cash Balance of $750,000 (measured each month at month end).

4.   The Borrower shall at all times during the term of this Agreement  maintain
     a maximum  ratio of Modified  Total  Liabilities  to Modified  Tangible Net
     Worth of 1.50 to 1.00 (measured each month at month end).

DEFINITIONS:

     "CASH BALANCE" means the sum of cash and marketable securities.

     "CURRENT ASSETS" means the sum of cash,  accounts receivable and marketable
     securities.

     "CURRENT  LIABILITIES"  means the sum of (a) all current  liabilities other
     than  deferred  revenue plus (b) amounts  outstanding  under the  Revolving
     Credit not classified as current liabilities.

     "MODIFIED TOTAL  LIABILITIES"  means all current and long term liabilities,
     less deferred revenues.

     "MODIFIED TANGIBLE NET WORTH" means Tangible Net Worth plus 75% of deferred
     revenues (calculated in accordance with GAAP).

     "NEGATIVE NET OPERATING  INCOME" means  earnings  before  interest,  taxes,
     depreciation and amortization  less than zero calculated in accordance with
     generally accepted accounting principles.

     "TANGIBLE  NET WORTH" means  shareholders'  equity less  intangible  assets
     (calculated in accordance with generally accepted  accounting  principles),
     plus all equity or subordinated and/or convertible debt investments created
     after the date of this Agreement.



     6. AMENDED  NOTES.  Simultaneously  with the execution and delivery of this
Amendment  No. 3, the  Borrower  shall  execute and deliver to the Bank a Second
Amended  and  Restated  Line of Credit  Note and a Third  Amended  and  Restated
Equipment Line of Credit Note (the "AMENDED NOTES").

<PAGE>

     7.  SECURITY/COLLATERAL.  All  obligations of the Borrowers,  or any one of
them, to the Bank under the Revolving Credit and the Equipment Line, as amended,
and the  Amended  Notes  shall  constitute  Obligations  as  defined in the Loan
Agreement and in the Security  Agreement  dated as of May 6, 1999 by and between
Borrower  and the Bank,  and shall be entitled to the benefits of and be secured
by the Security Documents.

     8. FACILITY  FEE. The Borrower  shall pay to the Bank (a) a facility fee of
$20,000 (.50% of the increased amount of the Facility), and (b) an amendment fee
of $7,500 (.125% of the aggregate amount of the Facility), each such fee payable
upon execution of this Amendment No. 3.

     9.  REPRESENTATIONS  AND  WARRANTIES.  The Borrower  hereby  represents and
warrants to the Bank as follows:

         (a) all representations,  warranties and covenants made by the Borrower
to the Bank that are contained in the Loan Agreement,  as modified  hereby,  the
Amended Notes,  and each of the other Loan Documents are true and correct on and
as of the date  hereof  with the same  effect  as though  such  representations,
warranties  and  covenants  had been made on and as of the date  hereof  (except
representations  and warranties which expressly relate solely to an earlier date
or time, which  representations  and warranties shall be true and correct on and
as of the specific dates or times referred to therein);

         (b) to the Borrower's knowledge,  no event or condition has occurred or
exists which,  with the giving of notice or the passage of time, or both,  would
constitute an Event of Default under any of the Loan Documents;

         (c) the  Borrower has  delivered  copies of its most  recently  amended
Certificate of Incorporation and Bylaws to the Bank together with this Amendment
No. 3, and such amended  Certificate and Bylaws have not been amended,  revised,
supplemented,  restated  or changed in any way since their  respective  dates of
adoption and are still in full force and effect; and

         (d)  the  execution  and  delivery  of  this  Amendment  No.  3 and the
consummation of the  transactions  contemplated  hereby and by the Amended Notes
and any other documents executed by the Borrower required to be delivered to the
Bank in  connection  with  this  Amendment  No. 3 have  been  duly  and  validly
authorized by the Borrower and all such documents together constitute the legal,
valid and binding agreement of the Borrower, enforceable against the Borrower in
accordance with their respective terms.

     10. REIMBURSEMENT OF EXPENSES.  The Borrower shall reimburse the Bank, upon
the execution of this  Amendment,  and otherwise on demand,  all  reasonable and
necessary  costs  and  expenses  incurred  by the  Bank in  connection  with the
preparation,  negotiation  and delivery of this  Amendment No. 3 and the Amended
Notes and any  modifications  thereto.  The  obligations

<PAGE>

of the  Borrower to pay expenses  hereunder  are in addition to, and not in lieu
of, any similar obligations set forth in the Loan Agreement.

     11. NOTICES. The addresses for notices provided in Section 11.1 of the Loan
Agreement are hereby amended and restated as follows:

To the Bank:                                To the Borrower:

PNC Bank, National Association              InforMax, Inc.
Venture Bank @ PNC                          6010 Executive Boulevard
11600 Sunrise Valley Drive                  N. Bethesda, MD  20852
Reston, VA  20191                           Attention:  Joseph Lehnen
Attention:  Katharine S. Kappler            Facsimile No.:  240-223-0025
Facsimile No.:  703-391-9734

     12.  COUNTERPARTS.  This  Amendment  No. 3 may be  executed  in one or more
counterparts by any party hereto in separate counterparts, each of which when so
executed and delivered to the other party shall be deemed an original.  All such
counterparts together shall constitute one and the same instrument.

     13. WAIVERS.  This Amendment No. 3 shall not, except as expressly set forth
above,  serve to waive,  supplement  or amend  the Loan  Agreement,  which  Loan
Agreement shall remain in full force and effect as amended hereby.


                           [Signature Page to Follow]

<PAGE>

     WITNESS the due execution of this  Amendment  No. 3 to Loan  Agreement as a
document under seal, as of the date first written above.

ATTEST:                                     INFORMAX, INC.



By: /s/ Joseph E. Lehnen                     By: /s/ Alex Titomirov
    ________________________                   _________________________ (SEAL)

Print Name: Joseph E. Lehnen                Print Name: Alex Titomirov
            ________________                            _________________

Title: CEO                                  Title: CEO
      ________________________                     ______________


                                            PNC BANK,
                                            NATIONAL ASSOCIATION


                                            By: /s/ Katherine Kappler
                                              _________________________ (SEAL)

                                            Print Name: Katherine Kappler
                                                        _________________

                                            Title: Vice President
                                                  __________________________











<PAGE>

                                                              K&L DRAFT: 4/13/00

                                 AMENDMENT NO. 4
                                       TO
                                 LOAN AGREEMENT

     THIS AMENDMENT NO. 4 TO LOAN AGREEMENT ("AMENDMENT NO. 4"), effective as of
February 29, 2000 (the "AMENDMENT  DATE"),  between  INFORMAX,  INC., a Delaware
corporation (the "BORROWER"), and PNC BANK, NATIONAL ASSOCIATION (the "BANK").

                                   WITNESSETH:

     WHEREAS,  the Borrower and the Bank entered into a Loan Agreement  dated as
of May 6, 1999 (the "ORIGINAL LOAN AGREEMENT") wherein the Bank agreed to extend
certain  credit  facilities  to the  Borrower,  including  an  $800,000  Secured
Revolving  Credit (the  "REVOLVING  CREDIT")  and a $200,000  Equipment  Line of
Credit  (the  "EQUIPMENT  LINE"),  subject  to the terms and  conditions  of the
Original Loan Agreement; and

     WHEREAS,  the Borrower and the Bank entered into an Amendment No. 1 to Loan
Agreement, dated as of August 6, 1999 ("AMENDMENT NO. 1"), pursuant to which the
parties  agreed to  increase  the  Equipment  Line to  $600,000  and  extend the
amortization term for each of the First Term Loan and Second Term Loan; and

     WHEREAS,  the Borrower and the Bank entered into an Amendment No. 2 to Loan
Agreement,  dated as of November 30, 1999 ("AMENDMENT NO. 2"), pursuant to which
the parties  agreed to (i) increase the maximum  availability  under each of the
Revolving Credit and the Equipment Line to $1,000,000,  (ii) adjust the interest
rates  applicable  to each of the Revolving  Credit and the  Equipment  Line and
(iii) modify certain  covenants of the Borrower as described in Amendment No. 2;
and

     WHEREAS,  the Borrower and the Bank entered into an Amendment No. 3 to Loan
Agreement,  dated as of February __, 2000  ("AMENDMENT NO. 3") pursuant to which
the parties  agreed to (i) increase the maximum  availability  under each of the
Revolving  Credit  and  the  Equipment  Line  to  $3,000,000,  (ii)  extend  the
expiration  date for the Revolving  Credit,  and (iii) modify certain  financial
covenants of the Borrower (the Original Loan Agreement,  as amended by Amendment
No. 1,  Amendment No. 2 and Amendment No. 3, is referred to herein as the ("LOAN
AGREEMENT"); and

     WHEREAS,  the Borrower has  requested  that the Bank further amend the Loan
Agreement to modify the definition of "Cash Balance" as such term is used in one
or more of the Borrower's financial covenants,  set forth in the Addendum to the
Loan Agreement.

<PAGE>

         NOW, THEREFORE,  in consideration of the premises herein and other good
and valuable  consideration,  the  Borrower and the Bank,  with the intent to be
legally bound hereby, agree as follows:

     1. DEFINED TERMS. Capitalized terms used in this Amendment No. 4 shall have
the meanings  provided in the Loan  Agreement  unless a different  definition is
provided herein.

     2. MODIFICATION OF CERTAIN COVENANTS.  The definition of "Cash Balance" set
forth in the Addendum to the Loan  Agreement  is hereby  amended and restated in
its entirety as follows:

         "CASH BALANCE" means the sum of cash and marketable  securities plus an
         amount equal to the Borrower's excess  availability under the Revolving
         Credit.

     3.  REPRESENTATIONS  AND  WARRANTIES.  The Borrower  hereby  represents and
warrants to the Bank as follows:

         (a) all representations,  warranties and covenants made by the Borrower
to the Bank that are contained in the Loan Agreement,  as modified  hereby,  and
each of the other  Loan  Documents  are true and  correct  on and as of the date
hereof  with the same  effect as though  such  representations,  warranties  and
covenants had been made on and as of the date hereof (except representations and
warranties  which  expressly  relate  solely to an earlier  date or time,  which
representations  and  warranties  shall  be true  and  correct  on and as of the
specific dates or times referred to therein);

         (b) to the Borrower's knowledge,  no event or condition has occurred or
exists which,  with the giving of notice or the passage of time, or both,  would
constitute an Event of Default under any of the Loan Documents;

         (c) the  copies of the  Borrower's  Certificate  of  Incorporation  and
Bylaws  most  recently  delivered  to the Bank have not been  amended,  revised,
supplemented,  restated  or changed in any way since their  respective  dates of
adoption and are still in full force and effect; and

         (d)  the  execution  and  delivery  of  this  Amendment  No.  4 and the
consummation of the  transactions  contemplated  hereby and by the Amended Notes
and any other documents executed by the Borrower required to be delivered to the
Bank in  connection  with  this  Amendment  No. 4 have  been  duly  and  validly
authorized by the Borrower and all such documents together constitute the legal,
valid and binding agreement of the Borrower, enforceable against the Borrower in
accordance with their respective terms.

     4.  REIMBURSEMENT OF EXPENSES.  The Borrower shall reimburse the Bank, upon
the execution of this  Amendment No. 4, and otherwise on demand,  all reasonable
and necessary  costs and expenses  incurred by the Bank in  connection  with the
preparation,   negotiation  and  delivery  of  this  Amendment  No.  4  and  any
modifications hereto. The obligations of the

<PAGE>

Borrower to pay expenses  hereunder  are in addition to, and not in lieu of, any
similar obligations set forth in the Loan Agreement.

     5.  COUNTERPARTS.  This  Amendment  No.  4 may be  executed  in one or more
counterparts by any party hereto in separate counterparts, each of which when so
executed and delivered to the other party shall be deemed an original.  All such
counterparts together shall constitute one and the same instrument.

     6.  LIMITATION  OF  WAIVERS.  This  Amendment  No. 4 shall  not,  except as
expressly  set  forth  above,  serve to  waive,  supplement  or  amend  the Loan
Agreement, which Loan Agreement shall remain in full force and effect as amended
hereby.


                           [Signature Page to Follow]

<PAGE>

     WITNESS the due execution of this  Amendment  No. 4 to Loan  Agreement as a
document under seal, as of the date first written above.

ATTEST:                                     INFORMAX, INC.


ATTEST:                                     INFORMAX, INC.



By: /s/ Cecile A. Thorp                     By: /s/ Alex Titomirov
    ________________________                   _________________________ (SEAL)

Print Name: Cecile A. Thorp                Print Name: Alex Titomirov
            ________________                            _________________

Title: Benefits Administrator              Title: President/CEO
      ________________________                     ______________


Original documents                          PNC BANK,
appeared and signed before                  NATIONAL ASSOCIATION
me this 17th day of
April, 2000                                 By: /s/ Katharine Kappler
                                                _________________________ (SEAL)

                                            Print Name: Katharine Kappler
                                                        _________________
Notary Public
State of Maryland
Commission expires:
February 3, 2004                            Title: Managing Director
                                                __________________________

<PAGE>


                                 AMENDMENT NO. 5

                                       TO

                                 LOAN AGREEMENT

     THIS  AMENDMENT NO. 5 TO LOAN  AGREEMENT (" AMENDMENT NO. 5"),  dated as of
June 19,  2000 (the  "AMENDMENT  DATE"),  between  INFORMAX,  INC.,  a  Delaware
corporation (the "BORROWER"), and PNC BANK, NATIONAL ASSOCIATION (the "BANK").

                                  WITNESSETH:

     WHEREAS,  the Borrower and the Bank entered into a Loan Agreement  dated as
of May 6, 1999 (the "ORIGINAL LOAN AGREEMENT") wherein the Bank agreed to extend
certain  credit  facilities  to the  Borrower,  including  an  $800,000  Secured
Revolving  Credit (the  "REVOLVING  CREDIT")  and a $200,000  Equipment  Line of
Credit  (the  "EQUIPMENT  LINE"),  subject  to the terms and  conditions  of the
Original Loan Agreement; and

     WHEREAS,  the Borrower and the Bank entered into an Amendment No. 1 to Loan
Agreement, dated as of August 6, 1999 ("AMENDMENT NO. 1"), pursuant to which the
parties  agreed to  increase  the  Equipment  Line to  $600,000  and  extend the
amortization term for each of the First Term Loan and Second Term Loan; and

     WHEREAS,  the Borrower and the Bank entered into an Amendment No. 2 to Loan
Agreement,  dated as of November 30, 1999 ("AMENDMENT NO. 2"), pursuant to which
the parties  agreed to (i) increase the maximum  availability  under each of the
Revolving Credit and the Equipment Line to $1,000,000,  (ii) adjust the interest
rates  applicable  to each of the Revolving  Credit and the  Equipment  Line and
(iii) modify certain  covenants of the Borrower as described in Amendment No. 2;
and

     WHEREAS,  the Borrower and the Bank entered into an Amendment No. 3 to Loan
Agreement,  dated as of February 7, 2000  ("AMENDMENT  NO. 3") pursuant to which
the parties  agreed to (i) increase the maximum  availability  under each of the
Revolving  Credit  and  the  Equipment  Line  to  $3,000,000,  (ii)  extend  the
expiration  date for the Revolving  Credit,  and (iii) modify certain  financial
covenants of the Borrower; and

     WHEREAS,  the Borrower and the Bank entered into an Amendment No. 4 to Loan
Agreement,  effective  as of February 29, 2000  ("AMENDMENT  NO. 4") pursuant to
which the parties agreed to modify the definition of "Cash Balance" set forth in
the Addendum to the Original Loan  Agreement  (the Original Loan  Agreement,  as
amended by Amendment No. 1, Amendment No. 2, Amendment No. 3 and Amendment No. 4
is referred to herein as the "LOAN AGREEMENT"); and

<PAGE>

     WHEREAS,  the Borrower has  requested  that the Bank further amend the Loan
Agreement  to (i)  provide  a  %3,000,000  bridge  loan to fund  the  Borrower's
operating expenses; (ii) modify certain financial covenants of the Borrower.

     NOW, THEREFORE,  in consideration of the premises herein and other good and
valuable consideration, the Borrower and the Bank, with the intent to be legally
bound hereby, agree as follows:

     1. DEFINED TERMS. Capitalized terms used in this Amendment No. 5 shall have
the meanings  provided in the Loan  Agreement  unless a different  definition is
provided herein.

     2. FACILITY.  The term "Facility" is hereby amended to include a $3,000,000
Bridge Loan ("BRIDGE LOAN").  The proceeds of the Bridge Loan shall be used only
for funding operating expenses.

     3. BRIDGE LOAN EXPIRATION DATE. All outstanding borrowings under the Bridge
Loan,  together with all fees and expenses  related thereto and interest accrued
thereon,  shall  become due and  payable in their  entirety  upon the earlier to
occur of (i)  December  19,  2000 and (ii)  closing  date of an  initial  public
offering of any capital  stock of the Borrower or any other equity event whereby
any holder or holders  of the  Borrower's  capital  stock  infuse(s)  additional
assets,  whereby  cash or  non-cash,  to Borrower  either as a  contribution  of
capital,  loan or otherwise of at least  $3,000,000 (the "BRIDGE LOAN EXPIRATION
DATE").

     4. MANDATORY PREPAYMENTS.  The Borrower shall made Mandatory Prepayments as
follows:

        (i)    From Effective Date through  Expiration  Date. From the effective
               date of this  Amendment No. 5 through the Bridge Loan  Expiration
               Date, all contributions to the equity of the Borrower,  including
               but not limited to funds raised through venture  capital rounds,
               sales of equity to strategic  investors,  private placements,  or
               other sales of equity,  will give rise to an obligation to make a
               prepayment  (a  "MANDATORY  PREPAYMENT")  to the Bank on the same
               Business  Day in the  amount of the equity  contribution,  net of
               reasonable  expenses,  up to the maximum  aggregate amount of the
               principal  amount of the Bridge Loan outstanding at such date and
               accrued interest thereon; provided, however, contributions to the
               Borrower's  equity in an  aggregate  amount of up to Four Million
               Dollars ($4,000,000) from Emerging Tech Ventures,  Cogene Biotech
               Ventures  and   Partech   International,   or  their   respective
               affiliates, will not cause a Mandatory Prepayment.

        (ii)   Application of Prepayments. Mandatory Prepayments will be applied
               first to accrued interest and then to principal.  Amounts prepaid
               may not be reborrowed.

                                       -2-

<PAGE>

     5. INTEREST  RATE.  The interest rate for the Bridge Loan is the Prime Rate
(as  defined in the Loan  Agreement)  plus 2.50% per  annum.  Interest  shall be
calculated  on the basis of a year of 360 days and shall be  payable  monthly in
arrears.

     6. FACILITY FEE. The Borrower  shall pay the Bank a facility fee of $7,500,
payable upon the execution of this Amendment No. 5.

     7.  AVAILABILITY.  Subject  to the  other  terms  and  conditions  of  this
Amendment  No. 5 and provided  that the Borrower is in  compliance  with all the
other terms and  conditions of the Loan  Agreement,  the Borrower may draw up to
$1,500,000  within 10 days of the  execution of this  Amendment  No. 5 and up to
$500,000 (in increments of $250,000) each month for the three months  thereafter
up to a maximum aggregate amount of $3,000,000.

     8. BRIDGE LOAN NOTE.  The obligation of the Borrower to repay the aggregate
unpaid  principal  amount of the Bridge Loan,  together with  interest  thereon,
shall be  evidenced  by a promissory  note of the  Borrower  attached  hereto as
Exhibit A (the "BRIDGE NOTE" and together with the Revolving Credit Note and the
Term Note, as amended, the "NOTES") payable to the order of the Bank.

     9. MODIFICATION OF CERTAIN COVENANTS. Section I of the Addendum to the Loan
Agreement is hereby amended and restated in its entirety as follows:

                            "I. FINANCIAL COVENANTS

1. The Borrower will not permit its Modified  Tangible Net Worth to be less than
the following amounts by the end of the fiscal quarters specified below:

            ------------------------------------------------
            Quarter Ending             Modified Tangible Net
            --------------             ---------------------
                                       Worth
                                       -----
            ------------------------------------------------
            June 30, 2000              $1,078,000
            ------------------------------------------------
            September 30, 2000            357,000
            ------------------------------------------------
            December 31, 2000           3,006,000
            ------------------------------------------------

   Beginning with the quarter ending December 31, 2000, the Borrower  shall  not
not experience two consecutive quarters of Negative Net Operating Income.

2. The  Borrower  shall at all times  during the term of this  Agreement  have a
minimum ratio of Current  Assets to Current  liabilities  of 1.50:1.0  (measured
each month at month end);  provided,  however,  that the  Borrower  shall not be
required to satisfy this  financial  covenant  until the Bridge Loan  Expiration
Date.

3. The Borrower shall at all times during the term of this Agreement  maintain a
minimum Cash Balance of $750,000 (measured each month at month end).



                                      -3-

<PAGE>

4. The Borrower shall at all times during the term of this Agreement  maintain a
maximum ratio of Modified Total  Liabilities  to Modified  Tangible Net Worth of
1.50:1.0  (measured  each  month  at month  end);  provided,  however,  that the
Borrower  shall not be required to satisfy  this  financial  covenant  until the
Bridge Loan Expiration Date.

5. While  amounts due under the Bridge Loan are  outstanding,  Borrower will not
permit its Pre-Tax Loss  (calculated  in accordance  with GAAP)  determined on a
cumulative  basis, to be more than the following  amounts at the times specified
below:

            ------------------------------------------------
             Quarter Ending            Maximum Pre-Tax Loss
            ------------------------------------------------
             June 30, 2000             ($1,581,000)
            ------------------------------------------------
             September 30, 2000         (3,158,000)
            ------------------------------------------------
             December 31, 2000          (1,861,000)
            ------------------------------------------------
             March 31, 2001               (490,000)
            ------------------------------------------------

6. While  amounts due under the Bridge Loan are  outstanding,  Borrower will not
permit its Revenue,  determined on a cumulative basis from January 1, 2000 until
December 31, 2000 and on a rolling  four-quarter  basis  thereafter,  to be less
than the following amounts at the times specified below:

            ------------------------------------------------
             Quarter Ending            Minimum Revenue
            ------------------------------------------------
             June 30, 2000             $6,599,000
            ------------------------------------------------
             September 30, 2000         9,626,000
            ------------------------------------------------
             December 31, 2000         14,951,000
            ------------------------------------------------
             March 31, 2001            18,045,000
            ------------------------------------------------

DEFINITIONS:

     "CASH  BALANCE"  means the sum of cash and  marketable  securities  plus an
amount equal to the Borrower's excess availability under the Revolving Credit.

     "CURRENT ASSETS" means the sum of cash,  accounts receivable and marketable
securities.

     "CURRENT  LIABILITIES"  means the sum of (a) all current  liabilities other
than deferred  revenue plus (b) amounts  outstanding  under the Revolving Credit
not classified as current liabilities.

     "MODIFIED TOTAL  LIABILITIES"  means all current and long term liabilities,
less deferred revenues.

     "MODIFIED TANGIBLE NET WORTH" means Tangible Net Worth plus 75% of deferred
revenues (calculated in accordance with GAAP).


                                      -4-

<PAGE>

     "NEGATIVE NET OPERATING  INCOME" means  earnings  before  interest,  taxes,
depreciation and amortization less than zero calculated in accordance with GAAP.

     "PRE-TAX LOSS" for any period (cumulative or rolling) means earnings before
calculation  and  payment  of  taxes as  reported  on the  balance  sheet of the
Borrower on the last day of the reporting period.

     "REVENUE" means the sum of cumulative and deferred revenues.

     "TANGIBLE  NET WORTH" means  shareholders'  equity less  intangible  assets
(calculated in accordance  with GAAP),  plus all equity or  subordinated  and/or
convertible debt investments created after the date of this Agreement."

     10. SECURITY/COLLATERAL.  All obligations of the Borrower to the Bank under
the Revolving  Credit,  Equipment  Line,  Bridge Loan and the Notes, as amended,
constitute  Obligations  as defined in the Loan  Agreement  and in the  Security
Agreement dated as of May 6, 1999 by and between Borrower and Bank,  entitled to
the benefits of and secured by the Security Documents.

     11.  WARRANTS.  In  partial  consideration  for  the  Bridge  Loan  and the
financial accommodations extended to the Borrower under and pursuant to the Loan
Agreement  provided  herein,  the  Borrower  will,  upon the  execution  of this
Amendment  No. 5, grant to Bank  warrants  to  purchase  the  non-voting  common
capital stock of Borrower (the  "WARRANTS")  (i) in the initial  amount of 9,000
shares; and (ii) an additional 6,000 shares if amounts due under the Bridge Loan
are unpaid on September 19, 2000, in accordance with and subject to the terms of
the  Warrant  Purchase  Agreement  attached  hereto as Exhibit B (the   "WARRANT
AGREEMENT")  and at an exercise  price set forth in the Warrant  Agreement  (the
Loan Agreement,  this Amendment No. 5, the Notes, the Security Documents and the
Warrant Agreement are collectively referred to as the "LOAN DOCUMENTS").

     12.  REPRESENTATIONS  AND WARRANTIES.  The Borrower  hereby  represents and
warrants to the Bank as follows:

          (a) all representations, warranties and covenants made by the Borrower
to the Bank that are contained in the Loan Agreement,  as modified  hereby,  and
each of the other  Loan  Documents  are true and  correct  on and as of the date
hereof  with the same  effect as though  such  representations,  warranties  and
covenants had been made on and as of the date hereof (except representations and
warranties  which  expressly  relate  solely to an earlier  date or time,  which
representations  and  warranties  shall  be true  and  correct  on and as of the
specific dates or times referred to therein);

          (b) to the Borrower's knowledge, no event or condition has occurred or
exists which,  with the giving of notice or the passage of time, or both,  would
constitute an Event of Default under any of the Loan Documents;

                                      -5-

<PAGE>

          (c) the copies of the  Borrower's  Certificate  of  Incorporation  and
Bylaws  most  recently  delivered  to the Bank have not been  amended,  revised,
supplemented,  restated  or changed in any way since their  respective  dates of
adoption and are still in full force and effect; and

         (d)  the  execution  and  delivery  of  this  Amendment  No.  5 and the
consummation of the transactions  contemplated hereby and by the Bridge Note and
any other  documents  executed by the  Borrower  required to be delivered to the
Bank in  connection  with  this  Amendment  No. 5 have  been  duly  and  validly
authorized by the Borrower and all such documents together constitute the legal,
valid and binding agreement of the Borrower, enforceable against the Borrower in
accordance with their respective terms.

     13. CONDITIONS.  The Bank's obligation to make any Advance under the Bridge
Loan is subject to the  conditions  set forth in the Loan  Agreement  and to the
following conditions as of the date of this Amendment:

         (a) Authorized Documents. The Borrower shall have furnished to the Bank
certified  copies of  resolutions  of its  board of  directors  authorizing  the
execution of this Amendment, the Bridge Note and the Warrant Agreement;

         (b) Legal  Opinion.  The  Borrower  shall have  furnished to the Bank a
legal opinion in form and substance satisfactory to the Bank; and

         (c)  Effective  Date.  The Borrower has executed  this  Amendment,  the
Bridge Loan Note, the Warrant Agreement and any other documentation  required by
the Bank on or before June 30, 2000.

     14. REIMBURSEMENT OF EXPENSES.  The Borrower shall reimburse the Bank, upon
the execution of this  Amendment No. 5, and otherwise on demand,  all reasonable
and necessary  costs and expenses  incurred by the Bank in  connection  with the
preparation,   negotiation  and  delivery  of  this  Amendment  No.  5  and  any
modifications  hereto. The obligations of the Borrower to pay expenses hereunder
are in addition to, and not in lieu of, any similar obligations set forth in the
Loan Agreement.

     15.  COUNTERPARTS.  This  Amendment  No. 5 may be  executed  in one or more
counterparts by any party hereto in separate counterparts, each of which when so
executed and delivered to the other party shall be deemed an original.  All such
counterparts together shall constitute one and the same instrument.

     16.  LIMITATION OF  AMENDMENT.  This  Amendment No. 5 shall not,  except as
expressly set forth above,  serve to  supplement or amend the Loan  Agreement or
the other Loan  Documents,  which Loan  Agreement and the Loan  Documents  shall
remain in full force and effect as amended hereby.

                                      -6-

<PAGE>

     WITNESS the due execution of this  Amendment  No. 5 to Loan  Agreement as a
document under seal, as of the date first written above.

ATTEST:                                  INFORMAX, INC.



By:  /s/ Joseph E. Lehnen                By: /s/ Alex Titomirov        (SEAL)
     ------------------------                --------------------------

Print Name: Joseph E. Lehnen             Print Name: Alex Titomirov
            -----------------                        --------------

Title:      CFO                          Title:        CEO/Chair
      -----------------------                  --------------------

                                         PNC BANK,
                                         NATIONAL ASSOCIATION


                                         By: /s/ Katharine Kappler     (SEAL)
                                             --------------------------

                                         Print Name: Katharine Kappler
                                                     ------------------

                                         Title:     Managing Director
                                               ------------------------






                                      -7-

<PAGE>


                                   Exhibit A

                                  Bridge Note


<PAGE>

                                   Exhibit B

                           Warrant Purchase Agreement