Document:

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                                                                   Exhibit 10.16

                          TECHNOLOGY LICENSE AGREEMENT

     Agreement made as of the 1st day of February, 1999 (the "Effective Date"),
between VERTEX PHARMACEUTICALS INCORPORATED, a Massachusetts corporation
(together with its Affiliates, "Vertex"), and ALTUS BIOLOGICS INC., a
Massachusetts corporation (together with its Affiliates, "Altus").

     WHEREAS, Altus and Vertex are parties to a Technology License Agreement
dated as of December 31, 1992 (the "Old License Agreement") with respect to the
research, development, manufacturing and sale of cross-linked protein crystals
and other stabilized proteins;

     WHEREAS, each of Vertex and Altus is the respective owner of certain patent
rights, technology and intellectual property relating to protein stabilization
and has the right to transfer or grant licenses or sublicenses under said patent
rights, technology and intellectual property;

     WHEREAS, Altus and Vertex desire to terminate the Old License Agreement as
of the Effective Date and enter into a new agreement with respect to the subject
matter thereof;

     NOW THEREFORE, in consideration of the mutual covenants herein contained,
and for other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, the parties hereto agree as follows:

1.   DEFINITIONS

     1.1. "AFFILIATE" shall mean any corporation or legal entity which controls,
or is controlled by, or is -under common control with the designated party.
"Control" means the ownership, directly or through one or more Affiliates, of
more than fifty percent (50%) of the shares of stock entitled to vote for the
election of directors, in the case of a corporation, or more than fifty percent
(50%) of the equity interest, in the case of any other type of legal entity.

     1.2. "ALTUS FIELD" shall mean all fields of use.

     1.3. "ALTUS MANUFACTURING KNOW-HOW" shall mean that portion of Vertex
Technology, Existing Altus Technology, Subsequent Altus Patents or Subsequent
Altus Technology which is necessary or useful in the manufacture or production
of cross-linked protein crystals.

     1.4. "COLLABORATORS" shall mean entities in collaboration with Vertex with
respect to the research, development or manufacture of Vertex Products and which
are engaged in the business of researching, developing, or manufacturing
pharmaceutical products for human or animal therapeutics, but specifically
excluding: (i) entities engaged in contract manufacturing of such Vertex
Products; (ii) entities engaged in contract process development of such Vertex
Products; and (iii) entities which are academic institutions or not-for-profit
research institutions.

     1.5. "CONFIDENTIAL INFORMATION" shall mean (i) the Vertex Technology, the
Existing Altus Technology, the Subsequent Altus Patents, or the Subsequent Altus
Technology; and (ii) any other product, technology, or information of or about
Vertex, its Collaborators, or Altus that is provided by a party to the other
party hereunder; provided, however, that "Confidential

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.
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Information" shall not include any information described in subsections (i)
through (iv) of Section 5.3 hereof.

     1.6. "EXISTING ALTUS PATENTS" shall mean the patent applications and
patents listed on Schedule 1.6 hereto, together with any divisionals,
continuations, continuations-in-part, foreign counterparts, reissues, renewals,
reexaminations, substitutions or extensions of or to any such patent
applications or patents, and any patents issuing from any of the foregoing.
Schedule 1.6 shall be updated from time to time, but in no event less often than
once [****************], to include all patents and patent applications
comprising the Existing Altus Patents.

     1.7. "EXISTING ALTUS TECHNOLOGY" shall mean (i) the Existing Altus Patents,
(ii) any and all proprietary processes, trade secrets, technical information,
know-how, technology and other intellectual property of Altus, whether or not
patented or patentable, existing as of the Effective Date and which are
necessary or useful in the research, development, manufacture, use and sale of
products for human and animal therapeutic applications, and which are owned, or
have been acquired, developed, or licensed by Altus as of the Effective Date,
and as to which Altus has the right to grant licenses or sublicenses in the
Vertex Field.

     1.8. "LICENSED PRODUCT(S)" shall mean any product (i) the development,
manufacture, use, sale, or import of which would, but for the licenses granted
to Altus hereunder, infringe the Vertex Patents, or which is covered by a claim
of a pending patent application included in the Vertex Patents, or (ii) which is
developed, manufactured, produced or used through the use of any Vertex
Technology or which incorporates the Vertex Technology.

     1.9. "SUBSEQUENT ALTUS PATENTS" shall mean patent applications and patents
claiming Subsequent Altus Technology, and any divisions, continuations,
continuations-in-part, foreign counterparts, reissues, renewals, reexaminations,
substitutions or extensions of or to any such patent applications or patents,
and any patents issuing from any of the foregoing. Subsequent Altus Patents
shall be set forth on Schedule 1.9, and Schedule 1.9 shall be updated from time
to time, but in no event less often that once [****************], to include all
patents and patent applications comprising the Subsequent Altus Patents.

     1.10. "SUBSEQUENT ALTUS TECHNOLOGY" shall mean any and all proprietary
processes, trade secrets, technical information, know-how, technology and
intellectual property of Altus with respect to cross-linked protein crystals,
whether or not patented or patentable, which are necessary or useful in the
research, development, manufacture, use and sale of products for human and
animal therapeutic applications and which are acquired, developed, or licensed
by Altus during the [***********] period beginning on the Effective Date, and as
to which Altus has the right to grant licenses or sublicenses in the Vertex
Field.

     1.11. "THIRD PARTY" means any entity other than Vertex and its Affiliates
or Collaborators, or Altus and its Affiliates.

     1.12. "VERTEX FIELD" shall mean small molecule drugs for human and animal
therapeutic uses.

     1.13. "VERTEX PATENTS" shall mean (i) the patent applications and patents
listed on Schedule 1.13 hereto; and (ii) any patent applications and patents
claiming Vertex Technology

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                      -2-

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identified in Section 1.15(iii) below, together with any divisionals,
continuations, continuations-in-part, foreign counterparts, reissues, renewals,
reexaminations, substitutions or extensions of or to any such patent
applications or patents, and any patents issuing from any of the foregoing.
Schedule 1.13 shall be updated from time to time, but in no event less often
than [*********************], to include all patent applications and patents
comprising the Vertex Patents, including, without limitation, all patent
applications filed after the Effective Date and claiming Vertex Technology
identified in Section 1.15 (iii) below.

     1.14. "VERTEX PRODUCT" shall mean any small molecule drug researched,
discovered, developed or produced for human or animal therapeutic uses using the
Subsequent Altus Patents, the Subsequent Altus Technology, the Vertex Technology
or the Existing Altus Technology.

     1.15. "VERTEX TECHNOLOGY" shall mean (i) the Vertex Patents, (ii) any and
all proprietary processes, trade secrets, technical information, know-how,
technology and other intellectual property of Vertex claimed in or relating to
the Vertex Patents, or which is necessary or useful to practice the technology
described in the Vertex Patents existing on the Effective Date and, on the
Effective Date of this Agreement, owned or licensed to Vertex with the right to
grant licenses or sublicenses thereunder, and (iii) any and all proprietary
processes, trade secrets, technical information, know-how, and other
intellectual property, whether or not patented or patentable, first developed,
conceived or reduced to practice by Vertex or its Collaborators within
[************] after the Effective Date, which constitutes an improvement to the
technology described in clause 1.15(i) or 1.15(ii) above, and as to which Vertex
has the right to grant licenses or sublicenses.

2.   LICENSES GRANTED: TERMINATION OF OLD LICENSE AGREEMENT

     2.1. License to Altus Under Vertex Technology.

     Vertex hereby grants to Altus an exclusive, worldwide, royalty-free,
fully-paid right and license in the Altus Field under the Vertex Technology to
develop, make, use, sell, and import Licensed Products; provided, however, that
Vertex shall retain non-exclusive rights for itself and its Collaborators in the
Vertex Field under the Vertex Technology to develop, make, use, sell, and import
Vertex Products; and provided, further, that Vertex shall give Altus prompt
notice of any such use or access to the Vertex Technology by its Collaborators.
Vertex will make available to Altus, at such time or times and in such manner as
Altus shall reasonably request, such written or oral information and documents
as constitute the Vertex Technology. Altus shall have the right to grant
sublicenses to Third Parties under the Vertex Technology, provided, that, it
shall give Vertex prompt notice of each such sublicense granted. Neither Vertex
nor its Collaborators shall have the right to grant rights or licenses under the
Vertex Technology to any Third Party, except as permitted by Section 2.3 hereof.

     2.2. License to Vertex Under Existing Altus Technology, Subsequent Altus
Patents and Subsequent Altus Technology. Altus hereby grants to Vertex a
nonexclusive, worldwide, royalty-free, fully-paid right and license in the
Vertex Field under the Existing Altus Technology, the Subsequent Altus Patents,
and the Subsequent Altus Technology, to develop, make, use, sell, and import
Vertex Products. Altus will make available to Vertex, at such time or times and
in such manner as Vertex shall reasonably request, such written or oral
information

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                     -3-

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and documents as constitute the Existing Altus Technology and the Subsequent
Altus Technology. Vertex shall have the right to grant sublicenses hereunder to
Collaborators in the Vertex Field; provided, that, it shall give Altus prompt
notice of each such sublicense granted; and provided, further, that Altus
Manufacturing Know-How shall not be disclosed or sublicensed to a Collaborator
except as provided in Section 2.3.

2.3. Altus Manufacturing Know-How.

     (a) Vertex may disclose, license and/or sublicense Altus Manufacturing
Know-How to its Collaborators, solely for the purpose of permitting such
Collaborators to develop, make, use, sell, or import any Vertex Products;
provided, that, each such Collaborator shall first enter into confidentiality
and non-use agreements with Vertex upon terms at least as restrictive as those
set forth in Section 5 hereof. The Altus Manufacturing Know-How shall only be
disclosed to those employees of such Collaborators who have a specific need to
access and/or use the Altus Manufacturing Know-How for purposes permitted by
this Agreement. Vertex agrees to use commercially reasonable good faith efforts
to limit, where possible, its disclosure of Altus Manufacturing Know-How to
Collaborators.

     (b) In the event that Vertex requires the manufacture or production of
[***************************], Vertex may elect, in its sole judgment: (x) to
conduct such manufacture or production itself; (y) to conduct such manufacture
or production through one or more Collaborators; or (z) to cause Altus to
manufacture and produce Vertex's requirements of [***************************]
on commercially reasonable terms. If Altus is unable or unwilling to manufacture
and produce Vertex's requirements of [***************************] on terms
reasonably acceptable to Vertex, Vertex may: (yy) require Altus to manufacture,
produce and supply the same at a price equal to the [******] to produce the
[***************************] plus [***************], or (zz) cause a Third
Party to manufacture, produce, and supply such requirements. Selection of such
Third Party shall require Altus's consent, such consent not to be unreasonably
withheld or delayed. (As used in this subsection, [*********] shall mean
[**********************************************************************], plus a
reasonable allocation of [************].)

     (c) If Vertex selects a Third Party to manufacture, produce and supply its
requirements for [***************************] pursuant to clause (b)(zz) above,
then, upon receipt of Altus' consent as provided under Section 2.3(b) above,
Vertex may disclose, license and/or grant sublicenses with respect to Altus
Manufacturing Know-How to such Third Party solely for purposes of manufacturing,
producing and supplying Vertex's requirements for [***************************];
provided, that, such Third Party shall first enter into confidentiality and
non-use agreements with Vertex upon terms at least as restrictive as those set
forth in Section 5 hereof. The Altus Manufacturing Know-How shall only be
disclosed to those employees of such Third Party who have a specific need to
access and/or use the Altus Manufacturing Know-How for the purposes permitted
under this Agreement. Vertex agrees to use commercially reasonable good faith
efforts to limit, where possible, its disclosure of Altus Manufacturing Know-How
to Third Parties.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                      -4-

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     2.4. Old License Agreement Terminated. The Old License Agreement is
terminated as of the Effective Date, except for the provisions of Section 6
thereof ("Confidentiality"), which shall survive such termination; provided,
however, that to the extent Section 5 of this Agreement may conflict with
Section 6 of the Old License Agreement, Section 5 of this Agreement shall
govern.

     2.5. Trademark. The parties acknowledge that the trademarks "CLECO(R)" and
"CLECs(R)" and all rights thereunder have previously been assigned to Altus by
Vertex pursuant to an instrument dated September 27, 1996 and recorded with the
United States Patent and Trademark Office on October 11, 1996.

3.   PATENT PROSECUTION

     3.1. Altus shall be responsible for the preparation, filing, prosecution
and maintenance of the Vertex Patents, the Existing Altus Patents and the
Subsequent Altus Patents. Altus agrees to provide Vertex with [*******] updates
regarding the status (as such status relates to the Vertex Field) of all patent
applications and/or patents comprising the Vertex Patents, the Existing Altus
Patents and the Subsequent Altus Patents, and to respond in good faith to any
reasonable inquiries of Vertex regarding the status and/or scope of such patents
and/or patent applications. Vertex agrees to cooperate fully with Altus to
provide such consultation and assistance as may be necessary, or as is requested
by Altus, in the preparation, prosecution, filing and maintenance of such
patents or patent applications. Any information provided by Altus to Vertex
pursuant to this Section 3.1. shall be treated as the Confidential Information
of Altus hereunder.

     3.2. In the event that Altus decides to abandon or to cease prosecution or
fails to maintain a patent or patent applications included in the Vertex
Patents, the Existing Altus Patents or the Subsequent Altus Patents in any
jurisdiction, Vertex shall have the right, at its expense, to prepare, file,
prosecute and maintain the applicable patent(s) or patent application(s) in such
jurisdiction.

4.   INFRINGEMENT

     4.1. Each party shall promptly notify the other of infringement or alleged
infringement of any patent or other proprietary right included in the Vertex
Technology, the Existing Altus Technology, the Subsequent Altus Patents or the
Subsequent Altus Technology, or of any unauthorized or alleged unauthorized use
thereof, which comes to its attention. In such event, the parties shall confer
promptly with respect to the assertion of proprietary rights or to the
initiation and prosecution of litigation against the alleged infringer or
unauthorized user. If the parties agree to proceed jointly, they shall
[*************] with one another, in such proportions as they may mutually agree
upon from time to time, (i) [**********************], and (ii)
[**************************].

     4.2. If any claim, litigation or proceeding is threatened or brought by any
person against a party alleging that any use, application or disclosure of the
Vertex Technology, the Existing Altus Technology, the Subsequent Altus Patents,
or the Subsequent Altus Technology as contemplated by this Agreement infringes
any patent or other proprietary right held by such person, the parties shall
promptly confer with respect to such claim, litigation or proceeding. If

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                      -5-

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the parties agree to proceed jointly in the defense of such claim, litigation or
proceeding, the parties shall [*************] with one another, in such
proportions as they may mutually agree upon from time to time,
[**********************************************].

     4.3. Neither party shall settle or compromise any claim, litigation or
proceeding described in Section 4.1 or 4.2 hereof without the consent of the
other party, such consent not to be unreasonably withheld or delayed.

5.   CONFIDENTIALITY

     5.1. Vertex shall keep confidential, and shall require its Collaborators to
keep confidential, all Vertex Technology, Existing Altus Technology, Subsequent
Altus Patents and Subsequent Altus Technology, and Altus shall keep confidential
all Vertex Technology, and each party shall keep confidential any other
Confidential Information received from the other party. Neither party shall use
the other party's Technology or Confidential Information for any purpose other
than as permitted under this Agreement, without the prior written consent of the
other party. Each party shall take all reasonable steps necessary to insure such
confidential treatment and nonuse.

     5.2. The foregoing obligations of confidential treatment and nonuse shall
not prevent the disclosure of Vertex Technology, Existing Altus Technology or
Subsequent Altus Technology by Vertex to its Collaborators who have entered into
confidentiality and nonuse agreements with Vertex on terms at least as
restrictive as those set forth in this Section 5; provided, that, Vertex's
disclosure of Altus Manufacturing Know-How shall also be subject to the
restrictions set forth elsewhere in this Agreement, including without limitation
the restrictions set forth in Section 2.2. The foregoing obligations of
confidential treatment and nonuse shall not prevent the disclosure of Vertex
Technology by Altus to its collaborators or sublicensees who have entered into
confidentiality and nonuse agreements with Altus on terms at least as
restrictive as those set forth in this Section 5.

     5.3. The foregoing obligations of confidential treatment and nonuse shall
not apply to information which the receiving party shall sustain the burden of
proving:

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                      -6-

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          (a) was in the possession of the receiving party, other than under an
obligation of confidentiality, prior to receipt thereof from the disclosing
party, as shown by the receiving party's written records;

          (b) was already available to the public at the time of its disclosure
to the receiving party or became available to the public after its disclosure to
the receiving party other than through a breach of this Agreement by the
receiving party;

          (c) was received by the receiving party from a third party who had no
obligation not to disclose such information to others; or

          (d) is required to be disclosed by applicable law or regulation;
provided that, prior to any such disclosure, the party intending to make such
disclosure shall give the other party reasonable advance notice and shall use
its best efforts to obtain confidential treatment of the information to be
disclosed.

     5.4. The obligations of confidentiality hereunder shall survive any
expiration or termination of this Agreement.

6.   PUBLICATIONS

     Altus and its employees, on the one hand, and Vertex and its employees, on
the other hand, will be free to publicly disclose (through journals, lectures,
or otherwise) research results generated through use of the Vertex Technology,
the Existing Altus Technology or the Subsequent Altus Technology, provided in
each case that the disclosing party shall have provided a copy of the proposed
disclosure to the other party for review at least [**************] prior to the
submission of any written publication or any oral public disclosure. During such
[*************] period the non-disclosing party shall review the proposed
disclosure and, prior to the expiration of such [*************] period shall
notify the disclosing party as to whether a patent application should be filed,
whether the proposed disclosure contains information the non-disclosing party
wishes to maintain as a trade secret, or whether the proposed disclosure
contains the Confidential Information of the non-disclosing party. In the event
that the non-disclosing party believes a patent application should be filed, the
disclosing party agrees to delay publication and disclosure of the proposed
disclosure until such time as a patent application is filed. If the
non-disclosing party reports that the proposed disclosure contains Confidential
Information, or if the non-disclosing party wishes to maintain certain
information as a trade secret, the disclosing party agrees to remove such
information from the proposed disclosure.

7.   REPRESENTATIONS AND WARRANTIES

     7.1. Right to Enter Agreement. Each party represents and warrants to the
other that it has the unencumbered right to enter into this Agreement and to
grant all rights granted herein and that it has not made or executed any
agreement in conflict herewith.

     7.2. Rights to Technology. Vertex represents that it is the owner of the
Vertex Technology and that it has the right to license the Vertex Technology as
set forth herein. Altus

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                      -7-

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represents that it has the right to license the Existing Altus Technology and
the Subsequent Altus Technology as set forth herein.

     7.3. Exclusion of Warranties. Nothing herein shall be construed as a
representation or warranty by either party:

          (a) that the utilization of its Technology does not or will not
constitute infringement of patent rights of others;

          (b) as to the results to be attained by the utilization of its
Technology;

          (c) that there is any warranty relating to its Technology, including
without limitation any warranty of merchantability or fitness for a particular
purpose, other than as expressly described herein.

     7.4. No Actual Knowledge. Notwithstanding the foregoing, each party
represents and warrants to the other that it does not have any actual knowledge
that the utilization of its Technology would constitute infringement of
presently existing valid patents of others.

8.   INDEMNIFICATION AND INSURANCE

     8.1. Altus Indemnity Obligations. Altus (the "Indemnitor") agrees to
defend, indemnify and hold Vertex, its Affiliates and their respective
directors, officers, employees, consultants, agents, successors and assigns (the
"Indemnitees") harmless from [*******], judgments, liabilities, damages, losses
or expenses [***************************************************************]
incurred by or imposed on the Indemnitees or any one of them in connection with:
(i) actual or asserted violations of any applicable law or regulation by Altus
or its Affiliates by virtue of which Licensed Products manufactured, distributed
or sold by Altus or its Affiliates shall be alleged or determined to be
adulterated, misbranded, mislabeled or otherwise not in compliance with such
applicable law or regulation; (ii) claims, suits, actions, demands, or judgments
arising out of any theory of product liability (including but not limited to
actions in the form of tort, warranty or strict liability) concerning any
Licensed Product sold, manufactured, used or distributed by Altus or its
Affiliates, (iii) a recall ordered by a governmental agency, or required by a
confirmed failure, of Licensed Products manufactured, distributed, or sold by
Altus or its Affiliates; or (iv) a breach by Altus of any of its representations
and warranties made pursuant to Section 7.

     8.2. Vertex Indemnity Obligations. Vertex (the "Indemnitor") agrees to
defend, indemnify and hold Altus and its respective directors, officers,
employees, consultants, agents, successors and assignees (the "Indemnitees")
harmless from [*******], judgments, liabilities, damages, losses or expenses
[**************************************************************] incurred by or
imposed on the Indemnitees or any one of them in connection with: (i) actual or
asserted violations of any applicable law or regulation by Vertex or its
Affiliates or Collaborators by virtue of which Vertex Products manufactured,
distributed or sold by Vertex, its Affiliates or Collaborators shall be alleged
or determined to be adulterated, misbranded, mislabeled or otherwise not in
compliance with such applicable law or regulation; (ii) claims, suits, actions,
demands, or judgments arising out of any theory of product liability (including
but not limited to actions in the form of tort, warranty or strict liability)
concerning any Vertex

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                      -8-

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Product sold, manufactured, used or distributed by Vertex, its Affiliates or
Collaborators; (iii) a recall ordered by a governmental agency, or required by a
confirmed failure, of Vertex Products manufactured, distributed, or sold by
Vertex, its Affiliates or Collaborators; or (iv) a breach by Vertex of any of
its representations and warranties made pursuant to Section 7.

     8.3. Limitation on Indemnity Obligations. Neither party, nor its Affiliates
or Collaborators (in the case of Vertex), nor its and their respective employees
and agents, shall be entitled to the indemnities set forth in this Section 8
where the claim, loss, damage or expense for which indemnification is sought was
caused by a negligent act or intentional act of misconduct or omission by such
party, its directors, officers, employees or authorized agents.

     8.4. Procedure. In the event that an Indemnitee intends to claim
indemnification under this Section 8, such Indemnitee shall promptly notify the
Indemnitor of any loss, claim, damage, liability or action in respect of which
the Indemnitee intends to claim such Indemnification, and the Indemnitor shall
assume the defense thereof with counsel mutually satisfactory to the parties;
provided, however, that an Indemnitee shall have the right to retain its own
counsel, [*****************************************************], if
representation of such Indemnitee by the counsel retained by the Indemnitor
would be inappropriate due to actual or potential differing interests between
such Indemnitee and any other party represented by such counsel in such
proceedings. The indemnity agreement in this Section 8 shall not apply to
amounts paid in settlement of any loss, claim, damage, liability or action if
such settlement is effected without, the consent of the Indemnitor, which
consent shall not be withheld unreasonably. The failure to deliver notice to the
Indemnitor within a reasonable time after the commencement of any such action,
if prejudicial to its ability to defend such action, shall relieve the
Indemnitor of any liability to the Indemnitee under this Section 8, but the
omission so to deliver notice to the Indemnitor will not relieve it of any
liability that it may have to any Indemnitee otherwise than under this Section
8. The Indemnitee under this Section 8, its employees and agents, shall
cooperate fully with the Indemnitor and its legal representatives in the
investigation of any action, claim or liability covered by this indemnification.

9.   TERM AND TERMINATION

     9.1. Term. This Agreement shall continue in full force and effect until
terminated as provided herein; provided that, with respect to the Vertex
Patents, the Existing Altus Patents or the Subsequent Altus Patents, the
licenses granted thereunder shall expire on a patent-by-patent and
country-by-country basis upon the expiration or invalidation of each patent
included in the Vertex Patents, the Existing Altus Patents or the Subsequent
Altus Patents, as the case may be.

     9.2. Termination. This Agreement may be terminated by either party in case
of a material violation or breach of any provision of this Agreement by the
other, which breach or default is not corrected within [*****] after receipt of
written notice specifying the violation or breach of this Agreement, or, if such
default cannot be cured or remedied within such [*************] period, if the
party in default does not commence and diligently continue actions to cure or
remedy such default. This Agreement may also be terminated at the option of
either party upon written notice to the other party if (i) a party is unable to
pay its material financial obligations as they become due, (ii) if a voluntary
or involuntary petition in bankruptcy is filed by or against such party and is
thereafter either consented to, acquiesced in or remains

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                       -9-

<PAGE>

undismissed for [*****], or (iii) if such party makes a general assignment for
the benefit of creditors or if a receiver is appointed for any such party.
Termination by reason of clause (i) above shall be rescinded by the terminating
party, and this Agreement shall continue in full force and effect, if within
[***************************] the defaulting party's financial situation has.
improved such that it is paying, and reasonably appears likely to be able to
continue to pay, its material financial obligations as they become due.

     9.3. Rights After Termination. In the event this Agreement is terminated
pursuant to Section 9.2 above, all licenses granted to the non-terminating party
hereunder shall terminate but the terminating party shall retain all rights and
licenses granted to it hereunder.

10.  GENERAL

     10.1. Benefit. This Agreement shall be binding upon the parties hereto and
shall inure to the benefit of the respective successors and permitted assigns of
each party. Nothing in this Agreement shall be construed to create any rights or
obligations except between the parties hereto, and no person or entity shall be
regarded as a third-party beneficiary of this Agreement.

     10.2. Severability. In the event that any court of competent jurisdiction
shall determine that any provisions, or any portion thereof, contained in this
Agreement shall be unreasonable or unenforceable in any respect, then such
provision shall be deemed limited to the extent that such court deems it
reasonable and enforceable, and as so limited shall remain in full force and
effect. In the event that such court shall. deem any such provision, or portion
thereof, wholly unenforceable, the remaining provisions of this Agreement shall
nevertheless remain in full force and effect, provided, that if without such
invalid provisions, the fundamental mutual objectives of the parties cannot be
achieved, then either party may terminate this Agreement without penalty by
written notice to the other.

     10.3. Governing Law. This Agreement shall be governed by and construed and
interpreted in accordance with the laws of the Commonwealth of Massachusetts, as
applied to contracts entered into and performed entirely in Massachusetts by
Massachusetts residents.

     10.4. Force Majeure. Neither party shall be responsible to the other for
any failure or delay in performing any of its obligations under this Agreement
if such delay or nonperformance is caused by strike, labor stoppage, lockout or
other labor trouble, fire, flood, accident, act of God or of the Government, or
by other cause unavoidable or beyond the control of such party, provided that
prompt notice is given of the cause for the delay or nonperformance and diligent
continuing efforts are made to resume performance.

     10.5. Nonassignability. This Agreement and the licenses granted herein
shall not be assignable by either party hereto, except to a wholly-owned
subsidiary or to a successor to all or substantially all of such party's
business without the prior written consent of the other party, such consent not
to be unreasonably withheld or delayed.

     10.6. Entire Agreement: Modification. This Agreement constitutes the entire
understanding between the parties hereto with respect to the subject matter
hereof and, except as set forth in Section 2.3 hereof, supersedes all prior
agreements, written or oral, with respect thereto. Only the licenses granted
pursuant to the express terms of this Agreement shall be of

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                      -10-

<PAGE>

any legal force and effect. No license rights shall be created by implication or
estoppel. No modification or amendment hereof shall be valid or binding upon the
parties hereto unless made in writing and duly executed on behalf of both
parties.

     10.7. Waiver. No actual waiver of breach or default by a party of any
provision of this Agreement shall be deemed or construed to be a waiver of any
succeeding breach or default of the same or any other provision.

     10.8. Notice. Any notice or other communication required or permitted to be
given hereunder shall be sufficient if (i) delivered by hand, (ii) made by
telecopy or facsimile transmission, (iii) sent by overnight courier, or (iv) by
certified or registered mail, return receipt requested, postage prepaid,
addressed as follows:

If to Altus, to:
     Altus Biologics Inc.
     625 Putnam Street
     Cambridge, MA 02139
     Attention: President

If to Vertex, to:
     Vertex Pharmaceuticals Incorporated
     130 Waverly Street
     Cambridge, MA 02139
     Attention: Chief Business Officer

or, in each case, to such other address as may be designated by written notice
given in the manner herein provided. Time of notice or other communication shall
be deemed to be the date of receipt.

     10.9. Headings. Titles or headings of articles, sections, or paragraphs
contained in this Agreement are inserted only as a matter of convenience and for
reference, and in no way are intended to define, limit, extend, or describe the
scope of this Agreement or the intent of any provision hereof.

     10.10. Counterparts. This Agreement may be executed in a number of
counterparts, all of which together shall constitute one Agreement.

     10.11. Relationship of Parties. For purposes of this Agreement, each party
is an independent contractor and not an agent or employee of the other party.
Neither party shall have any authority to make any statements, representations,
or commitments of any kind, or to take any action which shall be binding upon
the other party, except as may be explicitly provided for in this Agreement or
authorized in writing by the other party.

     10.12. Dispute Resolution.

          (a) Any dispute, controversy or claim (a "Dispute") arising pursuant
to this Agreement shall first be addressed by good faith, amicable discussion
between the chief executive officers of Vertex and Altus (the "Senior
Executives"). Within [***********] of

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                      -11-

<PAGE>

notice by a party to the other party of the existence of a Dispute, the Senior
Executives shall meet for the purpose of discussing and resolving the Dispute at
a mutually acceptable time and location. If a settlement of the Dispute is not
achieved by the Senior Executives within [**************] of the date of the
notice of the Dispute (which period may be extended by mutual agreement of the
Senior Executives) subject to any rights to injunctive relief, such Dispute
shall be resolved by binding arbitration as provided in Section 10.12(b) below.

          (b) Any Dispute not resolved by the parties pursuant to Section
10.12(a) above shall be submitted to binding arbitration conducted under the
Commercial Rules of the American Arbitration Association. Such arbitration shall
be conducted by a panel of three (3) arbitrators appointed in accordance with
such rules and who shall have experience in resolving disputes among parties in
the biotechnology industry. Each arbitrator shall be required to enter into a
confidentiality agreement with respect to any Confidential Information disclosed
to him or her in connection with the Dispute. The arbitration shall be conducted
in Cambridge, Massachusetts. The Federal Rules of Civil Procedure shall apply to
such arbitration. The arbitrators shall be required to reach a decision with
respect to the Dispute and report the same to the parties as soon as reasonable
considering the type and range of issues presented by the Dispute, but in any
event no later than [***************************] from the date of appointment
of the panel of three arbitrators.

          (c) The parties hereto agree to be bound by the decision of such
arbitrators, and that the payment of any and all legal fees in connection with
the arbitration of any Dispute hereunder shall be allocated by such arbitrators.
Judgment upon the award rendered may be entered in any court having jurisdiction
with respect thereto.

          (d) Nothing in the foregoing shall prevent either party from seeking
immediate injunctive or other provisional relief, without otherwise resorting to
the foregoing remedies, in order to protect its rights under this Agreement or
to compel the other party to comply with its obligations hereunder.

                      [THIS SPACE INTENTIONALLY LEFT BLANK]

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                      -12-

<PAGE>

     IN WITNESS WHEREOF; the parties hereto have duly executed this Agreement as
of the date first written above.

VERTEX PHARMACEUTICALS INCORPORATED     ALTUS BIOLOGICS INC.

By: /s/ Thomas G. Auchincloss           By: /s/ Peter Lanciano
    ---------------------------------       ------------------------------------
    Thomas G. Auchincloss, Jr.              Peter Lanciano
    Vice President, Finance                 President

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                      -13-

<PAGE>

PRIVILEGED AND CONFIDENTIAL

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company's application requesting
confidential treatment under Rule 406 of the Securities Act.

                                       14-

                                                                   Exhibit 10.55

                     SUPPLEMENTAL INDENTURE TO BE DELIVERED
                          BY GUARANTEEING SUBSIDIARIES

         Supplemental Indenture (this "Supplemental Indenture"), dated as of
November 1, 2005, among L-3 Communications Corporation (or its permitted
successor), a Delaware corporation (the "Company"), each subsidiary of the
Company signatory hereto (each, a "Guaranteeing Subsidiary", and collectively,
the "Guaranteeing Subsidiaries"), and The Bank of New York, as trustee under the
indenture referred to below (the "Trustee").

                               W I T N E S S E T H

               WHEREAS, the Company has heretofore executed and delivered to the
Trustee an indenture (the "Indenture"), dated as of June 28, 2002 providing for
the issuance of an aggregate principal amount of up to $750,000,000 of 7 5/8%
Senior Subordinated Notes due 2012 (the "Notes");

               WHEREAS, the Indenture provides that under certain circumstances
the Guaranteeing Subsidiaries shall execute and deliver to the Trustee a
supplemental indenture pursuant to which the Guaranteeing Subsidiaries shall
unconditionally guarantee all of the Company's obligations under the Notes and
the Indenture on the terms and conditions set forth herein (the "Subsidiary
Guarantee"); and

               WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee
is authorized to execute and deliver this Supplemental Indenture.

               NOW THEREFORE, in consideration of the foregoing and for other
good and valuable consideration, the receipt of which is hereby acknowledged,
the Guaranteeing Subsidiaries and the Trustee mutually covenant and agree for
the equal and ratable benefit of the Holders of the Notes as follows:

               1. CAPITALIZED TERMS. Capitalized terms used herein without
definition shall have the meanings assigned to them in the Indenture.

               2. AGREEMENT TO GUARANTEE. Each Guaranteeing Subsidiary hereby
agrees as follows:

                  (a)   Such Guaranteeing Subsidiary, jointly and severally with
                        all other current and future guarantors of the Notes
                        (collectively, the "Guarantors" and each, a
                        "Guarantor"), unconditionally guarantees to each Holder
                        of a Note authenticated and delivered by the Trustee and
                        to the Trustee and its successors and assigns,
                        regardless of the validity and enforceability of the
                        Indenture, the Notes or the Obligations of the Company
                        under the Indenture or the Notes, that:

                        (i)  the principal of, premium, interest and Additional
                             Amounts, if any, on the Notes will be promptly paid
                             in full when due, whether at maturity, by
                             acceleration, redemption or otherwise, and interest
                             on the overdue principal of, premium, interest and
                             Additional Amounts, if any, on the Notes, to the
                             extent lawful, and all other Obligations of the
                             Company to the Holders or the Trustee thereunder or
                             under the Indenture will be promptly paid in full,
                             all in accordance with the terms thereof; and

                                       1

                        (ii) in case of any extension of time for payment or
                             renewal of any Notes or any of such other
                             Obligations, that the same will be promptly paid in
                             full when due in accordance with the terms of the
                             extension or renewal, whether at stated maturity,
                             by acceleration or otherwise.

                  (b)   Notwithstanding the foregoing, in the event that this
                        Subsidiary Guarantee would constitute or result in a
                        violation of any applicable fraudulent conveyance or
                        similar law of any relevant jurisdiction, the liability
                        of such Guaranteeing Subsidiary under this Supplemental
                        Indenture and its Subsidiary Guarantee shall be reduced
                        to the maximum amount permissible under such fraudulent
                        conveyance or similar law.

               3. EXECUTION AND DELIVERY OF SUBSIDIARY GUARANTEES.

                  (a)   To evidence its Subsidiary Guarantee set forth in this
                        Supplemental Indenture, such Guaranteeing Subsidiary
                        hereby agrees that a notation of such Subsidiary
                        Guarantee substantially in the form of Exhibit F to the
                        Indenture shall be endorsed by an officer of such
                        Guaranteeing Subsidiary on each Note authenticated and
                        delivered by the Trustee after the date hereof.

                  (b)   Notwithstanding the foregoing, such Guaranteeing
                        Subsidiary hereby agrees that its Subsidiary Guarantee
                        set forth herein shall remain in full force and effect
                        notwithstanding any failure to endorse on each Note a
                        notation of such Subsidiary Guarantee.

                  (c)   If an Officer whose signature is on this Supplemental
                        Indenture or on the Subsidiary Guarantee no longer holds
                        that office at the time the Trustee authenticates the
                        Note on which a Subsidiary Guarantee is endorsed, the
                        Subsidiary Guarantee shall be valid nevertheless.

                  (d)   The delivery of any Note by the Trustee, after the
                        authentication thereof under the Indenture, shall
                        constitute due delivery of the Subsidiary Guarantee set
                        forth in this Supplemental Indenture on behalf of each
                        Guaranteeing Subsidiary.

                  (e)   Each Guaranteeing Subsidiary hereby agrees that its
                        obligations hereunder shall be unconditional, regardless
                        of the validity, regularity or enforceability of the
                        Notes or the Indenture, the absence of any action to
                        enforce the same, any waiver or consent by any Holder of
                        the Notes with respect to any provisions hereof or
                        thereof, the recovery of any judgment against the
                        Company, any action to enforce the same or any other
                        circumstance which might otherwise constitute a legal or
                        equitable discharge or defense of a guarantor.

                  (f)   Each Guaranteeing Subsidiary hereby waives diligence,
                        presentment, demand of payment, filing of claims with a
                        court in the event of insolvency or bankruptcy of the
                        Company, any right to require a proceeding first against
                        the Company, protest, notice and all demands whatsoever
                        and covenants that its Subsidiary Guarantee made
                        pursuant

                                       2

                        to this Supplemental Indenture will not be discharged
                        except by complete performance of the Obligations
                        contained in the Notes and the Indenture.

                  (g)   If any Holder or the Trustee is required by any court or
                        otherwise to return to the Company or any Guaranteeing
                        Subsidiary, or any custodian, Trustee, liquidator or
                        other similar official acting in relation to either the
                        Company or such Guaranteeing Subsidiary, any amount paid
                        by either to the Trustee or such Holder, the Subsidiary
                        Guarantee made pursuant to this Supplemental Indenture,
                        to the extent theretofore discharged, shall be
                        reinstated in full force and effect.

                  (h)   Each Guaranteeing Subsidiary agrees that it shall not be
                        entitled to any right of subrogation in relation to the
                        Holders in respect of any Obligations guaranteed hereby
                        until payment in full of all Obligations guaranteed
                        hereby. Each Guaranteeing Subsidiary further agrees
                        that, as between such Guaranteeing Subsidiary, on the
                        one hand, and the Holders and the Trustee, on the other
                        hand:

                        (i)  the maturity of the Obligations guaranteed hereby
                             may be accelerated as provided in Article 6 of the
                             Indenture for the purposes of the Subsidiary
                             Guarantee made pursuant to this Supplemental
                             Indenture, notwithstanding any stay, injunction or
                             other prohibition preventing such acceleration in
                             respect of the obligations guaranteed hereby; and

                        (ii) in the event of any declaration of acceleration of
                             such obligations as provided in Article 6 of the
                             Indenture, such obligations (whether or not due and
                             payable) shall forthwith become due and payable by
                             such Guaranteeing Subsidiary for the purpose of the
                             Subsidiary Guarantee made pursuant to this
                             Supplemental Indenture.

                  (i)   Each Guaranteeing Subsidiary shall have the right to
                        seek contribution from any other non-paying Guaranteeing
                        Subsidiary so long as the exercise of such right does
                        not impair the rights of the Holders or the Trustee
                        under the Subsidiary Guarantee made pursuant to this
                        Supplemental Indenture.

               4. GUARANTEEING SUBSIDIARY MAY CONSOLIDATE, ETC. ON CERTAIN
                  TERMS.

                  (a)   Except as set forth in Articles 4 and 5 of the
                        Indenture, nothing contained in the Indenture, this
                        Supplemental Indenture or in the Notes shall prevent any
                        consolidation or merger of any Guaranteeing Subsidiary
                        with or into the Company or any other Guarantor or shall
                        prevent any transfer, sale or conveyance of the property
                        of any Guaranteeing Subsidiary as an entirety or
                        substantially as an entirety, to the Company or any
                        other Guarantor.

                  (b)   Except as set forth in Article 4 of the Indenture,
                        nothing contained in the Indenture, this Supplemental
                        Indenture or in the Notes shall prevent any
                        consolidation or merger of any Guaranteeing Subsidiary
                        with or into a

                                       3

                        corporation or corporations other than the Company or
                        any other Guarantor (in each case, whether or not
                        affiliated with the Guaranteeing Subsidiary), or
                        successive consolidations or mergers in which a
                        Guaranteeing Subsidiary or its successor or successors
                        shall be a party or parties, or shall prevent any sale
                        or conveyance of the property of any Guaranteeing
                        Subsidiary as an entirety or substantially as an
                        entirety, to a corporation other than the Company or any
                        other Guarantor (in each case, whether or not affiliated
                        with the Guaranteeing Subsidiary) authorized to acquire
                        and operate the same; provided, however, that each
                        Guaranteeing Subsidiary hereby covenants and agrees that
                        (i) subject to the Indenture, upon any such
                        consolidation, merger, sale or conveyance, the due and
                        punctual performance and observance of all of the
                        covenants and conditions of the Indenture and this
                        Supplemental Indenture to be performed by such
                        Guaranteeing Subsidiaries, shall be expressly assumed
                        (in the event that such Guaranteeing Subsidiary is not
                        the surviving corporation in the merger), by
                        supplemental indenture satisfactory in form to the
                        Trustee, executed and delivered to the Trustee, by the
                        corporation formed by such consolidation, or into which
                        such Guaranteeing Subsidiary shall have been merged, or
                        by the corporation which shall have acquired such
                        property and (ii) immediately after giving effect to
                        such consolidation, merger, sale or conveyance no
                        Default or Event of Default exists.

                  (c)   In case of any such consolidation, merger, sale or
                        conveyance and upon the assumption by the successor
                        corporation, by supplemental indenture, executed and
                        delivered to the Trustee and satisfactory in form to the
                        Trustee, of the Subsidiary Guarantee made pursuant to
                        this Supplemental Indenture and the due and punctual
                        performance of all of the covenants and conditions of
                        the Indenture and this Supplemental Indenture to be
                        performed by such Guaranteeing Subsidiary, such
                        successor corporation shall succeed to and be
                        substituted for such Guaranteeing Subsidiary with the
                        same effect as if it had been named herein as the
                        Guaranteeing Subsidiary. Such successor corporation
                        thereupon may cause to be signed any or all of the
                        Subsidiary Guarantees to be endorsed upon the Notes
                        issuable under the Indenture which theretofore shall not
                        have been signed by the Company and delivered to the
                        Trustee. All the Subsidiary Guarantees so issued shall
                        in all respects have the same legal rank and benefit
                        under the Indenture and this Supplemental Indenture as
                        the Subsidiary Guarantees theretofore and thereafter
                        issued in accordance with the terms of the Indenture and
                        this Supplemental Indenture as though all of such
                        Subsidiary Guarantees had been issued at the date of the
                        execution hereof.

               5. RELEASES.

                  (a)   Concurrently with any sale of assets (including, if
                        applicable, all of the Capital Stock of a Guaranteeing
                        Subsidiary), all Liens, if any, in favor of the Trustee
                        in the assets sold thereby shall be released; provided
                        that in the event of an Asset Sale, the Net Proceeds
                        from such sale or other disposition are treated in
                        accordance with the provisions of Section 4.10 of the
                        Indenture. If the assets sold in such sale or other
                        disposition

                                       4

                        include all or substantially all of the assets of a
                        Guaranteeing Subsidiary or all of the Capital Stock of a
                        Guaranteeing Subsidiary, then the Guaranteeing
                        Subsidiary (in the event of a sale or other disposition
                        of all of the Capital Stock of such Guaranteeing
                        Subsidiary) or the Person acquiring the property (in the
                        event of a sale or other disposition of all or
                        substantially all of the assets of such Guaranteeing
                        Subsidiary) shall be released from and relieved of its
                        Obligations under this Supplemental Indenture and its
                        Subsidiary Guarantee made pursuant hereto; provided that
                        in the event of an Asset Sale, the Net Proceeds from
                        such sale or other disposition are treated in accordance
                        with the provisions of Section 4.10 of the Indenture.
                        Upon delivery by the Company to the Trustee of an
                        Officers' Certificate to the effect that such sale or
                        other disposition was made by the Company or the
                        Guaranteeing Subsidiary, as the case may be, in
                        accordance with the provisions of the Indenture and this
                        Supplemental Indenture, including without limitation,
                        Section 4.10 of the Indenture, the Trustee shall execute
                        any documents reasonably required in order to evidence
                        the release of the Guaranteeing Subsidiary from its
                        Obligations under this Supplemental Indenture and its
                        Subsidiary Guarantee made pursuant hereto. If the
                        Guaranteeing Subsidiary is not released from its
                        obligations under its Subsidiary Guarantee, it shall
                        remain liable for the full amount of principal of and
                        interest on the Notes and for the other obligations of
                        such Guaranteeing Subsidiary under the Indenture as
                        provided in this Supplemental Indenture.

                  (b)   Upon the designation of a Guaranteeing Subsidiary as an
                        Unrestricted Subsidiary in accordance with the terms of
                        the Indenture, such Guaranteeing Subsidiary shall be
                        released and relieved of its obligations under its
                        Subsidiary Guarantee and this Supplemental Indenture.
                        Upon delivery by the Company to the Trustee of an
                        Officers' Certificate and an Opinion of Counsel to the
                        effect that such designation of such Guaranteeing
                        Subsidiary as an Unrestricted Subsidiary was made by the
                        Company in accordance with the provisions of the
                        Indenture, including without limitation Section 4.07 of
                        the Indenture, the Trustee shall execute any documents
                        reasonably required in order to evidence the release of
                        such Guaranteeing Subsidiary from its obligations under
                        its Subsidiary Guarantee. Any Guaranteeing Subsidiary
                        not released from its Obligations under its Subsidiary
                        Guarantee shall remain liable for the full amount of
                        principal of and interest on the Notes and for the other
                        Obligations of any Guaranteeing Subsidiary under the
                        Indenture as provided herein.

                  (c)   Each Guaranteeing Subsidiary shall be released and
                        relieved of its obligations under this Supplemental
                        Indenture in accordance with, and subject to, Section
                        4.18 of the Indenture.

               6. NO RECOURSE AGAINST OTHERS. No past, present or future
director, officer, employee, incorporator, stockholder or agent of any
Guaranteeing Subsidiary, as such, shall have any liability for any obligations
of the Company or any Guaranteeing Subsidiary under the Notes, any Subsidiary
Guarantees, the Indenture or this Supplemental Indenture or for any claim based
on, in respect of, or by reason of, such obligations or their creation. Each
Holder of the Notes by accepting a Note waives and releases all such liability.
The waiver and release are part of the consideration for issuance of

                                       5

the Notes. Such waiver may not be effective to waive liabilities under the
federal securities laws and it is the view of the SEC that such a waiver is
against public policy.

               7. SUBORDINATION OF SUBSIDIARY GUARANTEES; ANTI-LAYERING. No
Guaranteeing Subsidiary shall incur, create, issue, assume, guarantee or
otherwise become liable for any Indebtedness that is subordinate or junior in
right of payment to any Senior Debt of a Guaranteeing Subsidiary and senior in
any respect in right of payment to any of the Subsidiary Guarantees.
Notwithstanding the foregoing sentence, the Subsidiary Guarantee of each
Guaranteeing Subsidiary shall be subordinated to the prior payment in full of
all Senior Debt of that Guaranteeing Subsidiary (in the same manner and to the
same extent that the Notes are subordinated to Senior Debt), which shall include
all guarantees of Senior Debt.

               8. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

               9. COUNTERPARTS. The parties may sign any number of copies of
this Supplemental Indenture. Each signed copy shall be an original, but all of
them together represent the same agreement.

               10. EFFECT OF HEADINGS. The Section headings herein are for
convenience only and shall not affect the construction hereof.

               11. THE TRUSTEE. The Trustee shall not be responsible in any
manner whatsoever for or in respect of the validity or sufficiency of this
Supplemental Indenture or for or in respect of the recitals contained herein,
all of which recitals are made solely by the Guaranteeing Subsidiaries and the
Company.

                                       6

                  IN WITNESS WHEREOF, the parties hereto have caused this
Supplemental Indenture to be duly executed, all as of the date first above
written.

Dated: November 1, 2005             L-3 COMMUNICATIONS CORPORATION

                                    By: /s/ Christopher C. Cambria
                                       --------------------------------------
                                       Name: Christopher C. Cambria
                                       Title: Senior Vice President, Secretary
                                              and General Counsel

                                       7

Dated: November 1, 2005        APCOM, INC., a Maryland corporation
                               BROADCAST SPORTS INC., a Delaware corporation
                               D.P. ASSOCIATES INC., a Virginia corporation
                               ELECTRODYNAMICS, INC., an Arizona corporation
                               HENSCHEL INC., a Delaware corporation
                               HYGIENETICS ENVIRONMENTAL SERVICES, INC., a
                                  Delaware corporation
                               INTELLIGENCE DATA SYSTEMS, INC., a
                                  Virginia corporation
                               INTERNATIONAL SYSTEMS, LLC, a California
                                  corporation
                               INTERSTATE ELECTRONICS CORPORATION, a California
                                  corporation
                               KDI PRECISION PRODUCTS, INC., a Delaware
                                  corporation
                               L-3 COMMUNICATIONS AEROMET, INC., an Oregon
                                  corporation
                               L-3 COMMUNICATIONS VERTEX AEROSPACE LLC, a
                                  Delaware limited liability company
                               L-3 COMMUNICATIONS AIS GP CORPORATION, a Delaware
                                  corporation
                               L-3 COMMUNICATIONS ADVANCED LASER SYSTEMS
                                  TECHNOLOGY, INC., a Florida corporation
                               L-3 COMMUNICATIONS AVIONICS SYSTEMS, INC., a
                                  Delaware corporation
                               L-3 COMMUNICATIONS AVISYS CORPORATION, a
                                  Texas corporation
                               L-3 COMMUNICATIONS CSI, INC., a California
                                  corporation
                               L-3 COMMUNICATIONS AYDIN CORPORATION, a Delaware
                                  corporation
                               L-3 COMMUNICATIONS CE HOLDINGS, INC., a Delaware
                                  corporation
                               L-3 COMMUNICATIONS CINCINNATI ELECTRONICS
                                  CORPORATION, an Ohio corporation
                               L-3 COMMUNICATIONS ELECTRON TECHNOLOGIES, INC., a
                                  Delaware corporation
                               L-3 COMMUNICATIONS EO/IR, INC., a Florida
                                  corporation
                               L-3 COMMUNICATIONS ESSCO, INC., a Delaware
                                  corporation
                               L-3 COMMUNICATIONS FLIGHT INTERNATIONAL AVIATION
                                  LLC, a Delaware limited liability company
                               L-3 COMMUNICATIONS FLIGHT CAPITAL LLC, a Delaware
                                  limited liability company
                               L-3 COMMUNICATIONS GOVERNMENT SERVICES, INC., a
                                  Virginia corporation
                               L-3 COMMUNICATIONS ILEX SYSTEMS, INC., a Delaware
                                  corporation
                               L-3 COMMUNICATIONS INFRAREDVISION TECHNOLOGY
                                  CORPORATION, a California corporation
                               L-3 COMMUNICATIONS INTEGRATED SYSTEMS L.P., a
                                  Delaware limited partnership
                               L-3 COMMUNICATIONS INVESTMENTS INC., a Delaware
                                  corporation
                               L-3 COMMUNICATIONS KLEIN ASSOCIATES, INC., a
                                  Delaware corporation
                               L-3 COMMUNICATIONS MAS (US) CORPORATION, a
                                  Delaware corporation

                                       8

                               L-3 COMMUNICATIONS MOBILE-VISION, INC., a New
                                  Jersey corporation
                               L-3 COMMUNICATIONS SECURITY AND DETECTION
                                  SYSTEMS, INC., a Delaware corporation
                               L-3 COMMUNICATIONS SONOMA EO, INC., a California
                                  corporation
                               L-3 COMMUNICATIONS TITAN CORPORATION, a Delaware
                                  corporation
                               L-3 COMMUNICATIONS VECTOR INTERNATIONAL AVIATION
                                  LLC, a Delaware limited liability company
                               L-3 COMMUNICATIONS WESTWOOD CORPORATION, a Nevada
                                  corporation
                               LINCOM WIRELESS, INC., a Delaware corporation
                               MCTI ACQUISITION CORPORATION, a Maryland
                                  corporation
                               MICRODYNE COMMUNICATIONS TECHNOLOGIES
                                  INCORPORATED, a Maryland corporation
                               MICRODYNE CORPORATION, a Maryland corporation
                               MICRODYNE OUTSOURCING INCORPORATED, a Maryland
                                  corporation
                               MPRI, INC., a Delaware corporation
                               PAC ORD INC., a Delaware corporation
                               POWER PARAGON, INC., a Delaware corporation
                               PROCOM SERVICES, INC., a California corporation
                               SHELLCO, INC., a Delaware corporation
                               SPD ELECTRICAL SYSTEMS, INC., a Delaware
                                  corporation
                               SPD SWITCHGEAR INC., a Delaware corporation
                               SYCOLEMAN CORPORATION, a Florida corporation
                               TITAN FACILITIES, INC., a Virginia corporation
                               TITAN SCAN TECHNOLOGIES CORPORATION, a Delaware
                                  corporation,
                               TROLL TECHNOLOGY CORPORATION, a California
                                  corporation
                               WESCAM AIR OPS INC., a Delaware corporation
                               WESCAM AIR OPS LLC, a Delaware limited liability
                                  company
                               WESCAM HOLDINGS (US) INC., a Delaware corporation
                               WESCAM LLC, a Delaware limited liability company
                               WOLF COACH, INC., a Massachusetts corporation

                                     As Guaranteeing Subsidiaries

                                     By: /s/ Christopher C. Cambria
                                        ----------------------------------------
                                        Name: Christopher C. Cambria
                                        Title: Vice President and Secretary

                                       9

Dated:  November 1, 2005            THE BANK OF NEW YORK,
                                    as Trustee

                                    By: /s/ Robert A. Massimillo
                                       -----------------------------------------
                                       Name:  Robert A. Massimillo
                                       Title: Vice President

                                       10

      NOTATION ON SENIOR SUBORDINATED NOTE RELATING TO SUBSIDIARY GUARANTEE

                  Pursuant to the Supplemental Indenture (the "Supplemental
Indenture") dated as of November 1, 2005 among L-3 Communications Corporation, a
Delaware corporation, the Guarantors party thereto (each a "Guarantor" and
collectively the "Guarantors") and The Bank of New York, as trustee (the
"Trustee"), each Guarantor (i) has jointly and severally unconditionally
guaranteed (a) the due and punctual payment of the principal of, and premium,
interest and Additional Amounts on the Notes, whether at maturity or an interest
payment date, by acceleration, call for redemption or otherwise, (b) the due and
punctual payment of interest on the overdue principal and premium of, and
interest and Additional Amounts on the Notes, and (c) in case of any extension
of time of payment or renewal of any Notes or any of such other Obligations, the
same will be promptly paid in full when due in accordance with the terms of the
extension or renewal, whether at stated maturity, by acceleration or otherwise
and (ii) has agreed to pay any and all costs and expenses (including reasonable
attorneys' fees) incurred by the Trustee or any Holder in enforcing any rights
under the Subsidiary Guarantee (as defined in the Supplemental Indenture).

                  Notwithstanding the foregoing, in the event that the
Subsidiary Guarantee of any Guarantor would constitute or result in a violation
of any applicable fraudulent conveyance or similar law of any relevant
jurisdiction, the liability of such Guarantor under its Subsidiary Guarantee
shall be reduced to the maximum amount permissible under such fraudulent
conveyance or similar law.

                  No past, present or future director, officer, employee, agent,
incorporator, stockholder or agent of any Guarantor, as such, shall have any
liability for any Obligations of the Company or any Guarantor under the Notes,
any Subsidiary Guarantee, the Indenture, any supplemental indenture delivered
pursuant to the Indenture by such Guarantor, or for any claim based on, in
respect of or by reason of such Obligations or their creation. Each Holder by
accepting a Note waives and releases all such liability.

                  The Subsidiary Guarantee shall be binding upon each Guarantor
and its successors and assigns and shall inure to the benefit of the successors
and assigns of the Trustee and the Holders and, in the event of any transfer or
assignment of rights by any Holder or the Trustee, the rights and privileges
herein conferred upon that party shall automatically extend to and be vested in
such transferee or assignee, all subject to the terms and conditions hereof.

                  The Subsidiary Guarantee shall not be valid or obligatory for
any purpose until the certificate of authentication on the Note upon which the
Subsidiary Guarantee is noted has been executed by the Trustee under the
Indenture by the manual signature of one of its authorized officers. Capitalized
terms used herein have the meaning assigned to them in the Indenture, dated as
of June 28, 2002, among L-3 Communications Corporation, the Guarantors party
thereto and the Trustee.

                                       11

Dated: November 1, 2005               APCOM, INC.
                                      BROADCAST SPORTS INC.
                                      D.P. ASSOCIATES INC.
                                      ELECTRODYNAMICS, INC.
                                      HENSCHEL INC.
                                      HYGIENETICS ENVIRONMENTAL SERVICES, INC.
                                      INTELLIGENCE DATA SYSTEMS, INC.
                                      INTERNATIONAL SYSTEMS, LLC
                                      INTERSTATE ELECTRONICS CORPORATION
                                      KDI PRECISION PRODUCTS, INC.
                                      L-3 COMMUNICATIONS AEROMET, INC.
                                      L-3 COMMUNICATIONS VERTEX AEROSPACE LLC
                                      L-3 COMMUNICATIONS AIS GP CORPORATION
                                      L-3 COMMUNICATIONS ADVANCED LASER SYSTEMS
                                         TECHNOLOGY, INC.
                                      L-3 COMMUNICATIONS AVIONICS SYSTEMS, INC.
                                      L-3 COMMUNICATIONS AVISYS CORPORATION
                                      L-3 COMMUNICATIONS CSI, INC.
                                      L-3 COMMUNICATIONS AYDIN CORPORATION
                                      L-3 COMMUNICATIONS CE HOLDINGS, INC.
                                      L-3 COMMUNICATIONS CINCINNATI ELECTRONICS
                                         CORPORATION
                                      L-3 COMMUNICATIONS ELECTRON TECHNOLOGIES,
                                         INC.
                                      L-3 COMMUNICATIONS EO/IR, INC.
                                      L-3 COMMUNICATIONS ESSCO, INC.
                                      L-3 COMMUNICATIONS FLIGHT INTERNATIONAL
                                         AVIATION LLC
                                      L-3 COMMUNICATIONS FLIGHT CAPITAL LLC
                                      L-3 COMMUNICATIONS GOVERNMENT SERVICES,
                                         INC.,
                                      L-3 COMMUNICATIONS ILEX SYSTEMS, INC.
                                      L-3 COMMUNICATIONS INFRAREDVISION
                                         TECHNOLOGY CORPORATION
                                      L-3 COMMUNICATIONS INTEGRATED SYSTEMS L.P.
                                      L-3 COMMUNICATIONS INVESTMENTS INC.
                                      L-3 COMMUNICATIONS KLEIN ASSOCIATES, INC.
                                      L-3 COMMUNICATIONS MAS (US) CORPORATION
                                      L-3 COMMUNICATIONS MOBILE-VISION, INC.
                                      L-3 COMMUNICATIONS TITAN CORPORATION
                                      L-3 COMMUNICATIONS SECURITY AND DETECTION
                                         SYSTEMS, INC.
                                      L-3 COMMUNICATIONS SONOMA EO, INC.
                                      L-3 COMMUNICATIONS VECTOR INTERNATIONAL
                                         AVIATION LLC
                                      L-3 COMMUNICATIONS WESTWOOD CORPORATION
                                      LINCOM WIRELESS, INC.
                                      MCTI ACQUISITION CORPORATION
                                      MICRODYNE COMMUNICATIONS TECHNOLOGIES
                                         INCORPORATED
                                      MICRODYNE CORPORATION
                                      MICRODYNE OUTSOURCING INCORPORATED
                                      MPRI, INC.
                                      PAC ORD INC.
                                      POWER PARAGON, INC.

                                       12

                                      PROCOM SERVICES, INC.
                                      SHELLCO, INC.
                                      SPD ELECTRICAL SYSTEMS, INC.
                                      SPD SWITCHGEAR INC.
                                      SYCOLEMAN CORPORATION
                                      TITAN FACILITIES, INC.
                                      TITAN SCAN TECHNOLOGIES CORPORATION
                                      TROLL TECHNOLOGY CORPORATION
                                      WESCAM AIR OPS INC.
                                      WESCAM AIR OPS LLC
                                      WESCAM HOLDINGS (US) INC.
                                      WESCAM LLC
                                      WOLF COACH, INC.

                                            As Guaranteeing Subsidiaries

                                        By: /s/ Christopher C. Cambria
                                           -------------------------------------
                                           Name: Christopher C. Cambria
                                           Title: Vice President and Secretary

                                       13

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