SAN DIEGO, Nov. 6, 1997 -- Protein Polymer Technologies, Inc. (Nasdaq: PPTI) announced today that it received a notice of allowance from the US Patent and Trademark Office (USPTO) for broad composition of matter claims based on its core protein engineering technology.  The U.S. patent is expected to issue within the next 6 months. PPTI currently has six issued U.S. patents, two of which issued this year, two USPTO notices of allowance, and fifteen other patent applications pending. Corresponding patent applications have been filed in major international markets. Many of the issued patents and pending applications relate to inventions that build upon, or which are components of, the broad proprietary position established by these newly allowed claims.
    "Composition of Matter" Patent.  The allowed claims cover recombinantly produced proteins that consist of relatively short sequences of amino acids found to be repeated in natural proteins. These "repeat units" are used by PPTI scientists as building blocks for creating "protein polymers" that have unique materials properties due to the repetition of these sequences throughout the polymer molecules. Silk and collagen are but two of the many natural proteins whose valuable properties result from such repeat units.
    The protein polymers PPTI creates, however, are not found in nature. Rather, these "designer" proteins isolate, amplify and combine properties found in natural proteins. The value of PPTI's proprietary technology platform is based on its capability to create new proteins with new performance properties for use in products designed to improve medical and surgical outcomes.
    Protein polymers are made using recombinant DNA technology to create synthetic genes which direct host cells, typically bacteria, to produce the protein designed by PPTI's scientists. By using a genetic template to direct the production process, high molecular weight polymers are created with an exquisite degree of control over their composition and properties. Such control is required in the natural production of proteins which sustain life, but has been unobtainable using traditional methods of polymer synthesis.
    Genetic "Methods" Patent. The synthesis and manipulation of DNA required to create synthetic genes encoding "protein polymers" is covered under U.S. Patent No. 5, 641, 648, which was issued to the Company in June 1997. In addition, related patent applications claiming methods useful in preparing synthetic repetitive DNA are pending. Prior to these inventions, scientists had not been successful in creating genes that would express high molecular weight proteins of repetitive amino acid sequences. Cells have built-in mechanisms to prevent multiple identical sequences of DNA encoding proteins from being maintained. Instead proteins are normally created with variation in their repeated amino acid segments to maintain genetic stability of the corresponding DNA.
    "Silk & Elastin" Protein Polymers.  One example of the usefulness of the technology was in the creation of a family of protein polymers combining repeat units from silk and elastin, another structural protein which provides elasticity to animal tissues including skin, blood vessels and lungs. These unique biomaterial compositions are covered in U.S. Patent No. 5,606,019, which was issued to the Company in February 1997. The Company's current product development efforts, based on this family of polymers, have a wide range of applications in large markets, including medical device coatings and soft tissue bulking agents, particularly for the treatment of stress urinary incontinence.
    Protein Polymers capable of Enzymatic cross-linking.  The technology also has been used in the development of polymers that are capable of being cross- linked by enzymes normally found in the body. Enzymatic cross-linking is, for example, the method used by the body to form blood clots, and is the mechanism underlying fibrin sealants which are marketed in Europe and Japan and under development for use in the United States. Although capable of sealing tissues to prevent the loss of blood, these blood-derived products set-up slowly and have low bond strength. PPTI has created protein polymers that incorporate more of the sites for enzymatic cross linking than are present in the natural protein substrate, fibrin. These polymers set up more quickly, with much higher bond strength, than fibrin sealant products.
    PPTI has received a notice of allowance from the USPTO for its patent application covering this enzymatic cross-linking technology. The U.S. patent is expected to issue within the next few months. The allowed claims are not limited to compositions for use in tissue adhesives or sealants, and should be useful in a number of PPTI's targeted product applications, particularly in enhancing the tissue regeneration process.
    "Thus far, this has been an outstanding year for PPTI's patent portfolio. This latest notice of allowance is for broad claims that significantly extend the protection of our powerful technology platform used to create unique protein polymers, and fortifies our pioneering position in the field of biomaterials" said J. Thomas Parmeter, President and Chief Executive Officer of Protein Polymer Technologies, Inc. "Our strategic and layered approach to intellectual property protection covers both protein and DNA compositions, the recombinant DNA methods used to create the genes which express the proteins, methods for purifying the protein compositions, and products which are based on the protein compositions.  We believe an exceptionally strong proprietary position has been established that will protect our commercial interests well into the future."
    Protein Polymer Technologies, a San Diego-based biotechnology company, has developed a number of different classes of biocompatible polymers that enable cell growth, promote the regeneration of tissue, bond to synthetic surfaces and resorb into tissue at controlled rates. Targeted applications include tissue adhesives and sealants, soft tissue augmentation, wound healing, contact lens coatings, surgical adhesion barriers and drug delivery vehicles. PPTI's lead products are being developed in collaboration with Ethicon, a Johnson & Johnson company, for use as a new generation of surgical adhesives and sealants to replace or augment the use of sutures and staples.
    This press release may contain forward-looking statements that are based on management's expectations. Actual results could differ materially from those expressed here; further, the Company is not obligated to comment specifically on those differences. Risks associated with the Company's activities include scientific and product development uncertainties, competitive products and approaches, continuing collaborative partnership interest and funding, regulatory testing and approvals, and manufacturing scale-up. The reader is encouraged to refer to the Company's 1996 Annual Report and 10-KSB, and recent filings with the Securities and Exchange Commission, copies of which are available from the Company, to further ascertain the risks associated with the above statements.

For more information on these and other issued patents, visit PPTI's online Patents page.