Genetic Synthesis of Periodic Protein Materials

Genetic engineering offers a novel approach to the development of advanced polymeric materials, in particular protein-based materials. Biological synthesis provides levels of control of polymer chain architecture that cannot yet be attained by current methods of chemical synthesis. In addition to employing naturally occurring genetic templates artificial genes can be designed to encode completely new materials with customized properties. In the present paper we: 1) review the concepts and technology of creating protein-based materials by genetic engineering, 2) discuss the merits of producing crystalline lamellar proteins by this approach, and 3) review progress made by our group in generating such materials by genetic strategies. Full descriptions appear elsewhere about the parameters to be considered in designing artificial protein genes of this type, the effectiveness of different gene construction and expression strategies utilized by us thus far and, the specific properties of the various materials derived from these efforts (1,2). Progress made by other groups involved in developing periodic proteins by molecular biological strategies are described in refs. 3-8. The latter studies include genetic engineering of artificial silk-like proteins (3,4), poly-aspartylphenylalanine (5), an α/β barrel domain (octarellin; 6), the collagen tripeptide GlyProPro (7) and human tropoelastin (8). Advances with the silk-like proteins (SLP) have been particularly impressive. In addition to producing multi-gram quantities of pure SLP homopolymers, this group has successfully generated block copolymers of SLP interspersed with core peptides of mammalian elastin and the human fibronectin cell attachment element. While publications are still lacking it appears that a numiber of groups are striving to create genetically engineered variants of the repetitive bioadhesive proteins produced by mussels and barnacles (9)