Processing and Characterization of Protein Polymers

Abstract

High molecular weight synthetic poly(peptides) of precisely controlled amino acid composition and sequence can be produced by the genetic engineering of Escherichia coli bacteria. By this route, novel protein polymers can be synthesized with combinations of amino acid sequences not found in any known natural polypeptide. Such well-defined biomaterials are of interest for a number of applications including cellular adhesion promoters, biosensors, and suture materials (Capperauld, 1989; Hubbell, 1993; Cappello et al., 1990; Cappello and Crissman, 1990; Cappello et al., 1990a, 1990b; Tirrell et al., 1991). By changing the composition of the protein, it is possible to control its biological activity and degradability. The ability to manipulate the three-dimensional structure of biopolymers may have significant implications for tissue engineering (Hubbell and Langer, 1995; Langer and Vacanti, 1993). To be successful in these applications, it will be necessary to determine how to process protein polymers into assemblies with desirable microstructural arrangements. Although the general feasibility of the genetic approach to protein molecular design and expression is now fairly well established, a fundamental understanding of appropriate processing methods, microstructural evolution, and the macroscopic properties of protein materials is only just beginning to emerge.