SYNTHESIS AND STRUCTURE OF POLYISOPEPTIDES

Polyisopeptides are non-peptidic polymers formed by alpha, omega-polyc ondensation of tri- or multi-functional alpha-amino acids. They are ex pected to possess physical and mechanical properties of synthetic poly amides (or polyesters) and to be biodegradable. In the present paper, the methods of polyisopeptide synthesis are reviewed. Many of them are specific to a given alpha-amino acid (and sometimes its derivatives, too). We discuss here about two methods giving satisfactory results. O ne is the polymerization of L-aspartic beta-lactam alpha-esters,in whi ch the structure of a resulting polymer varies according to the solven t used. A new interpretation on the basis of the nature of catalyst an ion species (free ion, ion pair) is presented. The other subject is th e active ester polycondensation method applied to the amino- and carbo xyl- protected L-cystine polyisopeptide and its selective deprotection successively until total deprotection to free amino- and free carboxy lic groups. The final polymer is the first poly-L-cystine ever reporte d in the literature.