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.