MOLECULAR DESIGN OF MULTICOMPONENT POLYAMINO ACIDS AS FUNCTIONAL BIOPOLYMERS

Amino acid copolymers composed of gamma-benzyl L-glutamate Glu(OBzl)), L-alanine (Ala), and S-benzyl-L-cystein (Cys(Bzl)) were synthesized by the copolymerization of N-carboxy-amino acid anhydride (NCA) derivatives in order to prepare biodegradable hydrogels which have high potentials in various medical applications. Amino acid compositions of the copolymers were determined by the elemental analyses and proton NMR spectral analyses. We also determined monomer reactivity ratios which have been shown to be quite useful to evaluate the degree of dispersion of amono acid residues in a polymer. We found that NCA's of Glu(OBzl), Ala, and Cys(Bzl) copolymerize in an ideally random fashion and that cystein residue are well dispersed. Thus the copolumerization of the NCA's seems promising for preparing hydrogels with controlable three-dimensional network structure owing to inter- or intra-chain disulfide bonds.