Synthesis and enzymatic hydrolysis of polydepsipeptides with functionalized pendant groups

Water-soluble polydepsipeptides with functionalized side-chain groups, i.e., alternating copolymers, consisting of glycolic acid (Glc) and L-lysine (L-Lys), L-aspartic acid (L-Asp) or L-glutamic acid (L-Glu) residues as a-hydroxy acid and a-amino acid residues, respectively, were synthesized, and their biodegradation behavior was investigated. Three kinds of polydepsipeptides, poly(Glc-alt-lys), poly(Glc-alt-Asp) and poly(Glc-alt-Glu), were synthesized by means of ring-opening polymerization of the corresponding cyclodepsipeptides and subsequent deprotection of benzyl and benzyloxycarbonyl groups. In order to estimate the main-chain cleavage behavior of polydepsipeptides with functionalized side-chain groups, the hydrolysis behavior of the obtained water-soluble polydepsipeptides was first investigated in phosphate buffer solution with or without an enzyme in vitro.