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 α‐hydroxy acid and α‐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.