Synthesis and enzymatic degradation of poly(ester-amide) stereocopolymers derived from alanine

Poly(ester-amide)s with L-alanine contents of 100 (LalaS-100), 90, 80, 70, 50, 30 and 0 were prepared by interfacial polycondensation of the mixture of 1,6-hexanediol diester of L- and D-alanine with sebacoyl chloride. The enzymatic degradation of the poly(ester-amide)s was followed by the weight loss in a buffer solution (pH 7.2) of proteolytic enzymes (proteinase-K, papain and α-chymotrypsin) and lipase enzymes (R. delemar, P. cepacia and C. rugosa) at 37°C. The former enzymes degrade LalaS-100 much faster than the latter. Above all proteinase-K degrades it most rapidly and the weight loss is about 78% after 8 h of incubation. It was found that the degradation with the proteolytic enzymes is not caused by hydrolysis of the semi-peptide linkage but of the ester linkage. The effect of the stereochemical composition on the enzymatic degradation was examined using proteinase-K and papain, which degrades LalaS-100 (100% L) as opposed to LalaS-0 (100% D). In contrast, the highest rate of degradation was observed for LalaS-90.