| Abstract: | Polymerization of the N-carboxy anhydride of N?-carbobenzyloxy-L -lysine in the presence of multifunctional polymeric initiator, copoly(L -lysine γ-methyl-L -glutamate) was studied in N,N-dimethylformamide containing 3% (v/v) of dimethyl sulfoxide. Multichain copoly(α-amino acid), i.e., multi-N?-poly(N?-carbobenzyloxy-L -lysine)copoly(L -lysine γ-methyl-L -glutamate), was obtained with linear poly(N?-carbobenzyloxy-L -lysine) as by-product that could be removed by reprecipitation as was evidenced by gel-permeation chromatography. The degree of polymerization of the branch polymer chains estimated by the osmometric molecular weight determination and amino acid analysis was between 20 and 60, which decreased with increasing lysine content of the polymeric initiator. The stability of α-helical conformation of the multichain copoly(α-amino acid) was studied in the chloroform–dichloroacetic acid system at 25°C by the ORD technique. The α-helical conformation of poly(N?-carbobenzyloxy-L -lysine) branches was less stable than those of linear poly(N?-carbobenzyloxy-L -lysine) and the core molecular chains of the multichain copoly(α-amino acid). |
