Synthesis of Polycysteine

Abstract

The synthesis of polycysteine via S-thiophenyl-l-cysteine was described. S-thiophenyl-l-cysteine was prepared from benzenesulfenyl chloride and l-cysteine hydrochloride in absolute alcohol and its chemical properties were studied. This amino acid was polymerized by the N-carboxy anhydride method in ethyl thioglycolate containing an active sulfhydryl group, and it was confirmed by the studies of infrared spectra of these substances that the resultant polymer was polycysteine contaminated with diketopipera-zine. Pure polycysteine was isolated by treating this polymer with thioglycolic acid and methanol. The benzoyl derivative and ethylester hydrochloride of S-thiophenyl-l-cysteine were prepared.