Free chymotrypsin-catalyzed synthesis of peptide bond in aliphatic alcohols with low water content

Abstract

The effect of water content on free chymotrypsin-catalyzed reaction of Ac-Tyr-OEt with HBr.Gly-NH2 in triethylamine-containing 2-propanol was studied. Maximum yield of dipeptide Ac-Tyr-Gly-NH2 was obtained in 2-propanol with 2% of water. Lower water content retards the reaction. Although higher water content accellerates the process, the yield of the dipeptide is reduced by enzymatically catalyzed hydrolysis of Ac-Tyr-OEt. The studied reaction proceeds analogously also in other aliphatic alcohols woth low content of water except in methanol; it does not take place in dimethylformamide or dimethyl sulfoxide containing 2% or 20% of water. In 2-propanol with 2% or 5% of water, syntheses of the protected amino-terminal oxytocine and vasopressin tripeptide, as well as other model peptides, were studied. In all the described experiments, α-chymotrypsin without any stabilization or immobilization was employed.