KINETICALLY CONTROLLED PEPTIDE-BOND FORMATION IN ANHYDROUS ALCOHOL CATALYZED BY THE INDUSTRIAL PROTEASE ALCALASE

The industrial alkaline protease alcalase has been found to be very stable (half life > 5 days in ethanol or 2-methyl-2-propanol) and active in alcoholic solvents (except methanol). Procedures have been developed for alcalase-catalyzed, kinetically controlled peptide bond formation in anhydrous alcohol(ethanol, 2-methyl-2-propanol). Studies of the selectivity of an alcalase-catalyzed reaction show that only L-amino acid acyl donors are substrates at the p-1 subsite of alcalase; at the p-1' subsite both D- and L-amino acid nucleophiles are substrates. Other amino compounds such as benzylamine and phenylhydrazine are good nucleophiles. Studies of the effect of the water content of the reaction solution on the yield in the synthesis of Moz-Phe-Leu-NH2 showed that the 95% yield obtained in anhydrous 2-methyl-2-propanol was decreased to 48% in 2-methyl-2-propanol containing 4.86% water.