STRUCTURAL AND STEREOCHEMICAL STUDIES OF ESTERIFICATION OF AROMATIC-AMINO-ACIDS BY ALPHA-CHYMOTRYPSIN IN ALCOHOL SOLVENTS

α-Chymotrypsin catalyses the esterification of N-acetyl-l-tryptophan in ethanol, 1-propanol, 2-propanol, 1-butanol, 3-methyl-1-butanol, cyclopentanol, and cyclohexanol. No esterification was observed in methanol or 2-methyl-2-propanol; however, esterification proceeds in ethanol/2-methyl-2-propanol mixtures but not in ethanol/methanol mixtures. Esterification of N-acetyl-dl-tryptophan in ethanol is enantiospecific and enantioselective, with only the L-ester produced. However, esterification of N-trifluoroacetyl-l-phenylalanine in 2-butanol is nondiastereoselective, since a mixture of 2-butyl esters is obtained. © 1990.