Enzymatic Reactions in Aqueous-Organic Media. XVII. Optical Resolution of Amino Acid Esters by Enzymatic Hydrolysis in Organic Solvents

Enantiospecific hydrolysis of Dl-tyrosine ethyl ester was carried out using α-chymotrypsin (CT) as a catalyst in organic solvents, and l-tyrosine was obtained with high optical purity. Activity and enantiospecificity of CT were found to be greatly altered by water content in the reaction media, and generally high enantiospecificity was observed at low water contents. Many of natural and unnatural amino acid esters were resolved by hydrolysis in organic solvents using CT, subtilisin Carlsberg, or subtilisin BPN′ as catalysts.