The alpha-chymotrypsin-catalyzed transesterification between a racemic N-trifluoroacetyl-phenylalanine ester and l-propanol, was carried out in organic media. Although activation of the substrate by introducing electron-withdrawing group to the ester moiety enhanced the rate of reaction, it decreased enantioselectivity at the same time. In the instance of subtilisin Carlsberg, inversion of the L-specificity was observed.