The hydrolysis (deacylation) of enantiomeric substrates by the chemically modified enzymes decanoyl-alpha-chymotrypsin and decanoyl-trypsin was studied. Reaction activity for decanoyl-alpha-chymotrypsin was lower than that for the native enzyme, although intriguingly the enantioselectivity was markedly enhanced as compared with the native enzyme. In particular, the apparently complete enantioselective