Several Block-L-Glu(OEt)-OEt (Block = amides, carbamates and trityl group) have been subjected to an aminolysis reaction catalyzed by the lipase B of Candida antarctica. The reaction took place in a regioselective manner and alpha-monoamides were obtained in all cases (except the bulky trityl group that did not react). Besides the synthetic value of the method, the results may empirically point out to some features of the active site of the enzyme as the reaction rate was severely affected by volume and electronic characteristics of the blocking group. (C) 1997 Elsevier Science Ltd.