Process for producing optically active 3-aminocarboxylic acid ester compounds of general Formula I, and the ammonium salts thereof, in which R1 stands for alkyl, alkoxyalkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl, or hetaryl, and R2 stands for alkyl, cycloalkyl or aryl, in which an enantiomeric mixture of a simply N-acylated 3-aminocarboxylic acid ester of general formula (I.b), in which R1 and R2 have the meanings given above and R3 stands for hydrogen, alkyl, cycloalkyl or aryl, is submitted to an enantioselective deacylation by adding a polypeptide according to claim 1.