Abstract: A peptide having the formulaA--Bwherein A represents an N-terminal protected amino acid residue or an optionally N-terminal protected peptide residue and B represents an optionally C-terminal protected amino acid residue, is prepared by reacting a substrate component selected from the group consisting of optionally N-terminal protected peptides of the formulaA--Xwherein A is as defined above and X represents an amino acidwith an amine component selected from the group consisting of(a) amino acids of the formulaH--B--OH,(b) optionally N-substituted amino acid amides of the formulaH--B--NHR.sup.3wherein B is an amino acid residue and R.sup.3 represents hydrogen, hydroxy, amino or alkyl, aryl or aralkyl, and(c) amino acid esters of the formula H--B--OR.sup.4 or H--B--SR.sup.4 wherein B is an amino acid residue and R.sup.4 represents alkyl, aryl and aralkyl,in the presence of a carboxypeptidase enzyme in an aqueous solution or dispersion having a pH from 5 to 10.5, preferably at a temperature of from 30 to 50.