Influence of the Substrate Structure on Carboxypeptidase Y Catalyzed Peptide Bond Formation

It is shown that for carboxypeptidase Y catalyzed peptide synthesis the coupling yields using peptide esters as substrates and amino acids as nucleophiles are strongly dependent on the C-terminal amino acid residue. A dependence on the length of the acyl donating peptide chain is also observed, indicating the influence of residues other than the one directly involved in acylation of the enzyme. Using amino acid amides as nucleophiles, the yields are generally high (80 %-100 96). No peptide ester substrate with C-terminal D-amino acid residue can be used in this method of peptide synthesis since they are not substrates of the enzyme. However, the presence of Damino acids in the penultimate position does not prevent peptide synthesis. No dependence on the size of the leaving group of esterand depsipeptide substrates could be observed.