Wheat Carboxypeptidase-Catalyzed Peptide Synthesis by Aminolysis of N-Acyl Amino Acid Ester. Indication of the Acyl-Enzyme Mechanism

Article abstract of DOI:10.1246/bcsj.60.1403

Dipeptide synthesis from N-<3-(2-furyl)acryloyl>-acylated (Fua-) amino acid ethyl ester and amino acid amide catalyzed by wheat bran carboxypeptidase (carboxypeptidase W) was studied.The optimum pH for peptide formation was at pH 8; more than 60 percent of the initial N-Fua-L-phenylalanine ethyl ester was converted to N-Fua-L-phenylalnylglycinamide under optimum conditions.The dependence of peptide formation on the concentration of amino acid amide showed an apparent saturation; this could be successfully explained by a reaction scheme which involved an acylated enzyme attacked by an enzyme-bound amine.The results for a reaction in the presence of two different amine components also supported this mechanism.Gly-NH2 had a better affinity to the acylated carboxypeptidase and the apparent dissociation constants (K_N(app)) was about 50 mM.These results were compared with those for those reactions catalyzed by carboxypeptidases from yeast and malt.