Synthesis of delicious peptide fragments catalyzed by immobilized proteases

The synthesis of benzyloxycarbonyl-lysine-glycine methyl ester (CBZ-Lys-Gly-OMe) and benzyloxycarbonyl-serine-leucine methyl ester (CBZ-Ser-Leu-OMe) have been carried out in aqueous organic systems catalyzed by immobilized trypsin and thermolysin respectively. The dipeptides originated by the elimination of benzyloxycarbonyl and methoxy groups are two fragments of the delicious peptide, which is an octapeptide of industrial interest with a taste profile umami/sour. In both synthesis we have studied the influence of pH, temperature and substrate concentration on the yield and the rate of synthesis. In the optimum conditions, the synthetic yields were 80% for CBZ-Lys-Gly-OMe and 100% for CBZ-Ser-Leu-OMe. Both synthesis present an inhibition effect by the acyl donor when the concentrations of CBZ-Lys and CBZ-Ser are higher than 20 mM. In the synthesis of CBZ-Ser-Leu-OMe an anomalous role of thermolysin has been observed forming oligopeptides of higher molecular weight by addition of new molecules of aminoacid Leu-OMe. © 1997 Elsevier Science B.V. All rights reserved.