Kinetically controlled synthesis of dipeptides using ficin as biocatalyst.

The application of the sulfhydryl protease ficin as biocatalyst is proposed as a novel method for enzyme-catalyzed synthesis of dipeptides. The negligible peptidase but considerable esterase activity at alkaline pH facilitated the kinetically controlled formation of peptide bonds by coupling the ester substrates Z-Ala-OMe and Z-Gly-OMe with L-alanine, D-alanine, L-glutamine, D-glutamine and L-Cys(acetamidomethyl) respectively. The reaction is accomplished without the occurrence of secondary peptide hydrolysis. Under optimum reaction conditions (pH 9.2, high ratio nucleophile/carboxyl component, 4.8% ethanol, 40 degrees C), the peptide yields ranged from 5 to 91%, depending on the structure of the amino and/or carboxyl component. No racemization was observed in the enzymatic reaction. Application of short-chain peptides has been advocated recently in clinical nutrition. Ficin-catalyzed peptide synthesis might be an attractive biotechnological approach for the synthesis of suitable dipeptides in this respect.