Application of Bacillus licheniformis γ-glutamyltranspeptidase to the biocatalytic synthesis of γ-glutamyl-phenylalanine

Several γ-glutamyl compounds are known to have attractive features for food industry applications. In this study, we report a straightforward procedure for the biocatalytic synthesis of γ-glutamyl-phenylalanine (γ-Glu-Phe) using recombinant Bacillus licheniformis γ-glutamyltranspeptidase (BlGGT). The qualitative analysis of reaction products was carried out by thin-layer chromatography technique and computer-assisted image analysis. The optimized conditions for the biocatalytic process were pH 9.0, 50 °C, l-glutamine and l-phenylalanine in a 1:1 ratio, and BlGGT at a working concentration of 2.0 U/ml. Preparative synthesis of γ-Glu-Phe was also performed at mmol scale. The desired product from the reaction mixture was then verified by mass spectrometry/nuclear magnetic resonance analyses. Strikingly, the experimental results suggest the high potentiality of BlGGT-catalyzed reaction in the enzymatic synthesis of γ-glutamyl peptides.