EPSILON-(GAMMA-GLUTAMYL)LYSINE - HYDROLYSIS BY GAMMA-GLUTAMYL-TRANSFERASE OF DIFFERENT ORIGINS, WHEN FREE OR PROTEIN-BOUND

epsilon-(gamma-Glutamyl)lysine, a moiety found in various tissues, org ans, and processed foods, is the product of either intrinsic transglut aminase reaction or chemical reaction during cooking processes. From a nutritional viewpoint, hydrolysis of the epsilon-(gamma-glutamyl)lysi ne bond and bioavailability of its constituent lysine have been the ta rgets of investigation. In this study, cleavage of the epsilon-(gamma- glutamyl)lysine bond and liberation of free lysine and glutamic acid b y gamma-glutamyltranspeptidase (gamma-GTP) from bovine kidney were fou nd. Also, after exhaustive hydrolysis of transglutaminase-catalyzed cr oss-linked minced fish paste (''surimi'') protein, undigested epsilon- (gamma-glutamyl)lysine moiety in the hydrolysate by current gastrointe stinal hydrolytic enzymes was cleaved by gamma-GTP. These results sugg est that during the gastrointestinal digestion of the cross-linked pro teins, gamma-GTP in the intestinal mucosal wall would hydrolyze and ly sine in the proteins would be utilized normally.