STUDIES ON GAMMA-GLUTAMYLPEPTIDES IN L-GLUTAMIC ACID FERMENTATION BROTHS .3. MECHANISM OF FORMATION OF GAMMA-GLUTAMYLPEPTIDES DURING L-GLUTAMIC ACID FERMENTATION CONTRIBUTED SOLELY BY GAMMA-GLUTAMYLTRANSPEPTIDASE

The enzyme of Corynebacterium glutamicum that catalyzes the formation of various r-L(D)-glutamylpeptides by the reversal of hydrolysis was found to be T-glutamyltranspeptidase, The enzyme catalyzed γ-l(d)-glutamyl transfer reaction from various γ -l(d)-glut amyl-pep tides including glutathione. The susceptibility of D-isomers was 17% of that of L-isomers. Many kinds of α-L-amino acids and peptides such as γ -L-GIu-L-GIu could be γ -glutamyl acceptors. These findings offered full explanation on the formation of γ L-glutamylpeptides in the L-glutamic acid fermentation. In the supposed mechanism, γ -L-GIu-l-GIu is formed mainly by the reversal of hydrolysis from L-glutamic acid being richly produced by the bacteria. The other four minor peptides are formed by the r-glutamyitranspeptidation from γ -L-GIu-L-Glu to some a-L-amino acids and to γ -L-GIu-L-GIu itself in the broths. The enzyme was found to be widely distributed among bacteria, especially in some strains of Corynebacterium, Bacillus, Erwinea, Serratia, Pseudomonas, Achromobacter, and Alcaligenes. © 1978 Taylor & Francis Group, LLC.