Abstract
With lentinic acid as the substrate, γ-glutamyltransferase from Lentinus edodes catalyzed both hydrolytic and transfer reactions in the early stages of incubation. Prolonged incubation led to the exclusive formation of free glutamic acid and desglutamyl lentinic acid irrespective of the presence or absence of an added acceptor amino acid. The hydrolytic activity was at a maximum around pH 6.5, while the transfer activity increased with an increasing pH, reaching a constant level above pH 9.0. The pH-activity profiles of the respective reactions were interpreted as having an α-amino group of the enzyme protein functioning as a primary determinant of the reaction pathways. An apparent Michaelis constant of about 2mM was obtained when the transferase reaction was coupled with the high activity of alliin lyase. Prima facie evidence is given for the function of the γ-glutamyltransferase involved in the lenthionine evolution mechanism from lentinic acid.
