Enzyme-catalized Evolution of Lenthionine from Lentinic Acid

抄録

Protein fraction, prepared from fresh fruiting bodies of shiitake mushroom, is found capable of converting lentinic acid to lenthionine, the principal aroma-bearing substance of the mushroom. A simple Michaelis-Menten kinetics is also valid for the reaction. The reaction products identified, besides lenthionine and unidentified compounds, are glutamic acid, pyrubic acid, acetaldehyde, ammonia, and formaldehyde. Two different kinds of enzyme are envisaged to participate in the reaction; γ-glutamyl transpeptidase removing glutamyl moiety from lentinic acid, and pyridoxal phosphate dependent S-alkyl-L-cysteine sulfoxide lyase acting next on the resultant intermediate to produce an unstable inter-mediate which is then converted spontaneously to polythiepanes. A reaction pathway is proposed for lenthionine evolution from lentinic acid based on the experimental evidences obtained in this and other papers.