A new method for the synthesis of gamma-glutamylmethylamide is presented. Glutamic acid gamma-methyl ester was used as substrate for gamma-glutamylmethylamide synthesis catalyzed by Escherichia coli with gamma-glutamyltranspeptidase activity. Reaction conditions were optimized by using 300 mM glutamic acid gamma-methyl ester and 3,000 mM methylamine at pH 10 and 40 A degrees C. Bioconversion rate of gamma-glutamylmethylamide reached 87 % after 10 h. gamma-Glutamyltranspeptidase was reversibly inhibited only when glutamic acid gamma-methyl ester was above 300 mM.