A mutant library of the key amino acid residue site E387 in γ-glutamyltranspeptidase was constructed to screen the mutant enzymes with significantly improved thermal stability (E387Q). The reaction temperature of the mutant enzyme (E387Q) was 10℃ higher than that of the parent enzyme. Ultrasound-assisted synthesis of L-theanine by γ-glutamyltranspeptidase was investigated. The effects of ultrasonic power, reaction pH and substrate concentration on the enzymatic synthesis of L-theanine were studied by the response surface method. The results showed that the optimal process conditions are ultrasonic power of 100 W, reaction pH of 9, substrate L-glutamine concentration of 120 mmol/L, reaction temperature of 45℃, and L-theanine yield of 89.1%. The yield of L-theanine is 2.61 times higher than that obtained without ultrasound. Ultrasound can significantly promote the synthesis of L-theanine by γ-glutamyltranspeptidase.

构建了γ-谷氨酰转肽酶中关键氨基酸残基位点E387的突变体文库，以筛选具有显着改善的热稳定性（E387Q）的突变体酶。突变酶（E387Q）的反应温度比亲本酶高10℃。研究了γ-谷氨酰转肽酶的超声辅助合成L-茶氨酸。通过响应面法研究了超声功率，反应pH和底物浓度对酶催化合成L-茶氨酸的影响。结果表明，最佳工艺条件为：超声功率100 W，反应pH 9，底物L-谷氨酰胺浓度120 mmol / L，反应温度45℃，L-茶氨酸产率89.1％。L-茶氨酸的产率是没有超声时的2.61倍。