Department of Life and Food Science, Suzhou University, Suzhou 234000, China.
Department of Life and Food Science, Suzhou University, Suzhou 234000, China.
Bioresour Technol. 2020 Jul;307:123251. doi: 10.1016/j.biortech.2020.123251. Epub 2020 Mar 26.
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-谷氨酰转肽酶关键氨基酸残基 E387 的突变文库，以筛选热稳定性显著提高的突变酶（E387Q）。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 值和底物浓度对 L-茶氨酸酶合成的影响。结果表明，最佳工艺条件为超声功率 100 W、反应 pH 值 9、底物 L-谷氨酰胺浓度 120 mmol/L、反应温度 45℃、L-茶氨酸得率 89.1%。L-茶氨酸的产量比无超声时提高了 2.61 倍。超声能显著促进γ-谷氨酰转肽酶合成 L-茶氨酸。
