谷氨酰胺合成酶催化合成茶氨酸条件的优化

Optimization of theanine biosynthesis catalyzed by glutamine synthetase

在不同诱导条件下,对谷氨酰胺合成酶催化合成茶氨酸体系进行优化,确定最适诱导表达条件,为微生物发酵合成茶氨酸提供技术依据。研究结果表明:基因工程菌最佳培养温度为30℃,最佳诱导剂异丙基硫代-β-D半乳糖苷浓度为0.1 mmol.L-1,最佳诱导温度为28℃。合成茶氨酸的最适pH值为9.5,适合的缓冲液为100 mmol.L-1咪唑;反应体系中咪唑缓冲液优于磷酸钾缓冲液;低浓度L-谷氨酸钠、高浓度盐酸乙胺和高浓度三磷酸腺苷对茶氨酸的合成均有一定的促进作用,可以提高茶氨酸的生成量。

Theanine biosynthesis system catalyzed by glutamine synthetase was optimized. This work afforded a necessary technical foundation for theanine biosynthesized by microbe zymolysis. The results were as follows, the optimum temperature for bacterium culture was 30 ℃, the optimum IPTG （isopropylthio-β-D-galactoside） concentration was 0. 1 mmol ·L-1 , and the optimum tem- perature for enzyme inducement was 28 ℃. It was also manifested that pH 9. 5, imidaxole buffer 100 mmol · L-1 were most suit- able for theanine biosynthsis. The effection of imidaxole buffer was better than that of potassium phosphate buffer. The concentra- tion of L-sodium glutamate and ethylamine HC1 and ATP were optimiz to obtain higher theanine.