【摘要】 报道了制备D-谷氨酰胺的一种新方法,即利用大肠杆菌AS1.505的L-谷氨酰胺脱羧酶立体选择性地将D,L-谷氨酰胺中L型对映体降解为4-氨基-丁酰胺,分离得到D-谷氨酰胺。同时考察了转化体系温度、pH等因素对L-谷氨酰胺脱羧酶活力的影响。实验结果表明最佳条件为:温度37℃,转化体系pH=4.8,菌体质量浓度5 g/L,吐温-80质量浓度0.15 g/L,菌龄14 h,底物质量浓度40 g/L。L-谷氨酰胺脱羧酶在最适转化条件下比酶活可以达到4 200 U,L-谷氨酰胺在8 h内完全转化成4-氨基-丁酰胺,D-谷氨酰胺收率达到理论收率的92%。更多还原

【Abstract】 Optically pure D-glutamine is initially prepared by biotransformations of D,L-glutamine in the presence of L-glutamine decarboxylase in Escherichia coli AS1.505.Factors that affected the enzymatic activity such as converting temperature,pH value,etc.,were studied.The results show that the specific enzyme’s activity can come up to 4200U,and L-glutamine can be completely degraded by the decarboxylase for 8 h under the optical conditions as follows:37℃,4.8 of pH value,5 g/L of cell concentration,0.15 g/L of tween-80,14 h of strain age,and 40 g/L of the substrate concentration.更多还原