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.

考察了大肠杆菌AS1.505的L-谷氨酸脱羧酶对L-谷氨酸的专一脱羧作用,分析了转化体系温度、pH值等因素对L-谷氨酸脱羧酶活力的影响.实验结果表明最佳工艺为:温度37℃,转化体系pH值4.8,菌体浓度6 g/L,吐温-80 0.15 g/L,菌龄14 h,底物浓度50 g/L.L-谷氨酸脱羧酶在最适转化条件下比酶活可以达到15036 U.1 g湿菌体可重复使用3次共转化DL-谷氨酸25 g,其中L-谷氨酸可以完全转化为γ-氨基丁酸.D谷氨酸及γ-氨基丁酸的总收率可以分别达到理论收率的87%和85%.

Protected L-glutamic acid was prepared using inexpensive phthaloyl as protecting group.Then N-phthaloyl-L-glutamic acid anhydride was synthesized with protected L-glutamic acid and acetic anhydride under reflux for 10 minutes.Under ambient temperature and pressure,N-phthaloyl-L-theanine and N-phthaloyl-L-glutamine were produced by reaction of N-phthaloyl-L-glutamic acid anhydride with 2 mol/L ethylamine solution and 2 mol/L ammonia solution respectively.Subsequently,the phthaloyl group was removed from the intermediates with 0.5 mol/L hydrazine hydrate under ambient temperature for 48 h.As a result,L-theanine and L-glutamine were obtained in 61% and 57% yields respectively.

DL-茶氨酸经乙酰化可生成N-乙酰-DL-茶氨酸,然后利用米曲霉氨基酰化酶拆分N-乙酰-DL-茶氨酸可以获得L-茶氨酸.本文对氨基酰化酶酶促反应也进行了初步研究,考察了反应温度、反应时间、pH值和底物浓度等因素对酶促反应的影响.实验表明,转化温度40℃、转化时间30h、pH为7.0和底物浓度0.2mol/L时,目的产物L-茶氨酸的产率最高.

L-Alanyl-L-glutamine(Dipeptiven) was prepared in 10 t/a pilot-plant-scale by using phthalyl method and mixed anhydride method.The result showed that the optimal solvent used to dissolve N-Pht-L-alanine was ethyl acetate,the optimal temperature was 0 ℃,and the molar ratio of N-Pht-L-alanine to L-glutamine was 1∶1.The overall molar yield was 34.4% based on L-alanine.w(L-alanyl-L-glutamine(Dipeptiven))=98.6%.