D-谷氨酰胺的制备

报道了以化学合成和生物转化的方法制备光学纯D-谷氨酰胺. 首先在中试规模上用化学方法合成DL-谷氨酰胺. 即以廉价的DL-谷氨酸为原料, 采用邻苯二甲酰基作为保护基保护L-谷氨酸的α-氨基, 醋酐回流15 min, 使其分子内脱水生成N-邻苯二甲酰-DL-谷氨酸酐, 在常温、常压条件下, 分别与2 mol/L氨水反应生成中间产物N-邻苯二甲酰-DL-谷氨酰胺, 中间产物在室温条件下与0.5 mol/L水合肼反应48 h脱除保护基, 以57%总收率得到DL-谷氨酰胺. 在37 ℃, pH 4.8的条件下, 利用大肠杆菌(E. coli. AS 1.505)脱羧酶将底物浓度30 g/L的DL-谷氨酰胺中L型对映体在8 h内完全转化为4-氨基丁酰胺, 分离得到D-谷氨酰胺.

Preparation of D-Glutamine from Glutamic Acid

Optically pure D-glutamine was prepared by biotransformations of DL-glutamine manufactured by chemical synthesis. Firstly, DL-glutamine was synthesized from DL-glutamic acid on larger scale. Protected DL-glutamic acid was prepared by using inexpensive phthaloyl as protecting group. Then N-phthaloyl-DL-glutamic acid anhydride was synthesized with protected DL-glutamic acid and acetic anhydride under reflux for 15 min. Un-der ambient temperature and normal pressure, N-phthaloyl-DL-glutamine was produced by reacting N-phthaloyl-DL-glutamic acid anhydride with 2 mol/L ammonia solution. After the phthaloyl was removed from the intermediate with 0.5 mol/L hydrazine hydrate under ambient temperature for 48 h DL-glutamine mixture was obtained in 57% yields. L-Glutamine in the racemic mixture was selectively decarboxylated to 4-aminobutanamide by the decarboxylase of E. coli AS1.505. Under the following conditions: temperature of 37 ℃, reaction time of 8 h, pH of 4.8, substrate concentration of 30 g/L, D-glutamine was efficiently produced.