一菌双酶法制备L-4-氟苯丙氨酸

The preparation of L-4-fluorophenylalanine catalyzed by coupled two enzymes produced from recombinant E.coli

利用重组E．coli产天冬氨酸酶和天冬氨酸转氨酶催化生产L-4-氧苯丙氨酸的工艺。实验结果表明最佳转化条件为-37℃，pH值4．5—8．5，菌体与酮酸的质量浓度比为1.5，CTAB的质量分数为0．04％，酮酸的质量浓度11．28g／L，富马酸铵与酮酸的摩尔比为3．0：1．0，添加1mmol／L的Fe^2＋,L-天冬氨酸与酮酸的摩尔比为0．4：1。在最适条件下，经过14h酶转化反应达到平衡，酮酸转化率可达到95％以上，L-4-氟苯丙氨酸得率也可达到80％以上。此法原料简单易得，为L-4-氟苯丙氨酸的制备提供了一种新方法：

Preparation of L-4-fluorophenylalanine catalyzed by aspartate ammonia-lyase and aspartate aminotransferase from a recombinont strain of E. coli was studied. At first step, fumaric acid turned into L- aspartic acid as the donor of ammonia group for further reaction, catalyzed by aspartate ammonia-lyase. With the ammonia donor 4-fluorophenylpyruvate was converted to L-4-fluorophenylalanine catalyzed by aspartate aminotransferase. After 14 h, the bioconversion of 4-fluorophenylpyruvate was over 95% and the yield of L-4-fluorophenylalanine could be above 80% under the optimal conditions as follows ： 37 ℃ , pH value range of 4.5 - 8.5, 1.5 of the mass ratio of cell to 4-fluorophenylpyruvate, 0. 04% of the mass ratio of CTAB, 11.28 g/L of the 4-fluorophenylpyruvate concentration, n （ （ NH4 ） 2 Fuma） ： n （4-fluorophenylpyruvate） = 3.0： 1, lmmol/L Fe^2＋ , and n（L-Asp） ： n（4-fluorophenylpyruvate） = 0. 4： 1. The raw materials of this preparation were cheap and easy to obtain.