双酶偶联生物合成L-酪氨酸

多酶偶联催化是酶法制备手性药物中间体的重要方法之一。该文采用双酶偶联体系,利用天冬氨酸转氨酶全细胞催化L-天冬氨酸转氨至苯丙酮酸,生成L-苯丙氨酸,同时得到中间产物丙酮酸;反应体系中的酪氨酸酚裂解酶全细胞催化丙酮酸、苯酚和氨酶法合成L-酪氨酸。经考察确定了双酶偶联反应的最佳条件为:温度40℃,pH=8.5,底物苯丙酮酸质量浓度为25 g/L,苯丙酮酸与L-天冬氨酸摩尔比1∶1.2,天冬氨酸转氨酶与酪氨酸酚裂解酶细胞质量比1∶1,4 mmol/L PLP,0.1 g/L吐温80。30 g/L的氯化铵对双酶偶联反应有促进作用。双菌双酶偶联生物法合成L-酪氨酸,充分利用了反应副产物丙酮酸得到附加值较高的产品,对资源合理利用及绿色合成工艺具有参考意义。

Biosynthesis of L-Tyrosine with Whole Cell Coupled Aspartate Aminotransferase and Tyrosine Phenol-Lyase

Multi enzyme coupled catalysis is one of the important methods in the enzymatic preparation of chiral drug intermediates. In this study, the ammonia of L-aspartic acid was transferred to the phenylpyruvic acid, and L-phenylalanine with byproduct pyruvic acid were synthesized by aspartate aminotransferase (AspAT) whole cell. Then, L-tyrosine was enzymatic synthesized when substrate phenol and tyrosine phenol-lyase (TPL) whole cell were added into the reaction system. Some factors affecting dual enzymatic catalysis were investigated. The optimal conditions were 40oC, pH 8.5, 25 g/L of phenylpyruvic acid (PPA), n (PPA): n (L-Asp)=1:1.2, m (AspAT): m (TPL)=1:1, 4 mmol/L of PLP, 0.1 g/L of Tween 80. 30 g/L of ammonium chloride had a promoting effect on dual enzyme coupled catalysis reaction. The method biological synthesis of L-tyrosine with coupled dual enzyme in dual host, not only makes full use of the by-product of the reaction pyruvic acid for higher value-added products, but has reference significance for the reasonable utilization of resources and green synthesis process.