三酶偶联全细胞生物合成L-酪氨酸

Biosynthesis of L-Tyrosine with Aldolase, D-Serine Dehydratase and Tyrosine Phenol-Lyase

摘要:

通过将醛缩酶（Aldolase，ALD）、D-丝氨酸脱水酶（D-Serine Dehydratase，SDH）和酪氨酸酚裂解酶（Tyrosine Phenol-Lyase，TPL）三酶偶联，催化甘氨酸、甲醛和苯酚合成L-酪氨酸（L-Tyrosine，L-Tyr）。经考察确定了三酶偶联最佳反应条件：pH 8.5，温度35 ℃，6 g/L乙酸铵、0.1 g/L PLP，三种酶细胞质量配比(ALD∶SDH∶TPL)为6∶3∶5。当甘氨酸加量为50 g/L，利用上述工艺进行10000 L转化验证，反应11 h，L-Tyr浓度可达117 g/L，转化率为97%，转化体系放大后转化率提高4 %，收率为85%。三酶偶联生物法合成L-Tyr直接将底物甘氨酸、甲醛和苯酚经酶催化反应获得L-Tyr，节省了D-丝氨酸和丙酮酸铵的提取步骤，对资源的合理利用以及对绿色合成工艺的开发具有重要的参考意义。

Abstract:

We used multienzyme coupled catalysis to produce L-Tyrosine(L-Tyr). In this study, Glycine was catalyzed to synthesize D-Serine by Aldolase(ALD), and D-Serine was transferred to pyruvic acid ammonium by D-Serine Dehydratase(SDH). Then, L-Tyr was synthesized by Tyrosine Phenol-Lyase(TPL) when the substrate phenol was added into the reaction system.The optimal reaction conditions were shown as follows: pH=8.5, 35 ℃, 6 g/L of ammonium acetate, 0.1 g/L of PLP, m(ALD)：m(SDH)：m(TPL)=6∶3∶5. We used the above conditions to catalyze glycine at the concentration of 50 g/L for 11 h, the concentration of L-Tyr was 117 g/L with a conversion of 97%, increasing by 4% compared with small-scale test and the yield reached 85%.The method of biosynthesis of L-Tyr can not only eliminate the purification process of D-Serine and pyruvic acid ammonium, but also has a reference significance for the reasonable utilization of resources and green synthesis process.