重组酪氨酸酚裂解酶全细胞催化合成L-酪氨酸

Synthesis of L-Tyrosine by Whole Cell with Recombinant Tyrosine Phenol Lyase

利用基因工程手段重组表达了弗氏柠檬酸杆菌来源的酪氨酸酚裂解酶(TPL),以丙酮酸和L-丝氨酸为底物全细胞催化合成L-酪氨酸,考察了pH、温度、表面活性剂、金属离子、铵盐种类和氯化铵浓度等因素对L-酪氨酸合成的影响,并比较了两种底物合成L-酪氨酸的转化率。结果表明,TPL的最适反应条件是45℃,pH=8.0,4mmol/L PLP,氯化铵浓度350 mmol/L。1 mmol/L triton-x 100对TPL酶活有促进作用,金属离子对TPL酶活都有明显的抑制作用。0.1 mol/L丙酮酸的转化率约是L-丝氨酸的1.8倍。

The tyrosine phenol lyase（TPL） from Citrobacterfreundii was recombinantly expressed in E. coli BL21 （DE3） with the vector pETDuet - 1. The enzymatic properties of the recombinant tyrosine phenol lyase were studied, and several influence factors of enzyme reaction such as pH, temperature, surfactants, metal ions, ammonium salts, and ammonium chloride concentration were investigated. The results indicate that the optimum reaction conditions of TPL were 45 ℃, pH = 8.0,4 mmol/L PLP,350 mmol/L NH4C1,1 mmoL/L triton-x 100. The conversion rate of pyruvate substrate was 1.8 times higher than that of serine substrate.