l-Threonine transaldolase could catalyze the transaldolation of l-threonine and aldehyde to generate β-hydroxy-α-amino acids with high diastereoselectivity. A novel l-threonine transaldolase (PmLTTA) was identified from Pseudomonas sp. through genome mining. PmLTTA exhibited high activity in the synthesis of l-threo-phenylserine from l-threonine and benzaldehyde, with specific activity of 5.48 U mg^–1. However, the application of PmLTTA was impeded by the low conversion ratio and variable diastereoselectivity, which were caused by the toxicity of aldehydes and kinetic/thermodynamic controls in the transaldolation reaction. To solve these issues, alcohol dehydrogenase was used to remove the by-product acetaldehyde, and then carboxylic acid reductase was introduced to alleviate the inhibition of benzaldehyde and toxicity of DMSO. Finally, a multi-enzyme cascade reaction, comprising of PmLTTA, carboxylic acid reductase, alcohol dehydrogenase and glucose dehydrogenase, was constructed to prepare l-threo-phenylserine from cheap benzoic acid, in which alleviated inhibition of aldehydes and desirable diastereoselectivity were achieved. Under the optimized conditions, the conversion ratio of 57.1% and de value of 95.3% were reached. This study provides an efficient and green approach for the synthesis of chiral l-threo-phenylserine from industrial byproduct, and provides guidance for the development of cascade reactions influenced by the toxic intermediates and complicated kinetic/thermodynamic controls.

l-苏氨酸转醛缩酶可催化L-苏氨酸和醛的转醛缩生成具有高非对映选择性的β-羟基-α-氨基酸。从假单胞菌属中鉴定出一种新的l-苏氨酸转醛缩酶 ( Pm LTTA) 。通过基因组挖掘。Pm LTTA在从l-苏氨酸和苯甲醛合成l-苏氨酸-苯丝氨酸中表现出高活性，比活性为5.48 U mg ^–1。但是，Pm的应用LTTA 受到低转化率和可变非对映选择性的阻碍，这是由醛的毒性和转醛化反应中的动力学/热力学控制引起的。为解决这些问题，先用乙醇脱氢酶去除副产物乙醛，然后引入羧酸还原酶来减轻DMSO对苯甲醛的抑制作用和毒性。最后，构建了由Pm LTTA、羧酸还原酶、乙醇脱氢酶和葡萄糖脱氢酶组成的多酶级联反应制备l-苏式。来自廉价苯甲酸的-苯基丝氨酸，其中减少了醛的抑制作用并实现了理想的非对映选择性。在优化条件下，转化率达到57.1%，de值达到95.3%。本研究为工业副产物合成手性l-苏-苯丝氨酸提供了一种高效、绿色的途径，并为受有毒中间体和复杂的动力学/热力学控制影响的级联反应的发展提供了指导。