重组L-苏氨酸醛缩酶催化合成L-4-硝基苯基丝氨酸

Enzymatic Synthesis of L-4-Nitrophenylserine by Recombinant L-Threonine Aldolase

摘要:

利用pGEX-KG载体在大肠杆菌BL21(DE3)中重组表达了L-苏氨酸醛缩酶，以4-硝基苯甲醛、甘氨酸为底物酶法合成了L-4-硝基苯基丝氨酸，考察了反应温度、pH、底物摩尔比和甘氨酸浓度对酶活的影响。最佳转化条件为：反应温度45℃，pH=8.0，甘氨酸与4-硝基苯甲醛底物摩尔比5:1，底物甘氨酸最适浓度为500 mmol/L；0.1 g湿细胞菌体在10 mL反应体系中在最佳反应条件下反应24 h，底物4-硝基苯甲醛转化率为43%，产物L-4-硝基苯基丝氨酸达到9.72g/L，总收率为35%。

Abstract:

Enzymatic synthesis of L-4-nitrophenylserine from glycine and 4-nitrobenzaldehyde catalyzed by recombinant L-threonine aldolase in Escherichia coli BL21(DE3) with pGEX-KG plasmid was studied. Some factors influencing enzymatic reaction, such as temperature, pH, molar ratio of glycine to 4-nitrobenzaldehyde and substrate concentration were investigated. The optimal temperature and pH value were 45oC and 8.0. The optimal molar ratio of glycine to 4-nitrobenzaldehyde was 5:1, The optimal glycine concentration was 500 mmol/L. Under the optimal conditions, the bioconversion rate of 4-nitrobenzaldehyde reached 43% after 24 h. The concentration of L-4-nitrophenylserine reached 9.72 g/L, with yield of 35%.