水/有机溶剂双相体系中色氨酸合成酶酶法合成L-色氨酸

在水/有机溶剂双相体系中,利用重组大肠杆菌DM206 pET28a-trpBA/BL21 (DE3)]色氨酸合成酶催化L-丝氨酸和吲哚合成了L-色氨酸.考察了有机溶剂、有机相乙酸乙酯体积分数、反应温度、水相pH、底物L-丝氨酸与吲哚摩尔比、底物L-丝氨酸浓度、表面活性剂和酶添加量对色氨酸合成酶酶活的影响.结果表明,酶...

Enzymatic Synthesis of L-Tryptophan Catalyzed by Tryptophan Synthase in a Water/Organic Solvent Biphase System

Enzymatic synthesis of L-tryptophan from L-serine and indole catalyzed by tryptophan synthase from recombinant Escherichia coli DM206 pET28a-trpBA/BL21(DE3)] in an aqueous/organic biphasic system was carried out.The effects of organic solvents,volume fraction of ethyl acetate,reaction temperature,pH value of the aqueous phase,molar ratio of L-serine to indole,L-serine concentration,sur-factants,and enzyme amount were investigated.Ethyl acetate was found to be the best organic solvent for the reaction.The optimal volume fraction of ethyl acetate was 2.5%.The optimal temperature and pH value were 35 oC and 8,respectively.The optimal molar ratio of L-serine to indole was 1:1.2.The optimal L-serine concentration was 100 mmol/L.The optimal mass fraction of Tween 80 was 0.4%.The optimal enzyme amount was 20 g/L.Under the optimal conditions,bioconversion rate of L-serine reached 95% after 2.5 h in the aqueous/organic biphasic system.