枯草芽胞杆菌PnbA酯酶选择性拆分制备l-薄荷醇  

Enantioselective hydrolysis of dl-menthyl propionate in enzymatic preparation of l-menthol by PnbA esterase from Bacillus subtilis

作　　者：陶惟一 徐娴[1] 李霜[1] 

机构地区：[1]南京工业大学生物与制药工程学院,江苏南京211800

出　　处：《生物加工过程》2015年第6期43-48,共6页Chinese Journal of Bioprocess Engineering

基　　金：国家重点基础研究发展计划(973计划)(2011CB710800);国家自然科学基金青年基金(21406111)

摘　　要：利用重组大肠杆菌表达来源于枯草芽胞杆菌CICC 20034中的PnbA酯酶,不对称催化水解dl-薄荷醇丙酸酯制备l-薄荷醇。考察助溶剂种类、助溶剂添加浓度、温度、催化剂用量、底物浓度以及p H等对反应的影响。结果表明:添加25%(体积分数)助溶剂乙醇可显著提升该酯酶对l-薄荷醇的立体选择性,对映选择率(E)由2.4提高到99.43,为不加乙醇条件下的40倍。酶催化最佳条件:25%乙醇作为助溶剂,反应温度37℃,缓冲液为0.1 mol/L Tris-HCl(p H 8.0)并保持p H 8.0反应条件,底物量50 mmol/L,反应体系中酶的添加量750 U/m L,在此条件下,酶促反应30 min后,l-薄荷醇转化率可达34%,产物光学纯度对映体过量值(e.e._p)达95%。The PnbA esterase from Bacillus subtilis CICC 20034 was expressed in recombinant Escherichia coli and used to produce /-menthol through enantioselective hydrolysis of d/-menthyl propionate. The effects of co-solvents, temperature, pH, substrate titers and enzyme dosage on the enantioselective hydrolysis reaction were studied. Results showed that ethanol was the most suitable co-solvent; adding 25% （V/V） ethanol could significantly improve the optical purity of/-menthol, enantiomerie selectivity （E） enhanced from 2.4 to 99.43, about 40 times higher than that of the control.The optimized conditions for hydrolysis of dl-menthyl propionate to prepare/-menthol by PnbA were 25% （V/V） ethanol ,0. 1 mol/ L Tris-HC1 buffer （pH8.0）, 50 mmol/L dl-menthyl piopionate ,750 U/mL crude enzyme solution, 37 ~C and pH 8.0. Under these conditions , /-menthol could be obtained with the conversion rate obove 34% and the optical purity above 95% in 30 rain reaction.

关 键 词：PnbA酯酶 对映选择率 L-薄荷醇 助溶剂 选择性拆分 

分 类 号：TQ033[化学工程]