含水有机溶剂体系中固定化Acetobacter sp.CCTCC M209061细胞催化乙酰乙酸乙酯不对称还原反应

Biocatalytic Asymmetric Reduction of Ethyl Acetoacetate with Immobilized Acetobacter sp. CCTCC M209061 Cells in a Micro-water-containing Organic Solvent

本论文报道了含微水有机溶剂体系中固定化Acetobacter sp.CCTCC M209061细胞催化乙酰乙酸乙酯不对称还原为(R)-3-羟基丁酸乙酯。研究表明,Acetobacter sp.CCTCC M209061细胞能遵循反Prelog规则高选择性地催化乙酰乙酸乙酯不对称还原。与单水相反应体系相比,含有机溶剂体系不仅可有效地解决底物和产物的抑制作用,而且可提高反应底物的浓度和产率。在所研究的不同有机溶剂中,正己烷为该反应的最适有机相,其能较好溶解底物且对Acetobacter sp.CCTCC M209061细胞的毒性较小,从而导致反应的初速度较快,产率较高。异丙醇为该反应的最佳辅底物,其最适浓度为60 mmol/L;该反应体系中的最适正己烷体积百分比、反应温度、底物浓度分别为约100.00%(水含量约为0.01 wt%),35℃,40 mmol/L。在此条件下,反应的初速率、产率和产物的e.e.值分别为0.72μmol/min,85.24%和99.00%以上,明显好于水单相反应体系进行该反应的结果。

In present study, the highly anti-Prelog stereoselective reduction of ethyl acetoacetate（EAA） to（R）-ethyl-3-hydroxybutyrate（EHB） with immobilized Acetobacter sp. CCTCC M209061 cells was successfully conducted in a micro-water-containing organic solvent. Use of organic solvent-containing system as the reaction medium, in place of aqueous monophasic system, could not only effectively eliminate the inhibition of the substrate and product, but also improve the concentration of the substrate and the product yield of the tested organic solvents, n-hexane was selected as the most suitable organic phase for the reaction, due to its good ability to dissolve the substrate and biocompatibility with Acetobacter sp. CCTCC M209061 cells. Therefore, the bioreduction reaction with n-hexane became faster and the achieved product yield was relatively higher. Isopropanol was found to be the best co-substrate for the bioreduction and its optimal concentration was 60 mmol/L. For the bioreduction of EAA with immobilized Acetobacter sp. CCTCC M209061 cells, the optimum percentage of n-hexane, reaction temperature, substrate concentration were 100.00%（containing around 0.01 wt% water）, 35 ℃, 40 mmol/L, respectively. Under the optimized reaction conditions, the obtained initial reaction rate, yield and product e.e. was 0.72 μmol/min, 85.24% and 99.00% above, which was better than the results observed with aqueous monophasic system as the reaction medium.