培养基碳源对固定化酵母细胞催化乙酰基三甲基硅烷不对称还原反应的影响

 尽管含芳香基等较大取代基团的底物能被生物转化为高对映体纯手性有机硅醇,但生物催化其他底物还原反应的产物收率及对映体选择性均较低. 作者筛选到一株能高效催化羰基/羟基不对称转化的酵母菌株,探讨了用固定化酵母细胞高效催化乙酰基三甲基硅烷不对称还原制1-三甲基硅乙醇的可能性,系统研究了培养基碳源及其浓度对该反应的影响. 发现在水/正己烷两相体系中,固定化酵母细胞能催化乙酰基三甲基硅烷不对称还原成1-三甲基硅乙醇. 可通过调节培养基碳源的种类及其浓度在一定程度上控制反应的产物收率及对映体选择性. 以最适碳源(3.0%麦芽汁)培养的酵母细胞催化该反应的产物收率和对映体过量值分别为91.3%和72.8%,远高于文献报道值.

Effect of Carbon Source on Asymmetric Reduction of Acetyltrimethyl-silane Catalyzed by Immobilized Cells

Although highly enantioselective bioreduction of organosilanes with bulky substitutes like aromatic groups has been successfully performed, the product yield and the product enantiomeric excess (e.e.) for the reduction of other organosilanes are disappointingly low. We have succeeded in isolating a new yeast strain Rhodotorula sp. AS2.2241 capable of highly stereoselectively catalyzing carbonyl/hydroxyl conversion. In this paper, the possibility of the asymmetric reduction of acetyltrimethylsilane to 1-trimethylsilylethanol catalyzed by immobilized Rhodotorula sp.AS2.2241 cells was explored and the effects of carbon source and its concentration in the culture medium on the reaction were systematically examined. In the aqueous/hexane biphase system, the immobilized Rhodotorula sp.AS2.2241 cells could catalyze the reaction. The yield and stereoselectivity of the reaction can be adjusted to some extent by changing the carbon source and its concentration. The product yield and the product e.e. value achieved were as high as 91.3% and 72.8% respectively, when the immobilized Rhodotorula sp.AS2.2241 cells were cultured in the optimized medium (3.0%wort).