近平滑假丝酵母细胞催化乙酰基三甲基硅烷不对称还原反应

 采用近平滑假丝酵母细胞用于催化乙酰基三甲基硅烷不对称还原反应, 可高选择性地生成 (R)-1-三甲基硅乙醇. 结果表明, 固定化于海藻酸钙的细胞催化该反应的产物收率比游离细胞的高. 不同辅底物对该反应的影响显著, 以葡萄糖为辅底物时, 反应的初速率较快, 产物收率较高. 该反应的最适条件为: 辅底物 (葡萄糖) 浓度 110 mmol/L, 振荡速度 180 r/min, 缓冲液 pH 值 6.0, 反应温度 30 oC, 底物浓度 20 mmol/L. 在此反应条件下反应的初速率、产物收率和产物的 ee 值分别为 11.4 μmol/h, 96.5% 和 99.9%.

Asymmetric Reduction of Acetyltrimethylsilane Catalyzed by Candida parapsi-losis CCTCC M203011 Cells

The asymmetric reduction of acetyltrimethylsilane (ATMS) to (R)-1-trimethylsilylethanol (TMSE) catalyzed by Candida parapsilosis CCTCC M203011 cells was studied. It was found that the Candida parapsilosis CCTCC M203011 cells were capable of mediating the reduction of ATMS to (R)-1-TMSE with excellent enantioselectivity. The yield of (R)-1-TMSE with the cells immobilized on calcium alginate was higher than that with free cells. In addition, different co-substrates manifested a distinct effect on the bioreduction, and the initial reaction rate was clearly faster and the product yield was much higher using glucose as a co-substrate in the bioreduction. Moreover, the optimal glucose concentration, shaking rate, buffer pH, reaction temperature, and substrate concentration for the bioreduction were found to be 110 mmol/L, 180 r/min, 6.0, 30 ^oC,?and 20 mmol/L, respectively. Under these conditions, the initial reaction rate, maximum product yield, and product ee value were 11.4 μmol/h, 96.5%, and 99.9%, respectively.