选择性抑制面包酵母中R型酶的溶剂效应

为了提高面包酵母在不对称还原过程中的立体选择性，以乙酰乙酸乙酯为模型底物，还原得到(S)-(+)-3-羟基丁酸乙酯，提出了以丙烯酸、乙醚、二甲基亚砜、丙烯酰胺、正己烷等有机溶剂对酵母进行预处理的方法，以实现选择性地抑制酵母中R型酶，提高反应立体选择性的目的.考察了不同有机溶剂浓度和不同预处理时间对催化能力的影响，结果表明，经有机溶剂预处理后可以明显提高反应的立体选择性，能将S型产物的对映体过量值由70%左右提高到85%～98%, 其中二甲基亚砜在提高立体选择性的同时，能保持原有的产物收率，而其他4种有机溶剂的反应收率都有不同程度的下降.

Solvent effect to selective inhibition of R-enzymes in Baker's yeast

The asymmetric reduction of ethyl acetoacetate to ethyl(S)-( )-3-hydroxybutanoate was used as the model reaction to achieve high stereo selectivity with yeast.A novel method was proposed to selectively inhibit R-enzymes in yeast before reaction,in which Baker's yeast was pretreated with acrylic acid,ether,dimethylsulfoxide,acryl amide and hexane,respectively.The effects of organic solvent concentration and pretreatment time were investigated.After pretreatment with organic solvents,the enantiomeric excess of S-product was raised from 70% to 85%~98%.Among these solvents,dimethylsulfoxide can improve the stereo selectivity with no drop of yield,while the other four solvents decreased the yield to different degrees.