光学纯的3-奎宁醇是一种重要的手性医药中间体,目前已报道的通过酶催化3-奎宁酮的不对称还原几乎都是得到(R)-3-奎宁醇.在前期的工作中我们筛选获得一株能催化还原得到(S)-3-奎宁醇的红串红球菌(Rhodococcus erythropolis WY1406),其ee值达到99%.本研究从该红串红球菌中克隆得到6个3-奎宁酮还原酶基因,并将其转入到大肠杆菌BL21(DE3)中诱导表达,利用粗酶液检测它们催化3-奎宁酮还原的活性及立体选择性.结果发现其中两种酶Re QR-13和Re QR-25催化3-奎宁酮还原生成(S)-3-奎宁醇,ee值大于99%.此外还发现了能催化生成(S)-3-奎宁醇的ee值分别为83%、46%和57%的奎宁酮还原酶Re QR-18、Re QR-27和Re QR-28.其中表达Re QR-25的整细胞催化5 g/L的底物3-奎宁酮还原,转化率达93%.本研究为合成光学纯的(S)-3-奎宁醇提供了一种新的方法.
Optically pure quinuclidinol is an important chiral pharmaceutical intermediate.The straightforward method of metal-catalyzed reduction to synthesize quinuclidinol does not meet the need of high optical purity for the product.Enzymatic reduction of quinuclidinone can give(R)-3-quinuclidinol with high optical purity.In our previous study,we identified a strain of Rhodococcus erythropolis WY1406,which catalyzed the reduction of quinuclidinone to produce(S)-3-quinuclidinol with 99% ee.In this study,6 quinuclidinone reductase genes were cloned from this strain and expressed in E.coli,which could produce(S)-3-quinuclidinol with quinuclidinone hydrochloride as a substrate.Among the reductases,Re QR-13 and Re QR-25 catalyzed the reduction of quinuclidinone to afford(S)-3-quinuclidinol with〉 99% ee.The who le E.coli cells expressing Re QR-25 gene catalyzed the reduction of 5 g/L quinuclidinone with 93% conversion in 14 h.This offers a new method for the synthesis of optically pure(S)-quinuclidinol.