Luo Xi, Wang Ya-Jun, Zheng Yu-Guo
Institute of Bioengineering, Zhejiang University of Technology, Hangzhou, People's Republic of China.
Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou, People's Republic of China.
Biotechnol Appl Biochem. 2016 Nov;63(6):795-804. doi: 10.1002/bab.1439. Epub 2015 Sep 28.
Optically pure t-butyl 6-cyano-(3R, 5R)-dihydroxyhexanoate ((R)-1b) is the key precursor for atorvastatin calcium, the most widely used cholesterol-lowering drug. In this work, a strain ZJB-09224 capable of asymmetrically reducing t-butyl 6-cyano-(5R)-hydroxy-3-oxohexanoate (1a) to corresponding optically pure (R)-1b was successfully isolated from soil sample, identified belonging to Rhodotorula glutinis based on the morphology, physiological tests, and the 18S rDNA sequence analysis. It was found that heat treatment of cell suspension at 45 °C for 25 Min significantly improved R. glutinis ZJB-09224 stereoselectivity. The asymmetric bioreduction of 1a was most efficient at pH 7.5, 35 °C, 50 mM (15.0 g L ) substrate concentration, 40.0 g DCW L cell loading size, 0.54 M (60.0 g L ) sodium lactate acting as co-substrate. Under these optimal conditions, 0.046 M (R)-1b was produced with de (diastereomeric excess) value of 99.2% after 40 H conversion. Moreover, R. glutinis ZJB-09224 has a broad substrate spectrum, making it a potential tool for some valuable chiral alcohol pharmaceutical intermediates synthesis.
光学纯的6-氰基-(3R,5R)-二羟基己酸叔丁酯((R)-1b)是阿托伐他汀钙的关键前体，阿托伐他汀钙是使用最广泛的降胆固醇药物。在本研究中，从土壤样品中成功分离出一株能够将6-氰基-(5R)-羟基-3-氧代己酸叔丁酯(1a)不对称还原为相应光学纯的(R)-1b的菌株ZJB-09224，通过形态学、生理测试和18S rDNA序列分析鉴定其属于粘红酵母。发现将细胞悬浮液在45℃热处理25分钟可显著提高粘红酵母ZJB-09224的立体选择性。1a的不对称生物还原在pH 7.5、35℃、50 mM(15.0 g/L)底物浓度、40.0 g DCW/L细胞装量、0.54 M(60.0 g/L)乳酸钠作为共底物的条件下效率最高。在这些最佳条件下，转化40小时后产生了0.046 M的(R)-1b，非对映体过量(de)值为99.2%。此外，粘红酵母ZJB-09224具有广泛的底物谱，使其成为合成一些有价值的手性醇药物中间体的潜在工具。
