Engineering 7β-Hydroxysteroid Dehydrogenase for Enhanced Ursodeoxycholic Acid Production by Multiobjective Directed Evolution

详细信息    查看全文

• 作者：Ming-Min ZhengKe-Cai Chen ; Ru-Feng Wang ; Hao Li ; Chun-Xiu Li ; Jian-He Xu
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2017
• 出版时间：February 15, 2017
• 年：2017
• 卷：65
• 期：6
• 页码：1178-1185
• 全文大小：429K
• ISSN：1520-5118

文摘

Ursodeoxycholic acid (UDCA) is the main active ingredient of natural bear bile powder with multiple pharmacological functions. 7β-Hydroxysteroid dehydrogenase (HSDH) is a key biocatalyst for the synthesis of UDCA. However, all the 7β-HSDHs reported commonly suffer from poor activity and thermostability, resulting in limited productivity of UDCA. In this study, a multiobjective directed evolution (MODE) strategy was proposed and applied to improve the activity, thermostability, and pH optimum of a 7β-HSDH. The best variant (V_3–1) showed a specific activity 5.5-fold higher than and a half-life 3-fold longer than those of the wild type. In addition, the pH optimum of the variant was shifted to a weakly alkaline value. In the cascade reaction, the productivity of UDCA with V_3–1 increased to 942 g L^–1 day^–1, in contrast to 141 g L^–1 day^–1 with the wild type. Therefore, this study provides a useful strategy for improving the catalytic efficiency of a key enzyme that significantly facilitated the bioproduction of UDCA.