化学
甘草甜素
生物转化
定点突变
酶动力学
定向诱变
立体化学
活动站点
突变
突变体
生物化学
天冬氨酸
米曲霉
酶
氨基酸
生物
突变
药理学
基因
作者
Qiaofeng Li,Tian Jiang,Rui Liu,Xudong Feng,Chun Li
标识
DOI:10.1007/s00253-019-09790-3
摘要
In this study, we aimed to shift the optimal pH of acidic β-glucuronidase from Aspergillus oryzae Li-3 (PGUS) to the neutral region by site-directed mutagenesis, thus allowing high efficient biotransformation of glycyrrhizin (GL) into glycyrrhetinic acid (GA) under higher pH where the solubility of GL could be greatly enhanced. Based on PGUS structure analysis, five critical aspartic acid and glutamic acid residues were replaced with arginine on the surface to generate a variant 5Rs with optimal pH shifting from 4.5 to 6.5. The catalytic efficiency (kcat /Km) value of 5Rs at pH 6.5 was 10.7-fold higher than that of PGUS wild-type at pH 6.5, even 1.4-fold higher than that of wild-type at pH 4.5. Molecular dynamics simulation was performed to explore the molecular mechanism for the shifted pH profile and enhanced pH stability of 5Rs.
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