期刊
JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC
卷 118, 期 -, 页码 62-69出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.molcatb.2015.05.002
关键词
beta-Glycosidase; Sulfolobus acidocaldarius; pH-activity; Cellobiose hydrolysis; Transglycosylation; Active site mutations
资金
- TEKES
- Finnish Funding Agency for Technology and Innovation [40147/07]
- Emil Aaltonen foundation
Sulfolobus acidocaldarius beta-glycosidase (BGAL_SULAC) was used as an extremophilic enzyme model to study the effect of mutations close to the catalytic residues on the enzyme activity and the pH-activity profile. We report here the results for three mutations (N211D, V212D and V212T) changing the polarity close to the putative acid/base catalyst E209. N211D was outside the H-bonding distance from E209, whereas V212D and V212T were in H-bonding distance from E209. V212D and V212T shifted the pH-activity profile towards acidic pH with both lactose and cellobiose as substrates. N211D and V212D decreased clearly the activity. Although V212T increased 6-fold the K-m value with cellobiose, the mutant showed higher specific activity in high substrate concentrations. The reason was greatly reduced production of trisaccharide by V212T from cellobiose by transglycosylation. Threonine differs by the terminal oxygen from valine, indicating that additional hydrogen bonding to substrate or reaction products may affect the reaction behavior of the enzyme. Although the mutations in the active site are often harmful, the mutation V212T showed biotechnologically promising properties. (C) 2015 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据