Loops Adjacent to Catalytic Region and Molecular Stability of Man1312

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• 作者：Haiyan Zhou ; Jie Yong ; Han Gao ; Zhihui Yuan…
• 关键词：Mannanase ; Rational design ; Loop ; Molecular stability
• 刊名：Applied Biochemistry and Biotechnology
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：180
• 期：1
• 页码：122-135
• 全文大小：2,814 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Biotechnology
  Biochemistry
  
• 出版者：Humana Press Inc.
• ISSN：1559-0291
• 卷排序：180

文摘

Hemicelluloses are the second major polysaccharides in nature and can be converted to ethanol product by a variety of enzymes including mannanases. Mannanase is an important enzyme that hydrolyses mannose-containing polysaccharides which are abundant in plants. An optimized mannanase could help to improve conversion process and make the technology efficiently and competitively. In this work, the effects of loops adjacent to active region on enzymic properties of Man1312 were investigated. Loop 6 and 10 are two loops neighboring to Man1312 catalytic region, and deletion mutagenesis and residue substitution were performed on both loops. Deletion on sites S145, Q148, N244, and S255 and substitution on sites N146, S147, S156, and T157 gave significant increased stability to enzyme. The quadruplet mutant ManD4I4 combined all the mutations and had higher optimal temperature and T_m value by 5 and 4 °C than Man1312, respectively. From our data, we are able to conclude the loops of enzymes are important to design mutagenesis and obtain improved properties, especially the loops neighboring to catalytic region from tertiary structure. In our experiment, residue deletion and substitution on loops neighboring to catalytic region made significant improvement on enzyme properties.