Loops Adjacent to Catalytic Region and Molecular S

Authors: Haiyan Zhou Jie Yong Han Gao Zhihui Yuan Wenjiao Yang Yun Tian Yongyao Wu

Publish Date: 2016/05/18

Volume: 180, Issue: 1, Pages: 122-135

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Abstract

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 mannosecontaining 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 propertiesHZ carried out the molecular dynamics and design studies and drafted the manuscript JY and ZY analyzed the loop sequences and entropy HG participated in the loop analysis and helped to draft the manuscript WY carried out the assay of mutants and performed the statistical analysis YT participated in the assay of mutants and molecular design YW conceived the design of the study and participated in the drafting of the manuscript All authors read and approved the final manuscript

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