Three-dimensional structure of an alkaline xylanase Xyn11A-LC from alkalophilic Bacillus sp. SN5 and improvement of its thermal performance by introducing arginines substitutions |
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Authors: | Wenqin Bai Cheng Zhou Yanfen Xue Chun-Hsiang Huang Rey-Ting Guo Yanhe Ma |
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Institution: | 1. National Engineering Lab for Industrial Enzymes, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China 2. School of Life Science, Shanxi Normal University, Linfen, 041004, China 3. National Engineering Lab for Industrial Enzymes, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
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Abstract: | The alkaline xylanase Xyn11A-LC from the alkalophilic Bacillus sp. SN5 was expressed in E. coli, purified and crystallized. The crystal structure was determined at a resolution of 1.49 Å. Xyn11A-LC has the β-jelly roll structure typical of family 11 xylanases. To improve its thermostability and thermophilicity, a mutant SB3 was constructed by introducing three arginines on the different sides of the protein surface. SB3 increased the optimum temperature by 5 °C. The wild type and SB3 had the half-lives of 22 and 68 min at 65 °C at pH 8.0 (Tris/HCl buffer), respectively. CD spectroscopy revealed that the melting temperature (T m) of the wild type and SB3 were 55.3 and 66.9 °C, respectively. These results showed that the introduction of arginines enhance the thermophilicity and thermostability of Xyn11A-LC. |
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