| 论文题目: | Cloning, expression, and characterization of a novel alkali-tolerant xylanase from alkaliphilic Bacillus sp SN5 |
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| 作者: | Bai Wenqin , Xue Yanfen , Zhou Cheng , and Ma Yanhe*. |
| 联系作者: | |
| 刊物名称: | Biotechnology and Applied Biochemistry |
| 期: | 62 |
| 卷: | 2 |
| 页: | 208-217 |
| 年份: | 2015 |
| 影响因子: | 1.43 |
| 论文下载: | |
| 摘要: | A xylanase gene (xyn11A) was cloned from the genomic library of alkalophilic Bacillus sp. SN5. It encoded a polypeptide of 366 amino acids, consisting of a family 11 glycoside hydrolase, a short linker region, and a family 36 carbohydrate-binding module (CBM). The intact xylanase Xyn11A and the CBM-linker-truncated Xyn11A-LC were expressed in Escherichia coli BL21 (DE3). Both purified recombinant proteins exhibited the highest activity at 55 degrees C. The optimal pH for Xyn11A activity was 7.5, whereas Xyn11A-LC showed a broad pH profile (>80% activity at pH 5.5-8.5) with optimal activity at pH 5.5 and 7.5-8.0. They had high alkali tolerance, retaining over 80% residual activity after preincubation at pH 8.5-11.0 at 37 degrees C for 1H. Xyn11A-LC showed better thermal stability, lower affinity, and lower catalytic activity to insoluble xylan than Xyn11A, whereas its specific activity for soluble beechwood xylan (4,511.9U/mg) was greater than that of Xyn11A (3,136.4U/mg). These results implied that the CBM of Xyn11A could change the enzymatic properties and play a role in degrading insoluble xylan. Xyn11A-LC is a family 11 alkali-tolerant cellulase-free xylanase with high specific activity, which qualifies it as a potential candidate for industrial applications, especially in the paper industry. (C) 2014 International Union of Biochemistry and Molecular Biology, Inc. |
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