Cloning, expression and characterization of a novel alkali-tolerant xylanase from alkaliphilic Bacillus sp. SN5----中国科学院微生物研究所

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论文题目:	Cloning, expression and characterization of a novel alkali-tolerant xylanase from alkaliphilic Bacillus sp. SN5
作者:	Bai Wenqin, Xue Yanfen, Zhou Cheng, Ma Yanhe*
联系作者:	Ma Yanhe*
刊物名称:	Biotechnology and applied biochemistry
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年份:	2014
影响因子:	1.388
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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), respectively. Both purified recombinant proteins exhibited the highest activity at 55 masculineC. The optimal pH for Xyn11A activity was 7.5, while 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, respectively. They had high alkali-tolerance, retaining over 80% residual activity after pre-incubation at pH 8.5-11.0 at 37 masculineC for 1 h. 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 (4511.9 U/mg) was greater than that of Xyn11A (3136.4 U/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. This article is protected by copyright. All rights reserved.