Characterization of two novel family 12 xyloglucanases from the thermophilic Rhizomucor miehei

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• 作者：Shuang Song (1)
  Yanbin Tang (1)
  Shaoqing Yang (1)
  Qiaojuan Yan (2)
  Peng Zhou (1)
  Zhengqiang Jiang (1)
  
• 关键词：Xyloglucanase ; Xyloglucan ; specific endo ; 1 ; 4 ; glucanase ; Xyloglucan hydrolysis ; Rhizomucor miehei ; Specific activity
• 刊名：Applied Microbiology and Biotechnology
• 出版年：2013
• 出版时间：December 2013
• 年：2013
• 卷：97
• 期：23
• 页码：10013-10024
• 全文大小：
• 作者单位：Shuang Song (1)
  Yanbin Tang (1)
  Shaoqing Yang (1)
  Qiaojuan Yan (2)
  Peng Zhou (1)
  Zhengqiang Jiang (1)
  
  1. Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, No.17 Qinghua Donglu, Haidian District, Post Box 294, Beijing, 100083, China
  2. Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing, 100083, China
  
• ISSN：1432-0614

文摘

Two novel glycoside hydrolase (GH) family 12 xyloglucanase genes (designated RmXEG12A and RmXEG12B) were cloned from the thermophilic fungus Rhizomucor miehei. Both genes contained open reading frames of 729bp encoding 242 amino acids. Their deduced amino acid sequences shared 68% identity with each other and less than 60% with other xyloglucanases. The two genes, without the sequences for the signal peptides, were cloned and successfully expressed in Escherichia coli as active xyloglucanases, designated RmXEG12A and RmXEG12B, with similar molecular masses5.6 and 25.9kDa, respectively. RmXEG12A showed optimal activity at pH6.5 and 65, RmXEG12B at pH5.0 and 60. Both recombinant xyloglucanases displayed very high specific activities, 6,681.4 and 3,092.2Umg1, respectively, toward tamarind xyloglucan, but no activity toward carboxymethylcellulose, Avicel, or p-nitrophenyl derivatives. The main products of tamarind xyloglucan hydrolysis by the two xyloglucanases were XXXG, XXLG/XLXG, and XLLG (where G is an unsubstituted d-Glc residue, X is a xylosylated d-Glc residue, and L is a d-Glc residue substituted by xylosyl-galactose).