- Molecular cloning and characterization of a novel thermostable xylanase from Paenibacillus campinasensis BL11
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An open reading frame (XylX) with 1131 nucleotides from Paenibacillus campinasensis BL11 was cloned and expressed in E. coli. It encodes a family 11 endoxylanase, designated as XylX, of 41kDa. The homology of the amino acid sequence deduced from XylX is only 73% identical to the next closest sequence. XylX contains a family 11 catalytic domain of the glycoside hydrolase and a family 6 cellulose-binding module. The recombinant xylanase was fused to a His-tag for affinity purification. The XylX activity was 2392IU/mg, with a Km of 6.78mg/ml and a Vmax of 4953mol/min/mg under optimal conditions (pH 7, 60°C). At pH 11, 60°C, the activity was still as high as 517IU/mg. Xylanase activities at 60°C under pH 5 to pH 9 remained at more than 69.4% of the initial activity level for 8h. The addition of Hg2+ at 5mM almost completely inhibited xylanase activity, whereas the addition of tris-(2-carboxyethyl)-phosphine (TCEP) and 2-mercaptoethanol stimulated xylanase activity. No relative activities for Avicel, CMC and d-(+)-cellobiose were found. Xylotriose constitutes the majority of the hydrolyzed products from oat spelt and birchwood xylan. Broad pH and temperature stability shows its application potentials for biomass conversion, food and pulp/paper industries.
- Ko, Chun-Han,Tsai, Chung-Hung,Tu, Jenn,Lee, Hang-Yi,Ku, Lan-Ting,Kuo, Pei-An,Lai, Yiu-Kay
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supporting information; experimental part
p. 1638 - 1644
(2011/12/03)
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