Cloning,purification and characterization of an alkali-stable endoxylanase from thermophilic <Emphasis Type="Italic">Geobacillus</Emphasis> sp. 71 |
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Authors: | Sabriye Canakc? Zeliha Cevher Kadriye Inan Muslum Tokgoz Fatmagul Bahar Murat Kacagan Fulya Ay Sal Ali Osman Belduz |
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Institution: | (1) Department of Biology, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey |
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Abstract: | The gene encoding a xylanase from Geobacillus sp. 71 was isolated, cloned, and sequenced. Purification of the Geobacillus sp 7.1 xylanase, XyzGeo71, following overexpression in E. coli produced an enzyme of 47 kDa with an optimum temperature of 75°C. The optimum pH of the enzyme is 8.0, but it is active over
a broad pH range. This protein showed the highest sequence identity (93%) with the xylanase from Geobacillus thermodenitrificans NG80-2. XyzGeo71 contains a catalytic domain that belongs to the glycoside hydrolase family 10 (GH10). XyzGeo71 exhibited
good pH stability, remaining stable after treatment with buffers ranging from pH 7.0 to 11.0 for 6 h. Its activity was partially
inhibited by Al3+ and Cu2+ but strongly inhibited by Hg2+. The enzyme follows Michaelis–Menten kinetics, with Km and Vmax values of 0.425 mg xylan/ml and 500 μmol/min.mg, respectively. The enzyme was free from cellulase activity and degraded xylan
in an endo fashion. The action of the enzyme on oat spelt xylan produced xylobiose and xylotetrose. |
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