Fusion of carbohydrate binding modules from <Emphasis Type="Italic">Thermotoga neapolitana</Emphasis> with a family 10 xylanase from <Emphasis Type="Italic">Bacillus halodurans</Emphasis> S7 |
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Authors: | Gashaw Mamo Rajni Hatti-Kaul Bo Mattiasson |
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Institution: | (1) Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, 22100 Lund, Sweden |
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Abstract: | Xylanase A of Thermotoga neapolitana contains binding domains both at the N- and C-terminal ends of the catalytic domain. In the N-terminal position it contains
two carbohydrate-binding modules (CBM) which belong to family 22. These CBMs bind xylan but not to cellulose. The gene encoding
the mature peptide of these CBMs was fused with an alkaline active GH10 xylanase from Bacillus halodurans S7 and expressed in Escherichia coli. The (His)6 tagged hybrid protein was purified by immobilized metal affinity chromatography and characterized. Xylan binding by the chimeric
protein was influenced by NaCl concentration and pH of the binding medium. Binding increased with increasing salt concentration
up to 200 mM. Higher extent of binding was observed under acidic conditions. The fusion of the CBM structures enhanced the
hydrolytic efficiency of the xylanase against insoluble xylan, but decreased the stability of the enzyme. The optimum temperature
and pH for the activity of the xylanase did not change. |
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Keywords: | Xylanase Xylan binding domain CBM Chimeric gene Thermotoga neapolitana Bacillus halodurans |
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