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| Expression of Xylanase Gene xynB from Aspergillus niger in Escherichia coli and Characterization of Its Recombinant Xylanase |
| DENG Ping;CAO Yun-he;LU Wen-qing;GUO Xiao-hua |
| National Key Laboratory of Animal Nutrition, China Agricultural University, Beijing 100094, China |
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Abstract The gene xynB encoding β-1, 4-xylanase was cloned from Aspergillus niger mafic-005. The sequencing results showed that the full-length gene contained 745 bp, including an intron of 67 bp, and encoding a protein of 225 amino acids which had a presumed molecular mass of 24 kD(GenBank accession No. DQ174549). Compared this xylanase xynB gene with others from A. niger in GenBank, the homology was high. The xynB gene was inserted into the expression vector of pET-28a(+) and transformed into Escherichia coli BL21. The recombinant protein was expressed successfully in E. coli by inducing with IPTG, and purified by Ni-NTA Sepharose FF. The molecular mass of the recombinant protein was about 30 kD according to SDS-PAGE. Characterization of the recombinant enzyme indicated that the optimum temperature and pH of the recombinant xylanase were 40℃ and 5.0, respectively. The recombinant protein showed an extreme stability in the acidic solution and ambient temperature.
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Received: 29 November 2005
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Corresponding Authors:
CAO Yun-he
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