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KMID : 0880220100480030318
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Journal of Microbiology
2010 Volume.48 No. 3 p.318 ~ p.324
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Cel8H, a Novel Endoglucanase from the Halophilic Bacterium Halomonas sp. S66-4: Molecular Cloning, Heterogonous Expression, and Biochemical Characterization
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Huang Xiao-Luo
Shao Zong-Ze
Hong Yu-Zhi
Lin Ling
Li Chan-Juan
Huang Fei
Wang Hui
Liu Zi-Duo
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Abstract
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A recombinant Escherichia coli clone expressing an endoglucanase was identified from a genomic library of the halophilic bacterium Halomonas sp. S66-4, and the enzyme was designated Cel8H. The cel8H gene consisted of 1,053 bp and encoded 350 amino acids sharing the highest identity of 48% to other known endoglucanases. The protein was expressed in E. coli BL21 (DE3) and purified to homogeneity. The purified recombinant enzyme had an optimal activity of 4.9 U/mg at pH 5 and 45°C toward the substrate carboxymethylcellulose. It exhibited extraordinary properties which differed from endoglucanases reported previously at the point of high salt tolerance above 5 M, simultaneously with high pH stability at pH 4-12 and high temperature stability at 40-60°C. Various substrate tests indicated that the enzyme hydrolyzes β-1,4-glucosidic bonds specifically.
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KEYWORD
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endoglucanase, salt tolerance, pH stability, temperature stability, Halomonas sp.
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