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KMID : 0545120150250101660
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Journal of Microbiology and Biotechnology
2015 Volume.25 No. 10 p.1660 ~ p.1669
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Expression and Characterization of a Novel Nitrilase from Hyperthermophilic Bacterium Thermotoga maritima MSB8
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Chen Zhi
Chen Hua You
Ni Zhong
Tian Rui
Zhang Tian Xi
Jia Jin Ru
Yang Sheng Li
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Abstract
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The present study describes the gene cloning, overexpression and characterization of a novel nitrilase from hyperthermophilic bacterium Thermotoga maritima MSB8. The nitrilase gene consisted of 804 base pairs, encoding a protein of 268 amino acid residues with a molecular mass of 30.07 kDa after SDS-PAGE analysis. The optimal temperature and pH of the purified enzyme were 45°C and 7.5, respectively. The enzyme demonstrated good temperature tolerance, with 40% residual activity after 60 min of heat treatment at 75°C. The kinetic constants Vmax and Km of this nitrilase toward 3-cyanopyridine were 3.12 μmol/min/mg and 7.63 mM, respectively. Furthermore, this novel nitrilase exhibited a broad spectrum toward the hydrolysis of the aliphatic nitriles among the tested substrates, and particularly was specific to aliphatic dinitriles like succinonitrile, which was distinguished from most nitrilases ever reported. The catalytic efficiency kcat/Km was 0.44 /mM/s toward succinonitrile. This distinct characteristic might enable this nitrilase to be a potential candidate for industrial applications for biosynthesis of carboxylic acid.
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KEYWORD
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Nitrilase, Hyperthermophilic bacterium, Thermotoga maritima, Temperature tolerance, Aliphatic dinitriles
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