A novel amidohydrolase (DmhA) from Sphingomonas sp. that can hydrolyze the organophosphorus pesticide dimethoate to dimethoate carboxylic acid and methylamine |
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Authors: | Chen Qing Chen Kai Ni Haiyan Zhuang Wen Wang Hongmei Zhu Jianchun He Qin He Jian |
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Institution: | 1.Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, People’s Republic of China ;2.College of Life Sciences, Zaozhuang University, Zaozhuang, 277160, People’s Republic of China ;3.College of City and Architecture Engineering, Zaozhuang University, Zaozhuang, 277160, People’s Republic of China ; |
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Abstract: | Objectives To characterize a novel dimethoate amidohydrolase from Sphingomonas sp. DC-6. ResultsA gene, dmhA, encoding the dimethoate amidohydrolase responsible for transforming dimethoate to dimethoate carboxylic acid and methylamine, was cloned from Sphingomonas sp. DC-6. Sequence analysis and molecular modeling indicate that DmhA shares 31–57 % amino acid sequence identities with other functionally confirmed amidohydrolase. DmhA was expressed in Escherichia coli BL21 (DE3) and purified by Ni–NTA affinity chromatography. The purified DmhA could hydrolyze 4-acetaminophenol, dimethoate and propanil. DmhA activity was optimal at 30 °C and pH 7.5. Hg2+, Zn2+, Cu2+, Cd2+, Tween 80, Triton X-100 or SDS strongly inhibited its activity. The K
m and k
cat values of DmhA for dimethoate are 0.02 mM and 1.2 s−1, respectively. ConclusionsDmhA was confirmed to be a novel dimethoate amidohydrolase which could eliminate the toxicity of dimethoate, providing a novel gene resource for the development of pesticide-degrading enzyme preparation and mechanistic study of dimethoate hydrolysis. |
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