Heterologous expression and characterization of a malathion-hydrolyzing carboxylesterase from a thermophilic bacterium, Alicyclobacillus tengchongensis |
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Authors: | Zhenrong Xie Bo Xu Junmei Ding Lingyun Liu Xuelin Zhang Junjun Li Zunxi Huang |
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Affiliation: | 2. College of Life Sciences, Yunnan Normal University, Kunming, Yunnan, 650500, People’s Republic of China 1. Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Kunming, Yunnan, 650500, People’s Republic of China
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Abstract: | A carboxylesterase gene from thermophilic bacterium, Alicyclobacillus tengchongensis, was cloned and expressed in Escherichia coli BL21 (DE3). The gene coded for a 513 amino acid protein with a calculated molecular mass of 57.82 kDa. The deduced amino acid sequence had structural features highly conserved among serine hydrolases, including Ser204, Glu325, and His415 as a catalytic triad, as well as type-B carboxylesterase serine active site (FGGDPENITIGGQSAG) and type-B carboxylesterase signature 2 (EDCLYLNIWTP). The purified enzyme exhibited optimum activity with β-naphthyl acetate at 60 °C and pH 7 as well as stability at 25 °C and pH 7. One unit of the enzyme hydrolyzed 5 mg malathion l?1 by 50 % within 25 min and 89 % within 100 min. The enzyme strongly degraded malathion and has a potential use for the detoxification of malathion residues. |
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