College of Life Sciences, Yunnan Normal University, Kunming, Yunnan, 650500, People's Republic of China.
Biotechnol Lett. 2013 Aug;35(8):1283-9. doi: 10.1007/s10529-013-1195-5. Epub 2013 Jun 26.
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.
从嗜热细菌 Alicyclobacillus tengchongensis 中克隆并在大肠杆菌 BL21 (DE3) 中表达了一个羧酸酯酶基因。该基因编码一个 513 个氨基酸的蛋白质，计算分子量为 57.82 kDa。推导的氨基酸序列在丝氨酸水解酶中具有高度保守的结构特征，包括作为催化三联体的 Ser204、Glu325 和 His415，以及 B 型羧酸酯酶丝氨酸活性位点 (FGGDPENITIGGQSAG) 和 B 型羧酸酯酶特征 2 (EDCLYLNIWTP)。纯化的酶在 60°C 和 pH 7 下对β-萘基乙酸酯表现出最佳活性和稳定性，在 25°C 和 pH 7 下稳定。该酶在 25 min 内通过 50%水解 5 mg 马拉硫磷 l(-1)，在 100 min 内水解 89%。该酶强烈降解马拉硫磷，具有解毒马拉硫磷残留的潜力。
