College of Life Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China.
Environ Sci Pollut Res Int. 2013 May;20(5):3232-9. doi: 10.1007/s11356-012-1221-5. Epub 2012 Oct 23.
The acyl carrier protein (ACP) phosphodiesterase gene (SO 4396) of Shewanella oneidensis MR-1 which was analyzed to have azoreductase activity was heterologously expressed in Escherichia coli. The ACP phosphodiesterase was found to reach maximum enzyme velocity 220.59 U/mg, named azoreductase in this study. The azoreductase had highest specific activity (153.16 U/mg) at pH 6.5, which showed a preference for nicotinamide adenine dinucleotide (NADH) as electron donor. The phylogenetic tree analysis indicated that the azoreductase had preference for NADH and dependence for flavin mononucleotide (FMN). However, the azoreductase from S. oneidensis MR-1 still had high enzyme activity in the absence of FMN. The Mg(2+) had a positive influence on the enzyme activity with 25 mM concentration, whereas Cr(3+), Cd(2+) usually had significantly negative effect on enzyme activity. The purified azoreductase retained nearly 100 % activity after incubating in 30 % dimethyl sulfoxide (DMSO), 30 % acetone, 30 % methanol, 20 % ethanol, 20 % isopropanol, and 10 % propanol.
希瓦氏菌属（Shewanella）MR-1 的酰基辅酶 A 磷酸二酯酶基因（SO 4396）被分析具有偶氮还原酶活性，在大肠杆菌中异源表达。发现酰基辅酶 A 磷酸二酯酶达到最大酶速度 220.59 U/mg，在本研究中命名为偶氮还原酶。该偶氮还原酶在 pH 6.5 时具有最高比活性（153.16 U/mg），表现出对烟酰胺腺嘌呤二核苷酸（NADH）作为电子供体的偏好。系统发育树分析表明，该偶氮还原酶优先利用 NADH，依赖黄素单核苷酸（FMN）。然而，来自 S. oneidensis MR-1 的偶氮还原酶在没有 FMN 的情况下仍具有高酶活性。Mg(2+) 对酶活性有积极影响，最佳浓度为 25 mM，而 Cr(3+)、Cd(2+) 通常对酶活性有显著的负面影响。纯化的偶氮还原酶在 30%二甲亚砜（DMSO）、30%丙酮、30%甲醇、20%乙醇、20%异丙醇和 10%丙醇孵育后保留近 100%的活性。
