Environment Research Institute, Shandong University, Qingdao, 266237, PR China.
School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China.
Chemosphere. 2020 May;247:125844. doi: 10.1016/j.chemosphere.2020.125844. Epub 2020 Jan 6.
Biphenyl 2,3-dioxygenase (BphA), a Rieske-type and first enzyme in the aerobic degradation process, plays a key role in the metabolizing process of biphenyl/polychlorinated biphenyl aromatic pollutants in the environment. To understand the catalytic mechanism of biphenyl 2,3-dioxygenase, the conversions leading to the cis-diols are investigated by means of quantum mechanics/molecular mechanics (QM/MM) method. A hydroperoxo-iron (III) species is involved in the enzyme-catalyzed reaction. Herein, we explored the direct reaction mechanism of hydroperoxo-iron (III) species with biphenyl and 4-4'-dichlorobiphenyl. The reaction process involves an epoxide intermediate, it could develop into a carbocation intermediate, and ultimately evolve into a cis-diol product. The important roles of several residues during the dioxygenation process were highlighted. This study may provide theoretical support for further directed mutations and enzymatic engineering of BphA, as well as promote the development of degrading environmentally persistent biphenyl/polychlorinated biphenyl aromatic contaminants.
联苯 2,3-双加氧酶（BphA）是一种 Rieske 型酶，也是好氧降解过程中的第一个酶，在环境中联苯/多氯联苯芳香族污染物的代谢过程中起着关键作用。为了理解联苯 2,3-双加氧酶的催化机制，通过量子力学/分子力学（QM/MM）方法研究了导致顺式二醇的转化。在酶催化反应中涉及过氧铁（III）物种。在此，我们探索了过氧铁（III）物种与联苯和 4-4'-二氯联苯的直接反应机制。反应过程涉及环氧化物中间体，它可以发展成碳正离子中间体，最终演变成顺式二醇产物。在双加氧过程中，几个残基的重要作用得到了强调。这项研究可能为进一步定向突变和酶工程 BphA 提供理论支持，并促进环境持久性联苯/多氯联苯芳香族污染物的降解。
