Lund J, Woodland M P, Dalton H
Eur J Biochem. 1985 Mar 1;147(2):297-305. doi: 10.1111/j.1432-1033.1985.tb08750.x.
Aerobic stopped-flow experiments have confirmed that component C is the methane monooxygenase component responsible for interaction with NADH. Reduction of component C by NADH is not the rate-limiting step for component C in the methane monooxygenase reaction. Removal and reconstitution of the redox centres of component C suggest a correlation between the presence of the FAD and Fe2S2 redox centres and NADH: acceptor reductase activity and methane monooxygenase activity respectively, consistent with the order of electron flow: NADH----FAD----Fe2S2----component A. This order suggests that component C functions as a 2e-1/1e-1 transformase, splitting electron pairs from NADH for transfer to component A via the one-electron-carrying Fe2S2 centre. Electron transfer has been demonstrated between the reductase component, component C and the oxygenase component, component A, of the methane monooxygenase complex from Methylococcus capsulatus (Bath) by three separate methods. This intermolecular electron transfer step is not rate-determining for the methane monooxygenase reaction. Intermolecular electron transfer was independent of component B, the third component of the methane monooxygenase. Component B is required to switch the oxidase activity of component A to methane mono-oxygenase activity, suggesting that the role of component B is to couple substrate oxidation to electron transfer, via the methane monooxygenase components.
需氧停流实验已证实，组分C是负责与NADH相互作用的甲烷单加氧酶组分。NADH对组分C的还原不是甲烷单加氧酶反应中组分C的限速步骤。组分C氧化还原中心的去除和重建表明，FAD和Fe2S2氧化还原中心的存在分别与NADH：受体还原酶活性和甲烷单加氧酶活性相关，这与电子流动顺序：NADH----FAD----Fe2S2----组分A一致。该顺序表明组分C作为一种2e-1/1e-1转化酶，将来自NADH的电子对分开，通过单电子携带的Fe2S2中心转移至组分A。通过三种不同方法已证明来自荚膜甲基球菌（巴斯）的甲烷单加氧酶复合物的还原酶组分（组分C）和加氧酶组分（组分A）之间存在电子转移。这种分子间电子转移步骤不是甲烷单加氧酶反应的限速步骤。分子间电子转移独立于甲烷单加氧酶的第三个组分组分B。需要组分B将组分A的氧化酶活性转换为甲烷单加氧酶活性，这表明组分B的作用是通过甲烷单加氧酶组分将底物氧化与电子转移偶联起来。
