How hydrogen peroxide is metabolized by oxidized cytochrome c oxidase.
How hydrogen peroxide is metabolized by oxidized cytochrome c oxidase.
复制标题
DOI：
10.1021/bi401078b
复制
发表时间：
2014-06-10
期刊：
影响因子：
2.9
通讯作者：
Fabian, Marian
中科院分区：
文献类型：
--
作者：
Jancura, Daniel;Stanicova, Jana;Palmer, Graham;Fabian, Marian
在没有外部电子供体的情况下，氧化的牛细胞色素c氧化酶（CcO）表现出分解过量H2 O2的能力。根据过氧化物的浓度，确定了两种降解机制。在亚毫摩尔过氧化物浓度下，分解过程中几乎不产生超氧化物和氧气。相反，在毫摩尔H2 O2浓度范围内，CcO从过氧化物产生超氧化物。在亚毫摩尔浓度下，H2 O2的分解至少发生在两个位点。一个是催化血红素a3-CuB中心，其中H2 O2被还原为水。在酶与H2 O2的相互作用期间，该中心通过两个氧代铁基状态的中间存在循环回到氧化的CcO。我们表明，在pH 8.0的两个分子的H2 O2与催化中心完成一个循环的反应。此外，在血红素a3-CuB中心的反应产生表面暴露的脂质基自由基，其参与过氧化物的分解。它还发现，不可逆的下降的催化活性的酶与亚毫摩尔浓度的H2 O2处理的结果，具体从减少的电子转移速率从血红素a的血红素a3-CuB中心在还原阶段的催化循环。从亚铁细胞色素c的血红素a的电子转移速率和动力学的完全还原的CCO与O2的氧化不受影响的过氧化物改性的CCO。
In the absence of external electron donors, oxidized bovine cytochrome c oxidase (CcO) exhibits the ability to decompose excess H2O2. Depending on the concentration of peroxide, two mechanisms of degradation were identified. At submillimolar peroxide concentrations, decomposition proceeds with virtually no production of superoxide and oxygen. In contrast, in the millimolar H2O2 concentration range, CcO generates superoxide from peroxide. At submillimolar concentrations, the decomposition of H2O2 occurs at least at two sites. One is the catalytic heme a3–CuB center where H2O2 is reduced to water. During the interaction of the enzyme with H2O2, this center cycles back to oxidized CcO via the intermediate presence of two oxoferryl states. We show that at pH 8.0 two molecules of H2O2 react with the catalytic center accomplishing one cycle. In addition, the reactions at the heme a3–CuB center generate the surface-exposed lipid-based radical(s) that participates in the decomposition of peroxide. It is also found that the irreversible decline of the catalytic activity of the enzyme treated with submillimolar H2O2 concentrations results specifically from the decrease in the rate of electron transfer from heme a to the heme a3–CuB center during the reductive phase of the catalytic cycle. The rates of electron transfer from ferrocytochrome c to heme a and the kinetics of the oxidation of the fully reduced CcO with O2 were not affected in the peroxide-modified CcO.
登录
查看更多内容
影响因子：
4.8
作者：
Chen, YR;Gunther, MR;Mason, RP
通讯作者：
Mason, RP
影响因子：
2.9
作者：
Adelroth, P;Gennis, RB;Brzezinski, P
通讯作者：
Brzezinski, P
影响因子：
64.8
作者：
IWATA, S;OSTERMEIER, C;MICHEL, H
通讯作者：
MICHEL, H
影响因子：
4.8
作者：
Chen, YR;Sturgeon, BE;Mason, RP
通讯作者：
Mason, RP
DOI：
10.1073/pnas.0802512105
发表时间：
2008-08-05
影响因子：
11.1
作者：
Gorbikova, Elena A.;Belevich, Ilya;Verkhovsky, Michael I.
通讯作者：
Verkhovsky, Michael I.