Siletsky Sergey A, Konstantinov Alexander A
Moscow State University, Moscow, Russia.
Biochim Biophys Acta. 2012 Apr;1817(4):476-88. doi: 10.1016/j.bbabio.2011.08.003. Epub 2011 Aug 16.
The paper presents a survey of time-resolved studies of charge translocation by cytochrome c oxidase coupled to transfer of the 1st, 2nd 3rd and 4th electrons in the catalytic cycle. Single-electron photoreduction experiments carried out with the A-class cytochrome c oxidases of aa(3) type from mitochondria, Rhodobacter sphaeroides and Paracoccus denitrificans as well as with the ba(3)-type oxidase from Thermus thermophilus indicate that the protonmotive mechanisms, although similar, may not be identical for different partial steps in the same enzyme species, as well as for the same single-electron transition in different oxidases. The pattern of charge translocation coupled to transfer of a single electron in the A-class oxidases confirms major predictions of the original model of proton pumping by cytochrome oxidase [Artzatbanov, V. Y., Konstantinov, A. A. and Skulachev, V.P. "Involvement of Intramitochondrial Protons in Redox Reactions of Cytochrome a." FEBS Lett. 87: 180-185]. The intermediates and partial electrogenic steps observed in the single-electron photoreduction experiments may be very different from those observed during oxidation of the fully reduced oxidase by O(2) in the "flow-flash" studies. .
本文介绍了一项关于细胞色素c氧化酶电荷转移的时间分辨研究的综述，该研究与催化循环中第1、2、3和4个电子的转移相关。使用来自线粒体、球形红细菌和反硝化副球菌的aa(3)型A类细胞色素c氧化酶以及嗜热栖热菌的ba(3)型氧化酶进行的单电子光还原实验表明，质子动力机制虽然相似，但对于同一酶种的不同部分步骤以及不同氧化酶中的相同单电子跃迁可能并不相同。A类氧化酶中与单电子转移相关的电荷转移模式证实了细胞色素氧化酶质子泵原模型的主要预测[阿尔扎特巴诺夫，V.Y.，康斯坦丁诺夫，A.A.和斯库拉切夫，V.P. “线粒体内质子参与细胞色素a的氧化还原反应。” 《欧洲生物化学学会联合会快报》87: 180 - 185]。在单电子光还原实验中观察到的中间体和部分电致步骤可能与在“流动闪光”研究中用O(2)氧化完全还原的氧化酶时观察到的非常不同。
