Pathways of proton transfer in cytochrome c oxidase
Pathways of proton transfer in cytochrome c oxidase
复制标题
DOI：
10.1023/a:1020567729941
复制
发表时间：
1998-02-01
影响因子：
3
通讯作者：
Ädelroth, P
中科院分区：
文献类型：
--
作者：
Brzezinski, P;Ädelroth, P
在过去几年中，我们对血红素铜氧化酶结构和功能的了解，因定点突变技术与生物物理技术相结合的应用而大大受益。这一点，再加上最近确定的细胞色素c氧化酶的晶体结构，现在使得设计针对特定泵机制的实验成为可能。在此，我们总结了我们近期对球形红细菌（Rhodobacter sphaeroides）的野生型及突变型细胞色素c氧化酶中电子和质子转移反应的动力学研究结果。这些研究使得在特定反应步骤中识别参与质子转移的氨基酸残基成为可能，并为讨论末端氧化酶中电子和质子转移机制提供了基础。结果表明，通过K(I - 362)/T(I - 359)的途径，而非通过D(I - 132)/E(I - 286)的途径，被用于在双核中心还原时将质子转移至一个与血红素a(3)发生静电相互作用的可质子化基团。通过D(I - 132)/E(I - 286)的途径在O - 2还原过程中的泵出步骤中用于摄取泵出的质子和底物质子。
During the last few years our knowledge of the structure and function of heme copper oxidases has greatly profited from the use of site-directed mutagenesis in combination with biophysical techniques. This, together with the recently-determined crystal structures of cytochrome c oxidase, has now made it possible to design experiments aimed at targeting specific pump mechanisms. Here, we summarize results from our recent kinetic studies of electron and proton-transfer reactions in wild-type and mutant forms of cytochrome c oxidase from Rhodobacter sphaeroides. These studies have made it possible to identify amino acid residues involved in proton transfer during specific reaction steps and provide a basis for discussion of mechanisms of electron and proton transfer in terminal oxidases. The results indicate that the pathway through K(I-362)/T(I-359), but not through D(I-132)/E(I-286), is used for proton transfer to a protonatable group interacting electrostatically with heme a(3), i.e., upon reduction of the binuclear center. The pathway through D(I-132)/E(I-286) is used for uptake of pumped and substrate protons during the pumping steps during O-2 reduction.