反硝化副球菌细胞色素c氧化酶的铜A突变体中的电子进入。关于初始电子进入金属中心的确凿证据。

Electron entry in a CuA mutant of cytochrome c oxidase from Paracoccus denitrificans. Conclusive evidence on the initial electron entry metal center.

作者信息

Malatesta F, Nicoletti F, Zickermann V, Ludwig B, Brunori M

机构信息

Department of Biochemical Sciences A. Rossi Fanelli and CNR Centre of Molecular Biology, University of Rome La Sapienza, Italy.

出版信息

FEBS Lett. 1998 Sep 4;434(3):322-4. doi: 10.1016/s0014-5793(98)01006-0.

DOI:10.1016/s0014-5793(98)01006-0

PMID:9742947

Abstract

A cytochrome c oxidase subunit II C216S mutant from Paracoccus denitrificans in which the CuA site was changed by site-directed mutagenesis to a mononuclear copper site [Zickermann, V., Wittershagen, A., Kolbesen, B.O. and Ludwig, B. Biochemistry 36 (1997) 3232-3236] was investigated by stopped-flow spectroscopy. Contrary to the behavior of the wild type enzyme, in this mutant cytochrome a cannot be reduced by excess cytochrome c in the millisecond time scale in which cytochrome c oxidation is observed. The results conclusively identify and establish CuA as the initial electron entry site in cytochrome c oxidase. Partial rapid reduction (ca. 20%) of the modified CuA site suggests that the mononuclear copper ion has a redox potential ca. 100 mV lower than the wild type, and that internal electron transfer to cytochrome a is > or = 10(3)-fold slower than with the wild type enzyme.

摘要

对来自反硝化副球菌的细胞色素c氧化酶亚基II C216S突变体进行了停流光谱研究，该突变体通过定点诱变将CuA位点转变为单核铜位点[齐克曼，V.，维特沙根，A.，科尔贝森，B.O.和路德维希，B.《生物化学》36(1997)3232 - 3236]。与野生型酶的行为相反，在这个突变体中，在观察到细胞色素c氧化的毫秒时间尺度内，过量的细胞色素c不能使细胞色素a还原。这些结果确凿地确定并证实了CuA是细胞色素c氧化酶中的初始电子进入位点。修饰后的CuA位点的部分快速还原(约20%)表明，单核铜离子的氧化还原电位比野生型低约100 mV，并且向细胞色素a的内部电子转移比野生型酶慢≥10³倍。