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

FEBS Letters

Malatesta, Francesco¹  Zickermann, Volker²  Brunori, Maurizio¹  Ludwig, Bernd²  Nicoletti, Flavia¹ 

[1] Department of Biochemical Sciences ‘A. Rossi Fanelli’ and CNR Centre of Molecular Biology, University of Rome ‘La Sapienza’, Piazzale Aldo Moro 5, 00185 Rome, Italy;Institute of Biochemistry, Molecular Genetics, University of Frankfurt, Biozentrum, Frankfurt, Germany

关键词: Cytochrome c oxidase;    Electron transfer;    Site-directed mutagenesis;   

DOI  :  10.1016/S0014-5793(98)01006-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A cytochrome c oxidase subunit II C216S mutant from Paracoccus denitrificans in which the Cu_A 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 Cu_A as the initial electron entry site in cytochrome c oxidase. Partial rapid reduction (ca. 20%) of the modified Cu_A 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 ≥10³-fold slower than with the wild type enzyme.

【 授权许可】

Unknown