Cytochrome c oxidase binding of hydrogen peroxide.

Published

Journal Article

Oxidized cytochrome c oxidase can bind hydrogen peroxide, as evidenced by changes in its spectrum and its ability to use hydrogen peroxide as an electron acceptor in cytochrome c oxidation. The affinity of the oxidized enzyme for hydrogen peroxide is high, with a Kd of less than 10 microM, and the binding is inhibited by ligands of cytochrome a3. Oxidized cytochrome c oxidase, in submitochondrial particles or solubilized in several ionic and nonionic detergents, binds peroxide with comparable affinities. The size of the spectral shift observed upon peroxide binding depends on the pH of the solution and differs in extinction coefficient between preparations, but all preparations tested appeared to bind peroxide. The differences in the magnitude of the spectral shift upon peroxide binding to different preparations suggest that oxidized cytochrome c oxidase as prepared may be made up of more than one species and that the proportion of the species which binds peroxide varies with the preparation. These studies of the binding of peroxide clarify the mechanism by which cytochrome c oxidase catalyzes the reduction of oxygen to water without the formation of free-radical intermediates.

Full Text

Duke Authors

Cited Authors

  • Bickar, D; Bonaventura, J; Bonaventura, C

Published Date

  • May 1, 1982

Published In

Volume / Issue

  • 21 / 11

Start / End Page

  • 2661 - 2666

PubMed ID

  • 6284205

Pubmed Central ID

  • 6284205

Electronic International Standard Serial Number (EISSN)

  • 1520-4995

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00540a013

Language

  • eng