Contribution of peroxidized cardiolipin to inactivation of bovine heart cytochrome c oxidase

Free Radic Biol Med. 2006 Jul 15;41(2):238-46. doi: 10.1016/j.freeradbiomed.2006.03.018. Epub 2006 Apr 1.

Abstract

The lipid-soluble peroxides, tert-butyl hydroperoxide and peroxidized cardiolipin, each react with bovine cytochrome c oxidase and cause a loss of electron-transport activity. Coinciding with loss of activity is oxidation of Trp19 and Trp48 within subunits VIIc and IV, and partial dissociation of subunits VIa and VIIa. tert-Butyl hydroperoxide initiates these structural and functional changes of cytochrome c oxidase by three mechanisms: (1) radical generation at the binuclear center; (2) direct oxidation of Trp19 and Trp48; and (3) peroxidation of bound cardiolipin. All three mechanisms contribute to inactivation since blocking a single mechanism only partially prevents oxidative damage. The first mechanism is similar to that described for hydrogen peroxide [Biochemistry43:1003-1009; 2004], while the second and third mechanism are unique to organic hydroperoxides. Peroxidized cardiolipin inactivates cytochrome c oxidase in the absence of tert-butyl hydroperoxide and oxidizes the same tryptophans within the nuclear-encoded subunits. Peroxidized cardiolipin also inactivates cardiolipin-free cytochrome c oxidase rather than restoring full activity. Cardiolipin-free cytochrome c oxidase, although it does not contain cardiolipin, is still inactivated by tert-butyl hydroperoxide, indicating that the other oxidation products contribute to the inactivation of cytochrome c oxidase. We conclude that both peroxidized cardiolipin and tert-butyl hydroperoxide react with and triggers a cascade of structural alterations within cytochrome c oxidase. The summation of these events leads to cytochrome c oxidase inactivation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cardiolipins / metabolism*
  • Cattle
  • Electron Transport Complex IV / antagonists & inhibitors*
  • Lipid Peroxidation
  • Lipid Peroxides / metabolism*
  • Myocardium / enzymology*
  • Oxidation-Reduction
  • Spectrometry, Mass, Electrospray Ionization
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Thiobarbiturates / metabolism

Substances

  • Cardiolipins
  • Lipid Peroxides
  • Thiobarbiturates
  • Electron Transport Complex IV
  • thiobarbituric acid