Biochemical and biophysical studies on cytochrome c oxidase. XX. Reaction with sulphide.
Biochim Biophys Acta, 1975/5/15;387(2):189-93.
Wever R, van GELDER BF, Dervartanian DV
PMID: 164940
Abstract
1. Upon addition of sulphide to oxidized cytochrome c oxidase, a low-spin heme sulphide compound is formed with an EPR signal at gx = 2.54, gy = 2.23 and gz = 1.87. Concomitantly with the formation of this signal the EPR-detectable low-spin heme signal at g = 3 and the copper signal near g = 2 decrease in intensity, pointing to a partial reduction of the enzyme by sulphide. 2. The addition of sulphide to cytochrome c oxidase, previously reduced in the presence of azide or cyanide, brings about a disappearance of the azido-cytochrome c oxidase signal at gx = 2.9, gy = 2.2, and gz = 1.67 and a decrease of the signal at g = 3.6 of cyano-cytochrome c oxidase. Concomitantly the sulphide-induced EPR signal is formed. 3. These observations demonstrate that azide, cyanide and sulphide are competitive for an oxidized binding site on cytochrome c oxidase. Moreover, it is shown that the affinity of cyanide and sulphide for this site is greater than that of azide.
MeSH terms
Animals; Azides; Binding Sites; Cattle; Copper; Cyanides; Electron Spin Resonance Spectroscopy; Electron Transport Complex IV; Heme; Myocardium; Oxidation-Reduction; Protein Binding; Protein Conformation; Sulfides
More resources
EndNote: Download