title: The number of Fe atoms in the iron-sulphur centers of the respiratory chain.
abstract: 1. From the 57Fe hyperfine interaction in EPR spectra of reduced submitochondrial particles from the yeast Candida utilis, grown with 57Fe, it is concluded that all Fe-S centers in these particles detectable in spectra at 35-80 K are [2Fe-2S]2-(2-; 3-) centers. These are the centers 1 of NADH and succinate dehydrogenase, the Rieske Fe-S center and possibly center 2 of succinate dehydrogenase. 2. The signals of the reduced particles detectable only at temperatures below 20 K are [4Fe-4S]2-(2-; 3-) clusters. These are the centers 2,3 and 4 of NADH dehydrogenase. 3. EPR spectra of the [2Fe-2S]3- centers of Complex I and II, but not that of Complex III, display a great inequality of the Fe nuclei in the effective hyperfine interaction in the x-y direction.
mesh_terms: D002175:Candida / Q000032:analysis; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D007501:Iron / Q000032:analysis*; D007506:Iron-Sulfur Proteins / Q000032:analysis*; D008667:Metalloproteins / Q000032:analysis*; D008928:Mitochondria / Q000032:analysis* / Q000201:enzymology; D009247:NADH, NADPH Oxidoreductases / Q000032:analysis*; D010084:Oxidation-Reduction; D013057:Spectrum Analysis; D013385:Succinate Dehydrogenase / Q000032:analysis*
chemical_list: D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D007501:Iron; D013385:Succinate Dehydrogenase; D009247:NADH, NADPH Oxidoreductases