title: Iron-sulfur cluster 3 of beef heart succinate-ubiquinone oxidoreductase is a 3-iron cluster.
abstract: From a study of the magnetic field dependence of the linear electric field effect (LEFE) in EPR spectroscopy, we demonstrate that iron-sulfur cluster 3 in air-oxidized, beef heart succinate-ubiquinone oxidoreductase (Complex II) is a 3-iron cluster. This suggests that cluster 3 may arise by oxidative degradation from a 4-iron cluster originally present in the enzyme and may be reconverted back into a 4-iron cluster under reducing conditions. Linear electric field effect studies of succinate-reduced Complex II are in accord with the view that cluster 1 is a 2-iron cluster.
mesh_terms: D000818:Animals; D002417:Cattle; D004578:Electron Spin Resonance Spectroscopy; D042963:Electron Transport Complex II; D007501:Iron / Q000032:analysis; D007506:Iron-Sulfur Proteins / Q000032:analysis*; D008280:Magnetics; D008667:Metalloproteins / Q000032:analysis*; D008929:Mitochondria, Heart / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000378:metabolism*
chemical_list: D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D009097:Multienzyme Complexes; D007501:Iron; D010088:Oxidoreductases; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase