title: The orientation of iron-sulfur clusters and a spin-coupled ubiquinone pair in the mitochondrial membrane.
abstract: Oriented multilayers made from beef heart and yeast mitochondria and submitochondrial particles were studied using electron paramagnetic resonance. EPR signals from membrane-bound iron-sulfur clusters and from a spin-coupled ubiquinone pair are highly orientation dependent, implying that these redox centers are fixed in the membrane at definite angles relative to the membrane plane. Typically the iron-iron axis (gz) of the binuclear iron-sulfur clusters is in the membrane plane. This finding is discussed in terms of the protein structure. The tetranuclear iron-sulfur clusters can have their gz axis either perpendicular or parallel to the membrane plane, but intermediate orientation was not observed.
mesh_terms: D000818:Animals; D002417:Cattle; D004227:Dithionite; D004578:Electron Spin Resonance Spectroscopy; D007425:Intracellular Membranes / Q000201:enzymology / Q000648:ultrastructure*; D007506:Iron-Sulfur Proteins / Q000032:analysis*; D008667:Metalloproteins / Q000032:analysis*; D008928:Mitochondria / Q000201:enzymology / Q000648:ultrastructure*; D008929:Mitochondria, Heart / Q000201:enzymology* / Q000648:ultrastructure*; D009247:NADH, NADPH Oxidoreductases / Q000032:analysis; D012440:Saccharomyces / Q000032:analysis; D013385:Succinate Dehydrogenase / Q000032:analysis; D014451:Ubiquinone / Q000032:analysis*
chemical_list: D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D014451:Ubiquinone; D004227:Dithionite; D013385:Succinate Dehydrogenase; D009247:NADH, NADPH Oxidoreductases