title: Spectroscopic identification of the axial ligands of cytochrome b560 in bovine heart succinate-ubiquinone reductase.
abstract: The axial ligands of low potential cytochrome b560 in the five subunit bovine heart succinate-ubiquinone reductase complex and in the isolated quinone binding proteins have been investigated using EPR and near-infrared magnetic circular dichroism spectroscopies. The results are consistent with bis-histidine ligation with near-perpendicular imidazole rings for cytochrome b560 in the four-subunit complex. The pronounced changes in EPR properties that accompany isolation of the cytochrome-b560 containing quinone binding proteins, are attributed to perturbation of the orientation of the imidazole rings of the heme bis-histidine ligands, rather than a change in axial ligation.
authors.affiliation: Department of Chemistry, University of Georgia, Athens 30602, USA.
authors.forename: B R
authors.initials: BR
authors.lastname: Crouse
authors.forename: C A
authors.initials: CA
authors.lastname: Yu
authors.forename: L
authors.initials: L
authors.lastname: Yu
authors.forename: M K
authors.initials: MK
authors.lastname: Johnson
mesh_terms: D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D003573:Cytochrome b Group / Q000737:chemistry*; D042963:Electron Transport Complex II; D008024:Ligands; D009097:Multienzyme Complexes / Q000737:chemistry*; D009206:Myocardium / Q000201:enzymology*; D010088:Oxidoreductases / Q000737:chemistry*; D013057:Spectrum Analysis; D013385:Succinate Dehydrogenase / Q000737:chemistry*
chemical_list: D003573:Cytochrome b Group; D008024:Ligands; D009097:Multienzyme Complexes; C025355:cytochrome b560; D010088:Oxidoreductases; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase