title: Identification of the axial heme ligands of cytochrome b556 in succinate: ubiquinone oxidoreductase from Escherichia coli.
abstract: Electron paramagnetic resonance (EPR) and near-infrared magnetic circular dichroism (MCD) have been used to identify the ligands to the cytochrome b556 component of succinate: ubiquinone oxidoreductase (succinate dehydrogenase) from Escherichia coli. The 'highly axial low spin' (HALS) EPR spectrum suggests bis(histidine) ligation of the heme with the histidines in a staggered configuration. The near-infrared MCD spectrum exhibits a low energy maximum at 1600 nm which is also clearly indicative of bis(histidine) ligation of the heme iron. The data unambiguously demonstrate that the heme b556 is ligated to E. coli succinate dehydrogenase via two histidines.
authors.affiliation: Department of Chemistry, University of Alabama, Tuscaloosa 35487.
authors.forename: J
authors.initials: J
authors.lastname: Peterson
authors.forename: C
authors.initials: C
authors.lastname: Vibat
authors.forename: R B
authors.initials: RB
authors.lastname: Gennis
mesh_terms: D001665:Binding Sites; D002942:Circular Dichroism; D003573:Cytochrome b Group / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D042963:Electron Transport Complex II; D004926:Escherichia coli / Q000737:chemistry* / Q000201:enzymology; D006418:Heme / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry; D008024:Ligands; D009097:Multienzyme Complexes / Q000737:chemistry*; D010088:Oxidoreductases / Q000737:chemistry*; D013385:Succinate Dehydrogenase / Q000737:chemistry*
chemical_list: D003573:Cytochrome b Group; D008024:Ligands; D009097:Multienzyme Complexes; C018256:cytochrome b556; D006418:Heme; D006639:Histidine; D010088:Oxidoreductases; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase