title: Q-band ENDOR spectra of the Rieske protein from Rhodobactor capsulatus ubiquinol-cytochrome c oxidoreductase show two histidines coordinated to the [2Fe-2S] cluster.
abstract: Electron nuclear double resonance (ENDOR) experiments were performed on 14N (natural abundance) and 15N-enriched iron-sulfur Rieske protein in the ubiquinol-cytochrome c2 oxidoreductase from Rhodobactor capsulatus. The experiments proved that two distinct nitrogenous ligands, histidines, are undoubtedly ligated to the Rieske [2Fe-2S] center. The calculations of hyperfine tensors give values similar but not identical to those of the Rieske-type cluster in phthalate dioxygenase of Pseudomonas cepacia and suggest a slightly different geometry of the iron-sulfur cluster in the two proteins.
authors.affiliation: Department of Chemistry, Northwestern University, Evanston, Illinois 60208.
authors.forename: R J
authors.initials: RJ
authors.lastname: Gurbiel
authors.forename: T
authors.initials: T
authors.lastname: Ohnishi
authors.forename: D E
authors.initials: DE
authors.lastname: Robertson
authors.forename: F
authors.initials: F
authors.lastname: Daldal
authors.forename: B M
authors.initials: BM
authors.lastname: Hoffman
mesh_terms: D000595:Amino Acid Sequence; D004578:Electron Spin Resonance Spectroscopy; D014450:Electron Transport Complex III / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000737:chemistry; D016354:Rhodobacter capsulatus / Q000201:enzymology*; D013050:Spectrometry, Fluorescence
chemical_list: D007506:Iron-Sulfur Proteins; C037989:Rieske iron-sulfur protein; D006639:Histidine; D014450:Electron Transport Complex III; D009584:Nitrogen