title: Flash-induced electrogenic reactions in the SA(L223) reaction center mutant in Rhodobacter sphaeroides chromatophores.
abstract: The charge transfer events in the SA(L223) reaction center mutant Rhodobacter sphaeroides chromatophores were investigated by direct electrometry. Besides the primary charge separation, the small stigmatellin-sensitive electrogenic reaction due to the electron transfer from the primary to the secondary quinone acceptor in the reaction center complex was observed after the first flash. The second flash-induced electrogenic phase of the secondary quinone protonation and subsequent electrogenic reactions of the cytochrome bc1 complex were much slower than those in chromatophores of the wild type. It is suggested that replacement of Ser-L223 by Ala impairs both specific proton-conducting pathways leading to the secondary quinone QB.
authors.affiliation: A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russian Federation.
authors.forename: S I
authors.initials: SI
authors.lastname: Bibikov
authors.forename: D A
authors.initials: DA
authors.lastname: Bloch
authors.forename: D A
authors.initials: DA
authors.lastname: Cherepanov
authors.forename: D
authors.initials: D
authors.lastname: Oesterhelt
authors.lastname: Semenov AYu
mesh_terms: D000409:Alanine / Q000502:physiology; D020130:Bacterial Chromatophores / Q000502:physiology*; D001483:Base Sequence; D004269:DNA, Bacterial; D004579:Electron Transport; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010777:Photochemistry; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics; D011090:Polyenes / Q000494:pharmacology; D012242:Rhodobacter sphaeroides / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D012694:Serine / Q000502:physiology
chemical_list: D004269:DNA, Bacterial; D045322:Photosynthetic Reaction Center Complex Proteins; D011090:Polyenes; D012694:Serine; C041573:stigmatellin; D000409:Alanine