title: A new membrane-bound b-type cytochrome, cytochrome b-558, from photosynthetically grown Rhodopseudomonas sphaeroides.
abstract: A new membrane-bound b-type cytochrome, cytochrome b-558, was removed from chromatophore membranes of photosynthetically grown Rhodopseudomonas sphaeroides strain R-26 by deoxycholate-cholate extraction. The cytochrome was purified by ammonium sulfate fractionation and ion-exchange chromatography. Cytochrome b-558 had absorption maxima at 280 and 405 nm in the oxidized form, and at 558, 528, and 420 nm in the reduced form. It had a midpoint potential of--130 mV at pH 7.0. The minimal molecular weight of this protein was 42,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and it contained one mole heme per mole of protein. The isoelectric point was 8.5. The electrophoretic pattern of heme-carrying proteins and the redox potentiometry showed that cytochrome b-558 was present in membranes from wild type, strain R-26, and strain GA grown photosynthetically, but not from any strain grown aerobically.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D020130:Bacterial Chromatophores / Q000201:enzymology; D001665:Binding Sites; D002462:Cell Membrane / Q000201:enzymology; D003573:Cytochrome b Group / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D006418:Heme / Q000032:analysis; D019255:NADPH Oxidases; D010084:Oxidation-Reduction; D010788:Photosynthesis; D012242:Rhodobacter sphaeroides / Q000201:enzymology*; D013053:Spectrophotometry
chemical_list: D000596:Amino Acids; D003573:Cytochrome b Group; D006418:Heme; C036888:cytochrome b558; D019255:NADPH Oxidases