title: Soluble cytochrome composition of the purple phototrophic bacterium, Rhodopseudomonas sphaeroides ATCC 17023.
abstract: A detailed study of the soluble cytochrome composition of Rhodopseudomonas sphaeroides (ATCC 17023) indicates that there are five c-type cytochromes and one b-type cytochrome present. The molecular weights, heme contents, amino acid compositions, isoelectric points, and oxidation-reduction potentials were determined and the proteins were compared with those from other bacterial sources. Cytochromes c2 and c' have previously been well characterized. Cytochrome c-551.5 is a diheme protein which has a very low redox potential, similar to certain purple bacterial and algal cytochromes. Cytochrome c-554 is an oligomer, which is spectrally similar to the low-spin isozyme of cytochrome c' found in other purple bacteria (e.g., Rhodopseudomonas palustris cytochrome c-556). An unusual high-spin c-type heme protein has also been isolated. It is spectrally distinguishable from cytochrome c' and binds a variety of heme ligands including oxygen. A large molecular-weight cytochrome b-558 is also present which appears related to a similar protein from Rhodospirillum rubrum, and the bacterioferritin from Escherichia coli. None of the soluble proteins appear to be related to the abundant membrane-bound c-type cytochrome in Rps. sphaeroides which has a larger subunit molecular weight similar to mitochondrial cytochrome c1 and chloroplast cytochrome f.
authors.forename: T E
authors.initials: TE
authors.lastname: Meyer
authors.forename: M A
authors.initials: MA
authors.lastname: Cusanovich
mesh_terms: D001426:Bacterial Proteins; D003573:Cytochrome b Group / Q000032:analysis; D003574:Cytochrome c Group / Q000032:analysis; D003580:Cytochromes / Q000032:analysis* / Q000235:genetics; D045362:Cytochromes c2; D006420:Hemeproteins / Q000032:analysis; D019255:NADPH Oxidases; D012242:Rhodobacter sphaeroides / Q000032:analysis* / Q000235:genetics; D012995:Solubility
chemical_list: D001426:Bacterial Proteins; D003573:Cytochrome b Group; D003574:Cytochrome c Group; D003580:Cytochromes; D006420:Hemeproteins; C083951:cytochrome c553; D045362:Cytochromes c2; C017167:cytochrome C(551); C022302:cytochrome C-552; C036888:cytochrome b558; D019255:NADPH Oxidases