1,720,992 research outputs found
Isolation of cytochrome b form the cytochrome b/c1 complex of Rhodopseudomonas sphaeroides GA
No full textThe purification and the biochemical characterization of cytochrome b of the cytochrome b/c1 complex from Rhodobacter capsulatus is reported
Characterization of cytochrome b in the isolated ubiquinol-cytochrome c2 oxidoreductase from Rhodopseudomonas sphaeroides GA.
No full textExtinction coefficients for cytochrome b and c1 in the isolated cytochrome bc1 complex from Rhodopseudomonas sphaeroides GA have been determined. They are 25 mM-1 . cm-1 at 561 nm for cytochrome b and 17.4 mM-1 . cm-1 at 553 nM for cytochrome c1, for the difference between the reduced and the oxidized state. Cytochrome b is present in two forms in the complex. One form has an Em7 of 50 mV, an alpha-peak of 557 nm at liquid N2 temperature and of 561 nm at RT, which is red-shifted by antimycin A. The other form has an Em7 of -90 mV, a double alpha-peak of 555 and 561 nm at liquid N2 temperature corresponding to 559 and 566 nm at RT. The absorption at 566 nm is red-shifted by myxothiazol. The two shifts are independent of each other. Both midpoint potentials of cytochromes b are pH-dependent. The redox center compositions of the cytochrome bc1 complexes from Rhodopseudomonas sphaeroides and from mitochondria are identical
A cytochrome b/c1 complex with ubiquinol--cytochrome c2 oxidoreductase activity from Rhodopseudomonas sphaeroides GA.
No full textA cytochrome b/c1 complex which catalyses the reduction of cytochrome c by ubiquinol has been isolated from Rhodopseudomonas sphaeroides GA. It contains two hemes b and substoichiometric amounts of ubiquinone-10 and of the Rieske Fe-S center per cytochrome c1, and is essentially free of reaction center and bacteriochlorophyll. The complex consists of three major polypeptides with apparent molecular masses of 40, 34 and 25 kDa. The 34-kDa polypeptide carries heme. Cytochrome c1 has a midpoint potential of 285 mV. For cytochrome b two midpoint potentials, at 50 and -60 mV, at pH 7.4, can be derived if one assumes two components of equal amount. Ubiquinol--cytochrome c oxidoreductase activity is specific for ubiquinol and bacterial cytochromes c, and is inhibited by antimycin A and 5-n-undecyl-6-hydroxy-4,7-dioxobenzothiazole. The complex shows oxidant-induced reduction of cytochrome b
Comparative aspects of quinol-cytochrome c/plastocyanin oxidoreductases.
No full textThe similarities of the electron and proton transfers through quinones and cytochrome bc complexes isolated from different organisms is discussed in this review
Cytochrome b/c complexes with polyprenylquinol-cytochrome c oxidoreductase activity from chloroplasts, a cyanobacterium and a Rhodopseudomonas
No full textThe homologies between the structure and function of the cytochrome complexes isolated from photosynthetic bacteria, cyanobacteria and chlotoplasts are described
Ubiquinol-cytochrome c2 oxidoreductase from Rhodopseudomonas sphaeroides GA
No full textThe purification of the cytochrome b/c1 complex from photosynthetic bacteria and the biochemical characterization is reported
Cloning and expression of the fbc operon encoding the FeS protein, cytochrome b and cytochrome c1 from the Rhodopseudomonas sphaeroides b/c1 complex.
No full textThe gene for the FeS protein of the Rhodopseudomonas sphaeroides b/c1 complex was identified by means of cross-hybridization with a segment of the gene encoding the corresponding FeS protein of Neurospora crassa. Plasmids (pRSF1-14) containing the cross-hybridizing region, covering in total 13.5 kb of chromosomal DNA, were expressed in vitro in a homologous system. One RSF plasmid directed the synthesis of all three main polypeptides of the R. sphaeroides b/c1 complex: the FeS protein, cytochrome b and cytochrome c1. The FeS protein and cytochrome c1 were apparently synthesized as precursor forms. None of the pRSF plasmids directed the synthesis of the 10-kd polypeptide found in b/c1 complex preparations. Partial sequencing of the cloned region was performed. Several sites of strong homology between R. sphaeroides and eukaryotic polypeptides of the b/c1 complex were identified. The genes encode the three b/c1 polypeptides in the order: (5') FeS protein, cytochrome b, cytochrome c1. The three genes are transcribed to give a polycistronic mRNA of 2.9 kb. This transcriptional unit has been designated the fbc operon; its coding capacity corresponds to the size of the polycistronic mRNA assuming that only the genes for the FeS protein (fbcF), cytochrome b (fbcB) and cytochrome c1 (fbcC) are present. This could indicate that these three subunits constitute the minimal catalytic unit of the b/c1 complex from photosynthetic membranes
Cytochrome b/c complexes with polyprenyl quinol:cytochrome c oxidoreductase activity from Anabaena variabilis and Rhodopseudomonas sphaeroides GA: comparison of preparations from chloroplasts and mitochondria.
No full textThe polypeptide composition and the characterization of electron transport through the cytochrome b/c1 complexes isolated from photosynthetic bacteria and cyanobacteria are described in this article
Extra proton translocation and membrane potential generation--universal properties of cytochrome bc1/b6f complexes reconstituted into liposomes.
No full textIsolated cytochrome complexes from different sources like beef heart mitochondria, spinach chloroplasts, cyanobacteria, and photosynthetic bacteria were incorporated into liposomes by sonication as revealed by sucrose density gradient centrifugation and electron microscopy. The reconstituted cytochrome complexes show suppressed rates of quinol-cytochrome c/plastocyanin oxidoreduction which can be stimulated by ionophores and uncouplers. In addition, extra proton translocation out of the vesicles and membrane potential generation during electron transport were observed, suggesting a universal mechanism of electron and proton transport through all the tested cytochrome complexes
Organization and function of photosynthetic and respiratory cytochrome b/c-FeS complexes.
No full textThe structural homologies between the electron transport chain of photosynthetic organisms and that of mitochondria is described
- …
