The presence of cytochrome c₁ in the purple sulfur bacterium Chromatium vinosum

Abstract

A cytochrome-enriched preparation derived from Chromatium vinosum chromatophores has been used to demonstrate the presence of a previously undetected high potential cytochrome c in C. vinosum. The reduced cyt~hrome has cy. ,L? and Soret band maxima at 552-553, 523 and 422 nm respectively and a probable I% of 31000. The cytochrome appears to have E,,, near +245 mV. These properties of the C. vinosum cytochrome suggest that it is similar to cytochrome ~1. Cytochrome cl PhotosynthesisPhotosynthetic bacteria (Chromatium vinosum)

Isolation of cytochrome bc 1 complexes from the photosynthetic bacteria Rhodopseudomonas viridis and Rhodospirillum rubrum

“…viridis or R. rubrum complex. The 30 kDa apparent molecular weight for cytochrome c~ in the two complexes is similar to Mr values obtained for the cytochrome in several other cytochrome bcl complexes [18,17,15,42,32]. The absence of Mr = 24 and 35kDa peptides and of a 38 kDa heme-staining peptide in the Rps.…”

“…+ 200mV) components. The difference spectra both reveal the presence of a component with absorbance maxima (a-band = 553nm and /3-band = 523-524nm) consistent with the presence of cytochrome cl [18,10,17,9,15,42,32] in both the Rps. virMis and R. rubrurn complexes.…”

“…However, should cytochrome b indeed be present in Cfl. aurantiacus, it would seem likely that this gliding green bacterium (like representative species from all other known families of photosynthetic bacteria [18,10,17,9,19,40] …”

“…However, it is possible that the R. rubrum complex contains more than one species of b-cytochrome since R. rubrum chromatophore membranes are known to contain at least two different b-type cytochromes active in photosynthetic electron transport [37,13]. As cytochrome bcl complexes isolated from a variety of sources contain the Rieske iron-sulfur protein [18,10,17,9], the acid-labile sulfide and nonheme iron contents oftheRps, viriclis andR. rubrum complexes were examined to determine whether these components of the prosthetic group of the Rieske protein [ 18] were present.…”

“…It has recently become clear that the membrane-bound electron transfer chains of mitochondria, chloroplasts, cyanobacteria and bacteriochlorophyll a-containing photosynthetic bacteria contain similar multi-peptide complexes that catalyze electron flow from quinol to a soluble cytochrome c or its functional equivalent, the copper-containing protein plastocyanin [18,10,17,9]. This complex contains cytochrome ci, two b cytochromes and the Rieske iron-sulfur protein.…”