The Rhodospirillum rubrum cytochrome bc1 complex: pep tide composition, prosthetic group content and quinone binding

Aidas Kriauciunas, Linda Yu, Chang An Yu, R. Max Wynn, David B. Knaff

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

A cytochrome bc1 complex, essentially free of bacteriochlorophyll, has been purified from the photosynthetic purple non-sulfur bacterium Rhodospirillum rubrum. The complex catalyzes electron flow from quinol to cytochrome c (turnover number = 75 s-1) that is inhibited by low concentrations of antimycin A and myxothiazol. The complex contains only three peptide subunits: cytochrome b (Mr = 35000); cytochrome c1 (Mr = 31000) and the Rieske iron-sulfur protein (Mr = 22400). Em values (pH 7.4) were measured for cytochrome c, (+ 320 mV) and the two hemes of cytochrome b (- 33 and -90 mV). Electron flow from quinol to cytochrome c is inhibited when the complex is pre-illuminated in the presence of a ubiquinone photoaffinity analog (azido-Q). During illumination, the azido-Q becomes covalently attached to the cytochrome b peptide and, to a lesser extent, to cytochrome c1.

Original languageEnglish (US)
Pages (from-to)70-76
Number of pages7
JournalBBA - Bioenergetics
Volume976
Issue number1
DOIs
StatePublished - Aug 1989

Keywords

  • (R. rubrum)
  • Cytochrome bc complex
  • Electron transport chain
  • Purple bacteria
  • Quinone binding

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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