PMID: 6260161Mar 12, 1981

Cytochrome b oxidation and reduction reactions in the ubiquinone-cytochrome b/c2 oxidoreductase from Rhodopseudomonas sphaeroides

Biochimica Et Biophysica Acta
D P O'Keefe, P L Dutton

Abstract

1. The kinetics of cytochrome b reduction and oxidation in the ubiquinone-cytochrome b/c2 oxidoreductase of chromatophores from Rhodopseudomonas sphaeroides Ga have been measured both in the presence and absence of antimycin, after subtraction of contributions due to absorption changes from cytochrome c2, the oxidized bacteriochlorophyll dimer of the reaction center, and a red shift of the antenna bacteriochlorophyll. 2. A small red shift of the antenna bacteriochlorophyll band centered at 589 nm has been identified and found to be kinetically similar to the carotenoid bandshift. 3. Antimycin inhibits the oxidation of ferrocytochrome b under all conditions; it also stimulates the amount of single flash activated cytochrome b reductions 3- to 4-fold under certain if not all conditions. 4. A maximum of approximately 0.6 cytochrome b-560 (Em(7) = 50 mV, n = 1, previously cytochrome b50) hemes per reaction center are reduced following activating flashes. This ratio suggests that there is one cytochrome b-560 heme functional per ubiquinone-cytochrome b/c2 oxidoreductase. 5. Under the experimental conditions used here, only cytochrome b-560 is observed functional in cyclic electron transfer. 6. We describe the existence of three dist...Continue Reading

Citations

Sep 1, 1988·Photosynthesis Research·D P O'Keefe
Aug 1, 1983·Journal of Bioenergetics and Biomembranes·A V Oleskin, V D Samuilov
Jul 24, 2010·Biochimica Et Biophysica Acta·Armen Y Mulkidjanian
Jun 20, 2006·Biochimica Et Biophysica Acta·Armen Y Mulkidjanian
Jan 4, 2007·Photochemical & Photobiological Sciences : Official Journal of the European Photochemistry Association and the European Society for Photobiology·Armen Y Mulkidjanian

Related Concepts

Bacteriochlorophylls
Cytochrome b Group
Cytochrome c Group
Cytochromes
Multienzyme Complexes
NADH, NADPH Oxidoreductases
Oxidation-Reduction
Menaquinone Reductases
Rhodobacter sphaeroides
Spectrophotometry

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