Electron transfer from ubiquinol to cytochrome c of complex III

Stable Identifier
Reaction [transition]
Homo sapiens
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The protonmotive Q cycle is the mechanism by which complex III transfers electrons from ubiquinol to cytochrome c, linking this process to translocation of protons across the membrane. This cycle is complicated by the fact that both ubiquinol is oxidised and ubiquinone is reduced during this process. Through a complex series of electron transfers, Complex III consumes two molecules of ubiquinol (QH2) and two molecules of oxidized cytochrome c, generates one molecule of ubiquinone (Q) and two molecules of reduced cytochrome c, regenerates one molecule of ubiquinol (QH2), and mediates the translocation of two protons from the mitochondrial matrix to the mitochondrial intermembrane space. The overall reaction can be summed up as

2QH2 + 2cyt c (ox.) + Q + 2H+ (matrix) = 2Q + 2cyt c (red.) + QH2 + 4H+ (intermemb. space)

Literature References
PubMed ID Title Journal Year
239860 Protonmotive redox mechanism of the cytochrome b-c1 complex in the

Mitchell, P

FEBS Lett 1975
186667 Possible molecular mechanisms of the protonmotive function of cytochrome

Mitchell, P

J Theor Biol 1976
Event Information
Catalyst Activity

ubiquinol-cytochrome-c reductase activity of Ubiquinol-cytochrome c reductase [mitochondrial inner membrane]

Orthologous Events
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