Quinone and non-quinone redox couples in Complex III.
The Q cycle mechanism proposed by Peter Mitchell in the 1970's explicitly considered the modification of ubiquinone two-electron redox properties upon binding to Complex III to match the thermodynamics of the other single-electron redox cofactors in the complex, and guide electron transfer to support the generation of a proton electro-chemical gradient across native membranes. A better understanding of the engineering of Complex III is coming from a now moderately well defined thermodynamic description of the redox components as a function of pH, including the Qi/heme b(H) cluster. The redox properties of the most obscure component, Qo, is finally beginning to be resolved.
Zhang
Haibo
H
Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA.
Chobot
Sarah E
SE
Osyczka
Artur
A
Wraight
Colin A
CA
Dutton
P Leslie
PL
Moser
Christopher C
CC
D014450:Electron Transport Complex III / Q000737:chemistry / Q000266:history* / Q000378:metabolism; D049673:History, 20th Century; D008954:Models, Biological; D010084:Oxidation-Reduction; D018892:Proton-Motive Force; D011809:Quinones / Q000737:chemistry; D013816:Thermodynamics
D011809:Quinones; D014450:Electron Transport Complex III