ABSTRACT
Radical Source)..............................................................................167 11.2.3 Interaction of Redox-Cycling Ubisemiquinones with Hydrogen-Peroxide
(HO
Radical Source)............................................................................................171 11.2.4 Antioxidant-Derived Ubiquinol Metabolites with Prooxidant Activities.............175 11.2.5 Interaction of Redox-Cycling Ubisemiquinone with Nitrite
(Nitrite Reductase Activity) ..................................................................................176 11.3 Conclusions .........................................................................................................................177 References ......................................................................................................................................179
The physico-chemical properties of coenzyme Q are optimal for its functional involvement in energization of biomembranes. Conditions required for this function are the free diffusion within the various sections of a phospholipid bilayer in combination with the acceptance and release of single electrons and single protons. The intermediate reduction state of coenzyme Q between its fully oxidized and its fully reduced form is the semiquinone that can be obtained both from oneelectron reduction of coenzyme Q (ubiquinone) and one-electron oxidation of the divalently reduced coenzyme Q (ubiquinol).
