KINETICS OF REDOX CONVERSION AT A GOLD ELECTRODE OF WATER-INSOLUBLE UBIQUINONE (UQ((10))) AND PLASTOQUINONE (PQ((9))) INCORPORATED IN SUPPORTED PHOSPHOLIPID LAYERS

The cyclic voltammetry of UQ((10)) and PQ((9)) incorporated in a suppo rted lipid bilayer and reacting at a gold electrode is quantitatively analyzed assuming that the electrochemical process consists of a nine- member square scheme and using the approach developed earlier by Lavir on. The striking change affecting the shape of the cathodic peak in th e cyclic voltammograms when pH is increased from less than 7.5 to high er values reflects a shift from kinetic control of the cathodic proces s by the equivalent first electron exchange to kinetic control by the equivalent second electron exchange. Reasonable values are found for t he thermodynamic and kinetic characteristics of the electrochemical pr ocess. (C) 1998 Elsevier Science S.A. All rights reserved.