The electrochemistry of ubiquinone-10 in a phospholipid model membrane.
The electrochemistry of ubiquinone-10, UQ, incorporated over a phospholipid layer adsorbed on a mercury drop electrode has been investigated over a wide pH range. It is shown that the position of the quinone headgroup in relation to the lipid determines the reversibility of the redox chemistry. For pH <7, the reaction follows a disproportionation route involving the ubiquione radical. There is evidence for the presence of a parallel reaction sequence. The bifurcation point appears to occur for the UQ molecule, which disproportionates after protonation and reduction, in parallel with direct electron transfer to yield the UQ--radical anion. The incorporation of UQ in a lipid monolayer makes its reduction very irreversible for pH > 7.
Gordillo
G J
GJ
INQUIMAE, Departamento de Química, Facultád de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Cuidad Universitaria, Pabellón II, Buenos Aires, 1428, Argentina.
Schiffrin
D J
DJ
D000465:Algorithms; D004563:Electrochemistry; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000737:chemistry*; D014451:Ubiquinone / Q000737:chemistry*
D008567:Membranes, Artificial; D010743:Phospholipids; D014451:Ubiquinone