Abstract

In order to study the behaviour of ubiquinone inside a phospholipid matrix, the E-pH diagrams for CoQ(10) adsorbed on a graphite electrode and on a phospholipid modified graphite electrode were compared. The stabilization area for the protonated free radical HQ was found to be larger in the presence of phospholipids, contrary to results obtained for the charged species. This fact strongly supports the role proposed for ubiquinone in the respiratory chain model where a stable neutral semiubiquinone radical would allow the unitary electron transport through the inner mitochondrial membrane.