Bernd Giese, Matthias Napp, Olivier Jacques, Hassen Boudebous, Alexander M. Taylor, and Jakob Wirz, "Multistep Electron Transfer in Oligopeptides: Direct Observation of Radical Cation Intermediates", Angew. Chem. Int. Ed. Engl. 2005, 44, 4073-4075; Angew. Chem. 2005, 117, 4141-4143.
Abstract: Charge transport reactions through proteins over long distances are important processes in biological systems. In this manuscript we describe our studies of electron hole transport through artificial oligopeptides, which contain amino acids with aromatic side chains. The experiments demonstrate that the charge hops in our systems between these aromatic side chains. We detected the intermediate radical cations and measured the absolute rates of the hopping reactions in time resolved laser experiments. The effect of the number of proline units, which separate the aromatic redox centers, indicates that the charge transfer occurs through space and not through the bonds of the peptide chain.