Effect of GC Base Pairs on Charge Transfer through DNA Hairpins: The Importance of Electrostatic Interactions

DNA hairpins in which an electron donor and an electron acceptor are attached to the ends are excellent model systems for the study of charge transfer in weakly coupled π-stacked systems. In this communication we report on a computational study of the effect of the base pair sequence in these DNA hairpins on the kinetics of charge transfer. We show that the rate of charge transfer strongly depends on the actual position of a GC base pair in a sequence that otherwise only contains AT base pairs. This can be explained by evaluating the energy landscape through which the charge travels. It is shown that including the electrostatic interaction between electron and hole can explain the experimentally observed dependence on the position of the GC in the DNA. We conclude that electrostatic interactions are important to consider when explaining the charge transfer kinetics in GC containing DNA sequences.