Variations in DNA Charge Transport with Nucleotide Composition and Sequence

Long-range oxidative damage to DNA has been demonstrated in experiments using a variety of remotely bound oxidants. However, the mechanism(s) by which charge is transported through the base pair stack needs still to be established. Recent theoretical proposals bring together tunneling and hopping mechanisms to describe charge transport. On the basis of measurements of damage yield, it has been proposed that charge transport occurs by hopping between guanine sites and tunneling through TA steps. In accord with guanine hopping, oxidative damage over long distances was not observed when 5‘-TATATA-3‘ intervened between G sites. Phonon-assisted polaron hopping has been suggested as an alternative mechanism. In this model, the sequence-dependent conformational dynamics of DNA are expected to aid in charge transport