Abstract
To elucidate the hole transfer in DNA including multi-step processes, we used pulse radiolysis which provides a system for the hole transfer process free from charge recombination. Hole gen-erated in DNA was monitored by the transient absorption of radical cation of end-capped pyrene (pyrene.+) during pulse radiolysis of pyrene-conjugated oligodeoxynucleotides with different num-bers of intervening A-T base pairs between the G-region (5'-GTGTGTG-3') and pyrene. The results demonstrated a distance dependence of the hole transfer from G radical cation (G.+) to pyrene. This method revealed the hole transfer in DNA over the period of 100, us, which strongly suggests that G (-H.+) . : C (+H+) + can be present in DNA more than 100, us, and that this long life-time is at the very origin of the long-range hole transfer in DNA. We also determined a distance dependence of the single-step hole transfer process as β = 0.6 Å-1 which is consistent with that of the photoinduced single-step electron transfer in DNA.
