Hole Transfer in Pyrene-conjugated DNA

摘要

To elucidate the hole transfer in DNA including multi-step processes, we used pulse radiolysis which provides a system for the hole transter process free from charge recombination. Hole generated in DNA was monitored by the transient absorption of radical cation of end-capped pyrene (pyrene~.+) during pules radiolysis of pyrene-conjugated oligodeoxynucleotides with different numbers 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 form G radical cation(G~+) to pyrene. This method revealed the hole transfer in DNA over the period of 100mus, which strongly suggests that G(-H~+)~.:C(+H~+)~+ can be present in DNA more than 100 mus, and that this long lifetime 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 beta=0.6 A~-1 which is consistent with that of the photoinduced single-step electron transfer in DNA.