The nucleotide 5′-dGMP and polynucleotide poly(dGdC)-poly(dGdC) have been irradiated by using a 200-fs, 200-nm laser pulses and spectrally characterized by using time-resolved infrared spectroscopy. Under the experimental conditions, 200-nm excitation generates both electronic excited states and radical cations through photoionization; the former decay rapidly to vibrationally hot ground state. By using infrared signatures we have been able to follow these processes, and at time scales of >1 ns we observe an infrared marker band at 1,702 cm-1 within both 5′-dGMP and the polynucleotide assigned to a photoionized product of guanine. This transient has also been reproduced through indirect chemistry through the reaction with photogenerated carbonate radical with 5′-dGMP. The ability to use time-resolved infrared spectroscopy in this way paves the way for developing solution-phase studies to investigate both direct and indirect radiation chemistry of DNA.
|Number of pages||4|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Publication status||Published - 14 Feb 2006|
- DNA damage
- Electron transfer
- Guanine radical cation
ASJC Scopus subject areas