title: Monitoring the direct and indirect damage of DNA bases and polynucleotides by using time-resolved infrared spectroscopy.
abstract: 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.
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Marina K
authors.initials: MK
authors.lastname: Kuimova
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Cowan
authors.forename: Pavel
authors.initials: P
authors.lastname: Matousek
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Parker
authors.forename: Xue Zhong
authors.initials: XZ
authors.lastname: Sun
authors.forename: Michael
authors.initials: M
authors.lastname: Towrie
authors.forename: Michael W
authors.initials: MW
authors.lastname: George
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000528:radiation effects*; D004249:DNA Damage; D007834:Lasers; D011089:Polydeoxyribonucleotides / Q000737:chemistry / Q000528:radiation effects; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D011089:Polydeoxyribonucleotides; C016681:poly(dG).poly(dC); D004247:DNA