DNA photodamage: Study of cyclobutane pyrimidine dimer formation in a locked thymine dinucleotide

Issue title: From Molecule to Tissue: XIII European Conference on the Spectroscopy of Biological Molecules, Palermo, Italy, August 28–September 2, 2009, Part 2 of 2

Article type: Research Article

Authors: Schreier, W.J. | Kubon, J. | Clivio, P. | Zinth, W.^; | Gilch, P.^;

Affiliations: Fakultät für Physik, LMU München, Lehrstuhl für BioMolekulare Optik, München, Germany and Munich Center for Integrated Protein Science CIPSM, München, Germany | Institut de Chimie Moléculaire de Reims, Université de Reims Champagne Ardenne, Reims, France

Note: [] Corresponding author: W. Zinth, Fakultät für Physik, LMU München, Lehrstuhl für BioMolekulare Optik, Oettingen str. 67, 80538 München, Germany and Munich Center for Integrated Protein Science CIPSM, München, Germany. Tel.: +49 89 2180 9200; Fax: +49 89 2180 9202; E-mail: [email protected].

Note: [] Present address: Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf Universitäts str. 1, 40225 Düsseldorf, Germany.

Abstract: The cyclobutane pyrimidine dimer (CPD) formed between two adjacent thymine bases is the most abundant DNA photolesion induced by UV radiation. The quantum yield of this reaction is on the order of ~1% in DNA. This small quantum yield hampers the study of damage formation in naturally occurring DNA. Investigations with increased accuracy become possible for a locked nucleotide model compound TLpTL which exhibits a quantum yield of about 10% for CPD formation. Time resolved IR spectroscopy on TLpTL and two other DNA model compounds (TpT and (dT)18) reveals that: (i) The absorption changes after ~1 ps are due to CPD photodamage. (ii) The quantum efficiency of CPD formation on the few picosecond time scale equals the quantum efficiency reported in stationary experiments. CPD photodamage formation in the investigated DNA constructs is thus predominantly formed from the primarily photoexcited singlet ππ* state, whereas the triplet channel does not play an essential role.

Keywords: Infrared spectroscopy, DNA photolesion, CPD damage, thymine dimer

DOI: 10.3233/SPE-2010-0437

Journal: Spectroscopy, vol. 24, no. 3-4, pp. 309-316, 2010