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UV ‐induced DNA Damage: The Role of Electronic Excited States
Author(s) -
Markovitsi Dimitra
Publication year - 2015
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12533
Subject(s) - excited state , delocalized electron , chemistry , singlet state , dna , pyrimidine dimer , chemical physics , dna damage , atomic physics , photochemistry , physics , biochemistry , organic chemistry
The knowledge of the fundamental processes induced by the direct absorption of UV radiation by DNA allows extrapolating conclusions drawn from in vitro studies to the in‐vivo DNA photoreactivity. In this respect, the characterization of the DNA electronic excited states plays a key role. For a long time, the mechanisms of DNA lesion formation were discussed in terms of generic “singlet” and “triplet” excited state reactivity. However, since the beginning of the 21 st century, both experimental and theoretical studies revealed the existence of “collective” excited states, i.e . excited states delocalized over at least two bases. Two limiting cases are distinguished: Frenkel excitons (delocalized ππ* states) and charge‐transfer states in which positive and negative charges are located on different bases. The importance of collective excited states in photon absorption (in particular in the UVA spectral domain), the redistribution of the excitation energy within DNA , and the formation of dimeric pyrimidine photoproducts is discussed. The dependence of the behavior of the collective excited states on conformational motions of the nucleic acids is highlighted.