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Sequence dependence on DNA photochemistry: a computational study of photodimerization pathways in TpdC and dCpT dinucleotides

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Abstract

The excited states involved in the main photodimerization paths in TpdC and dCpT are mapped by PCM/TD-M052X calculations, considering different dinucleotide conformers. As for TT steps, a cyclobutane pyrimidine dimer (CPD) is formed on the PES of the lowest energy exciton, delocalized over two stacked pyrimidines; 6–4 pyrimidine–pyrimidone (64-PP) adduct's formation involves instead a 5′-ter → 3′-ter charge transfer state. For dCpT, 64-PP dimerization occurs via a two-step reaction, which proceeds through an oxetane intermediate. For TpdC, instead, the final 64-PP product is obtained in a single step and it is as stable as the CPD photoproduct, explaining the relatively large yield of 64-PP found experimentally for TC steps in DNA.

Graphical abstract: Sequence dependence on DNA photochemistry: a computational study of photodimerization pathways in TpdC and dCpT dinucleotides

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Publication details

The article was received on 29 Jan 2018, accepted on 22 Mar 2018 and first published on 23 Mar 2018


Article type: Paper
DOI: 10.1039/C8PP00040A
Citation: Photochem. Photobiol. Sci., 2018, Advance Article
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    Sequence dependence on DNA photochemistry: a computational study of photodimerization pathways in TpdC and dCpT dinucleotides

    L. Martínez-Fernández and R. Improta, Photochem. Photobiol. Sci., 2018, Advance Article , DOI: 10.1039/C8PP00040A

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