Sequence dependence on DNA photochemistry: a computational study of photodimerization pathways in TpdC and dCpT dinucleotides - Archive ouverte HAL Access content directly
Journal Articles Photochemical & Photobiological Sciences Year : 2018

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.

Dates and versions

cea-01978125 , version 1 (11-01-2019)

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Lara Martinez-Fernandez, Roberto Improta. Sequence dependence on DNA photochemistry: a computational study of photodimerization pathways in TpdC and dCpT dinucleotides. Photochemical & Photobiological Sciences , 2018, 17 (5), pp.586-591. ⟨10.1039/C8PP00040A⟩. ⟨cea-01978125⟩
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