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

Lara Martinez-Fernandez 1, 2 Roberto Improta 1, 2
1 DICO - Biomolécules Excitées
IRAMIS - Institut Rayonnement Matière de Saclay, LIDyl - Laboratoire Interactions, Dynamiques et Lasers (ex SPAM)
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.
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https://hal-cea.archives-ouvertes.fr/cea-01978125
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Submitted on : Friday, January 11, 2019 - 12:13:24 PM
Last modification on : Monday, September 2, 2019 - 5:32:02 PM

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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 , Royal Society of Chemistry, 2018, 17 (5), pp.586-591. ⟨10.1039/C8PP00040A⟩. ⟨cea-01978125⟩

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