Issue 5, 2018

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

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

Supplementary files

Article information

Article type
Paper
Submitted
29 Jan 2018
Accepted
22 Mac 2018
First published
23 Mac 2018

Photochem. Photobiol. Sci., 2018,17, 586-591

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, 17, 586 DOI: 10.1039/C8PP00040A

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