Shape Resonances in DNA: Nucleobase Release, Reduction, and Dideoxynucleoside Products Induced by 1.3 to 2.3 eV Electrons.

J Phys Chem B

Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada.

Published: July 2022

Understanding the details of DNA damage caused by high-energy particles or photons is complicated by the multitude of reactive species, arising from the ionization and dissociation of HO, DNA, and protein. In this work, oligonucleotides (ODNs) are irradiated with a beam of low-energy electrons of 1.3 to 2.3 eV, which can only induce damage via the decay of shape resonances into various dissociative electron attachment channels. Using LC-MS/MS analysis, the major products are the release of nonmodified nucleobases (NB; Cyt ≫ Thy ∼ Ade > Gua). Additional damage includes 5,6-dihydropyrimidines (dHT > dHU) and eight nucleosides with modified sugar moieties consisting of 2',3'- and 2',5'-dideoxynucleosides (ddG > ddA ∼ ddC > ddT). The distribution of products is remarkably different in a 16-mer ODN compared to that observed previously with thymidylyl-(3'-5')-thymidine. This difference is explained by electron delocalization occurring within a sufficiently long strand, the DEA theory of O'Malley, and recent time-dependent density functional theory calculations.

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http://dx.doi.org/10.1021/acs.jpcb.2c01851DOI Listing

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