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Electron-Induced Repair of 2'-Deoxyribose Sugar Radicals in DNA: A Density Functional Theory (DFT) Study.


ABSTRACT: In this work, we used ?B97XD density functional and 6-31++G** basis set to study the structure, electron affinity, populations via Boltzmann distribution, and one-electron reduction potentials (E°) of 2'-deoxyribose sugar radicals in aqueous phase by considering 2'-deoxyguanosine and 2'-deoxythymidine as a model of DNA. The calculation predicted the relative stability of sugar radicals in the order C4' > C1' > C5' > C3' > C2'. The Boltzmann distribution populations based on the relative stability of the sugar radicals were not those found for ionizing radiation or OH-radical attack and are good evidence the kinetic mechanisms of the processes drive the products formed. The adiabatic electron affinities of these sugar radicals were in the range 2.6-3.3 eV which is higher than the canonical DNA bases. The sugar radicals reduction potentials (E°) without protonation (-1.8 to -1.2 V) were also significantly higher than the bases. Thus the sugar radicals will be far more readily reduced by solvated electrons than the DNA bases. In the aqueous phase, these one-electron reduced sugar radicals (anions) are protonated from solvent and thus are efficiently repaired via the "electron-induced proton transfer mechanism". The calculation shows that, in comparison to efficient repair of sugar radicals by the electron-induced proton transfer mechanism, the repair of the cyclopurine lesion, 5',8-cyclo-2'-dG, would involve a substantial barrier.

SUBMITTER: Bell M 

PROVIDER: S-EPMC7916153 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Electron-Induced Repair of 2'-Deoxyribose Sugar Radicals in DNA: A Density Functional Theory (DFT) Study.

Bell Michael M   Kumar Anil A   Sevilla Michael D MD  

International journal of molecular sciences 20210209 4


In this work, we used ωB97XD density functional and 6-31++G** basis set to study the structure, electron affinity, populations via Boltzmann distribution, and one-electron reduction potentials (E°) of 2'-deoxyribose sugar radicals in aqueous phase by considering 2'-deoxyguanosine and 2'-deoxythymidine as a model of DNA. The calculation predicted the relative stability of sugar radicals in the order C4'<sup>•</sup> > C1'<sup>•</sup> > C5'<sup>•</sup> > C3'<sup>•</sup> > C2'<sup>•</sup>. The Boltz  ...[more]

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