Photoinduced electron transfer in 5-bromouracil labeled DNA. A contrathermodynamic mechanism revisited by electron transfer theories

Lorenzo Cupellini , Paweł Wityk , Benedetta Mennucci , Janusz Rak


The understanding of the 5-bromouracil (BrU) based photosensitization mechanism of DNA damage is of large interest due to the potential applications in photodynamic therapy. Photoinduced electron transfer (ET) in BrU labeled duplexes comprising the 5′-GBrU or 5′-ABrU sequence showed that a much lower reactivity was found for the 5′-GBrU pattern. Since the ionization potential of G is lower than that of A, this sequence selectivity has been dubbed a contrathermodynamic one. In the current work, we employ the Marcus and Marcus–Levich–Jortner theory of ET in order to shed light on the observed effect. By using a combination of Density Functional Theory (DFT) and solvation continuum models, we calculated the electronic couplings, reorganization energies, and thermodynamic stimuli for electron transfer which enabled the rates of forward and back ET to be estimated for the two considered sequences. The calculated rates show that the photoreaction could not be efficient if the ET process proceeded within the considered dimers. Only after introducing additional adenines between G and BrU, which accelerates the forward and slows down the back ET, is a significant amount of photodamage expected.
Author Lorenzo Cupellini
Lorenzo Cupellini,,
, Paweł Wityk (FCh/DPCh/LBS) - [Politechnika Gdańska]
Paweł Wityk,,
- Laboratory of Biological Sensitizers
- Politechnika Gdańska
, Benedetta Mennucci
Benedetta Mennucci,,
, Janusz Rak (FCh/DPCh/LBS)
Janusz Rak,,
- Laboratory of Biological Sensitizers
Journal seriesPhysical Chemistry Chemical Physics, ISSN 1463-9076, (N/A 100 pkt)
Issue year2019
Publication size in sheets0.50
ASJC Classification1606 Physical and Theoretical Chemistry; 3100 General Physics and Astronomy
Languageen angielski
Score (nominal)100
Score sourcejournalList
ScoreMinisterial score = 100.0, 28-01-2020, ArticleFromJournal
Publication indicators WoS Citations = 1.000; Scopus SNIP (Source Normalised Impact per Paper): 2016 = 1.117; WoS Impact Factor: 2018 = 3.567 (2) - 2018=3.963 (5)
Citation count*2 (2020-06-24)
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* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.
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