1. One Way Traffic: Base‐to‐backbone Hole Transfer in Nucleoside Phosphorodithioates
- Author
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Roman Dembinski, Sergey A. Denisov, Renata Kaczmarek, Alexander D. Stark, Amitava Adhikary, Michael D. Sevilla, Taisiya Jacobs, Samuel Ward, Pascal Pernot, Anil Kumar, Mehran Mostafavi, Viacheslav Shcherbakov, Dipra Debnath, Dariusz Korczyński, Department of Bioorganic Chemistry Centre of Molecular and Macromolecular Studies Polish Academy of Sciences, Polish Academy of Sciences (PAN), Oakland University, Institut de Chimie Physique (ICP), and Institut de Chimie du CNRS (INC)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Anions ,Guanine ,Radical ,Dimer ,Radiation chemistry ,010402 general chemistry ,01 natural sciences ,Article ,Catalysis ,Phosphates ,chemistry.chemical_compound ,thiyl radicals ,base-to-backbone hole transfer ,backbone-to-base hole transfer ,Spectroscopy ,Phosphorodithioate ,Aqueous solution ,010405 organic chemistry ,Organic Chemistry ,Electron Spin Resonance Spectroscopy ,Water ,Nucleosides ,DNA ,General Chemistry ,guanine cation radical ,3. Good health ,0104 chemical sciences ,[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry ,Crystallography ,chemistry ,Radiolysis ,Density functional theory ,Ionization energy ,Pulse Radiolysis ,Oxidation-Reduction - Abstract
The directionality of the hole-transfer processes between DNA backbone and base was investigated by using phosphorodithioate [P(S- )=S] components. ESR spectroscopy in homogeneous frozen aqueous solutions and pulse radiolysis in aqueous solution at ambient temperature confirmed initial formation of G.+ -P(S- )=S. The ionization potential of G-P(S- )=S was calculated to be slightly lower than that of guanine in 5'-dGMP. Subsequent thermally activated hole transfer from G.+ to P(S- )=S led to dithiyl radical (P-2S. ) formation on the μs timescale. In parallel, ESR spectroscopy, pulse radiolysis, and density functional theory (DFT) calculations confirmed P-2S. formation in an abasic phosphorodithioate model compound. ESR investigations at low temperatures and higher G-P(S- )=S concentrations showed a bimolecular conversion of P-2S. to the σ2 -σ*1 -bonded dimer anion radical [-P-2S - . 2S-P-]- [ΔG (150 K, DFT)=-7.2 kcal mol-1 ]. However, [-P-2S - . 2S-P-]- formation was not observed by pulse radiolysis [ΔG° (298 K, DFT)=-1.4 kcal mol-1 ]. Neither P-2S. nor [-P-2S - . 2S-P-]- oxidized guanine base; only base-to-backbone hole transfer occurs in phosphorodithioate.
- Published
- 2020
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