DNA Nucleobase under Ionizing Radiation: Unexpected Proton Transfer by Thymine Cation in Water Nanodroplets |
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Authors: | Dr Abderrahmane Semmeq Dr Michael Badawi Prof Abdellatif Hasnaoui Prof Said Ouaskit Dr Antonio Monari |
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Institution: | 1. Université de Lorraine and CNRS, LPCT UMR 7019, 54000 Nancy, France;2. LS3M, Faculté Polydisicplinaire-Khouribga, University Sultan Moulay Slimane of Beni Mellal, B.P 145, 25000 Khouribga, Morocco;3. Laboratoire de Physique de la Matière Condensée LPMC Faculté des, Sciences Ben M'sik, University Hassan II of Casablanca, BP 7955 Av. Driss El Harti, Sidi Othmane, 20000 Casablanca, Morocco |
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Abstract: | The effect of ionizing radiation on DNA constituents is a widely studied fundamental process using experimental and computational techniques. In particular, radiation effects on nucleobases are usually tackled by mass spectrometry in which the nucleobase is embedded in a water nanodroplet. Here, we present a multiscale theoretical study revealing the effects and the dynamics of water droplets towards neutral and ionized thymine. In particular, by using both hybrid quantum mechanics/molecular mechanics and full ab initio molecular dynamics, we reveal an unexpected proton transfer from thymine cation to a nearby water molecule. This leads to the formation of a neutral radical thymine and a Zundel structure, while the hydrated proton localizes at the interface between the deprotonated thymine and the water droplet. This observation opens entirely novel perspectives concerning the reactivity and further fragmentation of ionized nucleobases. |
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Keywords: | ab initio calculations hydrogen bonds molecular dynamics nucleobases proton transport water chemistry |
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