Electron-induced dissociation of the potential radiosensitizer 5-selenocyanato-2′-deoxyuridine
Rebecca Meißner , Samanta Makurat , Witold Kozak , Paulo Limão-Vieira , Janusz Rak , Stephan Denifl
Abstract5-Selenocyanato-2′-deoxyuridine (SeCNdU) is a recently proposed radiosensitizer based on 2′-deoxyuridine (dU) with the electron-affinic selenocyanato (−SeCN) side group attached at the C5 position of uracil. Since electron interaction processes may be an important source of DNA damage by ionizing radiation, we have studied low-energy dissociative electron attachment to SeCNdU in the gas phase. Negative ion formation has been obtained by means of mass spectrometry, where a rich fragmentation pattern is observed even at ∼0 eV. The reaction pathways exhibiting the highest ion yields are C4N2O2H2Se•− and CN−, both involving a cleavage of the Se−CN bond. The heaviest fragment anion observed is C9N2O5H10Se•−, where besides the charged species, the hydrogen and cyano radicals are also formed. Further decomposition channels also yield the highly reactive hydroxyl radical, which possesses a high DNA damage potential. All observed channels have experimentally determined onsets at 0 eV, which are supported by calculations performed at the M06-2X/aug-ccpVTZ level. The calculations comprise the thermochemical thresholds at standard and experimental (428.15 K, 3 × 10−11 atm) conditions together with the adiabatic electron affinities. The present study shows that low-energy electrons very effectively decompose SeCNdU upon attachment of thermal electrons, producing a large variety of charged fragments and radicals.
|Journal series||Journal of Physical Chemistry B, ISSN 1520-6106, (A 30 pkt)|
|Publication size in sheets||0.5|
|Score|| = 30.0, ArticleFromJournal|
= 30.0, ArticleFromJournal
|Publication indicators||: 2017 = 3.146 (2) - 2017=3.101 (5)|
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