Electron-Induced Dissociation of the Potential Radiosensitizer 5-Selenocyanato-2′-deoxyuridine

Rebecca Meißner, Samanta Makurat, Witold Kozak, Paulo Limão-Vieira, Janusz Rak, Stephan Denifl

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

5-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 C 4 N 2 O 2 H 2 Se •- and CN - , both involving a cleavage of the Se-CN bond. The heaviest fragment anion observed is C 9 N 2 O 5 H 10 Se •- , 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-cc-pVTZ 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.

Original languageEnglish
Pages (from-to)1274-1282
Number of pages9
JournalJournal of Physical Chemistry B
Volume123
Issue number6
DOIs
Publication statusPublished - 14 Feb 2019

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