Electron interactions with aminomethane sulphonic acid and taurine as probed by experimental and theoretical methods

Autor: Meneses, G., Sanchez, de A., Bettega, Márcio H.F., Kopyra, J., Krasuska, J., García, Gustavo, Ferreira da Silva, F., Limão-Vieira, P.
Rok vydání: 2015
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
instname
Popis: POSMOL 2015, 17-20 July 2015, Lisboa, Portugal; conferencia invitada; http://eventos.fct.unl.pt/posmol2015/
Seminal studies of Sanche and co-workers revealed the capability of secondary electrons, with energies ¿ 20 eV, to induce single and double strand breaks to DNA [1]. Given the resonant-like behavior of the quantum yield profiles for induction of Double Strand Breaks (DSBs), Single Strand Breaks (SSBs) and loss of the supercoiled DNA form, several theoretical and experimental studies concerning dissociative electron attachment (DEA) to biological relevant molecules in the gas-phase have been performed. In the last few years, special attention has also been given to electron transfer processes in potassium-(bio)molecule collisions [2]. This dissociation mechanism represents an alternative approach to mimic electron driven dissociation reactions within the physiological medium. The scientific community has become more aware of the importance of studies on electron driven reactions in sulphur containing biomolecules, in order to further investigate the role of sulphur in redox reactions. Recent studies on DEA to sulphur containing analogues of thymine and uracil show that the main fragmentation is assigned to sulphur containing anions [3,4]. Here we give the first set of comprehensive experimental and theoretical analysis on the electron interactions with aminomethane sulphonic acid and taurine, two sulphur containing compounds. Taurine is an amino acid comprising several physiological functions. Aminomethane sulfonic acid represents the taurine molecule with one less CH2 group in the carbon chain. The experimental results have been obtained through DEA and electron transfer, from the Siedlce and Lisbon laboratories with negative ions detected by quadrupole and time-of-flight mass spectrometry. From the ionic yields we note a rich fragmentation pattern where the parent anion was not observed. The anionic yields show evidence of resonance-like features with main contributions centered at ~4.7 eV. These resonances are consistent with theoretical predictions obtained through Schwinger multichannel implemented with pseudopotentials, where the data from the Brazilian group indicates a ¿* a shape resonance around 4.75 eV and suggests a ¿* shape resonance around the same energy. Results of electron transfer to taurine reveal that this mechanism may promote further dissociation of the molecule when compared to free electron attachment.
Databáze: OpenAIRE
Externí odkaz: