Proton irradiation of DNA nucleosides in the gas phase

摘要: The four DNA nucleosides guanosine, adenosine, cytidine and thymidine have been produced in the gas phase by a laser thermal desorption source, irradiated beam of protons with 5 keV kinetic energy. molecular ions as well energetic neutrals formed analyzed mass spectrometry order to shed light on ionization fragmentation processes triggered proton collision. A range 8–20 eV has estimated for binding energy electron captured proton. Glycosidic bond cleavage between base sugar observed high probability all nucleosides, resulting predominantly intact but not where are dominant. This behavior is influenced energies nucleobases (G < C T), which seems determine localization charge following initial ionization. transfer process can also be inferred from production protonated ions, similar dependence potential, although affinity might play role. Other dissociation pathways identified, including further moieties respectively, partial breakup ring without glycosidic mainly adenosine cytidine. These results show that irradiation important determining channels isolated could turn influence direct radiation damage DNA.