title: Bond- and site-selective loss of H- from pyrimidine bases.
abstract: Electron attachment to gas phase thymine and uracil leads to H- loss within a broad and structured feature in the energy range between about 5 and 12 eV consisting of 4 overlapping resonances. By using thymine and uracil methylated at the N1 and N3 positions, respectively, and taking into account recent results from partly deuterated thymine, we find that by tuning the electron energy, H- loss turns out to be not only bond selective, i.e., (C-H) versus (N-H) bonds, but also site selective (N1 versus N3 site). Such a bond and site selectivity by energy has not been observed before in dissociative electron attachment. Implications for the mechanism of strand breaks observed in plasmid DNA are considered.
authors.affiliation: Institut für Ionenphysik and Center of Molecular Biosciences Innsbruck, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Ptasińska
authors.forename: Stephan
authors.initials: S
authors.lastname: Denifl
authors.forename: Verena
authors.initials: V
authors.lastname: Grill
authors.forename: Tilmann D
authors.initials: TD
authors.lastname: Märk
authors.forename: Eugen
authors.initials: E
authors.lastname: Illenberger
authors.forename: Paul
authors.initials: P
authors.lastname: Scheier
mesh_terms: D004247:DNA / Q000737:chemistry*; D004249:DNA Damage; D004583:Electrons; D006859:Hydrogen / Q000737:chemistry; D008745:Methylation; D010957:Plasmids / Q000737:chemistry; D013816:Thermodynamics; D013941:Thymine / Q000737:chemistry*; D014498:Uracil / Q000737:chemistry*
chemical_list: D014498:Uracil; D006859:Hydrogen; D004247:DNA; D013941:Thymine