title: Electron stimulated desorption of anions from native and brominated single stranded oligonucleotide trimers.
abstract: We measured the low energy electron stimulated desorption (ESD) of anions from thin films of native (TXT) and bromine monosubstituted (TBrXT) oligonucleotide trimers deposited on a gold surface (T = thymidine, X = T, deoxycytidine (C), deoxyadenosine (A) or deoxyguanosine (G), Br = bromine). The desorption of H(-), CH(3)(-)/NH(-), O(-)/NH(2)(-), OH(-), CN(-), and Br(-) was induced by 0 to 20 eV electrons. Dissociative electron attachment, below 12 eV, and dipolar dissociation, above 12 eV, are responsible for the formation of these anions. The comparison of the results obtained for the native and brominated trimers suggests that the main pathways of TBrXT degradation correspond to the release of the hydride and bromide anions. Significantly, the presence of bromine in oligonucleotide trimers blocks the electron-induced degradation of nuclobases as evidenced by a dramatic decrease in CN(-) desorption. An increase in the yields of OH(-) is also observed. The debromination yield of particular oligonucleotides diminishes in the following order: BrdU > BrdA > BrdG > BrdC. Based on these results, 5-bromo-2(')-deoxyuridine appears to be the best radiosensitizer among the studied bromonucleosides.
authors.affiliation: Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Polska
authors.forename: Janusz
authors.initials: J
authors.lastname: Rak
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Bass
authors.forename: Pierre
authors.initials: P
authors.lastname: Cloutier
authors.forename: Léon
authors.initials: L
authors.lastname: Sanche
mesh_terms: D000327:Adsorption; D000838:Anions / Q000737:chemistry*; D004583:Electrons; D054879:Halogenation; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry*; D011838:Radiation-Sensitizing Agents
chemical_list: D000838:Anions; D009841:Oligonucleotides; D011838:Radiation-Sensitizing Agents