title: Reactions of the hydrated electron with pyrimidine nucleosides halogenated at the sugar moiety: e.s.r. and spin-trapping with 2-methyl-2-nitrosopropane.
abstract: Free radicals produced by the reactions of hydrated electrons with pyrimidine nucleosides halogenated at the sugar moiety (2'-chloro-2'-deoxyuridine and 2'-chlorothymidine) were studied by e.s.r. and spin-trapping. 2-Methyl-2-nitrosopropane was used as the spin-trap. The usual spin-trapping technique was extended to frozen and deoxygenated systems to avoid contamination of the trapped radicals with side-products by spin-trapping 2-methyl-2-nitrosopropane itself. When this method was applied to 2'-chloro-2'-deoxyuridine, a free radical at the C-2' position of the sugar moiety was spin-trapped together with a free radical at the C-5 position of the base moiety. This indicates that hydrated electrons both add to the base moiety and eliminate halogen anions from the halogenated sugar moiety. In the case of 2'-chlorothymidine, however, only a free radical attributed to H-addition at the C-6 position of the thymine base was observed. No radicals produced by the reaction of hydrated electrons with the halogenated sugar could be spin-trapped.
mesh_terms: D003857:Deoxyuridine / Q000031:analogs & derivatives*; D004578:Electron Spin Resonance Spectroscopy; D009603:Nitroso Compounds; D013113:Spin Labels; D013936:Thymidine / Q000031:analogs & derivatives*
chemical_list: D009603:Nitroso Compounds; D013113:Spin Labels; C037291:2'-chloro-2'-deoxyuridine; C038765:2'-chlorothymidine; C034526:tert-nitrosobutane; D013936:Thymidine; D003857:Deoxyuridine