OH-induced free radicals in purine nucleosides and their homopolymers: e.s.r. and spin-trapping with 2-methyl-2-nitrosopropane.
Free radicals produced by X-irradiation of N2O-saturated aqueous solutions of purine nucleosides (2'-deoxyadenosine, adenosine, 2'-deoxyguanosine, 3'-deoxyadenosine, guanosine and inosine) and the corresponding homopolymers (poly A and poly I) have been investigated by the technique of spin-trapping and e.s.r. spectroscopy. 2-Methyl-2-nitrosopropane was used as a spin-trap. For 2'-deoxyadenosine and 2'-deoxyguanosine, the resulting spin-adducts were separated by Bio-Gel P-2 column chromatography and analysed by e.s.r. spectroscopy. For homopolymers, e.s.r. spectra were recorded at 50 degrees C after enzymatic digestion to obtain signals with narrower line width. The e.s.r. signal consisting of only a primary triplet without further splittings, which is consistent with assignment to the trapping of an H-abstraction radical at the C4' position of the sugar moiety, was observed in all cases. For 2'-deoxyguanosine an e.s.r. signal consisting of a secondary triplet was observed. Examinations using other spin-trapping reagents such as PBN, 4-PyOBN and DMPO provided no positive evidence supporting the proposal that this was due to an alpha-nitrogen. The e.s.r. signal consisting of a secondary doublet which further splits into a doublet was observed for 2'-deoxyadenosine, adenosine, 3'-deoxyguanosine, 2'-deoxyguanosine, and inosine, and tentatively associated with a radical centered in the sugar moiety.
D000241:Adenosine; D002851:Chromatography, High Pressure Liquid; D003839:Deoxyadenosines; D003849:Deoxyguanosine; D004578:Electron Spin Resonance Spectroscopy; D006151:Guanosine; D006878:Hydroxides; D017665:Hydroxyl Radical; D007288:Inosine; D009603:Nitroso Compounds; D011061:Poly A / Q000528:radiation effects; D011069:Poly I / Q000528:radiation effects; D011684:Purine Nucleosides / Q000528:radiation effects
D003839:Deoxyadenosines; D006878:Hydroxides; D009603:Nitroso Compounds; D011684:Purine Nucleosides; D006151:Guanosine; D011061:Poly A; D011069:Poly I; D017665:Hydroxyl Radical; D007288:Inosine; D003849:Deoxyguanosine; C034526:tert-nitrosobutane; D000241:Adenosine