OH-induced free radicals in 3'-UMP and poly(U): spin-trapping and radical chromatography.
Characterization of OH-induced free radicals using 3'-UMP and poly(U) was performed by a method combining spin-trapping and radical chromatography. A N2O-saturated aqueous solution containing 3'-UMP and 2-methyl-2-nitrosopropane as a spin-trap was X-irradiated. The spin adducts generated by the reactions of OH radicals with 3'-UMP were separated by paired-ion HPLC and the separated spin adducts were identified by ESR spectroscopy. In the case of poly(U), the spin adducts were digested to oligonucleotides with RNase A and then separated and identified in the same manner as 3'-UMP. The free radicals observed for poly(U) were identical to those for 3'-UMP. The 5-yl radical and the 6-yl radical were identified as precursors of various oxidized products of the base moiety, and the 4'-yl radical and 5'-yl radical, formed by H-abstraction at the C-4' and C-5' positions of the sugar moieties, respectively, were identified as precursors of strand breaks. The 1'-yl radical, produced by H-abstraction at the C-1' position of the sugar moiety, was also identified. From the similarity of the free radicals of 3'-UMP and poly(U), it is suggested that the reactivities of OH radicals with nucleotides are identical to those in polynucleotides.
Inanami
O
O
Department of Radiation Biology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Kuwabara
M
M
Sato
F
F
D002851:Chromatography, High Pressure Liquid; D005609:Free Radicals; D006878:Hydroxides; D017665:Hydroxyl Radical; D009603:Nitroso Compounds; D011072:Poly U; D013113:Spin Labels; D014500:Uracil Nucleotides; D014542:Uridine Monophosphate
D005609:Free Radicals; D006878:Hydroxides; D009603:Nitroso Compounds; D013113:Spin Labels; D014500:Uracil Nucleotides; D011072:Poly U; D017665:Hydroxyl Radical; D014542:Uridine Monophosphate; C034526:tert-nitrosobutane