The effects of ionizing radiation on DNA: the role of thiols as radioprotectors
Autor: | Abbas Pezeshk |
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Rok vydání: | 2003 |
Předmět: |
Free Radicals
DNA damage Radical Radiation-Protective Agents DNA Solutions Photochemistry General Biochemistry Genetics and Molecular Biology Ionizing radiation law.invention chemistry.chemical_compound law Radiation Ionizing Radiation damage Animals Sulfhydryl Compounds General Pharmacology Toxicology and Pharmaceutics Electron paramagnetic resonance Electron Spin Resonance Spectroscopy Tiopronin General Medicine DNA Thymine Cold Temperature chemistry Cattle DNA Damage |
Zdroj: | Life sciences. 74(19) |
ISSN: | 0024-3205 |
Popis: | Electron loss from N-(2-mercaptopropionyl) glycine (PSH) gave an EPR detectable radical anion, PS-.SP(-). When the PSH derivative was frozen in aqueous DNA solutions to 77 K and exposed to ionizing radiation, normal damage to the DNA was detected by EPR spectroscopy. However, on annealing above 77 K, central EPR features for the DNA base radical cations and anions gave central features assigned to PS-.SP(-) sigma*-radical anions, together with outer features for 5-6-dihydro-5-thymyl radicals, TH.. It is proposed that on freezing, the PSH molecules are constrained into a glassy region around the DNA, and that, on annealing, electron donation gives PS. radicals, with loss of quanine radical-cations, G(.+). The PS. radicals were not detectable, but on reaction with another PSH molecule, gave good EPR spectra for PS-.SP(-) radical-anions. These results indicate that PSH had little effect on the yield of the other base radicals C(.-)/T(.-). Also, growth of TH. radicals, formed from protonated thymine radical-anions, T(.-), were detected. We conclude that the primary effect of PSH is to capture the G(.+) centers, and thus could either prevent or repair radiation damage to DNA. |
Databáze: | OpenAIRE |
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