Free Radicals from Polycrystalline Pyrimidines and Purines upon Heavy Ion Bombardment at Low Temperatures: An Electron Spin Resonance Study
| Autor: | A. Schaefer, J. Hüttermann, G. Kraft |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Adenosine
Free Radicals Radiological and Ultrasound Technology Pyrimidine Radical Electron Spin Resonance Spectroscopy Photochemistry Thymine law.invention Ion Cytosine chemistry.chemical_compound chemistry law Freezing Radiology Nuclear Medicine and imaging Singlet state Particle Accelerators Spectroscopy Electron paramagnetic resonance Nuclear chemistry |
| Zdroj: | International Journal of Radiation Biology. 63:139-149 |
| ISSN: | 1362-3095 0955-3002 |
| DOI: | 10.1080/09553009314550191 |
| Popis: | The formation of free radicals in polycrystalline samples of the DNA constituents thymine, cytosine, and adenosine after bombardment with heavy ions at about 100 K was investigated by electron spin resonance (ESR) spectroscopy. Spectra were observed at 77 K after irradiation at 100 K, upon annealing to 300 K and after storage at 300 K. Individual radical patterns were isolated from the spectra by computer manipulation and assigned to structures by powder-simulations based on literature data. The spectra of thymine contain an allyl radical, the octet pattern of the 5-thymyl radical and contributions of the 6-yl radical formed by net hydrogen gain at carbon C5. The latter species is also present in cytosine which in addition displays the pattern due to H-addition at the carboxyl oxygen C2. Adenosine exhibits two H-addition radicals, one at C2, the other at C8. Additionally, the spectra of all DNA subunits studied contain as a radical component a Gaussian singlet of about 0.9 mT line width. The spectra obtained at low temperature already contain the secondary radicals but exhibit a large linewidth. This feature is attributed to dipolar coupling caused by radicals in close proximity. |
| Databáze: | OpenAIRE |
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