ESR and ENDOR Study of Adenosine Single Crystals X-Irradiated at 10 K

Single crystals of adenosine were X-irradiated at 10 K and investigated between 10 and 300 K using K-band ESR and ENDOR spectroscopy. Two free radicals were analyzed. Radical I exhibits small hyperfine couplings to the C8-H, C2-H, and a N3-H protons, and was identified as the N3 protonated base anio...

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Bibliographic Details
Published in:Radiation research 1989-03, Vol.117 (3), p.367-378
Main Authors: Close, David M., Nelson, William H.
Format: Article
Language:English
Subjects:
Adenosine - radiation effects
Amino radical
Anions
Biological and medical sciences
Biological effects of radiation
Crystals
Electron paramagnetic resonance
Electron Spin Resonance Spectroscopy
Free Radicals
Freezing
Fundamental and applied biological sciences. Psychology
Ionizing radiations
Molecules
Nuclear Physics
Purines
Single crystals
Space life sciences
Sugars
Tensors
Tissues, organs and organisms biophysics
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Summary:Single crystals of adenosine were X-irradiated at 10 K and investigated between 10 and 300 K using K-band ESR and ENDOR spectroscopy. Two free radicals were analyzed. Radical I exhibits small hyperfine couplings to the C8-H, C2-H, and a N3-H protons, and was identified as the N3 protonated base anion radical. Radical II exhibits small hyperfine couplings to a C8-H and an exocyclic - N10-H proton. It is suggested that this is therefore the N10 deprotonated base cation radical. Enough data were not available to analyze a third primary radical believed to be located on the ribose moiety. Upon warming Radical I decays at ca. 40 K with no apparent successor. Likewise, no successor was identified for Radical II, which decays at ca. 100 K. At ca. 200 K there is ESR evidence for the C2 and C8 H-addition radicals. Their precursors have not been identified.
ISSN:0033-7587
1938-5404
DOI:10.2307/3577344