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 anion radical. Radical II exhibits small hyperfine couplings to a C8-H and an exocyclic - N10-H proton. It is suggested that this is before 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.
Close, D. M.; and Nelson, W. H.. 1989. ESR and ENDOR Study of Adenosine Single Crystals X-Irradiated at 10 K. Radiation Research. Vol.117(3). 367-378. https://doi.org/10.2307/3577344 PMID: 2538857 ISSN: 0033-7587