Radical Formation in X-Irradiated Single Crystals of Guanine Hydrochloride Monohydrate. III. Secondary Radicals and Reaction Mechanisms
Document Type
Article
Publication Date
1-1-1988
Description
This work involves an ESR and ENDOR study of the reactions of the three primary radicals observed in X-irradiated single crystals of guanine hydrochloride monohydrate. Radical I, the O6-protonated anion, decays at 250 K yielding a stable room temperature radical (Radical V). The experimental evidence indicates that Radical V results from H-abstraction at N9 of a neighboring molecule. Radical II, the N7-deprotonated cation, decays at 60 K with no detectable successor. Radical IV, a C8 H-addition radical, is formed when an imidazole ring-opened radical (Radical III) decays at 150 K. The added H-atom was found to be from an easily exchangeable source. It is proposed that Radical III decays by the formation of a diamagnetic formamida molecule and an H-atom. It is important to note that Radical IV, the purine H-addition radical, is the result of basic oxidation events. Previous assumptions have been that purine H-addition radicals result either from reduction, i.e., protonation of a pristine anion, or from the 'excitation pathway', by addition of H-atoms dissociated from superexcited purine bases.
Citation Information
Close, D. M.; Sagstuen, E.; and Nelson, W. H.. 1988. Radical Formation in X-Irradiated Single Crystals of Guanine Hydrochloride Monohydrate. III. Secondary Radicals and Reaction Mechanisms. Radiation Research. Vol.116(3). 379-392. https://doi.org/10.2307/3577382 PMID: 2849779 ISSN: 0033-7587