IntroductionThe radical ions of the DNA bases have recently been reported as the primary intermediates in the radiolysis of DNA . Graslund, Ehrenberg, Rupprecht and Strom (1971) report that the anionic radical in y-irradiated DNA is likely that of thymine (or cytosine) and the cationic radical is that of quanine (or cytosine) . For these results it is clear that investigations of the ion radicals of the individual DNA bases are of importance to the understanding of the effect of radiation on DNA.The cation and anion radicals of the pyrimidines, thymine and cytosine, have been investigated and their further reactions elucidated in a number of e.s .r . studies employing aqueous glasses (Holroyd and Glass 1968, Srinivasan, Singh and Gopal-Ayengar 1969, Lion and van De Vorst 1971, Sevilla, Van Paemel and Nichols 1972, Sevilla, Van Paemel and Zorman 1972 . The ion radicals of the purines have not been as thoroughly investigated partially due to the poor resolution found for their e .s .r . spectra. However Lion and van De Vorst report studies of the anion radicals in alkaline aqueous glasses at low temperatures . The anions are reported to undergo protonation reactions upon U .V.-irradiation . Both the anions and cations of the purines, adenine and quanine, have been reported in e .s .r . studies of yirradiated polycrystalline purines (Dertinger and Hartig 1972) . Only the g values are reported by Dertinger and Hartig due to poor resolution of the e .s .r . spectra .In this work we have investigated the cation and anion radicals of the purine DNA bases in neutral aqueous glasses . The purpose of this investigation was to determine the g values of the purine ion radicals for comparison to those found in polycrystalline purines and to investigate possible protonation reactions of the purine anions in a neutral aqueous medium .

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