ENDOR study of the stable radicals in γ- or X-ray-irradiated single crystal of deoxycytidine-5'-phosphate

The room-temperature stable radicals formed by γ-or X-ray-irradiation of deoxycytidine-5'-phosphate were studied by EPR and ENDOR spectroscopy. While EPR was of limited use because of the complexity of the spectra, the ENDOR spectroscopic analysis showed the presence of at least three types of radicals, two of which were analyzed in greater detail. One of the radicals is formed from the primary radical, analyzed earlier, by the decomposition of the furanose ring. The observed couplings correspond to the Hsub((5')), H'sub((5')), and Hsub((4')) protons. In the second radical the unpaired electron is located mostly on the other side of the deoxyribose moiety, on Csub((1')). The relatively isotropic hyperfine couplings of the two β protons are shown to correspond to Hsub((2')) and H'sub((2')). (author)