ESR Study of the Sugar Radical in Irradiated Deoxyadenosine

Single crystals of deoxyadenosine monohydrate grown from H₂O and D₂O solutions have been x irradiated and studied by electron spin resonance techniques at room temperature. The results show an isotropic coupling of 7 ± 1.0 G to one $\beta$ proton and an anisotropic coupling of an $\alpha$ proton with principal values − 22.6 ± 0.5 G, − 16.4 ± 0.5 G, and − 5 ± 0.5 G. The spin density on the carbon atom ${\mathrm{(C}}_5\mathrm{\prime )}$ , calculated from the above results, is 0.64. The g‐tensor principal values are 2.0029 ± 0.0002, 2.0052 ± 0.0002, and 2.0075 ± 0.0002. These data are consistent with a radical formed in the deoxyribose sugar group as a result of hydrogen abstraction at the $C_5\prime$ position.