The reduction of nucleotides by ionizing radiation: Uridine 5′ phosphate and cytidine 3′ phosphate

Anions formed by the addition of an electron to the uracil base were observed in single crystals of the barium salt of uridine 5′ phosphate x-irradiated at 4.2 °K. The hyperfine coupling tensor for the C6–H proton was deduced from ENDOR measurements; the principal values are −59.12, −32.92, and −16.24 MHz. Similar measurements were made on single crystals of cytidine 3′ phosphate. The principal values for the C6–H proton hyperfine coupling in the anion formed on the cytosine base are −59.26, −33.98, and −14.68 MHz.