On the Mechanism of BUdR Sensitization: A Pulse Radiolysis Study of One Electron Transfe in Nucleic-acid Derivatives

SummaryStationary-state and pulse-radiolysis competition experiments are described, which provide a basis for the study of one-electron transfer from free radical ions derived from various pyrimidine and purine derivatives to their brominated analogues.Bimolecular rate constants in the range 0·3–1·1 × 109 M−1 sec−1 are reported for electron transfer. Reactions involving only the free bases are somewhat faster than those involving the corresponding nucleosides. Transfer from the cytosine electron-adduct to bromouracil is too slow to be observed by this pulse-radiolysis competition technique. The results are discussed in terms of current mechanisms of radiosensitization.