Determination of Bromide Production in Radiolysis of Nucleobases, Nucleosides, and Nucleotides Using HPLC

Abstract

Determination of the formation of bromide ions in intermolecular electron transfer in 5-bromouracil (BrUr) and its nucleoside and nucleotide derivatives with nucleobases, nucleosides, and nucleotides was carried out with high performance liquid chromatography (HPLC). Initial electron attachment, at high concentration of nucleobases, nucleosides, or nucleotides, is mainly on these molecules; intermolecular electron transfer then occurs between theses molecules and BrUr and the derivatives. The elimination of bromide ions from BrUr and the derivatives then follows. It is concluded that in neutral and basic solution (pH 6 to 10) there is a significant electron transfer from thymine (T), uracil (Ur), thymidine (dT), 2′-deoxyuridine (dU), or 2′-deoxyuridine-5′-monophosphate (dUMP) to BrUr and the derivatives. For example, at a concentration ratio of BrUr and T of 1 : 100, the yield of bromide ions is about 1.6, amounting to 59% of hydrated electron (e^{aq .}) yield in the radiolysis, in which the pseudo-first-order rate constants predict a bromide yield of less than 0.03.