Carbon-13 nuclear magnetic resonance investigations into the interactions of bisulfite with pyrimidine nucleosides and nucleotides

Abstract

13C NMR is utilized to demonstrate the attack of bisulfite anion on uridine, 5-fluorouridine and 5''-UMP. The attack produces a pair of diastereomeric adducts similar in structure to those seen in the uracil series. Intensity data from the equilibrium system give an estimate for the individual equilibrium constants. Thymidine and thymidine 5''-monophosphate show no evidence of nucleophilic attack by bisulfite. This evidence indicates that bisulfite addition to nucleosides and nucleotides models the enzymatic methylation of uridine by the enzyme thymidylate synthetase better than the uracil bisulfite system.