Fragmentation reactions of radicals formed from sugar phosphates and the hydroxyl radical: an investigation by electron spin resonance spectroscopy and pulse radiolysis

Abstract

E.s.r. spectroscopy has been employed with the radiomimetic Ti^III–H₂O₂ couple and an aqueous flow system to study the reactions between the hydroxyl radical and some sugar phosphates. For the furanose compounds hydrogen-atom abstraction from the carbon adjacent to the alicyclic oxygen is preferred: subsequent phosphate loss occurs when the radical centre is adjacent to the carbon bound to phosphate, and, as judged by steady-state e.s.r. and time-resolved pulse-radiolysis experiments, is faster for radicals from ribose 5-phosphate, α-D-glucose 1-phosphate, and glycerol phosphates (k ca. 10⁴s^–1) than for fructose phosphates (k ca. 10²–10³ s^–1).