Reactions of OH· and Br2̇ radicals with glutathione. A radiolysis study

Abstract

Interactions of OH^· and Br_{$\text{2}\text{̇}$}$$ radicals with glutathione (GSH) have been studied in buffered neutral aqueous solutions using γ and pulse radiolysis. In steady state radiolysis, initial G values of GSH loss and formation of GSSG have been measured for GSH concentrations ranging between 5 x 10⁻⁵ and 5 x 10⁻³ mol dm⁻³. In pulse radiolysis experiments the absorption spectra and the kinetics of transients formed by the action of OH^· radicals have been determined.

It has been found that the bromide radical anion reacts with glutathione, producing quantitatively GSSG with a G value of 2.9×10⁻⁷ molJ⁻¹. It is not the same for OH^· radicals which show a non stoichiometric oxidation of thiol group of glutathione. The OH^·-induced oxidation of glutathione in neutral aqueous solution by pulse radiolysis has been found to produce not only the sulphur-centered radical (GS^· and GSSG∸) but at least one other alkyl radical.