60Co γ radiolysis of reduced glutathione in aerated solutions at pH values between 1–7.0

Abstract

G-values for the formation of oxidised glutathione (GuS—SGu), glutathione sulphinic acid (GuSO2H), γ-glutamylalanylglycine (GuH), γ-glutamylserylglycine (GuOH), and hydrogen peroxide and G(—GuSH) have been estimated in the γ-radiolysis of aerated reduced glutathione solutions at pH values between 1–7.3. The results show excellent material balance for the radiolytic amino products. Oxygen is necessary for the production of both glutathione sulphinic acid and γ-glutamylserylglycine in the radiolysis of glutathione. Product yields increase with increasing GuSH concentration and reflect the occurrence of a small chain reaction. Although the spectrum of amino products is identical to the corresponding products from cysteine radiolysis under similar conditions, their yields are very much different. It is significant, that there is no evidence for the scission of the peptide chain, at any of the GuSH concentrations and pH's; thus the —SH group of glutathione is the site of attack of the primary species.A reaction mechanism, which explains most of the experimental results has been put forward. A rate expression for G(—GuSH) has been evaluated and it is found that the experimental and calculated G(—GuSH) are in good agreement.