Studies on the reaction of ferric iron with glutathione and some related thiols. Part III. A study of the iron catalyzed oxidation of glutathione by molecular oxygen

Abstract

Since the discovery of glutathione (GSH) by Hopkins and the recognition that this thiol could play a role in electron transfer [l-3], there have been many studies of the autocatalytic oxidation of this biologically important compound [l-4] and other related thiols [S-11]. The very low auto-oxidation of cysteine is accelerated by small quantities of iron [5]. And it is interesting to note that iron is always associated with cysteine and glutathione [1, 2, 5, 6, 12, 131 in biological systems. Warburg and Sauma [6] demonstrated that cysteine in aqueous solutions was not oxidized by atmospheric oxygen in the absence of heavy metals and Harrison [2] showed that this was true also for glutathione. The effects of traces of heavy metals like Cu2+ and Fe3+ on the oxidation of cysteine, glutathione, and other thiols have been reported in other studies [ 1,3] . Once the need for the metal catalyst was confirmed [l] , attempts were made to derive a mecha- *Authors to whom correspondence should be addressed. 0020-1693/83/$3.00 nism for this catalytic process [7-l 1, 14, 151. These were based on reduction potentials, reduction capacity and kinetic data