Mechanism and relevance of glutathione mutagenicity

The ubiquitous tripeptide glutathione (GSH) has previously been shown to be mutagenic to Salmonella typhimurium TA100 when incubated with kidney subcellular fractions at physiological concentrations (Glatt et al., 1983). Here we report that the mutagenic effect of GSH can be inhibited by the use of the gamma-glutamyl-transpeptidase (gamma-GT) inhibitor anthglutin and by the metal chelators bathocuproine, EDTA and diethyldithiocarbamate. As the chelating agents did not inhibit gamma-GT activity this suggested that the mechanism underlying the mutagenic effect of GSH was at least a two-step process, dependent upon the cleavage of GSH by gamma-GT and the presence of either free transition metals or those contained in enzymes such as glutathione oxidase. As gamma-GT is located on the outer surface of kidney tubule cells and is therefore exposed to relatively low concentrations of GSH, and the precise physiological control of levels of transition metals, this mechanism is unlikely to occur in vivo.