Role of GSH in Arsenic Reduction, Binding, and Methylation

Recent studies have shown that GSH reduces As to As MMA to MMA and DMA to DMA and forms the following complexes As GS)3, MMA (GS)2, and DMA (GS) (Scott et al. 1993 Delnomdedieu et al. 1994). Studies in Chinese hamster ovary (CHO) cells indicated that the cytotoxicity of As was inversely related to intracellular GSH concentration (Huang et al. 1993). In addition. As resistance in CHO cells has been associated with a high intracellular GSH concentration, elevated GSH-5-transferase activity, and increased efflux of As (Lee et al. 1989 Wang and Lee 1993). The relation between the possible roles of GSH in As-resistant CHO cells and mechanisms of As resistance in prokaryotes is discussed below. 

The methylation of As or MMA requires the presence of a normal intracellular (millimolar) concentration of GSH (Buchet and Lauwerys 1985). Methylation of arsenite or MMA did not occur in either rat or mouse liver or kidney homogenates without addition of GSH. Addition of GSH promoted both mono- and dimethylation in these homogenates. MMA 

---