Glutathione-glutaredoxin redox reaction (WP392)

The tripeptide glutathione (GSH: L-γ-glutamyl-L-cysteinylglycine) is a prevalent intracellular thiol that is able to act as a cellular redox buffer due to its low redox potential. GSH is involved in many biological processes including: protein and DNA synthesis; amino acid transport; enzyme regulation; protection of cells against reactive oxygen compounds and free radicals, xenobiotics and heavy metals. GSH can also be used as a source of sulfur and cysteine. Reactive oxygen species (ROS) such as hydrogen peroxide and alkylperoxides produced by various metabolic processes can cause irreversible oxidative damage to the cell if they are not rapidly detoxified by antioxidant defenses. The redox-active sulphydryl group of GSH can protect cells from ROS by directly scavenging free radicals and acting as a cofactor for antioxidant enzymes such as glutathione peroxidases (Gpx1p, Gpx2p and Gpx3p). Glutathione oxidized in this manner forms glutathione disulphide (GSSG), which is recycled back to GSH by the enzyme glutathione reductase (Glr1p). Some glutathione peroxidases such as Gpx2p, however, may be re-reduced by the thioredoxin system rather than the glutathione-glutaredoxin system. GSH also protects the cell from xenobiotics and heavy metals through the formation of GSH S-conjugates and their subsequent export in the vacuole or directly out of the cell. Some xenobiotics can react spontaneously with the thiol moiety of GSH to form GSH S-conjugates, while others react through GSH S-transferases (GST). Two GSTs (Gtt1p and Gtt2p) were identified in yeast and shown to have GST activity with 1-chloro-2,4-dintrobenzene. In yeast the GSH conjugates are transported to the vacuole by the GS-X pump Ycf1p or directly out of the cell by other GS-X pumps. Description from https://pathway.yeastgenome.org/.

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