United States Biological has improved the standard GSH/GSSG Assay Kit by using a new and improved GSH scavenger.||Reduced glutathione (GSH) is a tripeptide (gamma-glutamylcysteinylglycine) that contains a free thiol group. GSH is a major tissue antioxidant that provides reducing equivalents for the glutathione peroxidase (GPx) catalyzed reduction of lipid hydroperoxides to their corresponding alcohols and hydrogen peroxide to water:||H2O2 + 2GSH ---------> GSSG + 2H2O (catalyzed by GPx)||In the GPx catalyzed reaction, the formation of a disulfide bond between two GSH molecules gives rise to oxidized glutathione (GSSG). The enzyme glutathione reductase (GR) recycles GSSG to GSH with the simultaneous oxidation of beta-nicotinamide adenine dinucleotide phosphate (beta-NADPH):||GSSG + NADPH -----------> 2GSH + NADP+ (catalyzed by GR)||When cells are exposed to increased levels of oxidative stress, GSSG will accumulate and the ratio of GSH to GSSG will decrease. Therefore, the determination of the GSH/GSSG ratio and the quantification of GSSG are useful indicators of oxidative stress in cells and tissues.||Kit Components:|G8124-11A: Assay Buffer, 2X, 1x125ml. General buffer used to dilute samples and reagents|*G8124-11B: GSSG Standard (10uM), 1x2ml.|G8124-11C: Scavenger, 1x3ml. Thiol scavenger to keep GSSG in oxidized form.|G8124-11D: DTNB, 4x1vial. Lyophilized 5,5'-dithiobis-2-nitrobenzoic acid.|G8124-11E: MPA, 5%, 1x40ml. Metaphosphoric acid used to deproteinate samples.|*G8124-11F: Glutathione reductase, 1x130ul. Solution containing recombinant glutathione reductase.|*G8124-11G: NADPH, 4x1vial. Lyophilized beta-nicotinamide adenine dinucleotide phosphate.||Storage and Stability:|Store *G8124-11B, *G8124-11F and *G8124-11G at -20°C. Store other components at 4°C. Stable for 6 months after receipt. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.