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.