GSH/GSSG Ratio Assay

Glutathione is a tripeptide (g-glutamylcysteinylglycine) and exists in reduced (GSH) and oxidized (GSSG) states. Glutathione peroxidase catalyzes the formation of GSSG from GSH, and glutathione reductase recycles GSSG to GSH. With increased levels of oxidative stress, intracellular GSSG will accumulate, and the GSH/GSSG ratio will decrease. Therefore, the determination of the GSH/GSSG ratio is a useful indicator of oxidative stress in cells and tissues. This colorimetric assay is based on the reaction between 5', 5'-Dithiobis 2- nitrobenzoic acid (DTNB) and GSH to form TNB, which exhibits maximum absorbance at 412 nm. The intensity of the absorbance is proportional to the GSH level in the sample.