While glutathione helps protect cells from free radical damage as an antioxidant, it can also covalently attach to proteins through its sulfhydryl moiety upon derivatization by reactive oxygen species (ROS). Glutathione protein adducts can therefore serve as a marker of oxidative stress.
The OxiSelect™ s-Glutathione Adduct Competitive ELISA Kit quantifies the glutathionylation of proteins in a standard 96-well plate. Protein standards and unknown samples are added to a plate coated with an s-Glutathione protein conjugate. A primary anti-s-glutathione antibody is added and competes for binding between the s-glutathione adduct in the sample and the s-glutathione adduct bound to the plate. High concentrations of s-glutathione adduct in samples leave little antibody to bind to the plate, resulting in a low OD. When little to no s-glutathione adduct appears in samples, most antibody binds to the plate resulting in a high signal.