Figure 1.

A portion of the glutathione metabolic network showing the reaction of cysteine (cys) and glutamate (glu) to form γ-glutamylcysteine (γ-glu-cys) in a reaction catalyzed by glutamyl cysteine ligase (GCL). Glutathione can act by feedback inhibition to slow GCL activity. The second step adds glycine (gly) in a reaction catalyzed by glutathione synthetase (GS) to form glutathione (GSH). Under oxidative stress GSH can be oxidized to its disulfide (GSSG) which can be reduced via glutathione reductase (GR) back to GSH. Glutathione can react spontaneously with monobromobimane (mBBr) or via an enzyme catalyzed reaction to form the glutathione-bimane conjugate (GS-bim) which may be extruded from the cell by the multi-drug resistance related protein (MRP).