Glutathione and glutathione biosynthesis enzymes (GSH/GCL)

Glutathione (GSH) is a vital tripeptide antioxidant composed of glutamate, cysteine, and glycine (PubChem CID 124886). Its synthesis is catalyzed by two main enzymes: glutamate-cysteine ligase (GCL), which is the rate-limiting step, and glutathione synthetase (GSS) (UniProt P48506, P48960). The cysteine residues within these enzymes are essential for their catalytic function, while the thiol group of the cysteine in GSH is the active site for redox reactions and detoxification (PMC4684116). This system plays a central role in maintaining cellular redox homeostasis and protecting cells from oxidative damage and xenobiotics. In oncology, elevated GSH levels are often associated with tumor progression and resistance to chemotherapy and radiation (PMC3549305). Consequently, inhibiting GCL with agents like buthionine sulfoximine (BSO) is a strategy to sensitize cancer cells to treatment (PubChem CID 5462564). Conversely, replenishing GSH using N-acetylcysteine (NAC) is a standard clinical intervention for acetaminophen overdose and other oxidative stress-related conditions (PubChem CID 12035). The reactivity of the cysteine thiol makes this pathway a significant target for electrophilic drugs and redox-modulating therapies.

Other names

Glutathione biosynthesis pathwayGlutamate-cysteine ligaseGlutathione synthetaseGamma-glutamyl cycleGSH system

Inhibition of glutamate-cysteine ligase to deplete glutathione levels; provision of cysteine precursors to enhance glutathione synthesis; direct conjugation with glutathione to facilitate detoxification or cause depletion; electrophilic modification of enzyme active-site cysteine residues.