Glutamylcysteine

Glutamylcysteine, also known as gamma-glutamylcysteine, is a dipeptide composed of glutamate and cysteine linked by a gamma-glutamyl bond. It is the first committed intermediate in the biosynthesis of glutathione (GSH), one of the body's major intracellular antioxidants.

Biosynthesis and role in metabolism: Gamma-glutamylcysteine is synthesized from glutamate and cysteine by the enzyme glutamate–cysteine ligase (gamma-glutamylcysteine synthetase) with ATP. This step is the rate-limiting step in glutathione production. Subsequently, glutathione synthetase adds glycine to gamma-glutamylcysteine to form glutathione. As the immediate precursor to GSH, the cellular concentration of gamma-glutamylcysteine is governed by the activities of these two enzymes and reflects the capacity for glutathione synthesis.

Physiological significance: Because glutathione plays a central role in detoxification and redox balance, gamma-glutamylcysteine levels indirectly inform on the cell’s ability to mount a glutathione response. Changes in its concentration can occur in conditions of oxidative stress, impaired enzyme function, or limited cysteine availability. It is primarily discussed in the context of glutathione biosynthesis rather than as a dietary supplement.

Additional notes: Gamma-glutamylcysteine is mostly discussed in biochemical and physiological contexts. It is not commonly marketed or used as a standalone supplement, and its clinical applications are primarily research-oriented, focusing on glutathione metabolism and related disorders.