Glutatiooni

Glutatiooni, also known as glutathione in English, is a tripeptide composed of the amino acids glutamate, cysteine, and glycine. It exists predominantly in its reduced form (GSH) and can be oxidized to form the disulfide (glutathione disulfide, GSSG). It is the most abundant intracellular thiol and a central redox mediator in cells.

Biosynthesis occurs in the cytosol in two ATP-dependent steps. First, the enzyme gamma-glutamylcysteine synthetase (glutamate cysteine ligase) condenses glutamate and cysteine to form gamma-glutamylcysteine. Second, glutathione synthetase adds glycine to produce glutathione. GSH can be recycled from GSSG by glutathione reductase using NADPH.

Functions of glutatiooni include redox buffering, detoxification via conjugation with electrophilic compounds (catalyzed by glutathione S-transferases), maintenance of cellular thiol status through S-glutathionylation, and participation in various metabolic and immune processes. It is present in nearly all cells, with particularly high concentrations in the liver, kidneys, and erythrocytes.

Physiological and clinical relevance: intracellular GSH levels reflect cellular redox status, and depletion is associated with oxidative stress and various disease states. Levels can be influenced by aging, toxins, and disease. Some therapies aim to augment glutathione via precursor supplements such as N-acetylcysteine; direct oral glutathione supplementation has variable bioavailability.

In research, the ratio of GSH to GSSG is used as an index of oxidative stress, and assays commonly measure total glutathione, reduced glutathione, and oxidized glutathione in biological samples.