What Is Glutathione?
Glutathione (GSH) is a tripeptide consisting of glutamic acid, cysteine, and glycine. The amino group of cysteine and the carboxy group of glutamic acid’s side chain form an amide bond. Oxidized glutathione (GSSG) is formed when two molecules of glutathione form a disulfide bond. However, typically, ‘glutathione’ refers to the reduced form (GSH). Its chemical formula is C10H17N3O6S, and the CAS number is 70-18-8. It appears as a white powdery solid at room temperature, with a melting point of 195°C, soluble in water, and practically insoluble in ethanol and diethyl ether.
Uses of Glutathione
Glutathione is used as a reducing agent in synthetic organic chemistry and biochemistry. For example, it is used in elution buffers to elute GST (glutathione S-transferase) fusion proteins from glutathione-agarose beads. In living organisms, it serves as an antioxidant, protecting cells from reactive oxygen species such as free radicals and peroxides. Medications containing glutathione are available in both oral and injectable forms and are used for various conditions, including drug toxicity, acetonemic emesis, metal poisoning, hyperemesis gravidarum, and gestational hypertension.
Principle of Glutathione
1. Structure of Glutathione
Glutathione is a tripeptide formed from glutamic acid, cysteine, and glycine, denoted as L-γ-glutamyl-L-cysteinyl-glycine. It is characterized by a γ-glutamyl bond between the γ-carboxy group of glutamate and the α-amino group of cysteine.
2. Redox Reaction of Glutathione
Glutathione contains a thiol group on the cysteine residue’s side chain. When oxidized, two molecules of reduced glutathione (GSH) form a disulfide bond, converting to the oxidized form (GSSG). In animal cells, it reduces disulfide bonds in cytosolic proteins to cysteines. It also reduces peroxides and reactive oxygen species, playing a key role in removing oxidative stress.
3. Detoxification Action of Glutathione in Vivo
Glutathione acts nucleophilically through the sulfur moiety of the cysteine residue’s thiol group. In vivo, it is catalyzed by glutathione-S-transferases (GSTs) to bind to various substances, including poisons, antibiotics, leukotrienes, and prostaglandins, forming conjugates. These conjugates are then expelled from cells, aiding in detoxification.
Types of Glutathione
Glutathione is available as a chemical reagent for research and development as well as a pharmaceutical product in forms like tablets and injections. It is used to replenish glutathione in the human body and detoxify toxins. It is indicated for various conditions, including drug intoxication, acetonemic emesis, and impaired liver function in chronic liver diseases. Available in various quantities for research, such as 10mg to 500g, glutathione requires refrigerated storage to prevent oxidation. Both reduced and oxidized forms of glutathione are available, and it is essential to distinguish between them.