If you have been reading about GSH and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-06-24. Numbers and descriptions here follow the published literature rather than marketing material.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. It occurs in nearly all living cells, with highest concentrations in liver, kidney, and red blood cells, and exists in reduced (GSH) and oxidized disulfide (GSSG) forms. The cysteine thiol group enables reversible oxidation and reduction reactions. This property makes glutathione a central participant in cellular redox balance. The balance between these forms is often used as an indicator of oxidative stress.
Glutathione synthesis proceeds in two ATP-dependent steps catalyzed by glutamate-cysteine ligase and glutathione synthetase. The first step joins glutamate and cysteine to form gamma-glutamylcysteine and is generally rate-limiting. The second step adds glycine to complete the tripeptide. Cysteine availability, feedback inhibition by glutathione, and oxidative conditions influence flux through this pathway. The pathway is conserved across many organisms, and degradation by gamma-glutamyl transpeptidase and related peptidases recycles amino acids for new synthesis.
Within cells, glutathione serves as a cofactor for glutathione peroxidases and glutathione S-transferases. These enzymes reduce hydrogen peroxide and organic peroxides or conjugate electrophilic compounds to the thiol group. The resulting conjugates can be exported and processed through mercapturic acid pathways. Glutathione also contributes to protein thiol homeostasis and to recycling of other antioxidants such as ascorbate. Its precise roles vary by tissue, and many regulatory effects observed in laboratory systems remain difficult to quantify in whole organisms.
Glutathione is a small tripeptide made of glutamic acid, cysteine, and glycine. Its cysteine thiol group allows reversible oxidation and reduction, making it central to cellular redox chemistry. The reduced form, often abbreviated GSH, predominates inside most cells, while the oxidized disulfide form, GSSG, forms when two GSH molecules react. The ratio of GSH to GSSG is widely used as an indicator of oxidative stress in laboratory research, though it does not by itself diagnose a clinical condition.
Biosynthesis occurs in two ATP-dependent steps. The enzyme glutamate-cysteine ligase joins glutamate and cysteine, forming gamma-glutamylcysteine; glutathione synthetase then adds glycine to produce the complete tripeptide. Because the peptide bond from glutamate uses the gamma-carboxyl group, glutathione resists digestion by many ordinary peptidases. Tissues vary in synthesis capacity, and the liver generally contains high concentrations relative to many other organs. This uneven distribution contributes to organ-specific differences in redox buffering and affects how experimental results are interpreted across tissue types.
| Property | Value | Notes |
|---|---|---|
| Common name | Glutathione | Reduced form is abbreviated GSH |
| Chemical class | Tripeptide | Composed of glutamate, cysteine, and glycine |
| Molar mass | 307.32 g/mol | For reduced glutathione |
| CAS Registry Number | 70-18-8 | For reduced L-glutathione |
| Appearance | White crystalline powder | Typical solid reference material |
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. Its cysteine residue carries a thiol group, which allows the molecule to participate in reduction and oxidation reactions. The compound exists in most living cells, where the reduced form, often abbreviated GSH, is usually more abundant than the oxidized disulfide form, GSSG. Intracellular concentrations are commonly in the millimolar range, while extracellular concentrations are much lower. This uneven distribution supports its role as a major cellular redox buffer.
Cells synthesize glutathione through two ATP-dependent enzymatic steps. The first step combines glutamate and cysteine to form gamma-glutamylcysteine, catalyzed by glutamate-cysteine ligase. The second step adds glycine, producing the complete tripeptide, catalyzed by glutathione synthetase. Glutathione itself can inhibit the first enzyme, providing negative feedback when levels are high. Because cysteine is often limiting, its availability influences how quickly the pathway proceeds. These reactions occur in the cytosol, and the resulting glutathione can be distributed to other compartments.
Cells synthesize glutathione through two ATP-dependent steps: glutamate-cysteine ligase joins glutamate and cysteine, and glutathione synthetase adds glycine to form the complete tripeptide. Breakdown occurs through gamma-glutamyl transpeptidase and subsequent peptidase reactions, forming the gamma-glutamyl cycle. Within cells, glutathione also forms a disulfide-linked dimer called GSSG when two GSH molecules react. The balance between GSH and GSSG is widely used as an indicator of oxidative conditions, although the ratio can vary by compartment and tissue.
Glutathione supports several cellular processes beyond direct antioxidant action. It serves as a cofactor for glutathione peroxidase and glutathione S-transferase enzymes, which reduce peroxides and conjugate electrophiles, respectively. The molecule also acts as a reservoir of cysteine, an amino acid that can limit protein synthesis and redox signaling. In human nutrition, oral glutathione is sold as a supplement, but how much intact glutathione reaches tissues after ingestion remains an active research question. Clinical claims about supplementation are not uniformly supported by controlled trials.
Glutathione is a small tripeptide built from glutamate, cysteine, and glycine. The peptide bond between glutamate and cysteine uses the gamma-carboxyl group, a linkage that resists ordinary peptidases. Cells make it in two ATP-dependent steps: gamma-glutamylcysteine synthetase joins glutamate and cysteine, then glutathione synthetase adds glycine. The pathway is feedback-inhibited by glutathione itself, so intracellular levels tend to stay within a narrow range. Because cysteine is often limiting, sulfur amino acid supply influences how much glutathione a cell can produce.
In its reduced form, glutathione carries a sulfhydryl group that can donate electrons. This property lets it act as a major cellular antioxidant and redox buffer. Glutathione peroxidase uses it to reduce hydrogen peroxide and lipid peroxides, while glutathione reductase regenerates the reduced form using NADPH. The ratio of reduced glutathione to glutathione disulfide is widely used as an indicator of oxidative stress, though the ratio changes with compartment, cell type, and sample handling. Oxidized glutathione can also form mixed disulfides with proteins, affecting their activity.
Glutathione supports detoxification by conjugating reactive electrophiles through glutathione S-transferases. The resulting conjugates are processed and exported, often after further metabolism. It also stores cysteine, transports amino acids across membranes through the gamma-glutamyl cycle, and assists in the maturation of iron-sulfur clusters and some prostaglandins. In plants, animals, and many microbes, the molecule appears in similar roles, but concentrations vary enormously between tissues. Liver, kidney, and red blood cells tend to contain high amounts, while blood plasma contains much less.
In 2000, a gene therapy "success" resulted in SCID patients with a functional immune system. These trials were stopped when it was discovered that two of ten patients in one trial had developed leukemia resulting from the insertion of the gene-carrying retrovirus near an oncogene. By 2007, four of the ten patients had developed leukemias. Work aimed at improving gene therapy is now focusing on modifying the viral vector to reduce the likelihood of oncogenesis and using zinc-finger nucleases to further target gene insertion. No leukemia cases have yet been seen in trials of ADA-SCID, which does not involve the gamma c gene that may be oncogenic when expressed by a retrovirus. From the treatments of Ashanthi DeSilva in 1990, which is considered gene therapy's first success until 2014, around 60 patients were treated for either ADA-SCID or X-SCID using retroviruses vectors. As previously mentioned, the occurrence of leukemia cases forced researchers to make changes to improve safety. In 2019, a new method using an altered version of the HIV virus as a lentivirus vector was reported in the treatment of eight children with X-SCID, and in 2021 the same method was used in 50 children with ADA-SCID, obtaining positive results in 48 of them. There are also some non-curative methods for treating SCID. Reverse isolation involves the use of laminar air flow and mechanical barriers to avoid physical contact with others in order to isolate the patient from any harmful pathogens present in the external environment.
Ondarza RN, Abney R, Lopez-Colome AM (1969). "Characterization of a NADPH-dependent coenzyme A-SS-glutathione reductase from yeast". Biochim. Biophys. Acta. 191 (2): 239–48. doi:10.1016/0005-2744(69)90243-5. PMID 4390951. Ondarza RN, Escamilla E, Gutierrez J, De la Chica G (1974). "CoAS-Sglutathione and GSSG reductases from rat liver. Two disulfide oxidoreductase activities in one protein entity". Biochim. Biophys. Acta. 341 (1): 162–71. doi:10.1016/0005-2744(74)90076-x. PMID 4151341. Carlberg I, Mannervik B (1977). "Purification by affinity chromatography of yeast glutathione reductase, the enzyme responsible for the NADPH-dependent reduction of the mixed disulfide of coenzyme A and glutathione". Biochim. Biophys. Acta. 484 (2): 268–74. doi:10.1016/0005-2744(77)90083-3. PMID 334266.
After extensive testing, which can take up to six years, the new medicine is ready for marketing and selling. Because of these long timescales and the fact that only one out of every 5000 potential new medicines will ever reach the open market, this is an expensive way of doing things, often costing over 1 USD billion per drug. To recoup this outlay, pharmaceutical companies may do a number of things:
Sources: en.wikipedia.org
=== Generic names === Buspirone is the INNTooltip International Nonproprietary Name, BANTooltip British Approved Name, DCFTooltip Dénomination Commune Française, and DCITTooltip Denominazione Comune Italiana of buspirone, while buspirone hydrochloride is its USANTooltip United States Adopted Name, BANMTooltip British Approved Name, and JANTooltip Japanese Accepted Name.
=== Legal status === Zanidatamab was approved for medical use in the United States in November 2024. In April 2025, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a conditional marketing authorization for the medicinal product Ziihera, intended for the treatment of adults with unresectable locally advanced or metastatic HER2-positive biliary tract cancer. The applicant for this medicinal product is Jazz Pharmaceuticals Ireland Limited. Zanidatamab was authorized for medical use in the European Union in June 2025.
=== Selectively neutral similarities === Similarities which have no adaptive relevance cannot be explained by convergent evolution, and therefore they provide compelling support for universal common descent. Such evidence has come from two areas: amino acid sequences and DNA sequences. Proteins with the same three-dimensional structure need not have identical amino acid sequences; any irrelevant similarity between the sequences is evidence for common descent. In certain cases, there are several codons (DNA triplets) that code redundantly for the same amino acid. Since many species use the same codon at the same place to specify an amino acid that can be represented by more than one codon, that is evidence for their sharing a recent common ancestor. Had the amino acid sequences come from different ancestors, they would have been coded for by any of the redundant codons, and since the correct amino acids would already have been in place, natural selection would not have driven any change in the codons, however much time was available. Genetic drift could change the codons, but it would be extremely unlikely to make all the redundant codons in a whole sequence match exactly across multiple lineages. Similarly, shared nucleotide sequences, especially where these are apparently neutral such as the positioning of introns and pseudogenes, provide strong evidence of common ancestry.
Sources: en.wikipedia.org
== Career == Larsen worked for more than 35 years at DuPont. In her research in mass spectrometry, she worked with a number of ionization sources, from electrospray ionization, matrix-assisted laser desorption/ionization, solid probe introduction with corona discharge ionization, to laserspray ionization. Her fluorinated polymer extraction method, the Larsen method, is required by the Environmental Protection Agency for consumer safety. She is a consultant at Larsen Scientific Consulting. She serves on the editorial advisory board of Spectroscopy. She was an editor for the Journal of the American Society for Mass Spectrometry. She served on a number of board positions for the American Society for Mass Spectrometry: treasurer (1992-1994), vice president for programs (2004-2006), president (2006-2008), and past president (2008-2010). She was elected as an American Chemical Society Fellow in 2017.
Valve did not develop a non-VR version of Alyx as they were confident that it would only be possible in VR. They anticipated that fans would modify it to run without VR equipment. Though this bothered some on the team, Walker was not concerned, as he believed it would offer an inferior experience and demonstrate why they had chosen VR. In late 2018, Valve held a company-wide playtest of the entire game. The results convinced them that VR had been the right choice. The final weeks of development took place remotely due to the COVID-19 pandemic.
== Pathology == Defects in this receptor are known to be the cause of Jansen's metaphyseal chondrodysplasia (JMC) and chondrodysplasia Blomstrand type (BOCD) as well as enchondromatosis and primary failure of tooth eruption.
Colonial administration records (migrated archives): Malaya at The National Archives (Pg. 52) The UK Statute Law Database: Federation of Malaya Independence Act 1957 (c. 60) United Nations Treaty Collection: No.10760: Agreement relating to Malaysia FEDERATION OF MALAYA AGREEMENT OF 5 AUGUST 1957 Media related to Federation of Malaya at Wikimedia Commons
Sources: en.wikipedia.org
GSH is the reduced thiol form, while GSSG is the disulfide-linked oxidized dimer. The GSH:GSSG ratio is used as a redox indicator, though the ratio can vary with sample handling and cell type.
Glutathione is present in many foods, including meats, poultry, fish, some vegetables, and fruits. Cooking, storage, and digestion affect the amounts available for absorption.
Yes, both enzymatic steps in glutathione synthesis consume ATP. The first step, catalyzed by glutamate-cysteine ligase, is usually rate-limiting.
GSH is the reduced form of glutathione, with a free thiol group on cysteine. GSSG is the oxidized disulfide form, created when two GSH molecules become linked. The two forms exist together, and their balance is often reported as the GSH/GSSG ratio in laboratory studies.