A practical reference on thiol: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-10-01 and is reviewed periodically as new material appears.
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.
Accurate measurement of glutathione begins with careful sample handling. Because GSH oxidizes rapidly to GSSG, samples must be processed quickly or frozen immediately. Acid precipitation with metaphosphoric acid or perchloric acid is common; it lowers pH, precipitates proteins, and helps preserve the reduced form. Chelating agents such as EDTA can limit metal-catalyzed oxidation. For whole blood, hemolysis releases glutathione from erythrocytes, so plasma and serum values differ substantially from whole blood values.
Several analytical methods can quantify glutathione, including high-performance liquid chromatography (HPLC) with UV or fluorescence detection for separating GSH and GSSG. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) offers higher specificity and sensitivity, often detecting nanomolar concentrations. The enzymatic recycling assay, often called the Tietze method, measures total glutathione by coupling reduction of GSSG to a colorimetric or fluorometric readout. Capillary electrophoresis and electrochemical detection are also used in specialized laboratories. Each method has distinct advantages and limitations regarding throughput, cost, and susceptibility to interference.
| 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 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 cells, glutathione exists mainly in a reduced form called GSH. When two GSH molecules react, they form oxidized glutathione, or GSSG, which contains a disulfide bond. The ratio of GSH to GSSG is often used as an indicator of oxidative stress. Enzymes such as glutathione peroxidase and glutathione reductase help cycle the molecule between these two states. This cycling supports antioxidant defense, detoxification of reactive molecules, and regulation of certain signaling pathways.
Glutathione is present in most tissues, with especially high concentrations in the liver. It also serves as a cofactor for some enzymes and helps transport amino acids across cell membranes. In plants and microorganisms, glutathione contributes to stress responses and metal handling. The molecule is synthesized in two ATP-dependent steps, first producing gamma-glutamylcysteine and then adding glycine. Because cysteine availability often limits synthesis, dietary and metabolic factors can influence glutathione levels. Research continues to examine how these levels relate to health and disease.
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 glutamic acid, cysteine, and glycine. Its peptide bond between glutamate and cysteine involves the gamma-carboxyl group rather than the usual alpha-carboxyl group. This structure gives the molecule a reactive thiol on the cysteine residue. The reduced form, often abbreviated GSH, is the predominant intracellular species in many cell types. Because the thiol can donate electrons, glutathione participates in redox chemistry and in the conjugation of reactive molecules.
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.
=== Modulating fibrosis === Role of Thy-1 in fibrosis and fibroblast differentiation may have some tissue variation. Thy1 knock out mice have increased fibrosis in the lung. Fibrosis induced by chemotherapeutic agent Bleomycin is also increased in these mice.
Dose-ranging studies of flutamide in men with benign prostatic hyperplasia and prostate cancer alone and in combination with a GnRH agonist have been performed. Flutamide increases testosterone levels by 5- to 10-fold in gonadally intact male rats.
Vegetable oils, meat, and fish are rich in CoQ10. Dairy products are much poorer sources of CoQ10 than animal tissues. Among vegetables, broccoli and cauliflower are good sources of CoQ10. Most fruits and berries are poor sources of CoQ10, except avocados, which have relatively high oil and CoQ10 content.
Sources: en.wikipedia.org
== Further reading == "Bernie Sanders Explains... Why Americans Are Furious at the Democrats: The Nation Interview [by John Nichols]", The Nation, vol. 321, no. 4 (November 2025), pp. 30–34. "[T]he [Democratic] party is saying, '[W]e can't support [Zohran Mamdani, running for New York City mayor] because he is saying what 75 percent of Democrats say about Israel: No more money for Netanyahu.' [p. 32.] [T]he money people decide who the candidates are... [p. 33.] A few years ago ... a poll [showed that] [a]lmost 60 percent of the people said [they] were better off 50 years ago. [p. 34.]" Chiasson, Dan (2026). Bernie for Burlington: The Rise of the People's Politician. New York: Knopf. ISBN 978-0-59331-749-5. Rall, Ted (2016). Bernie. New York: Hollowbrook Publishing. ISBN 978-1-60980-698-9. Rice, Tom W. (1985). "Who Votes for a Socialist Mayor?: The Case of Burlington, Vermont". Polity. 17 (4): 795–806. doi:10.2307/3234575. ISSN 0032-3497. JSTOR 3234575. OCLC 5546248357. S2CID 153889856. Rosenfeld, Steven (1992). Making History in Vermont: The Election of a Socialist to Congress. Wakefield, NH: Hollowbrook Publishing. ISBN 978-0-89341-698-0. LCCN 91034055. OCLC 24468446. OL 1553980M. Soifer, Steven (1991). The Socialist Mayor: Bernard Sanders in Burlington, Vermont. Westport, CN: Praeger. ISBN 978-0-89789-219-3. LCCN 90048954. OCLC 22491683. OL 1887682M.
There is also in vitro evidence of synergy for colistimethate sodium used in combination with other antipseudomonal antibiotics. Colistimethate sodium aerosol (Promixin; Colomycin Injection) is used to treat pulmonary infections, especially in cystic fibrosis. In the UK, the recommended adult dose is 1–2 million units (80–160 mg) nebulised colistimethate twice daily. Nebulized colistin has also been used to decrease severe exacerbations in patients with chronic obstructive pulmonary disease and infection with Pseudomonas aeruginosa.
The Northern Cod biomass has been recovering slowly since the imposition of the moratorium. However, as of 2021, the growth of the cod population has been stagnant since 2017, and some scientists argue that the population will not rebound unless the Fisheries Department of Canada lower its yearly quota to 5,000 tons.
Sources: en.wikipedia.org
Many homes have a large kitchen area devoted to preparation of meals and food, and may have a dining room, dining hall, or another designated area for eating. Most societies also have restaurants, food courts, and food vendors so that people may eat when away from home, when lacking time to prepare food, or as a social occasion. At their highest level of sophistication, these places become "theatrical spectacles of global cosmopolitanism and myth." At picnics, potlucks, and food festivals, eating is the primary purpose of a social gathering. At many social events, food and beverages are made available to attendees. People usually have two or three meals a day. Snacks of smaller amounts may be consumed between meals. Doctors in the UK recommend three meals a day (with between 400 and 600 kcal per meal), with four to six hours between. Having three well-balanced meals (described as: half of the plate with vegetables, 1/4 protein food as meat, [...] and 1/4 carbohydrates as pasta, rice) will then amount to some 1800–2000 kcal, which is the average requirement for a regular person. In jurisdictions under Sharia law, eating may be proscribed for Muslim adults during the daylight hours of Ramadan.
Boosted considerably by the arrival of three South African brigades during the last months of 1940, the Commonwealth forces in Kenya had expanded to three divisions by the end of the year. No. 237 Squadron was relieved by South African airmen and redeployed to the Sudan in September. Rebasing at Khartoum, No. 237 Squadron undertook regular reconnaissance, dive-bombing and strafing sorties during October and November 1940. Meanwhile, the Southern Rhodesian Anti-Tank Battery arrived in Kenya in October and, following a period of training, received 2-pounder guns and joined the front at Garissa around the turn of the new year. No. 237 Squadron was partially re-equipped during January 1941, receiving some Westland Lysander Mk IIs, but most of the squadron continued operating Hardys. The British forces in Kenya under General Alan Cunningham, including Rhodesian officers and NCOs in the King's African Rifles and the Nigeria and Gold Coast Regiments, as well as the South African 1st South African Infantry Division, advanced into Abyssinia and Italian Somaliland during late January and February 1941, starting with the occupation of the ports of Kismayo and Mogadishu. The Italians retreated to the interior. No. 237 Squadron meanwhile provided air support to the 4th Indian Infantry Division and 5th Indian Infantry Division during Lieutenant-General William Platt's offensive into Eritrea from the Sudan, attacking ground targets and engaging Italian fighters. One of the Rhodesian Hardys was shot down near Keren on 7 February with the loss of both occupants.
=== Age-related macular degeneration === A Cochrane review concluded that there were no changes seen for risk of developing age-related macular degeneration (AMD) from long-term vitamin E supplementation and that supplementation may slightly increase the chances of developing late AMD.
=== Teaser tracks on social media === A video of Williams dancing to a song from the album was posted to Instagram by Gabriel Moses in August 2024. Pusha T posted a video to his Instagram account on May 7, 2025, captioned with the song title "So Far Ahead". The video, serving as a trailer for the song, featured footage of him getting ready for the 2025 edition of the Met Gala, spliced with images of figures like slave William Lee, boxer and activist Muhammad Ali, and artist Jean-Michel Basquiat. "So Be It" was previewed on Instagram Live by DJ Hed, and on radio station Hot 97 by disc jockey Funkmaster Flex, both on June 16, a day before the song's official release as a music video. Athlete LeBron James took to Instagram on June 23 to preview Nas' guest verse on "Let God Sort Em Out / Chandeliers."
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.
Glutathione oxidizes quickly when cells are disrupted or when samples sit at room temperature. Rapid processing or immediate freezing minimizes the conversion of GSH to GSSG. This step helps ensure that the measured ratio reflects the original biological state.