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 2026-08-01 and is reviewed periodically as new material appears.
Synthesis occurs in two ATP-dependent steps. The enzyme glutamate-cysteine ligase joins glutamate and cysteine to form gamma-glutamylcysteine, and glutathione synthetase adds glycine. The first step is rate-limiting and is influenced by cysteine availability and feedback inhibition by GSH. Breakdown involves gamma-glutamyl transferase and subsequent peptidases, which release constituent amino acids for reuse. Because turnover differs among tissues, measurements from blood, plasma, and tissues are not directly interchangeable. Research continues to clarify how compartment-specific pools are regulated in health and disease.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. It contains an unusual gamma-glutamyl bond between glutamate and cysteine, which resists cleavage by many peptidases. The reduced form, GSH, carries a thiol group on cysteine and is the dominant intracellular form in most cells. Its structure allows it to participate in redox reactions and to serve as a sulfur donor. The oxidized form, GSSG, consists of two GSH molecules joined by a disulfide bond.
Storage conditions strongly influence glutathione stability. The solid reduced form is commonly kept desiccated at or below minus twenty degrees Celsius, protected from light and moisture. Aqueous solutions are less stable because the thiol group reacts with dissolved oxygen, and oxidation accelerates at neutral or alkaline pH. Acidic solutions and oxygen-free handling can slow degradation, but repeated freeze-thaw cycles should be avoided. Researchers often verify concentration before use, because apparent losses can arise from oxidation or water uptake.
Measuring glutathione in biological samples requires attention to oxidation and matrix effects. High-performance liquid chromatography with ultraviolet or fluorescence detection can separate reduced and oxidized forms after derivatization. Liquid chromatography with tandem mass spectrometry offers higher specificity and can quantify glutathione alongside related thiols. Because glutathione can oxidize during sample handling, many protocols use rapid acidification with metaphosphoric acid or sulfosalicylic acid. Internal standards help correct for losses during extraction and analysis.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C10H17N3O6S | For reduced glutathione; the oxidized dimer has two sulfur atoms. |
| Molar mass | 307.32 g/mol | Calculated for the reduced form. |
| Appearance | White to off-white crystalline powder | Typical for solid reagent; solutions are usually colorless. |
| Solubility | Freely soluble in water | Poorly soluble in nonpolar organic solvents. |
| Typical storage | -20 °C, desiccated, protected from light | Limits oxidation, moisture uptake, and degradation. |
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 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.
For solid glutathione reagents, storage at low temperature and protection from moisture and light are typical precautions. Aqueous solutions can oxidize over time, and pH affects stability; alkaline conditions generally promote thiol oxidation. Some protocols prepare fresh solutions, while others use antioxidants or chelators to limit metal-catalyzed oxidation. Purity and counterion content can vary among commercial preparations, affecting concentration calculations. Certificates of analysis and validated assays help verify identity and purity.
Measuring glutathione in biological samples requires attention to oxidation, because GSH can convert to GSSG after sample collection. Blood and plasma samples are often treated with acid or alkylating agents to preserve the reduced form. Without stabilization, apparent GSH concentrations can fall while GSSG rises. Differences in sample type, handling delay, and deproteinization method can produce results that are not comparable across studies. Reporting preanalytical details is therefore important for interpreting findings.
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 is a tripeptide composed of glutamate, cysteine, and glycine. The peptide bond between glutamate and cysteine uses the gamma-carboxyl group of glutamate rather than the alpha-carboxyl group. This unusual linkage protects the molecule from many common peptidases. The cysteine side chain carries a thiol group that can undergo reversible oxidation. Because of this thiol, glutathione participates in redox reactions and helps maintain the reducing environment inside most cells in living systems.
Glutathione is synthesized in two ATP-dependent steps. First, gamma-glutamylcysteine synthetase links glutamate and cysteine; second, glutathione synthetase adds glycine to form the complete tripeptide. The pathway is feedback-inhibited by GSH itself, which helps maintain steady intracellular levels. Tissues vary widely in glutathione content, with the liver typically containing the highest concentrations, followed by the kidneys, lungs, and erythrocytes. Because cysteine is often limiting, its availability influences synthesis rates, and regulation of this pathway varies by cell type.
Glutathione serves as a cofactor for several enzymes, including glutathione peroxidase and glutathione S-transferase. These enzymes help reduce hydrogen peroxide and lipid peroxides, and they conjugate reactive electrophiles for excretion. The molecule also acts as a reservoir for cysteine, an amino acid that is prone to oxidation. In addition, glutathione participates in the metabolism of nitric oxide, leukotrienes, and prostaglandins. Its roles extend to cell signaling, apoptosis, and the regulation of protein function through S-glutathionylation.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine, and it is the most abundant non-protein thiol in most living cells. The reduced form, GSH, carries a sulfhydryl group that can donate electrons, while the oxidized form, GSSG, forms when two GSH molecules link via a disulfide bond. The balance between these two forms helps define the cellular redox environment, and their ratio is often used as an indicator of oxidative stress. Because the sulfhydryl group is reactive, glutathione participates in many cellular processes, including detoxification and protein regulation.
== Protactinium-233 == Protactinium-233 is also part of the thorium fuel cycle. It is an intermediate beta decay product between thorium-233 (produced from natural thorium-232 by neutron capture) and uranium-233 (the fissile fuel of the thorium cycle). Some thorium-cycle reactor designs try to protect 233Pa from further neutron capture producing 234Pa and 234U, which are not useful as fuel.
== Overdose == Zopiclone is sometimes used as a method of suicide. It has a similar fatality index to that of benzodiazepine drugs, apart from temazepam, which is particularly toxic in overdose. Deaths have occurred from zopiclone overdose, alone or in combination with other drugs. Overdose of zopiclone may present with excessive sedation and depressed respiratory function that may progress to coma and possibly death. Zopiclone combined with alcohol, opiates, or other central nervous system depressants may be even more likely to lead to fatal overdoses. Zopiclone overdosage can be treated with the GABAA receptor benzodiazepine site antagonist flumazenil, which displaces zopiclone from its binding site, thereby rapidly reversing its effects. Serious effects on the heart may also occur from a zopiclone overdose when combined with piperazine. Zopiclone is one of the most common drugs in drug poisoning suicides in elderly. When taken alone, it usually is not fatal, but when mixed with alcohol or other drugs such as opioids, or in patients with respiratory, or hepatic disorders, the risk of a serious and fatal overdose increases.
Gerry Gable (born 27 January 1937); political activist; was editor of Searchlight magazine; was member of Communist Party of Great Britain; worked as runner on Communist Party's Daily Worker newspaper; left the Communist Party because of their anti-Israel policy and because "first and foremost [he has] always been a Jewish trade unionist"; was commissioned by BBC to produce research for a BBC Panorama programme "Maggie's Militant Tendency"; was convicted in January 1964 of burglary of historian David Irving's flat Martha Gellhorn (8 November 1908 – 15 February 1998) American novelist, travel writer, and journalist who settled, retired and died in England; considered one of the great war correspondents of the 20th century. Andrew Gold (journalist) (b.1989); British Jewish journalist, YouTuber, filmmaker, author, podcaster;in 2023, Gold launched his YouTube podcast, Heretics; has written for UnHerd, Vice, Jewish News, HuffPost , Times of Israel and the BBC. Tanya Gold (born 31 December 1973) is an English journalist who has written for The Jewish Chronicle, The New York Times The Guardian, the Daily Mail, The Independent, The Daily Telegraph, The Sunday Times and the Evening Standard, and for The Spectator magazine. Vivien Goldman is a British punk rock and reggae journalist and historian, writer and musician of German Jewish ancestry.
== National differences and how to specialise == Australia In Australia, transfusion medicine is a sub-specialty of haematology. Training in transfusion medicine is covered by the Royal College of Pathologists of Australasia (RCPA). Australia has national blood services operated by the Australian Red Cross Blood Service. There are a series of guidelines and standards relevant to the laboratory released by the National Association of Testing Authorities, Australia (NATA), Australian and New Zealand Society of Blood Transfusion (ANZSBT) and RCPA. Similarly, there are a series of clinical practice, patient blood management guidelines by the National Blood Authority. In Australia, the Serious Transfusion Incident Reporting (STIR) system is in place to capture serious transfusion incidents and near-miss incidents.
== Nitrogen rule == The nitrogen rule states that organic compounds containing exclusively hydrogen, carbon, nitrogen, oxygen, silicon, phosphorus, sulfur, and the halogens either have an odd nominal mass that indicates an odd number of nitrogen atoms are present or an even nominal mass that indicates an even number of nitrogen atoms are present in the molecular ion.
Sources: en.wikipedia.org
Many common language terms used for fruit and seeds differ from botanical classifications. For example, in botany, a fruit is a ripened ovary or carpel that contains seeds, e.g., an orange, pomegranate, tomato or a pumpkin. A nut is a type of fruit (and not a seed), and a seed is a ripened ovule. In culinary language, a fruit is the sweet- or not sweet- (even sour-) tasting produce of a specific plant (e.g., a peach, pear or lemon); nuts are hard, oily, non-sweet plant produce in shells (e.g. hazelnut, acorn). Vegetables, so-called, typically are savory or non-sweet produce (e.g. zucchini, lettuce, broccoli, and tomato). But some may be sweet-tasting (sweet potato).
Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the intermediate liquid state. The verb form of sublimation is sublime, or less preferably, sublimate. Sublimate also refers to the product obtained by sublimation. The point at which sublimation occurs rapidly (for definition, see below) is called critical sublimation point, or simply, sublimation point. Notable examples include sublimation of dry ice at room temperature and atmospheric pressure, and that of solid iodine with heating. The reverse process of sublimation is deposition (also called desublimation), in which a substance passes directly from a gas to a solid phase, without passing through the intermediate liquid state. Technically, all solids may sublime, though most sublime at extremely low rates that are hardly detectable under usual conditions. At normal pressures, most chemical compounds and elements possess three different states at different temperatures. In these cases, the transition from the solid to the gas state requires an intermediate liquid state. The pressure referred to is the partial pressure of the substance, not the total (e.g. atmospheric) pressure of the entire system. Thus, any solid can sublime if its vapour pressure is higher than the surrounding partial pressure of the same substance, and in some cases, sublimation occurs at an appreciable rate (e.g. water ice just below 0 °C).
A defining characteristic of Wagyu beef is its abundant, finely distributed intramuscular fat, referred to in Japanese as sashi. Among the four Wagyu breeds, this high degree of marbling is especially characteristic of Japanese Black cattle, whose beef has been reported to contain more than 30% intramuscular fat. The degree of marbling is influenced by genetic, physiological, and feeding factors, although the mechanisms that enable Japanese Black cattle to produce such highly marbled beef are not yet fully understood. Pronounced marbling is also found in Mishima cattle. Mishima and Kuchinoshima cattle—the latter producing lean meat—are the two native Japanese cattle populations considered to have remained free from European genetic influence. The occurrence of pronounced marbling in Mishima cattle therefore suggests that at least some native Japanese cattle already possessed a genetic capacity for marbling before European crossbreeding was used to develop the modern Wagyu breeds. Among Japanese Black cattle, the Tajima strain is less prone to depositing subcutaneous and intermuscular fat but readily develops intramuscular marbling. The fat in Japanese Black beef contains a high proportion of monounsaturated fatty acids, particularly oleic acid. This composition gives the fat a relatively low melting point and soft consistency, contributing to the characteristic melt-in-the-mouth texture and rich juiciness of highly marbled Wagyu beef. Beef from Japanese Black cattle also develops a distinctive rich, sweet aroma during cooking, commonly called "Wagyu beef aroma".
=== Red blood cell production === Erythropoietin is an essential hormone for red blood cell production. Without it, definitive erythropoiesis does not take place. Under hypoxic conditions, the kidney will produce and secrete erythropoietin to increase the production of red blood cells by targeting CFU-E, proerythroblast and basophilic erythroblast subsets in the differentiation. Erythropoietin has its primary effect on red blood cell progenitors and precursors (which are found in the bone marrow in humans) by promoting their survival through protecting these cells from apoptosis, or cell death. Erythropoietin is the primary erythropoietic factor that cooperates with various other growth factors (e.g., IL-3, IL-6, glucocorticoids, and SCF) involved in the development of erythroid lineage from multipotent progenitors. The burst-forming unit-erythroid (BFU-E) cells start erythropoietin receptor expression and are sensitive to erythropoietin. Subsequent stage, the colony-forming unit-erythroid (CFU-E), expresses maximal erythropoietin receptor density and is completely dependent on erythropoietin for further differentiation. Precursors of red cells, the proerythroblasts and basophilic erythroblasts also express erythropoietin receptor and are therefore affected by it.
Sources: en.wikipedia.org
=== Rodents === The glans penis of the marsh rice rat is long and robust, averaging 7.3 mm (0.29 in) long and 4.6 mm (0.18 in) broad. Winkelmann's mouse can most readily be distinguished from its close relatives by its partially corrugated glans penis. In Thomasomys ucucha, the glans penis is rounded, short, and small and is superficially divided into left and right halves by a trough at the top and a ridge at the bottom. Most of the glans is covered with spines, except for an area near the tip. The glans penis of a male cape ground squirrel is large with a prominent baculum.
=== Pharmacodynamics === Gepirone acts as a selective partial agonist of the 5-HT1A receptor. Unlike its relative buspirone, however, gepirone has greater efficacy in activating the 5-HT1A and has negligible affinity for the D2 receptor (30- to 50-fold lower in comparison to buspirone). However, similarly to buspirone, gepirone metabolizes into 1-(2-pyrimidinyl)piperazine (1-PP), which is known to act as a potent antagonist of the α2-adrenergic receptor. Gepirone has been found to produce antiaggressive effects in rodents.
== Human defensins == Initially human alpha defensin peptides were isolated from the neutrophils and are thus called human neutrophil peptides. Human neutrophil peptides are also known as α-defensins. Human neutrophil-derived alpha-defensins (HNPs) are capable of enhancing phagocytosis by mouse macrophages. HNP1-3 have been reported to increase the production of tumor necrosis factor (TNF) and IL-1, while decreasing the production of IL-10 by monocytes. Increased levels of proinflammatory factors (e.g., IL-1, TNF, histamine and prostaglandin D2) and suppressed levels of IL-10 at the site of microbial infection are likely to amplify local inflammatory responses. This might be further reinforced by the capacity of some human and rabbit alpha-defensins to inhibit the production of immunosuppressive glucocorticoids by competing for the binding of adrenocorticotropic hormone to its receptor. Moreover, human alpha-defensins can enhance or suppress the activation of the classical pathway of complement in vitro by binding to solid-phase or fluid-phase complement C1q, respectively. The capacity of defensins to enhance phagocytosis, promote neutrophil recruitment, enhance the production of proinflammatory cytokines, suppress anti-inflammatory mediators and regulate complement activation argues that defensins upregulate innate host inflammatory defenses against microbial invasion. Human neutrophil defensin-1, -3, and -4 are elevated in nasal aspirates from children with naturally occurring adenovirus infection.
=== Mechanism of action === At therapeutic concentrations, ixazomib selectively and reversibly inhibits the protein proteasome subunit beta type-5 (PSMB5) with a dissociation half-life of 18 minutes. This mechanism is the same as of bortezomib, which has a much longer dissociation half-life of 110 minutes; the related drug carfilzomib, by contrast, blocks PSMB5 irreversibly. Proteasome subunits beta type-1 and type-2 are only inhibited at high concentrations reached in cell culture models. PSMB5 is part of the 20S proteasome complex and has enzymatic activity similar to chymotrypsin. It induces apoptosis, a type of programmed cell death, in various cancer cell lines. A synergistic effect of ixazomib and lenalidomide has been found in a large number of myeloma cell lines.
Excess 129Xe found in carbon dioxide well gases from New Mexico was believed to be from the decay of mantle-derived gases soon after Earth's formation. It has been suggested that the isotopic composition of atmospheric xenon fluctuated prior to the GOE before stabilizing, perhaps as a result of the rise in atmospheric O2.
Sources: en.wikipedia.org
GSH is the reduced form with a free thiol group, while GSSG is the oxidized disulfide-linked dimer. Most assays distinguish the two because their balance reflects redox conditions. The names are not interchangeable.
It is synthesized in the body from amino acids, so it is not classified as an essential dietary nutrient for most people. Dietary and supplemental forms are studied for their effects on tissue levels and health markers. Evidence varies by population and outcome.
The phrase highlights its high intracellular concentration and its role in several antioxidant and detoxification reactions. It is not the only antioxidant, and the term can oversimplify its functions. Scientific descriptions usually specify the pathway or enzyme involved.
Chromatographic methods can separate the two forms before detection. Enzymatic assays often measure total glutathione first and then use a separate procedure to estimate the oxidized fraction. The difference between total and oxidized amounts provides an indirect estimate of the reduced form.