A practical reference on thiol group: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-02-20. Anything still debated is marked as such rather than presented as settled.
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 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.
Glutathione functions in redox balance, detoxification, and sulfur amino acid storage. It participates in reactions that help maintain ascorbate and protein thiol status. The molecule serves as a cofactor for several enzymes, including glutathione peroxidases and glutathione S-transferases. These enzymes reduce peroxides and conjugate electrophiles, respectively. Glutathione also contributes to the metabolism of xenobiotics and to the transport of cysteine between tissues. How interorgan transport and tissue-specific regulation shape whole-body pools remains an active area of study.
| 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.
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.
Glutathione participates in detoxification reactions, amino acid transport, and the maintenance of protein thiols. It serves as a cofactor for several enzymes, including glutathione peroxidases and glutathione S-transferases. In research literature, altered glutathione status appears in studies of aging, infection, metabolic stress, and environmental exposure. Whether low glutathione is a cause, consequence, or marker of such conditions often remains unresolved. Direct measurement in blood or tissue provides a snapshot, but results depend on sample handling, timing, and the method used.
1955: the Mexican League, previously independent, was classified as Double-A 1961: final season of the Southern Association 1963: the Eastern League and original South Atlantic League were moved from Class A to Double-A 1964: the original South Atlantic League was reconstituted as the Southern League 1967: the Mexican League moved to Triple-A Entering the 2020 minor league season (which was not played, due to the COVID-19 pandemic) the Texas League had been in Double-A since 1946, the Eastern League since 1963, and the Southern League since 1964. Prior to the 2021 season, Major League Baseball (MLB) reorganized the minor leagues. At that time, the existing leagues were temporarily renamed: Eastern League as Double-A Northeast, Southern League as Double-A South, and Texas League as Double-A Central. Following MLB's acquisition of the rights to the names of the historical minor leagues, MLB announced on March 16, 2022, that the leagues would revert to their prior names, effective with the 2022 season.
=== 68Ga radiolabeling === 68Ga-Trivehexin is a radioactive drug. The radioactive atom, gallium-68 (68Ga), decays with a half-life of approximately 68 min to the stable isotope zinc-68 (68Zn), to 89% by β+ decay whereby a positron with a maximum kinetic energy of 1.9 MeV is emitted (the remaining 11% are EC decays). Due to the short half-life, 68Ga-Trivehexin can not be manufactured long before use but the 68Ga has to be introduced into the molecule shortly before application. This process is referred to as radiolabeling, and is done by complexation of the trivalent cation 68GaIII by the TRAP chelator in Trivehexin. 68GaIII is usually obtained from a dedicated mobile radionuclide source, a Gallium-68 generator, in form of a solution in dilute (0.04–0.1 M) hydrochloric acid (frequently and imprecisely referred to as "68Ga chloride solution in HCl" despite it contains no species with a Ga–Cl bond but [68Ga(H2O)6]3+ complex hydrate cations). For radiolabeling, the pH of the 68Ga containing generator eluate has to be raised from its initial value (depending on HCl concentration, pH 1–1.5) to pH 2–3.5 using suitable buffers, such as sodium acetate. Then, Trivehexin (5–10 nmol) is added to the buffered 68Ga-containing solution, and the mixture is briefly heated to 50–100 °C (usually 2–3 min) to finalize the complexation reaction.
== External links == Major+Histocompatibility+Complex at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Molecular Individuality Archived 2013-01-29 at the Wayback Machine—German online book (2012) NetMHC 3.0 server—predicts binding of peptides to a number of different MHC (HLA) alleles T-cell Group—Cardiff University The story of 2YF6: A Chicken MHC[link removed] RCSB Protein Data Bank: Molecule of the Month—Major Histocompatibility Complex dbMHC Home, NCBI's database of the Major Histocompatibility Complex
Sources: en.wikipedia.org
On the one hand, God remains responsible as the creator of the world and is thus also the ultimate cause of suffering—at least in the sense that his creation of the world made suffering possible in the first place. On the other hand, there are situations in which no finite power can save or help human beings. For by definition, only God is the reality that can save us even in death—if he exists. But how can I ask for help from the very one who made my misery possible in the first place? Kermani sees no way to rationally justify this question. Rather, he describes those voices that do not want to abandon God even in misery. The fools he cites do not simply lament the terror of God. Instead, they remind God of the promises he once made in creation. They insist on God's faithfulness, which God describes and promises in His self-revelation. The fools are therefore not blind to reality. On the contrary, they consider all the questions about the reality of a loving God that every human being experiences on a daily basis. Their adherence to God does not dull their senses or take away the horror of suffering. But it enables them to face the abysses and terror of reality without, however, giving up hope. Belief in God thus operates as an imposition that can drive one to madness. At the same time, however, it appears as the last possibility for putting up with the world in its ambiguity without losing one's own humanity.
=== American Hospital Association (AHA) === The American Hospital Association has expressed concern that FDA's proposal to classify LDTs as medical devices exceeds the agency's appropriate regulatory scope, urging the FDA to continue to apply its enforcement discretion to hospital and health system LDTs and defer regulation of these tests mainly to CMS's strict CLIA oversight, the CAP accreditation and state law. The organization has called on Congress to either exclude hospitals and health systems from this device classification framework or to modernize LDT oversight in a way that promotes innovation while maintaining test accessibility, safety, and effectiveness.
== External links == WHO fact sheet on opioid overdose Community management of opioid overdose (PDF). World Health Organization. 2014. ISBN 978-92-4-154881-6. Archived from the original (PDF) on 1 September 2022.
Sources: en.wikipedia.org
After his release from jail, Colonel Rhodes immediately joined his brother Cecil and the British South Africa Company in the Second Matabele War taking place just north of the Transvaal in Matabeleland. Cecil Rhodes was forced to resign as Prime Minister of Cape Colony in 1896 due to his apparent involvement in planning and assisting in the raid; he also, along with Alfred Beit, resigned as a director of the British South Africa Company. Jameson's raid had depleted Matabeleland of many of its troops and left the whole territory vulnerable. Seizing on this weakness, and a discontent with the British South Africa Company, the Ndebele revolted during March 1896 in what is now celebrated in Zimbabwe as the First War of Independence, the First Chimurenga, but it is better known to most of the world as the Second Matabele War. The Shona joined them soon thereafter. Hundreds of European settlers were killed within the first few weeks of the revolt and many more would die over the next year and a half. With few troops to support them, the settlers had to quickly build a laager in the centre of Bulawayo on their own. Against over 50,000 Ndebele held up in their stronghold of the Matobo Hills the settlers mounted patrols under such people as Burnham, Baden-Powell, and Selous. It would not be until October 1897 that the Ndebele and Shona would finally lay down their arms.
However, proactively smiling only increases happiness among those who believe smiling is a reaction to feeling happy, rather than a positive intervention. Ed Diener et al. (1999) suggested this equation: positive emotion – negative emotion = subjective well-being. Since tendency to positive emotion has a correlation of 0.8 with extroversion and tendency towards negative emotion is indistinguishable from neuroticism, the above equation could also be written as extroversion – neuroticism = happiness. These two traits could account for between 50% and 75% of happiness. These are all referring to the Big Five personality traits model of personality. An emotionally stable (the opposite of Neurotic) personality correlates well with happiness. Not only does emotional stability make one less prone to negative emotions, it also predicts higher social intelligence – which helps to manage relationships with others (an important part of being happy, discussed below). Cultivating an extroverted temperament may correlate with happiness for the same reason: it builds relationships and support groups. Some people may be fortunate, from the standpoint of personality theories that suggest individuals have control over their long-term behaviors and cognitions. Genetic studies indicate genes for personality (specifically extroversion, neuroticism and conscientiousness), and a general factor linking all 5 traits, account for the heritability of subjective well-being. Recent research suggests there is a happiness gene, the 5-HTT gene.
== Ecology == Viola species are used as food plants by the larvae of some Lepidoptera species, including the giant leopard moth, large yellow underwing, lesser broad-bordered yellow underwing, high brown fritillary, small pearl-bordered fritillary, pearl-bordered fritillary, regal fritillary, cardinal, and Setaceous Hebrew character. The larvae of many fritillary butterfly species use violets as an obligate host plant, although these butterflies do not always oviposit directly onto violets. While the ecology of this genera is extremely diverse, violets are mainly pollinated by members within the orders Diptera and Hymenoptera. Showy flowers are produced in early spring, and clonal cleistogamous flowers are produced from late spring until the end of the growing season under favorable conditions. Cleistogamy allows plants to produce offspring year round and have more chances for establishment. This system is especially important in violets, as these plants are often weak competitors for pollination due to their small size. Many violet species exhibit two modes of seed dispersal. Once seed capsules have matured, seeds are dispelled around the plant through explosive dehiscence. Viola pedata seeds have been reported being dispersed distances of up to 5 meters away from the parent plant. Often, seeds are then further dispersed by ants through a process called myrmecochory. Violets whose seeds are dispersed this way have specialized structures on the exterior of the seeds called elaiosomes.
=== Evaluation of a technique === The technique being evaluated uses voltammetric sensors combined in an electronic tongue (ET) to observe the antioxidant capacity in red wines. These electronic tongues (ETs) consist of multiple sensing units like voltammetric sensors, which will have unique responses to certain compounds. This approach is optimal to use since samples of high complexity can be analyzed with high cross-selectivity. Thus, the sensors can be sensitive to pH and antioxidants. As usual, the voltage in the cell was monitored using a working electrode and a reference electrode (silver/silver chloride electrode). Furthermore, a platinum counter electrode allows the current to continue to flow during the experiment. The Carbon Paste Electrodes sensor (CPE) and the Graphite-Epoxy Composite (GEC) electrode are tested in a saline solution before the scanning of the wine so that a reference signal can be obtained. The wines are then ready to be scanned, once with CPE and once with GEC. While cyclic voltammetry was successfully used to generate currents using the wine samples, the signals were complex and needed an additional extraction stage. It was found that the ET method could successfully analyze wine's antioxidant capacity as it agreed with traditional methods like TEAC, Folin-Ciocalteu, and I280 indexes. Additionally, the time was reduced, the sample did not have to be pretreated, and other reagents were unnecessary, all of which diminished the popularity of traditional methods.
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 is built from three amino acids: glutamate, cysteine, and glycine. The linkage involves the gamma-carboxyl group of glutamate rather than the alpha-carboxyl group, which is unusual for peptides. This structure protects the bond from some common peptidases.