The short version of thiol group fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-07-31. Anything still debated is marked as such rather than presented as settled.
In cells, glutathione helps maintain the reducing environment of the cytosol and supports enzymes that counteract reactive oxygen species. It acts as a cofactor for glutathione peroxidases, which reduce hydrogen peroxide and lipid peroxides, and for glutathione S-transferases, which conjugate electrophiles. The ratio of GSH to GSSG is often used as an indicator of oxidative stress, although the ratio can vary by compartment and cell type. Glutathione also stores cysteine, an amino acid that can be limiting for protein synthesis and antioxidant defense.
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.
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.
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 |
|---|---|---|
| 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. |
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.
Interpreting glutathione measurements requires attention to pre-analytical variables. The GSSG concentration in a sample can rise artificially during storage or processing, making the GSH/GSSG ratio unreliable if not controlled. Reference ranges vary by specimen type, assay, and population, so comparisons across studies are difficult. Plasma glutathione is low and sensitive to hemolysis, while whole blood reflects primarily erythrocyte content. Many studies measure total glutathione rather than the reduced and oxidized forms separately, which limits conclusions about redox status.
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.
Biosynthesis proceeds in two ATP-dependent steps. First, glutamate-cysteine ligase joins glutamate and cysteine. Second, glutathione synthetase adds glycine to the intermediate. The pathway is regulated by cysteine availability, enzyme expression, and feedback inhibition by glutathione itself. Liver tissue has a particularly high capacity for synthesis and export. Because the molecule is made inside cells, circulating glutathione reflects a balance of release, uptake, and breakdown rather than simple dietary supply.
Functionally, glutathione supports redox balance by donating electrons and becoming oxidized. It also serves as a cofactor for enzymes such as glutathione peroxidases and glutathione S-transferases. These enzymes participate in peroxide reduction and in conjugation reactions that help process reactive molecules. Separate from antioxidant roles, glutathione can modify protein cysteines through S-glutathionylation, influencing enzyme activity and signaling. Research continues to examine how these chemical roles translate into whole-organism effects.
The enzyme is named for the reaction in the direction from the nucleotide to quinolinic acid but in the mammalian liver only proceeds in the direction shown, with carbon dioxide and pyrophosphate (PPi) as byproducts. This reaction is part of the biosythesis pathway to the coenzyme, nicotinamide adenine dinucleotide, in both plants and animals. This enzyme is a glycosyltransferase, specifically a pentosyltransferase. The systematic name of this enzyme class is nicotinate-nucleotide:diphosphate phospho-alpha-D-ribosyltransferase (carboxylating). Other names in common use include quinolinate phosphoribosyltransferase (decarboxylating), quinolinic acid phosphoribosyltransferase, QAPRTase, NAD+ pyrophosphorylase, nicotinate mononucleotide pyrophosphorylase (carboxylating), and quinolinic phosphoribosyltransferase.
== Forensic detection == Worldwide, certain traditional Chinese medicines contain wild bear bile, banned under CITES legislation. Dip sticks, similar to common pregnancy tests, have been developed to detect the presence of bear albumin in traditional medicine products, indicating that bear bile had been used in their creation.
Individuals with this disorder typically experience progressive muscle weakness of the leg and pelvis muscles, which is associated with a loss of muscle mass (wasting). Muscle weakness also occurs in the arms, neck, and other areas, but is not as noticeably severe as in the lower half of the body. Calf muscles initially enlarge during the ages of 5–15 (an attempt by the body to compensate for the loss of muscle strength), but the enlarged muscle tissue is eventually replaced by fat and connective tissue (pseudohypertrophy) as the legs become less used (with use of a wheelchair).
=== Corruption === The phosphates sector – accounting for 40% of export revenues – is managed at the office of the president, and Abdi Latif Dahir, based on the Panama Papers, stated that contracts and permits to manage the sector are sold to benefit the president.
SO3 + H2O → H2SO4 (ΔfH = −200 kJ/mol) Gaseous sulfur trioxide fumes profusely even in a relatively dry atmosphere owing to formation of a sulfuric acid mist. SO3 is aggressively hygroscopic. The heat of hydration is sufficient that mixtures of SO3 and wood or cotton can ignite. In such cases, SO3 dehydrates these carbohydrates. Akin to the behavior of H2O, hydrogen fluoride adds to give fluorosulfuric acid:
Sources: en.wikipedia.org
=== United States === In the United States, semaglutide is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes, and to reduce the risk of major adverse cardiovascular events in adults with type 2 diabetes and established cardiovascular disease. In combination with a reduced-calorie diet and increased physical activity, semaglutide (as Wegovy) is indicated to reduce the risk of major adverse cardiovascular events (cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke) in adults with established cardiovascular disease and who are either obese or overweight; to reduce excess body weight and maintain weight reduction long term in obese individuals twelve years of age or older, or for overweight adults with at least one weight-related comorbid condition. In August 2025, the Food and Drug Administration (FDA) expanded the indication for semaglutide (as Wegovy) to include the treatment of noncirrhotic metabolic-associated steatohepatitis (MASH), formerly known as nonalcoholic steatohepatitis (NASH), with moderate to advanced liver fibrosis (consistent with stages F2 to F3 fibrosis) in adults. In October 2025, the FDA further expanded the indication for semaglutide (as Rybelsus) to reduce the risk of major adverse cardiovascular events (cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke) in adults with type 2 diabetes who are at high risk for these events.
Antagomirs were first developed to target miR-122, a microRNA that was abundant and specific to the liver, and this discovery has led to the development of other antagomirs that can pair with specific microRNAs present in the tumor microenvironment or in the cancer cells. A microRNA mimic to miR-655 was found to suppress EMT through the targeting of EMT inducing transcription factor ZEB1 and TGF-β receptor 2 in a pancreatic cancer cell line. Overexpression of the miR-655 mimic in the Panc1 cancer cell line upregulated the expression of E-cadherin and suppressed the migration and invasion of mesenchymal-like cancer cells. The use of microRNA mimics to suppress EMT has expanded to other cancer cell lines and holds potential for clinical drug development. However, microRNA mimics and antagomirs suffer from a lack of stability in vivo and lack an accurate delivery system to target these molecules to the tumor cells or tissue for treatment. Improvements to antagomir and microRNA mimic stability through chemical modifications such as locked nucleic acid (LNA) oligonucleotides or peptide nucleic acids (PNA) can prevent the fast clearing of these small molecules by RNases. Delivery of antagomirs and microRNA mimics into cells by enclosing these molecules in liposome-nanoparticles has generated interest however liposome structures suffer from their own drawbacks that will need to be overcome for their effective use as a drug delivery mechanism. These drawbacks of liposome-nanoparticles include nonspecific uptake by cells and induction of immune responses.
In 1920, Hermann Staudinger published his seminal work "Über Polymerisation", in which he proposed that polymers were in fact long chains of atoms linked by covalent bonds. His work was debated at length, but eventually it was accepted by the scientific community. Because of this work, Staudinger was awarded the Nobel Prize in 1953. After the 1930s polymers entered a golden age during which new types were discovered and quickly given commercial applications, replacing naturally-sourced materials. This development was fuelled by an industrial sector with a strong economic drive and it was supported by a broad academic community that contributed innovative syntheses of monomers from cheaper raw material, more efficient polymerisation processes, improved techniques for polymer characterisation and advanced, theoretical understanding of polymers.
GSH + R• → RH + GS• → 1/2 GSSG Thiyl radicals (such as glutathionyl radicals) are themselves oxidizing species in biology, with a single-electron reduction potential sufficient for oxidation of nucleic acids, proteins and polyunsaturated lipids. Therefore, GSH itself may not be effective at direct reduction of reactive oxygen species under physiological conditions. Under oxidizing conditions, hydrogen sulfide may react with glutathione (or other electrophilic oxidized forms of glutathione) to form glutathione hydropersulfide (GS–SH), which is a superior radical-trapping antioxidant and reductant. GSH is a highly important indirect antioxidant by acting as a coenzyme for various enzymes that couple GSH-to-GSSG oxidation to the reduction of harmful oxidizing species. Such enzymes include the glutathione peroxidase family, the glutaredoxin family, the peroxiredoxin family, and others.
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.
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.