The short version of thiol fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-04-06. 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.
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.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. Its glutamate-cysteine linkage uses the gamma-carboxyl group of glutamate, a feature that resists standard peptidases. The cysteine residue provides a thiol group, which gives the molecule its reducing character. In cells, glutathione is often the most abundant small-molecule thiol, with concentrations varying widely by tissue and compartment. It exists mainly in a reduced form called GSH, while oxidation produces a disulfide-linked dimer called GSSG.
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.
| 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. |
Synthesis occurs in two ATP-dependent steps: glutamate-cysteine ligase joins glutamate and cysteine to form gamma-glutamylcysteine, and glutathione synthetase adds glycine to complete the tripeptide. The pathway is feedback-inhibited by GSH and limited by cysteine availability, so cysteine supply often constrains production. Once formed, GSH participates in redox buffering, xenobiotic conjugation, and protein glutathionylation. Glutathione peroxidase uses GSH to reduce hydrogen peroxide and lipid peroxides, yielding GSSG, while glutathione reductase regenerates GSH using NADPH. Glutathione S-transferases conjugate electrophiles to GSH, supporting detoxification and excretion.
Because GSH is central to redox balance, its status is studied in aging, liver disease, neurodegenerative conditions, and metabolic disorders. Observational studies often report lower GSH or higher GSSG in affected tissues, but such associations do not establish that raising glutathione changes disease outcomes. Oral glutathione is digested into amino acids, and whether intact absorption occurs remains debated; precursors such as N-acetylcysteine and cysteine donors are also investigated. Regulatory agencies generally treat glutathione as a dietary supplement, not an approved drug, and clinical claims require evidence from controlled trials.
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.
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.
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.
=== Economics === In the United States, the price of for a vial of Humalog increased from US$35 in 2001 to $234 in 2015, or $10.06 and $29.36 per 100 units. In April 2019, Eli Lilly and Company announced they would produce a version selling for $137.35 per vial. The chief executive said that this was a contribution "to fix the problem of high out-of-pocket costs for Americans living with chronic conditions", but Patients for Affordable Drugs Now said it was just a public relations move, as "other countries pay $20 for a vial of insulin." In March 2023, Lilly announced a program capping their insulin prices at $35 per month.
Proponents of such an exception have asserted that there is precedent in allowing psychiatrists to speak out when someone presents a clear and present danger. General John Kelly, Trump's second chief of staff, purchased a copy of The Dangerous Case of Donald Trump in an attempt to understand the president's psychoses and consulted it while he was running the White House, which he was known to refer to as "Crazytown." Kelly told others that the book was a helpful guide to a president he came to consider a pathological liar, and mentally ill. In September 2017, Jeanne Suk Gerson wrote in The New Yorker: "A strange consensus does appear to be forming around Trump's mental state", including Democrats and Republicans who doubt Trump's fitness for office. Also in September 2017, journalist Bill Moyers interviewed psychiatrist Robert Jay Lifton and said that Trump "makes increasingly bizarre statements that are contradicted by irrefutable evidence to the contrary". Lifton replied, "He doesn't have clear contact with reality, though I'm not sure it qualifies as a bona fide delusion." As an example, Lifton said, when Trump claimed that former president Barack Obama was born in Kenya, "he was manipulating that lie as well as undoubtedly believing it in part." In September 2017, psychiatrist Jeffrey Lieberman published an article commenting on Donald Trump's mental health. He said that, in accordance with the Goldwater rule, no diagnosis should be made of public figures, but also stated that assessing the president's fitness for government should not be left to politicians alone.
Other cells Various other abnormal cells may be present in the blood in certain conditions. For example, lymphoma cells may be found on the manual differential in some cases of lymphoma, and in mast cell leukaemia, mast cells, which are normally confined to tissue, circulate in the blood. There is a very rare phenomenon called carcinocythemia in which tumour cells are seen on the peripheral blood smear.
HCTU is an amidinium coupling reagent used in peptide synthesis. It is analogous to HBTU. The HOBt moiety has a chlorine in the 6 position which improves reaction rates and the synthesis of difficult couplings HCTU and related reagents containing the 6-chloro-1-hydroxybenzotriazole moiety can be prepared by reaction with TCFH under basic conditions. It can exist in an N-form (guanidinium) or an O-form (uronium), but the N-form is generally considered to be more stable for this class of reagent. In vivo dermal sensitization studies according to OECD 429 confirmed HCTU is a strong skin sensitizer, showing a response at 0.50 wt% in the Local Lymph Node Assay (LLNA) placing it in Globally Harmonized System of Classification and Labelling of Chemicals (GHS) Dermal Sensitization Category 1A.
==== Percutaneous needle fasciotomy ==== Needle aponeurotomy is a minimally-invasive technique where the cords are weakened through the insertion and manipulation of a small needle. It is applicable only if the contracture is clearly visible. The hand is first numbed by injection with local anaesthetic. The cord is then sectioned at as many levels as possible in the palm and fingers, depending on the location and extent of the disease, using perhaps a 25-gauge needle mounted on a 10 ml syringe. Once weakened, the offending cords can be snapped by putting tension on the finger(s) and pulling the finger(s) straight. After the treatment a small dressing is applied for 24 hours, after which people are able to use their hands normally. No splints or physiotherapy are given. The advantage of needle aponeurotomy is the minimal intervention without incision (done in the office under local anesthesia) and the very rapid return to normal activities without need for rehabilitation, but the nodules may resume growing. A study reported postoperative gain is greater at the MCP joint level than at the level of the IP-joint and found a reoperation rate of 24%; complications are scarce. Needle aponeurotomy may be performed on fingers that are severely bent (stage IV), and not just in early stages. A 2003 study showed 85% recurrence rate after five years. A comprehensive review of the results of needle aponeurotomy in 1,013 fingers was performed by Gary M. Pess, MD, Rebecca Pess, DPT, and Rachel Pess, PsyD, and published in The Journal of Hand Surgery April 2012.
Sources: en.wikipedia.org
A small amount of D-phenylalanine appears to be converted to L-phenylalanine. D-Phenylalanine is distributed to the various tissues of the body via the systemic circulation. It appears to cross the blood–brain barrier less efficiently than L-phenylalanine, and so a small amount of an ingested dose of D-phenylalanine is excreted in the urine without penetrating the central nervous system. L-Phenylalanine is an antagonist at α2δ Ca2+ calcium channels with a Ki of 980 nM. In the brain, L-phenylalanine is a competitive antagonist at the glycine binding site of NMDA receptor and at the glutamate binding site of AMPA receptor. At the glycine binding site of NMDA receptor L-phenylalanine has an apparent equilibrium dissociation constant (KB) of 573 μM estimated by Schild regression which is considerably lower than brain L-phenylalanine concentration observed in untreated human phenylketonuria.L-Phenylalanine also inhibits neurotransmitter release at glutamatergic synapses in hippocampus and cortex with IC50 of 980 μM, a brain concentration seen in classical phenylketonuria, whereas D-phenylalanine has a significantly smaller effect.
Civilians returned to power in 1985 when José Sarney assumed the presidency. He became unpopular during his tenure through failure to control the economic crisis and hyperinflation he inherited from the military regime. Sarney's unsuccessful government led to the election in 1989 of the almost-unknown Fernando Collor, who was subsequently impeached by the National Congress in 1992. Collor was succeeded by his vice-president, Itamar Franco, who appointed Fernando Henrique Cardoso as Minister of Finance. In 1994, Cardoso devised a highly successful Plano Real that, after decades of failed economic plans made by previous governments attempting to curb hyperinflation, finally stabilized the Brazilian economy. Cardoso won the 1994 election, and again in 1998.
== Causes == Childhood obesity can be brought on by a range of factors which often act in combination. "Obesogenic environment" refers to a mixture of environmental factors that are permissive of obesity, especially for those who are genetically predisposed. The greatest risk factor for child obesity is the obesity of both parents. This may be reflected by the family's environment and genetics. Other reasons may also be due to psychological factors and the child's body type. A 2010 review stated that childhood obesity likely is the result of the interaction of natural selection favouring those with more parsimonious energy metabolism and today's consumerist society with easy access to cheap, energy-dense foods and less energy requirements in daily life. Factors include the increase in use of technology, increase in snacks and portion size of meals, and the decrease in the physical activity of children. A study found that children who use electronic devices three or more hours a day had between a 17–44% increased risk of being overweight, or a 10–61% increased risk of obesity (Cespedes 2011). Childhood obesity is common among children from low-income, African American and Hispanic communities. This is mainly because minority children spend less time playing outside the house and staying active. Parents may prefer their children stay inside the home because they fear gang and drug violence and other dangers.
==== The labile iron pool ==== In the cytoplasm, ferrous iron is found in a soluble, chelatable state which constitutes the labile iron pool (~0.001 mM). In this pool, iron is thought to be bound to low-mass compounds such as peptides, carboxylates and phosphates, although some might be in a free, hydrated form (aqua ions). Alternatively, iron ions might be bound to specialized proteins known as metallochaperones. Specifically, poly-r(C)-binding proteins PCBP1 and PCBP2 appear to mediate transfer of free iron to ferritin (for storage) and non-heme iron enzymes (for use in catalysis). The labile iron pool is potentially toxic due to iron's ability to generate reactive oxygen species. Iron from this pool can be taken up by mitochondria via mitoferrin to synthesize Fe-S clusters and heme groups.
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.
Glutathione is a sulfur-containing tripeptide made from glutamate, cysteine, and glycine. It is found in most cells and participates in redox balance and detoxification reactions.