The short version of thiol group fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-11-15. Anything still debated is marked as such rather than presented as settled.
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.
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.
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 |
|---|---|---|
| Molecular formula | C10H17N3O6S | Reduced form; oxidized dimer is C20H32N6O12S2 |
| Molar mass | 307.32 g/mol | For reduced glutathione (GSH) |
| Appearance | White crystalline powder | Typical laboratory and supplement-grade material |
| Solubility | Soluble in water | Poorly soluble in ethanol and other nonpolar solvents |
| Typical storage | -20 C, desiccated, protected from light | Reduced form can oxidize in solution |
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.
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.
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.
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.
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.
D* → D + hν For example, A could be luminol and B could be hydrogen peroxide. D would be 3-aminophthalate (3-APA). In theory, one photon of light should be given off for each molecule of reactant. In practice, the yield ("quantum efficiency") is often low owing to side reactions. Chemiluminescence differs from fluorescence or phosphorescence in that the electronic excited state is the product of a chemical reaction rather than of the absorption of a photon. It is the antithesis of a photochemical reaction, in which light is used to drive an endothermic chemical reaction. Instead, here light is generated from a chemically exothermic reaction. The chemiluminescence might be also induced by an electrochemical stimulus and in that case, it is called electrochemiluminescence.
Consultant Urologist, South Tyneside and Sunderland NHS Foundation Trust. For services to the NHS. Dr. Benjamin Marc Ellis. For services to Healthcare, to Equality and to the Jewish Community. Audley Horace English. Co-Founder, Society of Black Architects. For services to Architecture and Sustainability. Professor Stephen James Weston Evans. Emeritus Professor of Pharmacoepidemiology, London School of Hygiene and Tropical Medicine. For services to the Safety of Medicines. Stephen Wynne Evans. Founder, Belief. For voluntary and charitable services in North Wales. Helen Adesuwa Imatitkua Fadipe. Founder and Chair, BAME Planners Network. For services to Town Planning. Paul Fairweather. Trustee, Breakthrough Ltd. For services to Disabled People and to the LGBT Community in the North West. Catherine Susan, Baroness Fall. Lately Non Executive Director, Cultural Recovery Board. For services to Culture. Rhiane Estelle Fatinikun. Founder, Black Girls Hike. For services to Nature and to Diversity. Julie Patricia Felix. For services to Dance Education. James St John Fenny. Head of Office, Public Defender Service and Transplant Surgery Ambassador. For services to Criminal Justice and to Organ Donor Awareness. Dr. Julia Helen Fentem. Executive Vice President, Safety, Environmental and Regulatory Science, Unilever. For services to Human Health and Animal Welfare. Jacqueline Ferguson. President, London College of Dance Network and Volunteer, Healthwatch (Kensington and Chelsea). For services to the community in London. Lucy Catherine Ferguson. Founder and Director, Mediorite.
== History == The origins of CLIA can be traced back to the late 1960s, when cytology laboratories faced issues due to overworked personnel and a high incidence of errors in reading PAP smears. In response to these concerns, the Clinical Laboratory Improvement Amendment was introduced in 1967, which laid down the first set of regulations for laboratory standards, focusing mainly on independent and hospital laboratories. The Clinical Laboratory Improvement Act of 1988 (CLIA 88) was passed in the USA after the publication of an article in November 1987 in The Wall Street Journal entitled "Lax Laboratories: The Pap Test Misses Much Cervical Cancer Through Labs Errors", which alerted the public to the fact that a pap smear may be falsely negative. The article implied that false negative tests were largely due to carelessness among doctors. After this, claims involving pap smears showed an alarming growth. The Act aimed at a comprehensive regulation of gynecologic cytology laboratories.
===== Alloc and miscellaneous groups ===== The allyloxycarbonyl (alloc) protecting group is sometimes used to protect an amino group (or carboxylic acid or alcohol group) when an orthogonal deprotection scheme is required. It is also sometimes used when conducting on-resin cyclic peptide formation, where the peptide is linked to the resin by a side-chain functional group. The Alloc group can be removed using tetrakis(triphenylphosphine)palladium(0). For special applications like synthetic steps involving protein microarrays, protecting groups sometimes termed "lithographic" are used, which are amenable to photochemistry at a particular wavelength of light, and so which can be removed during lithographic types of operations.
This is thought to be helpful in competitive and social situations to conceal motives. Specifically, diurnal animals often have darker sclera to protect the eyes from UV, especially in larger animals where more sclera is exposed. Melanin plays an important role in the pigmentation of the sclera in humans and other animals. Melanin pigment in the sclera is similar to the pigment in the skin and irises where it absorbs UV radiation to prevent deeper penetration and damage to the eyes. Nocturnal animals have larger eyes and pupils to maximize light, while diurnal animals have smaller eyes to enhance visual acuity in bright light. This leads to increasing trends of nocturnal animals having larger sclera and eyeballs overall while diurnal animals have smaller ones for daylight activities.
Sources: en.wikipedia.org
==== Print media ==== While in Wisconsin covering the primary campaign for the United States presidential election of 1972, gonzo journalist Hunter S. Thompson submitted a satirical article to Rolling Stone accusing Democratic Party candidate Edmund Muskie of being addicted to ibogaine. Many readers, and even other journalists, did not realize that the Rolling Stone piece was facetious. The completely unfounded ibogaine assertion did significant damage to Muskie's reputation, and was cited as a factor in his loss of the nomination to George McGovern. Thompson later said he was surprised that anyone believed it. The article is included in Thompson's post-election anthology, Fear and Loathing on the Campaign Trail '72 (1973). Author and Yippie Dana Beal co-wrote the 1997 book The Ibogaine Story. American author Daniel Pinchbeck wrote about his own experience of ibogaine in his book Breaking Open the Head (2002), and in a 2003 article for The Guardian titled "Ten years of therapy in one night". Author and musician Geoff Rickly based his debut novel Someone Who Isn't Me on his real-life experiences with heroin addiction and an ibogaine clinic in Mexico. American investigative journalist, Rachel Nuwer, published a comprehensive feature for Reason magazine titled Can This Psychedelic Help Cure Opioid Addiction? In the article, Rachel speaks with experts in the field of opioid use disorder (OUD) and how ibogaine shows promising results for effective treatment and recovery. This is particularly true for those patients who also suffer from traumatic brain injuries (TBI).
It has been found to interact with AGEs and participate in their clearance. This receptor is primarily expressed on endothelial cells and plays a role in maintaining vascular health by reducing the burden of AGE-modified proteins. SR-BII (Scavenger Receptor Class B Type II):SR-BII is similar to SR-BI but has distinct functions. It binds AGEs and has been implicated in mediating the uptake of modified proteins. SR-BII is involved in lipid transfer processes and, like SR-BI, may contribute to mitigating AGE-induced cellular stress. DC-SIGN (Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin): DC-SIGN is a receptor expressed on dendritic cells that plays a key role in pathogen recognition and immune response. Emerging research suggests that DC-SIGN can bind AGEs and mediate their clearance, reducing AGE-induced immune activation.
For a given acid or base in water, pKa + pKb = pKw, the self-ionization constant of water. The association constant for the formation of a supramolecular complex may be denoted as Ka; in such cases "a" stands for "association", not "acid". For polyprotic acids, the numbering of stepwise association constants is the reverse of the numbering of the dissociation constants. For example, for phosphoric acid (details in the polyprotic acids section below):
Chorionic villi are villi that sprout from the chorion to provide maximal contact area with maternal blood. They are an essential element in pregnancy from a histomorphologic perspective, and are, by definition, a product of conception. Branches of the umbilical arteries carry embryonic blood to the villi. After circulating through the capillaries of the villi, blood returns to the embryo through the umbilical vein. Thus, villi are part of the border between maternal and fetal blood during pregnancy.
Sources: en.wikipedia.org
It is a tripeptide of glutamic acid, cysteine, and glycine. The linkage between glutamate and cysteine uses the gamma-carboxyl group, which is unusual for peptides.
GSH is the reduced form with a free thiol group. GSSG is the oxidized dimer formed when two GSH molecules join by a disulfide bond.
It is synthesized inside cells and is not classified as an essential dietary nutrient for most people. Dietary and supplemental sources are studied, but direct requirements are not established in the same way as for vitamins.
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.