The short version of thiol fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-21 and is reviewed periodically as new material appears.
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.
Laboratory measurement of glutathione requires attention to oxidation before analysis. Blood, tissue, or cell samples can lose reduced glutathione as it converts to GSSG or forms mixed disulfides with proteins. Acid extraction, rapid freezing, and thiol-blocking reagents are common strategies to preserve the original distribution. Reported concentrations therefore depend on collection protocol, extraction method, and the time between sampling and analysis. Comparisons across studies are most reliable when these pre-analytical variables are described.
Common analytical approaches include enzymatic recycling assays, high-performance liquid chromatography, and mass spectrometry. The enzymatic recycling assay uses glutathione reductase and a colorimetric or fluorometric reagent to amplify signal, which gives good sensitivity for total glutathione. Chromatographic methods can separate GSH from GSSG and related thiols, while mass spectrometry offers structural confirmation and multiplexing. Each approach has different requirements for calibration, internal standards, and validation. No single method captures every form of glutathione in every matrix.
| 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 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.
In cells, glutathione exists mainly in a reduced form called GSH. When two GSH molecules react, they form oxidized glutathione, or GSSG, which contains a disulfide bond. The ratio of GSH to GSSG is often used as an indicator of oxidative stress. Enzymes such as glutathione peroxidase and glutathione reductase help cycle the molecule between these two states. This cycling supports antioxidant defense, detoxification of reactive molecules, and regulation of certain signaling pathways.
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.
In living systems, glutathione occurs in millimolar concentrations in many cell types, while extracellular levels are generally much lower. The liver holds a substantial share of the body's total pool, and the molecule participates in reduction, detoxification, and amino acid transport. It also serves as a cofactor for enzymes such as glutathione peroxidase and glutathione S-transferase. Because the cysteine residue supplies a reactive thiol, glutathione can donate electrons and become oxidized. Cells regenerate reduced glutathione through glutathione reductase using NADPH.
Commercial glutathione is produced by microbial fermentation or chemical synthesis, then purified. Reduced and oxidized grades are offered separately, with purity specifications often exceeding 98 percent. The compound appears in foods such as fresh fruits, vegetables, and meats, although cooking and processing can lower amounts. Oral, topical, and inhaled forms are discussed in research and consumer contexts, but absorption and tissue delivery remain active areas of study. Regulatory status varies by country and intended use.
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.
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.
=== Archaea === In 2022, the discovery of serotonin N-acetyltransferase (SNAT)—the penultimate, rate-limiting enzyme in the melatonin biosynthetic pathway—in the archaeon Thermoplasma volcanium firmly places melatonin biosynthesis in all three major domains of life, dating back to ~4 Gya.
== Eutectic mixture == Separately, lidocaine and prilocaine are solid bases. When mixed in equal quantities by weight, however, they form a eutectic mixture – that is the melting point of the mixture is lower than the melting points of the individual components. The lidocaine/prilocaine eutectic mixture is an oil with a melting point of 18 °C, and can be formulated into preparations without the use of a non-aqueous solvent. This allows higher concentrations of anaesthetic to be formulated into the preparation and maintained during application.
1911 – Marie Sklodowska-Curie – discovery of radium & polonium 1935 – Irène Joliot-Curie – artificial radioactivity 1964 – Dorothy Crowfoot Hodgkin – protein crystallography 2009 – Ada E. Yonath – structure & function of the ribosome 2018 – Frances Arnold – directed evolution to engineer enzymes 2020 – Emmanuelle Charpentier and Jennifer Doudna – for CRISPR gene editing 2022 - Carolyn R. Bertozzi - for bioorthogonal chemistry Eight women have won the Nobel Prize in Chemistry (listed above), awarded annually since 1901 by the Royal Swedish Academy of Sciences. Marie Curie was the first woman to receive the prize in 1911, which was her second Nobel Prize (she also won the prize in physics in 1903, along with Pierre Curie and Henri Becquerel – making her the only woman to be award two Nobel prizes). Her prize in chemistry was for her "discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element." Irene Joliot-Curie, Marie's daughter, became the second woman to be awarded this prize in 1935 for her discovery of artificial radioactivity. Dorothy Hodgkin won the prize in 1964 for the development of protein crystallography. Among her significant discoveries are the structures of penicillin and vitamin B12. Forty five years later, Ada Yonath shared the prize with Venkatraman Ramakrishnan and Thomas A. Steitz for the study of the structure and function of the ribosome.
Sources: en.wikipedia.org
== Research == His main research was to uncover the basic mechanisms for how plants and bacteria use photosynthesis to convert light into chemical energy. In 1971, Feher's laboratory and Roderick Clayton's laboratory independently purified minimal bacterial photosynthetic reaction center preparations from Rhodobacter sphaeroides. Feher's main contributions to science were the development of spectroscopic tools and their applications, in particular, to problems in biochemistry and biophysics. He was the first to develop a form of double-frequency spectroscopy, Electron nuclear double resonance (ENDOR), for which he chose a name reminiscent of the biblical witch of Endor. This was the forerunner of many other double-resonance methods.
The verdict was treated with scepticism by much of the international media and the US Government led by President Jimmy Carter. On 2 February 1978, based on the evidence given at the inquest, the attorney general of the Eastern Cape stated that he would not prosecute the officers. After the inquest, Biko's family brought a civil case against the state; at the advice of their lawyers, they agreed to a settlement of R65,000 (US$78,000) in July 1979. Shortly after the inquest, the South African Medical and Dental Council initiated proceedings against the medical professionals who had been entrusted with Biko's care; eight years later two of the medics were found guilty of improper conduct. The failure of the government-employed doctors to diagnose or treat Biko's injuries has been frequently cited as an example of a repressive state influencing medical practitioners' decisions, and Biko's death as evidence of the need for doctors to serve the needs of patients before those of the state. After the abolition of apartheid and the establishment of a majority government in 1994, a Truth and Reconciliation Commission was established to investigate past human-rights abuses. The commission made plans to investigate Biko's death, but his family petitioned against this on the grounds that the commission could grant amnesty to those responsible, thereby preventing the family's right to justice and redress. In 1996, the Constitutional Court ruled against the family, allowing the investigation to proceed.
ENGERIX-B (produced by GSK) and RECOMBIVAX HB (produced by merck) are two recombinant subunit vaccines licensed for the protection against hepatitis B. Both contain HBsAg harvested and purified from Saccharomyces cerevisiae and are formulated as a suspension of the antigen adjuvanted with alum. Antibody concentration ≥10mIU/mL against HBsAg are recognized as conferring protection against hepatitis B infection. It has been shown that primary 3-dose vaccination of healthy individuals is associated with ≥90% seroprotection rates for ENGERIX-B, despite decreasing with older age. Lower seroprotection rates are also associated with presence of underlying chronic diseases and immunodeficiency. Yet, GSK HepB still has a clinically acceptable safety profile in all studied populations.
Sources: en.wikipedia.org
== Related compounds == Other carbamates include methyl carbamate, butyl carbamate, and phenyl carbamate (m. p. 149–152 °C), which can also be prepared from the corresponding chloroformate and ammonia. These esters are white, crystalline solids at room temperature. Except for the phenyl carbamate, they sublime at moderate temperatures; methyl carbamate sublimes at room temperatures. The first two and ethyl carbamate are very soluble in water, benzene, and ether. These other carbamates (methyl, butyl, and phenyl) are only used in small quantities for research purposes.
=== Sword === The sword is commonly thought to be a gift from the Fisher King to Perceval. This is then followed by Perceval's cousin's prophecy that the sword will break at a crucial moment. In two cases, the writers tell us that Perceval broke the sword: in Eschenbach, it fails him in his battle against his half-brother at the end of Parzival; and Gerbert de Montreuil describes how he shatters it on the gates of the "Earthly Paradise". The adventure of the broken sword is a theme originally introduced by Chrétien, who intended it as a symbol of Perceval's imperfections as a knight. The major example for his imperfection is that Perceval refused to ask about the Grail. This concept of punishment is also seen in Eschenbach's tale where Perceval is told: "your uncle gave you a sword, too, by which you have been granted since your eloquent mouth unfortunately voiced no question there." The sword remains as a plot device to both remind Perceval of how he failed to ask the healing question and as a physical reminder of the existence of "Munsalvaesche" (Eschenbach's name for Corbenic).
==== Revolts of the era of the Spring of Nations ==== The planned national uprising failed to materialize because the authorities in the partitions found out about secret preparations. The Greater Poland uprising ended in a fiasco in early 1846. In the Kraków uprising of February 1846, patriotic action was combined with revolutionary demands, but the result was the incorporation of the Free City of Cracow into the Austrian Partition. The Austrian officials took advantage of peasant discontent and incited villagers against the noble-dominated insurgent units. This resulted in the Galician slaughter of 1846, a large-scale rebellion of serfs seeking relief from their post-feudal condition of mandatory labor as practiced in folwarks. The uprising freed many from bondage and hastened decisions that led to the abolition of Polish serfdom in the Austrian Empire in 1848. A new wave of Polish involvement in revolutionary movements soon took place in the partitions and in other parts of Europe in the context of the Spring of Nations revolutions of 1848 (e.g. Józef Bem's participation in the revolutions in Austria and Hungary). The 1848 German revolutions precipitated the Greater Poland uprising of 1848, in which peasants in the Prussian Partition, who were by then largely enfranchised, played a prominent role.
Osborne's ligament, also Osborne's band, Osborne's fascia, Osborne's arcade, arcuate ligament of Osborne, or the cubital tunnel retinaculum, refers to either the connective tissue which spans the humeral and ulnar heads of the flexor carpi ulnaris (FCU) or another distinct tissue located between the olecranon process of the ulna and the medial epicondyle of the humerus. It is named after Geoffrey Vaughan Osborne, a British orthopedic surgeon, who described the eponymous tissue in 1957.
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.
Pre-analytical handling, extraction chemistry, and detection method all influence reported glutathione values. Oxidation during sample processing can shift the measured GSH/GSSG ratio. Standardized protocols and reference materials help reduce, but do not eliminate, these differences.