If you have been reading about thiol and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-11-19. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Measuring glutathione in biological samples requires attention to oxidation, because GSH can convert to GSSG after sample collection. Blood and plasma samples are often treated with acid or alkylating agents to preserve the reduced form. Without stabilization, apparent GSH concentrations can fall while GSSG rises. Differences in sample type, handling delay, and deproteinization method can produce results that are not comparable across studies. Reporting preanalytical details is therefore important for interpreting findings.
Common analytical approaches include enzymatic recycling assays, high-performance liquid chromatography, and mass spectrometry. Enzymatic recycling measures total glutathione after converting GSSG back to GSH, while separation methods can quantify GSH and GSSG separately. Derivatization may be used to improve detection or stability during analysis. LC-MS/MS offers high specificity and can distinguish glutathione from related thiols and adducts. Each method has different sensitivity, throughput, and susceptibility to interference, so method selection depends on the study question and sample matrix.
For solid glutathione reagents, storage at low temperature and protection from moisture and light are typical precautions. Aqueous solutions can oxidize over time, and pH affects stability; alkaline conditions generally promote thiol oxidation. Some protocols prepare fresh solutions, while others use antioxidants or chelators to limit metal-catalyzed oxidation. Purity and counterion content can vary among commercial preparations, affecting concentration calculations. Certificates of analysis and validated assays help verify identity and purity.
| Property | Value | Notes |
|---|---|---|
| Common name | Glutathione (reduced form) | Often abbreviated GSH |
| Chemical class | Tripeptide | Contains glutamate, cysteine, and glycine |
| Molecular formula | C10H17N3O6S | Refers to the reduced form |
| Molar mass | 307.32 g/mol | Calculated for C10H17N3O6S |
| Appearance | White to off-white powder | Typical laboratory-grade solid |
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. It occurs in nearly all living cells, with highest concentrations in liver, kidney, and red blood cells, and exists in reduced (GSH) and oxidized disulfide (GSSG) forms. The cysteine thiol group enables reversible oxidation and reduction reactions. This property makes glutathione a central participant in cellular redox balance. The balance between these forms is often used as an indicator of oxidative stress.
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.
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.
=== Hospital acute care === Bridion (sugammadex) ($1.7 billion in 2024 revenues) is a medication for the reversal of neuromuscular blockade induced by rocuronium and vecuronium in general anaesthesia. Prevymis (letermovir) ($0.8 billion in 2024 revenues) is used for the prevention of cytomegalovirus infections. Dificid (fidaxomicin) ($0.3 billion in 2024 revenues) is a tiacumicin. Zerbaxa (ceftolozane/tazobactam ($0.3 billion in 2024 revenues) is an antibiotic used to treat urinary tract infections. Noxafil (posaconazole) ($0.2 billion in 2024 revenues) is a triazole antifungal.
=== Specific diseases === A common cause for hyperprolactinemia is prolactinomas and other tumors arising near the pituitary. These adjacent tumors, such as those that cause acromegaly, can physically compress the pituitary stalk and block the flow of dopamine from the hypothalamus to the pituitary gland, causing prolactin levels to increase. Other causes include chronic kidney failure, hypothyroidism, liver cirrhosis, bronchogenic carcinoma and sarcoidosis. Hyperprolactinemia develops in one-third of individuals with chronic kidney disease due to impaired renal clearance and regulation. Some women with polyendocrine metabolic ovarian syndrome may have mildly elevated prolactin levels. Premenstrual dysphoric disorder appears to be also correlated with elevated prolactin levels. In men, hyperprolactinemia leads to hypoactive sexual desire and, occasionally, erectile dysfunction. However, the link between erectile dysfunction and prolactin levels is not conclusive. When prolactin levels return to normal in these individuals, sexual desire fully recovers; however, erectile dysfunction only partially recovers. Nonpuerperal mastitis may induce transient hyperprolactinemia (neurogenic hyperprolactinemia) of about three weeks' duration; conversely, hyperprolactinemia may contribute to nonpuerperal mastitis. Some inflammatory conditions, such as rheumatoid arthritis and systemic lupus erythematosus, are also linked to higher prolactin levels in certain regions.
=== Features that promote de novo gene birth === Its also of interest to compare features of recently emerged de novo genes to the pool of non-genic ORFs from which they emerge. Theoretical modeling has shown that such differences are the product both of selection for features that increase the likelihood of functionalization, and of neutral evolutionary forces that influence allelic turnover. In budding yeast, systematic deletion and overexpression assays of newly emerged ORFs found that overexpression is enriched for fitness benefits, and that adaptive emerging sequences are biased toward encoding transmembrane domains from thymine-rich intergenic regions. One proposed route to de novo membrane proteins is that poly-A–rich sequences can generate hydrophobic ORFs that are predicted to form transmembrane helices. Across Saccharomycotina yeasts, intergenic regions show widespread enrichment for putative transmembrane-domain encoding potential, and this enrichment (rather than raw hydrophobicity alone) correlates with the abundance of transmembrane domains in evolutionarily young genes. Laboratory studies comparing young de novo proteins to matched unevolved random-sequence proteins found broadly similar predicted biophysical-property distributions, but moderately higher in vitro solubility for de novo proteins (further increased by the DnaK chaperone system). High-throughput sorting of thousands of putative human de novo sORF-encoded proteins by structural compactness showed that older candidates are, on average, more compact and less disordered than younger ones.
Sources: en.wikipedia.org
Laser-based ambient ionization is a two-step process in which a pulsed laser is used to desorb or ablate material from a sample and the plume of material interacts with an electrospray or plasma to create ions. Lasers with ultraviolet and infrared wavelengths and nanosecond to femtosecond pulse widths have been used. Although atmospheric pressure MALDI is performed under ambient conditions, it is not generally considered to be an ambient mass spectrometry technique. Laser ablation was first coupled with mass spectrometry in the 1980s for the analysis of metals using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The laser ablates the sample material that is introduced into an ICP to create atomic ions.
In December 2010, 148 states supported a United Nations' General Assembly resolution calling for the states that use depleted uranium weapons in conflict to reveal where the weapons have been fired when asked to do so by the country upon whose territory they have been used. In April 2011, the Congress of Costa Rica passed a law prohibiting uranium weapons in its territories, becoming the second country in the world to do so. In December 2012, 155 states supported a United Nations' General Assembly resolution that recalled that, because of the ongoing uncertainties over the long-term environmental impacts of depleted uranium identified by the United Nations Environment Programme, states should adopt a precautionary approach to its use. In December 2014, 150 states supported a United Nations' General Assembly resolution encouraging states to provide assistance to states affected by the use of depleted uranium weapons, in particular in identifying and managing contaminated sites and material. In contrast to the previous biennial resolutions, Germany moved to an abstention from supporting to the resolutions. Prior to the vote, in a report to the United Nations Secretary General requested by 2012's resolution published in June 2014, Iraq had called for a global treaty ban on depleted uranium weapons.
=== Antimalarial === During WWII a British team led by Frank Rose discovered (see details there) that some biguanides are useful as antimalarial drugs. Much later it was demonstrated that they are prodrugs metabolised into active dihydrotriazine derivatives which, until recently, were believed to work by inhibiting dihydrofolate reductase. Examples include:
Sources: en.wikipedia.org
=== Alternative splicing === In humans, studies have shown that alternative splicing of the GHR gene can lead to increased rates of proteolysis. For example, a deletion within the mRNA that encodes part of the transmembrane domain of the protein effectively leads to non-translation of the intracellular domain due to the presence of a stop codon. This truncated version of GHR is cleaved more frequently into GHBP and may potentially explain the reasoning behind increased concentrations of GHBP present in some tissues. In mouse and rat models, the extracellular domain is formed primarily through alternative splicing of the precursor GHR mRNA to form a mature transcript that translate GHBP alone. These animals can potentially shed GHBP via post-translational modification as well, although this activity is minimal.
Adsorbents are used usually in the form of spherical pellets, rods, moldings, or monoliths with a hydrodynamic radius between 0.25 and 5 millimetres (0.0098 and 0.1969 in). They must have high abrasion resistance, high thermal stability, and small pore diameters, which results in higher exposed surface area and hence high capacity for adsorption. The adsorbents must also have a distinct pore structure that enables fast transport of the gaseous vapors. Most industrial adsorbents fall into one of three classes:
== Delivery == Granzyme B is released with perforin which inserts into a target cell's plasma membrane forming a pore. Perforin has a radius of 5.5 nm and granzyme B has a stokes radius of 2.5 nm and can therefore pass through the perforin pore into the target to be destroyed. Alternatively, once released, granzyme B can bind to negatively charged heparan sulfate containing receptors on a target cell and become endocytosed. The vesicles that carry the enzyme inside then burst, exposing granzyme b to the cytoplasm and its substrates. Hsp-70 has also been linked to aiding granzyme B entry. Granzyme B has also been proposed to enter a target by first exchanging its bound serglycin for negative phospholipids in a target's plasma membrane. Entry then occurs by the less selective process of absorptive pinocytosis.
Sources: en.wikipedia.org
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.
No. It is a tripeptide assembled from three amino acids. The term amino acid applies to the individual building blocks, not to the assembled molecule.
It is present in many tissues, with especially high amounts in liver. Intracellular concentrations are generally much higher than those found in blood plasma.
Preanalytical factors such as sample type, time to processing, and stabilization method can change GSH and GSSG amounts. Analytical method and calibration also contribute to variation. Comparing absolute values across studies requires caution.