This is a working overview of GSH, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-07 and is reviewed periodically as new material appears.
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.
Cells synthesize glutathione through two ATP-dependent steps: glutamate-cysteine ligase joins glutamate and cysteine, and glutathione synthetase adds glycine to form the complete tripeptide. Breakdown occurs through gamma-glutamyl transpeptidase and subsequent peptidase reactions, forming the gamma-glutamyl cycle. Within cells, glutathione also forms a disulfide-linked dimer called GSSG when two GSH molecules react. The balance between GSH and GSSG is widely used as an indicator of oxidative conditions, although the ratio can vary by compartment and tissue.
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.
| 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 |
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.
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.
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.
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.
After failing to secure a major label contract, Danniels founded the independent Moon Records and negotiated a distribution deal with London Records for a single and one full-length album. For their debut release, the band selected a cover of Buddy Holly's "Not Fade Away" as it had become a crowd favourite, with "You Can't Fight It", an original song, on the B-side. Released in September 1973, the single peaked at No. 88 on the national RPM Top Singles chart. The launch coincided with the band's first major high-profile engagement, opening for the New York Dolls in Toronto.
The three substrates of this enzyme are trans-zeatin, reduced nicotinamide adenine dinucleotide phosphate (NADPH) and a proton. Its products are dihydrozeatin and NADP+. The enzyme does not act on cis-zeatin. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is dihydrozeatin:NADP+ oxidoreductase.
=== System II === Cytochromes c in chloroplasts, Gram-positive bacteria, cyanobacteria, and some Pseudomonadota are produced by the cytochrome c synthesis (ccs) system. It is composed of two membrane proteins CcsB and CcsA. The CcsBA protein complex was suggested to act as a heme transporter during the attachment process. In some organisms such as Helicobacter hepaticus both proteins are found as a fused single protein. Apoprotein transport occurs via the Sec translocon as well.
=== Terrestrial === The composition of terrestrial species on the Kuril islands is dominated by Asian mainland taxa via migration from Hokkaido and Sakhalin Islands and by Kamchatkan taxa from the North. While highly diverse, there is a relatively low level of endemism on a species level. The WWF divides the Kuril Islands into two ecoregions. The southern Kurils, along with southwestern Sakhalin, comprise the South Sakhalin-Kurile mixed forests ecoregion. The northern islands are part of the Kamchatka-Kurile meadows and sparse forests, a larger ecoregion that extends onto the Kamchatka Peninsula and Commander Islands. The Miyabe Line dividing the differing sets of predominant plants of the Kurils corresponds to the Vries Strait between Iturup and Urup. Because of the generally smaller size and isolation of the central islands, few major terrestrial mammals have colonized these, though red and Arctic foxes were introduced for the sake of the fur trade in the 1880s. The bulk of the terrestrial mammal biomass is taken up by rodents, many introduced in historical times. The largest southernmost and northernmost islands are inhabited by brown bear, foxes, and martens. Leopards once inhabited the islands. Some species of deer are found on the more southerly islands. It is claimed that a wild cat, the Kurilian Bobtail, originates from the Kuril Islands. The bobtail is due to the mutation of a dominant gene. The cat has been domesticated and exported to nearby Russia and bred there, becoming a popular domestic cat.
Sources: en.wikipedia.org
APHL works with public health partners to build the foundation for quality testing, comprehensive standards and integrated public health laboratory systems. One of the initiatives, the Laboratory System Improvement Program, provides individual assessments of public health laboratory systems that include engaging stakeholders for system improvement, performance, implementation of strategies and continual evaluation. APHL also collaborates on the National Laboratory System project to build a public-private network of laboratories nationwide. APHL monitors trends in public health laboratory diagnostics, personnel and infrastructure in order to create quality assurance standards. By using these data points to benchmark individual labs against national norms, APHL is able to home in on key issues and help raise the standard of laboratory systems. Member labs have access to research and survey data online, which enables them to leverage new information quickly to identify promising strategies and practices.
To annotate the vast amounts of available NGS data, currently a large number of SNPs annotation tools are available. Some of them are specific to specific SNPs while others are more general. Some of the available SNPs annotation tools are as follows SNPeff, Ensembl Variant Effect Predictor (VEP), ANNOVAR, FATHMM, PhD-SNP, PolyPhen-2, SuSPect, F-SNP, AnnTools, SeattleSeq, SNPit, SCAN, Snap, SNPs&GO, LS-SNP, Snat, TREAT, TRAMS, Maviant, MutationTaster, SNPdat, Snpranker, NGS – SNP, SVA, VARIANT, SIFT, LIST-S2, PhD-SNP and FAST-SNP. The functions and approaches used in SNPs annotation tools are listed below. Variant annotation tools use machine learning algorithms to predict variant annotations. Different annotation tools use different algorithms. Common algorithms include: Interval/Random forest-eg.MutPred, SNPeff Neural networks-eg.SNAP Support Vector Machines-e.g. PhD-SNP, SNPs&GO Bayesian classification-eg.PolyPhen-2
4-Aminosalicylic acid was first synthesized by Seidel and Bittner in 1902. It was rediscovered by the Swedish chemist Jörgen Lehmann upon the report that the tuberculosis bacterium avidly metabolized salicylic acid. Lehmann first tried PAS as an oral TB therapy late in 1944. The first patient made a dramatic recovery. The manner in which Lehmann discovered the TB indication for PAS was salient in the history of drug discovery because it was a rare example in which a person mentally postulated the exact molecule for a drug based on their acquired knowledge of the biochemical behaviour of an analogue of the molecule. The drug proved better than streptomycin, which had nerve toxicity and to which TB could easily develop resistance. In 1948, researchers at Britain's Medical Research Council demonstrated that combined treatment with streptomycin and PAS was superior to either drug alone, and established the principle of combination therapy for tuberculosis. 4-Aminosalicylic acid has many names including para-aminosalicylic acid, p-aminosalicylic acid, 4-ASA, and simply P.
Oligosaccharides have diverse structures. The number of monosaccharides, ring size, the different anomeric stereochemistry, and the existence of the branched-chain sugars all contribute to the amazing complexity of the oligosaccharide structures. The essence of the reducing oligosaccharide synthesis is connecting the anomeric hydroxyl of the glycosyl donors to the alcoholic hydroxyl groups of the glycosyl acceptors. Protection of the hydroxyl groups of the acceptor with the target alcoholic hydroxyl group unprotected can assure regiochemical control. Additionally, factors such as the different protecting groups, the solvent, and the glycosylation methods can influence which anomer is formed.
Considering the likely abundance ratio of 244Pu to 238U in the early solar system (~0.008), this upper limit is still 18 times greater than the expected present 244Pu content in the bastnasite sample (1.2×10−21 g/g). Live interstellar plutonium-244 has been detected in meteorite dust in marine sediments, though the levels detected are much lower than would be expected from current modelling of the in-fall from the interstellar medium. Trace amounts of 244Pu were also found in rock from the Pacific ocean by a Japanese oil exploration company. It is important to recall, however, that in order to be a primordial nuclide – one whose origin lay in the amalgam orbiting the Sun that ultimately coalesced into the Earth – the plutonium-244 must have comprised some of the solar nebula, rather than having been replenished by extrasolar meteoritic dust.
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.
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.