glutathione synthetase is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-05-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Stability depends on pH, temperature, oxygen exposure, and trace metals. Aqueous solutions of reduced glutathione are susceptible to oxidation, especially when neutral or alkaline and exposed to air. Transition metal ions can catalyze thiol oxidation, so chelators and inert atmospheres are sometimes used in research settings. Standards are typically stored cold and desiccated, with limited freeze-thaw cycles. Questions remain about how closely in vitro stability data reflect the behavior of glutathione within intact cells and tissues.
Measuring glutathione requires attention to oxidation during sample handling, because GSH in biological samples can convert to GSSG or form mixed disulfides with proteins after collection. Acidic extraction, rapid cooling, and chelating agents are commonly used to limit such changes. Analytical methods usually distinguish free reduced glutathione, total glutathione, and protein-bound forms. Because these forms have different stability and reactivity, reported values depend heavily on the preparation protocol. No single preparation is universally suitable for every biological matrix or analytical goal.
Several techniques are used for quantification. Enzymatic recycling assays rely on glutathione reductase and a colorimetric or fluorescent readout, offering sensitivity for total glutathione. High-performance liquid chromatography can separate GSH from GSSG and other thiols, often with UV, fluorescence, or electrochemical detection. Mass spectrometry provides structural confirmation and can quantify low-abundance species when paired with separation. Each approach has trade-offs in specificity, throughput, and equipment requirements, so method selection depends on the research question and available instrumentation.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C10H17N3O6S | Refers to the reduced form |
| Molar mass | 307.32 g/mol | Calculated for the neutral molecule |
| Appearance | White crystalline powder | Often hygroscopic; protect from moisture |
| Water solubility | Soluble in water | Reported values vary with purity and form |
| Alternative names | GSH, reduced glutathione | GSH specifies the thiol form |
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.
Glutathione is a small tripeptide composed of glutamate, cysteine, and glycine, with the unusual gamma-glutamyl linkage between glutamate and cysteine. Its cysteine thiol group makes it a major non-enzymatic antioxidant in cells. The reduced form, GSH, predominates in most intracellular compartments, while the oxidized disulfide form, GSSG, is produced when GSH reduces reactive oxygen species. Intracellular concentrations often reach millimolar levels, whereas plasma concentrations are much lower, typically in the low micromolar range. This gradient reflects active synthesis, transport, and consumption rather than passive distribution.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine, and it is the most abundant non-protein thiol in most living cells. The reduced form, GSH, carries a sulfhydryl group that can donate electrons, while the oxidized form, GSSG, forms when two GSH molecules link via a disulfide bond. The balance between these two forms helps define the cellular redox environment, and their ratio is often used as an indicator of oxidative stress. Because the sulfhydryl group is reactive, glutathione participates in many cellular processes, including detoxification and protein regulation.
Glutathione is synthesized in two ATP-dependent steps. First, gamma-glutamylcysteine synthetase links glutamate and cysteine; second, glutathione synthetase adds glycine to form the complete tripeptide. The pathway is feedback-inhibited by GSH itself, which helps maintain steady intracellular levels. Tissues vary widely in glutathione content, with the liver typically containing the highest concentrations, followed by the kidneys, lungs, and erythrocytes. Because cysteine is often limiting, its availability influences synthesis rates, and regulation of this pathway varies by cell type.
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.
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.
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.
Nuclear fuel data and analysis from the U.S. Energy Information Administration World Uranium deposit maps Dittmar, William (1888). "Uranium" . Encyclopædia Britannica. Vol. XXIV (9th ed.). p. 7. Annotated bibliography for uranium from the Alsos Digital Library NLM Hazardous Substances Databank – Uranium, Radioactive CDC – NIOSH Pocket Guide to Chemical Hazards ATSDR Case Studies in Environmental Medicine: Uranium Toxicity Archived 4 February 2016 at the Wayback Machine U.S. Department of Health and Human Services Uranium at The Periodic Table of Videos (University of Nottingham)
=== DNA and gene synthesis === Driven by dramatic decreases in costs of oligonucleotide ("oligos") synthesis and the advent of PCR, the sizes of DNA constructions from oligos have increased to the genomic level. In 2000, researchers reported synthesis of the 9.6 kbp (kilo bp) Hepatitis C virus genome from chemically synthesized 60 to 80-mers. In 2002, researchers at Stony Brook University succeeded in synthesizing the 7741 bp poliovirus genome from its published sequence, producing the second synthetic genome, spanning two years. In 2003, the 5386 bp genome of the bacteriophage Phi X 174 was assembled in about two weeks. In 2006, the same team, at the J. Craig Venter Institute, constructed and patented a synthetic genome of a novel minimal bacterium, Mycoplasma laboratorium and were working on getting it functioning in a living cell. In 2007, it was reported that several companies were offering synthesis of genetic sequences up to 2000 base pairs (bp) long, for a price of about $1 per bp and a turnaround time of less than two weeks. Oligonucleotides harvested from a photolithographic- or inkjet-manufactured DNA chip combined with PCR and DNA mismatch error-correction allows inexpensive large-scale changes of codons in genetic systems to improve gene expression or incorporate novel amino-acids (see George M. Church's and Anthony Forster's synthetic cell projects.). This favors a synthesis-from-scratch approach. Additionally, the CRISPR/Cas system has emerged as a promising technique for gene editing.
== Clinical significance == Some can be useful in measuring rates of metabolic processes (for example, 3,4-dihydroxyphenylacetic acid or 3-aminoisobutyrate). Because they can represent unnatural points of entry into natural metabolic pathways, some (such as AICA ribonucleotide) are of interest to researchers in developing new therapies.
=== Laboratory applications === In the laboratory, EDTA is widely used for scavenging metal ions: In biochemistry and molecular biology, ion depletion is commonly used to deactivate metal-dependent enzymes, either as an assay for their reactivity or to suppress damage to DNA, proteins, and polysaccharides. EDTA also acts as a selective inhibitor against dNTP hydrolyzing enzymes (Taq polymerase, dUTPase, MutT), liver arginase and horseradish peroxidase independently of metal ion chelation. These findings urge the rethinking of the utilisation of EDTA as a biochemically inactive metal ion scavenger in enzymatic experiments. In analytical chemistry, EDTA is used in complexometric titrations and analysis of water hardness or as a masking agent to sequester metal ions that would interfere with the analyses. EDTA finds many specialised uses in the biomedical labs, such as in veterinary ophthalmology as an anticollagenase to prevent the worsening of corneal ulcers in animals. In tissue culture, EDTA is used as a chelating agent that binds to calcium and prevents joining of cadherins between cells, preventing clumping of cells grown in liquid suspension, or detaching adherent cells for passaging. In histopathology, EDTA can be used as a decalcifying agent making it possible to cut sections using a microtome once the tissue sample is demineralised. EDTA is also known to inhibit a range of metallopeptidases, the method of inhibition occurs via the chelation of the metal ion required for catalytic activity.
==== Animal biosynthesis and food sources ==== Most land-based vertebrates – mammals, reptiles, birds, and amphibians – produce vitamin D in response to ultraviolet light. Carnivores and omnivores also get the vitamins from their diets, and herbivores can get some vitamins from fungi that are consumed along with plant foods. In the wild, reptiles require either exposure to sunlight or consumption of prey, or both. In captivity, artificial lighting that provides UVB light is preferred to fortified food. The same holds true for birds and amphibians. There are some exceptions. Feline species and dogs are practically incapable of vitamin D synthesis due to the high activity of 7-dehydrocholesterol reductase, which converts any 7-dehydrocholesterol in the skin to cholesterol before it can be UVB light-modified, but instead get vitamin D from diet. Fish do not synthesize vitamin D from exposure to ultraviolet light. Wild-caught fish obtain vitamin D via a diet of phytoplankton, zooplankton, and the aquatic food chain. Commercially raised fish are fed D3 fortified diets. As with land-based vertebrates, the vitamin is transported by vitamin D binding protein to target cells. Aquaculture research shows that the vitamin is needed for bone health, optimizing growth, reducing fatty liver problems and supporting immune health. Unlike land-based vertebrates, large amounts of vitamin D3 are stored in the liver and fatty tissues, making fish a good dietary source for human consumption.
Sources: en.wikipedia.org
==== Canada ==== In Canada, Pfizer's patent 2,324,324 for Revatio (sildenafil used to treat pulmonary hypertension) was found invalid by the Federal Court in June 2010, on an application by Ratiopharm Inc. On 8 November 2012, the Supreme Court of Canada ruled that Pfizer's patent 2,163,446 on Viagra was invalid from the beginning because the company did not provide full disclosure in its application. The decision, Teva Canada Ltd. v. Pfizer Canada Inc., pointed to section 27(3)(b) of The Patent Act which requires that disclosure must include sufficient information "to enable any person skilled in the art or science to which it pertains" to produce it. It added further: "As a matter of policy and sound statutory interpretation, patentees cannot be allowed to 'game' the system in this way. This, in my view, is the key issue in this appeal." Teva Canada launched Novo-Sildenafil, a generic version of Viagra, on the day the Supreme Court of Canada released its decision. To remain competitive, Pfizer then reduced the price of Viagra in Canada. However, on 9 November 2012, Pfizer filed a motion for a re-hearing of the appeal in the Supreme Court of Canada, on the grounds that the court accidentally exceeded its jurisdiction by voiding the patent. Finally, on 22 April 2013, the Supreme Court of Canada invalidated Pfizer's patent altogether.
=== Water vascular system === The water vascular system of the starfish is a hydraulic system made up of a network of fluid-filled canals and is concerned with locomotion, adhesion, food manipulation and gas exchange. Water enters the system through the madreporite, a porous, often conspicuous, sieve-like ossicle on the aboral surface. It is linked through a calcareous-lined canal called the stone canal, to a ring canal around the mouth opening. A set of radial canals branch off from the ring canal; one radial canal runs along the ambulacral groove in each arm. There are short lateral canals branching off alternately to either side of the radial canal, each ending in an ampulla. These bulb-shaped organs are joined to tube feet (podia) on the exterior of the animal by short linking canals that pass through ossicles in the ambulacral groove. There are usually two rows of tube feet but in some species, the lateral canals are alternately long and short and there appear to be four rows. The interior of the whole canal system is lined with cilia. Water is pushed into the tube face when longitudinal muscles in the ampullae contract, and shut the valves in the lateral canals. This causes the tube feet to stretch and touch the substrate. Although the tube feet resemble suction cups in appearance, the gripping action is a function of adhesive chemicals rather than suction. Other chemicals and relaxation of the ampullae allow for release from the substrate. The tube feet latch on to surfaces and move in a wave, with one arm section attaching to the surface as another releases.
Subsequent to the initial publication in the Lancet, three letters to the editor and a response from the authors extended the analysis. The issue of contention is whether thiopental, like many lipid-soluble drugs, may be redistributed from blood into tissues after death, effectively lowering thiopental concentrations over time, or whether thiopental may distribute from tissues into the blood, successfully increasing postmortem blood concentrations over time. Given the near absence of scientific, peer-reviewed data regarding thiopental postmortem pharmacokinetics, the controversy continues in the lethal-injection community, and, in consequence, many legal challenges to lethal injection have not used the Lancet article. In 2007, the same group that authored the Lancet study extended its study of the lethal-injection process through a critical examination of the pharmacology of the barbiturate thiopental. This study – published in the online journal PLOS Medicine – confirmed and extended the conclusions made in the original article and goes further to disprove the assertion that the lethal-injection process is painless. To date, these two studies by the University of Miami team serve as the only critical peer-reviewed examination of the pharmacology of the lethal-injection process.
==== Netherlands ==== In the Netherlands, cider is not as commonly available as in its surrounding countries. In 2007, Heineken started testing a cider-based drink branded Jillz in a number of bars throughout the country. The beverage, an alcopop made by blending sparkling water, fruit flavouring, malt, and cider, is marketed towards female drinkers as an alternative to beer. At the same time, Heineken also introduced Strongbow Gold as a secondary brand to provide the choice of a real cider, which was targeted to a male audience. Both beverages contain 5% alcohol by volume, which is similar to a typical draught beer in the Netherlands. Other brands are available in supermarkets, most noticeably Magners and Savanna Cider, and in liquor stores, generally, a broader range may be obtained.
Sources: en.wikipedia.org
=== Health care === Wittman opposes the Affordable Care Act and has voted to repeal it. He said that Congress should not merely be "anti-Obamacare" and that congressional Republicans are ready to provide alternatives if it is deemed unconstitutional. In 2017, he voted for the American Health Care Act, which would have repealed and replaced the ACA.
S-Glutathionylation is the posttranslational modification of protein cysteine residues by the addition of glutathione, the most abundant and important low-molecular-mass thiol within most cell types. Protein S-glutathionylation is involved in the following:
Mescaline is biosynthesized from tyrosine, which, in turn, is derived from phenylalanine by the enzyme phenylalanine hydroxylase. In Lophophora williamsii (peyote), dopamine converts into mescaline in a biosynthetic pathway involving m-O-methylation and aromatic hydroxylation. Tyrosine and phenylalanine serve as metabolic precursors towards the synthesis of mescaline. Tyrosine can either undergo a decarboxylation via tyrosine decarboxylase to generate tyramine and subsequently undergo an oxidation at carbon 3 by a monophenol hydroxylase or first be hydroxylated by tyrosine hydroxylase to form L-DOPA and decarboxylated by DOPA decarboxylase. These create dopamine, which then experiences methylation by a catechol-O-methyltransferase (COMT) by an S-adenosyl methionine (SAM)-dependent mechanism. The resulting intermediate is then oxidized again by a hydroxylase enzyme, likely monophenol hydroxylase again, at carbon 5, and methylated by COMT. The product, methylated at the two meta positions with respect to the alkyl substituent, experiences a final methylation at the 4 carbon by a guaiacol-O-methyltransferase, which also operates by a SAM-dependent mechanism. This final methylation step results in the production of mescaline. Phenylalanine serves as a precursor by first being converted to L-tyrosine by L-amino acid hydroxylase. Once converted, it follows the same pathway as described above.
Sources: en.wikipedia.org
It is a tripeptide of glutamate, cysteine, and glycine. The glutamate-cysteine bond is unusual because it forms through the gamma-carboxyl group.
It reflects the balance between oxidant exposure and antioxidant capacity. The ratio is not a direct clinical diagnosis and depends on the tissue and sample method.
No. It also participates in detoxification, amino acid transport, and protein modification. Its roles vary by cell type and compartment.
Common methods include enzymatic recycling assays, liquid chromatography, and mass spectrometry. Many protocols separate reduced glutathione from its oxidized disulfide form before detection.