Everything below concerns Glutathione. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-03-26. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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 |
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.
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 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 serves as a cofactor for several enzymes, including glutathione peroxidase and glutathione S-transferase. These enzymes help reduce hydrogen peroxide and lipid peroxides, and they conjugate reactive electrophiles for excretion. The molecule also acts as a reservoir for cysteine, an amino acid that is prone to oxidation. In addition, glutathione participates in the metabolism of nitric oxide, leukotrienes, and prostaglandins. Its roles extend to cell signaling, apoptosis, and the regulation of protein function through S-glutathionylation.
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.
=== Radioactive contamination === RTGs pose a risk of radioactive contamination: if the container holding the fuel leaks, the radioactive material may contaminate the environment. For spacecraft, the main concern is that if an accident were to occur during launch or a subsequent passage of a spacecraft close to Earth, harmful material could be released into the atmosphere; therefore their use in spacecraft and elsewhere has attracted controversy. However, this event is not considered likely with current RTG cask designs. For instance, the environmental impact study for the Cassini–Huygens probe launched in 1997 estimated the probability of contamination accidents at various stages in the mission. The probability of an accident occurring which caused radioactive release from one or more of its three RTGs (or from its 129 radioisotope heater units) during the first 3.5 minutes following launch was estimated at 1 in 1,400; the chances of a release later in the ascent into orbit were 1 in 476; after that the likelihood of an accidental release fell off sharply to less than 1 in a million. If an accident which had the potential to cause contamination occurred during the launch phases (such as the spacecraft failing to reach orbit), the probability of contamination actually being caused by the RTGs was estimated at 1 in 10. The launch was successful and Cassini–Huygens reached Saturn. To minimize the risk of the radioactive material being released, the fuel is stored in individual modular units with their own heat shielding.
On 4 April, explosions were reported at an auxiliary building of the Bushehr Nuclear Power Plant as well as the Mahshahr Special Petrochemical Zone in Mahshahr, Iran. The airstrikes in Mahshahr killed at least five and injured 170 others. An Iranian missile strike hit in the vicinity of the IDF's HaKirya headquarters in Tel Aviv. On 5 April, after heavy fighting, the second stranded crew member from the F-15E downed on 3 April was recovered by US forces in a rescue operation, which resulted in damage to helicopters, the shooting down of an A-10 Thunderbolt II, and the destruction of two C-130 Hercules, three IRGC members killed, and several American service members injured. On 6 April, the IRGC announced that the head of the IRGC's intelligence organization, Major General Majid Khademi, had been killed in a joint US-Israeli airstrike. Their statement claimed that Khademi had "played a major role in Iran's intelligence and security apparatus over nearly five decades". Israel said that Yazdan Mir, a high-ranking commander of the IRGC Quds Force, had also been killed in the attacks. On the same day, before Trump's deadline for targeting Iranian infrastructure, Israel carried out strikes on the South Pars Petrochemical facility in Asaluyeh, Iran. The IAF said that "85% of Iran's petrochemical exports" had been taken offline by now. At least 34 people, including six children, were killed in US-Israeli airstrikes across Iran, including against Sharif University of Technology and residential areas.
== Career and research == Following his PhD, Scrutton was appointed as Lecturer (1995), then Reader (1997) and Professor (1999) at the University of Leicester before being appointed Professor at the University of Manchester in 2005. He has held successive research fellowships over 29 years from the Royal Commission for the Exhibition of 1851 (1851 Research Fellowship), St John's College, Cambridge, the Royal Society (Royal Society University Research Fellow and Royal Society Wolfson Research Merit Award), the Lister Institute of Preventive Medicine, the Biotechnology and Biological Sciences Research Council (BBSRC) and the Engineering and Physical Sciences Research Council (EPSRC). He has been Visiting Professor at Tsinghua University (Beijing, China) and Cardiff University (UK), and adjunct professor at VISTEC (Thailand) and Beijing University of Chemical Technology (China). He has made major contributions to the study of enzyme catalysis, the mechanisms and structures of enzymes and the photochemistry of photoreceptor proteins. His group has investigated quantum tunnelling and protein dynamics in enzyme H-transfer and conformational ensemble sampling in electron transfer reactions. He has also made contributions to enzyme kinetics, coenzyme chemistry, protein engineering, directed evolution, synthetic biology, biological engineering, biocatalysis and metabolic engineering, including the first rational redesign of the coenzyme specificity of an enzyme, the establishment of automated microorganism bioengineering platforms for the production of chemicals (e.g.
Sources: en.wikipedia.org
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=== Other === In traditional Japanese art, alum and animal glue were dissolved in water, forming a liquid known as dousa (ja:礬水), and used as an undercoat for paper sizing. Alum is an ingredient in some recipes for homemade modeling compounds, often called "play clay" or "play dough", intended for use by children. Potassium alum was formerly used as a hardener for photographic emulsions (films and papers), usually as part of the fixer. It has now been replaced in that use by other chemicals.
Formylation reactions are a form of electrophilic aromatic substitution and therefore work best with electron-rich starting materials. Phenols are a common substrate, as they readily deprotonate to excellent phenoxide nucleophiles. Other electron-rich substrates, such as mesitylene, pyrrole, or fused aromatic rings can also be expected to react. Benzene will react under aggressive conditions, but deactivated rings such as pyridine are difficult to formylate effectively. Many formylation reactions will select only the ortho product (e.g. salicylaldehyde), attributed to attraction between the phenoxide and the formylating reagent. Ionic interactions have been invoked for the cationic nitrogen centres in the Vilsmeier–Haack reaction and Duff reaction, and the electron-deficient carbene in the Reimer-Tiemann reaction; coordination to high oxidation metals has been invoked in the Casiraghi and Rieche formylations (cf. Kolbe–Schmitt reaction). The direct reaction between phenol and paraformaldehyde is possible via the Casiraghi formylation, but other methods apply masked forms of formaldehyde, in part to limit the formation of phenol formaldehyde resins. Aldehydes are strongly deactivating and as such phenols typically only react once. However certain reactions, such as the Duff reaction, can give double addition. Formylation can be applied to other aromatic rings. As it generally begins with nucleophilic attack by the aromatic group, the electron density of the ring is an important factor. Some aromatic compounds, such as pyrrole, are known to formylate regioselectively.
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.