tripeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Several analytical methods can quantify glutathione, including high-performance liquid chromatography (HPLC) with UV or fluorescence detection for separating GSH and GSSG. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) offers higher specificity and sensitivity, often detecting nanomolar concentrations. The enzymatic recycling assay, often called the Tietze method, measures total glutathione by coupling reduction of GSSG to a colorimetric or fluorometric readout. Capillary electrophoresis and electrochemical detection are also used in specialized laboratories. Each method has distinct advantages and limitations regarding throughput, cost, and susceptibility to interference.
| Property | Value | Notes |
|---|---|---|
| Common name | Glutathione | Tripeptide of glutamate, cysteine, and glycine |
| Reduced form | GSH | Dominant intracellular thiol |
| Oxidized form | GSSG | Disulfide-linked dimer |
| Molar mass | 307.32 g/mol | For reduced glutathione |
| Functional motif | Gamma-glutamyl-cysteinyl-glycine | Gamma linkage resists many peptidases |
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.
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.
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.
=== MP for Henley: 1974–2001 === Heseltine, by now a junior minister in the Heath government, was now forced to apply for a new candidacy, often in competition with other sitting Conservative MPs whose seats were also due for abolition. He applied for Mid Sussex in competition with Ian Gilmour, but they lost to Tim Renton. He also applied for Mid-Oxfordshire but lost to Douglas Hurd. In 1972 Edward Heath attempted to persuade Heseltine, a strong supporter of his, to challenge Powellite MP Ronald Bell for the Conservative nomination for the new seat of Beaconsfield. Heseltine wrote that he was "tempted" to enter the lists at Beaconsfield, but did not actually do so. Crick writes that he reached the final shortlist of four against Bell, before being "apparently persuaded" to withdraw. Bell's campaign within the local Conservative ranks was masterminded by Hugh Simmonds, chairman of the Young Conservatives, and he narrowly won. Heseltine was one of 180 applicants for the safe Conservative seat of Henley (the constituency association of which was known as North Oxfordshire), whose MP John Hay was stepping down. He reached the final shortlist of three along with two other sitting MPs, William Shelton and Norman Fowler, and in September 1972 was selected as candidate with a clear majority at the first ballot. Part of the reason was that the Association wanted a wealthy MP who would not be distracted by the need to earn money in business as Hay had been. He maintained a constituency home in Crocker End, near Nettlebed, and still maintained a London home at Wilton Crescent.
=== Ka–Ke === Henrik Kacser FRSE (1918–1995). British geneticist and biochemist at Edinburgh, founder of metabolic control analysis. Emil T. Kaiser (1938–1988). Hungarian-born American protein chemist at the University of Chicago, known for his work on enzyme modification. Member Natl. Acad. Sci. USA. Herman Kalckar (1908–1991). Danish biochemist at the New York Public Health Research Institute, who worked on cellular respiration, nucleotide metabolism and galactose metabolism. Member Natl. Acad. Sci. USA Nathan O. Kaplan (1917–1986) Enzymologist at UC San Diego, founding editor of Methods in Enzymology. Member Natl. Acad. Sci. USA Sir Bernard Katz FRS (1911–2003). German-British neuroscientist and biophysicist at University College London. Nobel Prize in Physiology or Medicine (1970) for work on nerve biochemistry and the pineal gland. Stuart Alan Kauffman (b. 1939). American theoretical biologist, expert on complex systems, now at the University of Pennsylvania. Fellow of the Royal Society of Canada. Douglas Kell (b. 1953). British biochemist at the University of Manchester, known for research on functional genomics, metabolomics and the yeast genome. John Kendrew FRS (1917–1997). British x-ray crystallographer at the European Molecular Biology Laboratory, Heidelberg, known for determining the crystal structure of myoglobin. Nobel Prize in Chemistry (1962). Sir Ernest Kennaway FRS (1881–1958), British pathologist at the Institute of Cancer Research, London, who carried out early work on carcinogenic effects of hydrocarbons. Eugene P.
=== Bag of cement and bag mix === The mass of an old bag of cement was one hundredweight (112 pounds, 51 kg). In the concrete and petroleum industry, however, a bag of cement is defined as 94 lb (43 kg) because it has an apparent volume close to 1 cubic foot (28 litres).
Sources: en.wikipedia.org
==== Ukraine ==== According to CrowdStrike from 2014 to 2016, the Russian APT Fancy Bear used Android malware to target the Ukrainian Army's Rocket Forces and Artillery. They distributed an infected version of an Android app whose original purpose was to control targeting data for the D-30 Howitzer artillery. The app, used by Ukrainian officers, was loaded with the X-Agent spyware and posted online on military forums. The attack was claimed by Crowd-Strike to be successful, with more than 80% of Ukrainian D-30 Howitzers destroyed, the highest percentage loss of any artillery pieces in the army (a percentage that had never been previously reported and would mean the loss of nearly the entire arsenal of the biggest artillery piece of the Ukrainian Armed Forces). According to the Ukrainian army this number is incorrect and that losses in artillery weapons "were way below those reported" and that these losses "have nothing to do with the stated cause". In 2014, the Russians were suspected to use a cyber weapon called "Snake", or "Ouroboros," to conduct a cyber attack on Ukraine during a period of political turmoil. The Snake tool kit began spreading into Ukrainian computer systems in 2010. It performed Computer Network Exploitation (CNE), as well as highly sophisticated Computer Network Attacks (CNA). On 23 December 2015 the Black-Energy malware was used in a cyberattack on Ukraine's power-grid that left more than 200,000 people temporarily without power. A mining company and a large railway operator were also victims of the attack.
Failure to thrive due to feeding difficulties Axial muscle weakness, particularly affecting neck and trunk flexors High pitched voice Myopathic facial features A high arched or cleft palate may be present. Later developing features include a progressive scoliosis and respiratory impairment. Ophthalmoplegic form (5–10% cases) This typically presents with weakness of abduction and upward gaze. Ptosis may occur. There is also weakness of the proximal limb muscles. Progressive form with hand involvement (10% cases) The type presents with progressive hand weakness and hypermobility. Hip girdle weakness may be present and exercise induced myalgia is common. Scoliosis and respiratory problems are mild or absent. Antenatal form with arthrogryposis multiplex congenita (10% cases) This diagnosis may be suspected prenatally with reduced fetal movements and polyhydramnios. This typically presents with contractures at birth due to poor foetal movement. Other features include a long head, low set ears and a short neck. The respiratory muscles can be moderately to severely affected and problems with breathing are common.
Neoplasms – Renal cell carcinoma, liver tumors, Von Hippel–Lindau disease, and endocrine abnormalities including pheochromocytoma and adrenal adenoma with Cushing's syndrome. Anabolic steroid use – people whose testosterone levels are high, including athletes who abuse steroids, people on testosterone replacement for hypogonadism or transgender hormone replacement therapy. Blood doping – Athletes who take erythropoietin-stimulating agents or receive blood transfusions to increase their red blood cell mass. Post-transplant erythrocytosis – About 10–15% of patients after renal transplantation are found to have polycythemia at 24 months after transplantation, which can be associated with increased thrombotic (clotting) risk.
Sources: en.wikipedia.org
Glutathione is a tripeptide made from glutamate, cysteine, and glycine. Its cysteine residue provides a thiol group that is central to its redox activity. The glutamate-cysteine bond forms through the gamma-carboxyl group of glutamate.
Reduced glutathione, GSH, can donate electrons and become oxidized to GSSG. The balance between these forms reflects the cell's redox environment. A shift toward GSSG is commonly interpreted as evidence of oxidative stress, though the ratio can vary by tissue and method.
Glutathione occurs in nearly all cell types, with notable amounts in the liver. It is also present in the lungs, kidneys, and red blood cells. Concentrations differ among tissues and change with age, diet, and disease states.
Glutathione oxidizes quickly when cells are disrupted or when samples sit at room temperature. Rapid processing or immediate freezing minimizes the conversion of GSH to GSSG. This step helps ensure that the measured ratio reflects the original biological state.