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.
Updated 2026-05-29. Numbers and descriptions here follow the published literature rather than marketing material.
Glutathione is a small tripeptide built from glutamic acid, cysteine, and glycine. Its peptide bond between glutamate and cysteine involves the gamma-carboxyl group rather than the usual alpha-carboxyl group. This structure gives the molecule a reactive thiol on the cysteine residue. The reduced form, often abbreviated GSH, is the predominant intracellular species in many cell types. Because the thiol can donate electrons, glutathione participates in redox chemistry and in the conjugation of reactive molecules.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C10H17N3O6S | Reduced form; oxidized dimer is C20H32N6O12S2 |
| Molar mass | 307.32 g/mol | For reduced glutathione (GSH) |
| Appearance | White crystalline powder | Typical laboratory and supplement-grade material |
| Solubility | Soluble in water | Poorly soluble in ethanol and other nonpolar solvents |
| Typical storage | -20 C, desiccated, protected from light | Reduced form can oxidize in solution |
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.
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.
Glutathione is present in most tissues, with especially high concentrations in the liver. It also serves as a cofactor for some enzymes and helps transport amino acids across cell membranes. In plants and microorganisms, glutathione contributes to stress responses and metal handling. The molecule is synthesized in two ATP-dependent steps, first producing gamma-glutamylcysteine and then adding glycine. Because cysteine availability often limits synthesis, dietary and metabolic factors can influence glutathione levels. Research continues to examine how these levels relate to health and disease.
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.
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.
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.
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.
The most important source of alkanes is natural gas and crude oil. Alkanes are separated in an oil refinery by fractional distillation. Unsaturated hydrocarbons are converted to alkanes by hydrogenation:
== Lubrication == Many driving chains (for example, in factory equipment, or driving a camshaft inside an internal combustion engine) operate in clean environments, and thus the wearing surfaces (that is, the pins and bushings) are safe from precipitation and airborne grit, many even in a sealed environment such as an oil bath. Some roller chains are designed to have o-rings built into the space between the outside link plate and the inside roller link plates. Chain manufacturers began to include this feature in 1971 after the application was invented by Joseph Montano while working for Whitney Chain of Hartford, Connecticut. O-rings were included as a way to improve lubrication to the links of power transmission chains, a service that is vitally important to extending their working life. These rubber fixtures form a barrier that holds factory applied lubricating grease inside the pin and bushing wear areas. Further, the rubber o-rings prevent dirt and other contaminants from entering inside the chain linkages, where such particles would otherwise cause significant wear. There are also many chains that have to operate in dirty conditions, and for size or operational reasons cannot be sealed. Examples include chains on farm equipment, bicycles, and chain saws. These chains will necessarily have relatively high rates of wear. Many oil-based lubricants attract dirt and other particles, eventually forming an abrasive paste that will compound wear on chains.
=== Nora Braverman === Nora Braverman (Mia and Ella Allan), the youngest of Adam and Kristina's three children, was born in late 2011. Her father Adam was negotiating a huge business deal at the time of her birth and was unable to get phone signal coverage; as a result, his brother, Crosby, helped Adam's wife deliver the child.
Glycated hemoglobin, also called glycohemoglobin, is any form of hemoglobin (Hb) that is chemically linked to a sugar. Most monosaccharides, including glucose, galactose, and fructose, spontaneously (that is, non-enzymatically) bond with hemoglobin when they are present in the bloodstream. However, glucose is only 21% as likely to do so as galactose and 13% as likely to do so as fructose, which may explain why glucose is used as the primary metabolic fuel in humans. The formation of excess sugar-hemoglobin linkages indicates the presence of excessive sugar in the bloodstream and is an indicator of diabetes or other hormone diseases in high concentration (HbA1c > 6.4%). A1c is of particular interest because it is easy to detect. The process by which sugars attach to hemoglobin is called glycation and the reference system is based on HbA1c, defined as beta-N-1-deoxy fructosyl hemoglobin as a component. There are several ways to measure glycated hemoglobin, of which HbA1c (or simply A1c) is a standard single test. HbA1c is measured primarily to determine the three-month average blood sugar level and is used as a standard diagnostic test for evaluating the risk of complications of diabetes and as an assessment of glycemic control. The test is considered a three-month average because the average lifespan of a red blood cell is three to four months. Normal levels of glucose produce a normal amount of glycated hemoglobin. As the average amount of plasma glucose increases, the fraction of glycated hemoglobin increases predictably.
Sources: en.wikipedia.org
=== Elastocaloric refrigeration === Another potential solid-state refrigeration technique and a relatively new area of study comes from a special property of super elastic materials. These materials undergo a temperature change when experiencing an applied mechanical stress (called the elastocaloric effect). Since super elastic materials deform reversibly at high strains, the material experiences a flattened elastic region in its stress-strain curve caused by a resulting phase transformation from an austenitic to a martensitic crystal phase. When a super elastic material experiences a stress in the austenitic phase, it undergoes an exothermic phase transformation to the martensitic phase, which causes the material to heat up. Removing the stress reverses the process, restores the material to its austenitic phase, and absorbs heat from the surroundings cooling down the material. The most appealing part of this research is how potentially energy efficient and environmentally friendly this cooling technology is. The different materials used, commonly shape-memory alloys, provide a non-toxic source of emission free refrigeration. The most commonly studied materials studied are shape-memory alloys, like nitinol and Cu-Zn-Al. Nitinol is of the more promising alloys with output heat at about 66 J/cm3 and a temperature change of about 16–20 K. Due to the difficulty in manufacturing some of the shape memory alloys, alternative materials like natural rubber have been studied.
=== Legal status === In Canada, amphetamines are in Schedule I of the Controlled Drugs and Substances Act, and can only be obtained by prescription. In Japan, the use, production, and import of any medicine containing amphetamines is prohibited. In South Korea, amphetamines are prohibited. In Taiwan, amphetamines including Adderall are Schedule 2 drugs with a minimum five-year prison term for possession. On the contrary, Ritalin can be legally prescribed as a form of treatment of ADHD. In Thailand, amphetamines are classified as Type 1 Narcotics. In the United Kingdom, amphetamines are regarded as Class B drugs. The maximum penalty for unauthorized possession is five years in prison and an unlimited fine. The maximum penalty for illegal supply is 14 years in prison and an unlimited fine. In the United States, amphetamine is a Schedule II prescription drug, classified as a central nervous system (CNS) stimulant. Internationally, amphetamine is in Schedule II of the Convention on Psychotropic Substances.
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=== Protein identification === There are two main ways MS is used to identify proteins. Peptide mass fingerprinting uses the masses of proteolytic peptides as input to a search of a database of predicted masses that would arise from digestion of a list of known proteins. If a protein sequence in the reference list gives rise to a significant number of predicted masses that match the experimental values, there is some evidence that this protein was present in the original sample. Purification steps therefore limit the throughput of the peptide mass fingerprinting approach. Alternatively, peptides can be fragmented with MS/MS to more definitively identify them. MS is also the preferred method for the identification of post-translational modifications in proteins versus other approaches such as antibody-based methods.
Adsorption refrigeration also uses a thermally driven sorption process, but the refrigerant is taken up by a solid adsorbent rather than dissolved in a liquid absorbent. Common adsorption working pairs include water with silica gel or zeolite, and methanol with activated carbon. In a basic adsorption cycle, heating the adsorbent releases refrigerant vapour, which is condensed. When the adsorbent is subsequently cooled, it adsorbs refrigerant vapour again; evaporation of the refrigerant during this part of the cycle produces the cooling effect. Adsorption systems can be driven by low-grade heat sources, including solar or waste heat. Adsorption refrigeration has been extensively studied as an alternative to conventional vapor-compression cooling. Reviews have noted advantages such as the potential use of low-grade thermal energy and relatively simple solid-sorbent systems, while also identifying limitations including comparatively low performance and continuing technical and economic challenges. The main difference from absorption cycle is that in adsorption cycle, the refrigerant (adsorbate) can be ammonia, water, methanol, etc., while the adsorbent is a solid, such as silica gel, activated carbon, or zeolite, while in the absorption cycle the absorbent is liquid. The reason adsorption refrigeration technology has been extensively researched in recent 30 years lies in that the operation of an adsorption refrigeration system is often noiseless, non-corrosive and environmentally friendly.
Sources: en.wikipedia.org
==== K ==== Katsuobushi – the Japanese name for dried, fermented, and smoked skipjack tuna (Katsuwonus pelamis). Keumamah – traditional Acehnese dried fish. Kipper – a whole herring, a small, oily fish, that has been split in butterfly fashion from tail to head along the dorsal ridge, gutted, salted or pickled, and cold smoked over smouldering woodchips (typically oak). Kusaya – a salted-dried and fermented fish that is produced in the Izu Islands, Japan. Though the smell of kusaya is strong, its taste is quite mellow.
== Evolutionary significance == The evolution of early reproductive proteins and enzymes is attributed in modern models of evolutionary theory to ultraviolet radiation. UVB causes thymine base pairs next to each other in genetic sequences to bond together into thymine dimers, a disruption in the strand that reproductive enzymes cannot copy. This leads to frameshifting during genetic replication and protein synthesis, usually killing the cell. Before formation of the UV-blocking ozone layer, when early prokaryotes approached the surface of the ocean, they almost invariably died out. The few that survived had developed enzymes that monitored the genetic material and removed thymine dimers by nucleotide excision repair enzymes. Many enzymes and proteins involved in modern mitosis and meiosis are similar to repair enzymes, and are believed to be evolved modifications of the enzymes originally used to overcome DNA damages caused by UV. Elevated levels of ultraviolet radiation, in particular UV-B, have also been speculated as a cause of mass extinctions in the fossil record.
On May 20, 2014, Riff Raff announced through his Twitter that after much delay, Neon Icon was scheduled for a June 24, 2014, release date. The same day the official track listing for the album was revealed, which included previously announced collaborations Mac Miller, Childish Gambino, Paul Wall, Mike Posner and Amber Coffman of Dirty Projectors as well as Slim Thug. On the 2015 Vans Warped Tour, Riff Raff hired We Came As Romans' bassist Andy Glass to play bass for him on the tour.
Fox Islands (the main islands are Unimak, Akutan, Unalaska and Umnak) Islands of Four Mountains (the main islands are Yunaska and Chuginadak) Andreanof Islands (the main islands are Adak, Atka, Amlia, Seguam, Kanaga and Tanaga) Rat Islands (the main islands are Kiska and Amchitka) Near Islands (the main islands are Attu Island, Agattu Island and the Semichi Islands - Alaid, Nizki and Shemya) Commander Islands (the main islands are Bering and Medny) All six are located between 51° and 55° N latitude and 172° E and 163° W longitude. The largest islands in the Aleutians are Attu, and Unalaska, Umnak, and Unimak in the Fox Islands. The largest of those is Unimak Island, with an area of 1,571.41 mi2 (4,069.9 km2), followed by Unalaska Island, the only other Aleutian Island with an area over 1,000 square miles (2,600 km2). The axis of the archipelago near the mainland of Alaska has a southwest trend, but at Tanaga Island (about 178° W) its direction changes to the northwest. This change of direction corresponds to a curve in the line of volcanic fissures that have contributed their products to the building of the islands. Such curved chains are repeated about the Pacific Ocean in the Kuril Islands, the Japanese chain, and in the Philippines. All these island arcs are at the edge of the Pacific Plate and experience much seismic activity, but are still habitable; the Aleutians lie between the Pacific and North American tectonic plates. The general elevation is greatest in the eastern islands and least in the western.
The proteasome subcomponents are often referred to by their Svedberg sedimentation coefficient (denoted S). The proteasome most exclusively used in mammals is the cytosolic 26S proteasome, which is about 2000 kDa in molecular mass containing one 20S protein subcomplex and one 19S regulatory cap subcomplex. Doubly capped proteasomes are referred to as 30S proteasomes also exist in the cell. The 20S core is hollow and provides an enclosed cavity in which proteins are degraded; openings at the two ends of the core are gates that allow the target protein to enter. Each end of the core particle can associate with a 19S regulatory subunit that contains multiple ATPase active sites and ubiquitin binding sites; it is this structure that recognizes polyubiquitinated proteins and transfers them to the catalytic core. Several alternative caps can also bind the 20S core: 11S (PA26) or Blm10 (PA200) are also known to associate with the core and can bind either one or both sides. An alternative form of regulatory subunit called the 11S particle can associate with the core in essentially the same manner as the 19S particle; the 11S may play a role in degradation of foreign peptides such as those produced after infection by a virus. Archaea and bacteria also have proteasomes and have alternative caps that bind their cores. The following will discuss the structure and function of these subcomplexes.
Sources: en.wikipedia.org
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.
GSH is the reduced form with a free thiol group. GSSG is the oxidized dimer formed when two GSH molecules join by a disulfide bond.
It is synthesized inside cells and is not classified as an essential dietary nutrient for most people. Dietary and supplemental sources are studied, but direct requirements are not established in the same way as for vitamins.
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.