thiol 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.
Updated 2025-10-20. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C10H17N3O6S | Reduced glutathione (GSH); oxidized form differs by disulfide linkage. |
| Molar mass | 307.32 g/mol | Calculated for the reduced tripeptide. |
| Appearance | White to off-white crystalline powder | Typical laboratory reagent description. |
| Solubility | Soluble in water | Aqueous solutions are acidic; solubility depends on pH and salt form. |
| CAS Registry Number | 70-18-8 | Refers to reduced L-glutathione; oxidized form has a different number. |
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 cells, glutathione helps maintain the reducing environment of the cytosol and supports enzymes that counteract reactive oxygen species. It acts as a cofactor for glutathione peroxidases, which reduce hydrogen peroxide and lipid peroxides, and for glutathione S-transferases, which conjugate electrophiles. The ratio of GSH to GSSG is often used as an indicator of oxidative stress, although the ratio can vary by compartment and cell type. Glutathione also stores cysteine, an amino acid that can be limiting for protein synthesis and antioxidant defense.
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 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.
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.
In late 2008, Valve released lifetime retail sales figures as part of a company profile in Game Informer magazine. The two main Half-Life games had sold 15.8 million units at retail (9.3 million for the first, 6.5 million for the second), while the Half-Life expansions had sold 1.9 million (Opposing Force: 1.1 million, Blue Shift: 800,000) and Half-Life 2 expansions 1.4 million units (all for Episode One) by the end of November 2008. Additionally, The Orange Box, which included Half-Life 2 and both of its episodic expansions, sold 3 million units at retail by November 2008. This put franchise sales at around 18.8 million full games (Half-Life: 9.3m, Half-Life 2: 6.5m) and approximately 6.3 million expansions (Opposing Force: 1.1m, Blue Shift: 0.8m, Episode One: 1.4m, Episode 2: 3.0m) at the same month. These figures did not account for digital sales. Half-Life: Counter-Strike sold 4.2 million units standalone by the same time, while its remake, Counter-Strike: Source was bundled with every sold retail copy of Half-Life 2. Forbes reported that, including digital sales, Half-Life 2 had sold over 12 million copies by February 2011.
=== Pharmacodynamics === Although the mechanism of action of valproate is not fully understood, traditionally, its anticonvulsant effect has been attributed to the blockade of voltage-gated sodium channels and increased brain levels of the inhibitory synaptic neurotransmitter gamma-aminobutyric acid (GABA). The GABAergic effect is also believed to contribute towards the anti-manic properties of valproate. In animals, sodium valproate raises cerebral and cerebellar levels of GABA, possibly by inhibiting GABA degradative enzymes, such as GABA transaminase, succinate-semialdehyde dehydrogenase and by inhibiting the re-uptake of GABA by neuronal cells. Prevention of neurotransmitter-induced hyperexcitability of nerve cells via Kv7.2 channel and AKAP5 may also contribute to its mechanism. Valproate has been shown to protect against a seizure-induced reduction in phosphatidylinositol (3,4,5)-trisphosphate (PIP3) as a potential therapeutic mechanism.
Although there is a theoretical yield of 38 ATP molecules per glucose during cellular respiration, such conditions are generally not realized because of losses such as the cost of moving pyruvate (from glycolysis), phosphate, and ADP (substrates for ATP synthesis) into the mitochondria. All are actively transported using carriers that utilize the stored energy in the proton electrochemical gradient.
Sources: en.wikipedia.org
=== Geographical territories === In the United States, the common blue violet Viola sororia is the state flower of Illinois, Rhode Island, New Jersey and Wisconsin. In Canada, the Viola cucullata is the provincial flower of New Brunswick, adopted in 1936. In the United Kingdom, Viola riviniana is the county flower of Lincolnshire.
==== Resistance exercise and muscle atrophy ==== Resistance exercise is exercising a muscle or muscle group against external resistance (see strength training). Studies have found that: a) mice feeding on a high fat or normal diet and given the resistance exercise of repeatedly climbing up a 1 meter ladder for 40 minutes had higher levels of α-ketoglutarate in their blood and seven muscles than non-exercising mice feeding respectively on the high fat or normal diet; b) mice conducting ladder climbing for several weeks and eating a high fat diet developed lower fat tissue masses and higher lean tissue masses than non-exercising mice on this diet; c) mice not in exercise training fed α-ketoglutarate likewise developed lower fat tissue and higher lean tissue masses than α-ketoglutarate-unfed, non-exercising mice; d) OXGR1 was strongly expressed in the mouse adrenal gland inner medullas and either resistance training or oral α-ketoglutarate increased this tissue's levels of the mRNA that is responsible for the synthesis of OXGR1; e) α-ketoglutarate stimulated chromaffin cells isolated from mouse adrenal glands to release epinephrine but reduction of these cells' OXGR1 levels by small interfering RNA reduced this response; f) α-ketoglutarate increased the blood serum levels of epinephrine in mice expressing OXGR1 but not in Oxgr1 gene knockout mice (i.e., mice lacking the OXGR1 gene and protein); g) mice on the high fat diet challenged with α-ketoglutarate increased their blood serum levels of epinephrine and developed lower fat tissue masses and higher lean tissue masses but neither OXGR1 gene knockout mice nor mice that had only their adrenal glands' OXGR1 gene knocked out showed these responses; and h) OXGR1 gene knockout mice fed the high fat diet developed muscle protein degradation, muscle atrophy (i.e., wasting), and falls in body weight whereas control mice did not show these fat diet-induced changes. These findings indicate that in mice resistance exercise increases muscle production as well as serum levels of α-ketoglutarate which in turn suppresses diet-induced obesity (i.e., low body fat and high lean body masses) at least in part by stimulating the OXGR1 on adrenal gland chromaffin cells to release epinephrine. Additional mechanisms include inhibition of hepatic gluconeogenesis via serpina1e signaling (reducing hyperglycemia) and activation of the PHD3/ADRB2 pathway in muscle cells. Supplementation studies have shown that oral α-ketoglutarate increases serum levels of α-ketoglutarate, suppresses obesity and improves glucose tolerance in mice. See § Glucose tolerance below.
As mentioned above, in field-flow fractionation the field can be hydraulic (with a cross flow through a semi-permeable membrane as the accumulation wall), gravitational, centrifugal, thermal, electrical, or magnetic. In all cases, the separation mechanism is produced by differences in particle mobility under the forces of the field, in a stationary equilibrium with the forces of diffusion: The field induces a downward drift velocity and concentration towards the accumulation wall, the diffusion works against this concentration gradient. After a certain time (called relaxation time) the two forces equilibrate in a stationary equilibrium. This is best visualized as a particle cloud, with all components in constant motion, but with an exponential decrease of the average concentration going away from the accumulation wall up into the channel. The decrease of air pressure going up from sea level has the same exponential decrease which is described in the barometric formula. After relaxation has been achieved, elution starts as the channel flow is activated. In the thin channel (typical height 250 to 350 μm) a parabolic laminar-flow-velocity profile exists, which is characterized by a strong increase of the flow velocity with increasing distance from the accumulation wall. This determines the velocity of a particular particle, based on its equilibrium position from the wall of the channel. Particles closer to the accumulation wall will migrate slower compared to others being higher up.
Sources: en.wikipedia.org
(1933), first African-American basketball player to be selected as All-American Alfred Skrobisch (1933), Olympic fencer Cliff Montgomery (1934), led the Columbia Lions football team to victory in the Rose Bowl John O'Brien (1938), basketball player for the Akron Wingfoots Ben Johnson (1938), sprinter who rivaled Jesse Owens Sid Luckman (1939), NFL Hall of Fame Chicago Bears quarterback Ken Germann (1943), football coach, athletic director of Columbia University, and former Southern Conference commissioner Paul Governali (1943), football player for the Boston Yanks and New York Giants Walt Budko (1948), basketball player for Baltimore Bullets and Philadelphia Warriors Bruce Gehrke (1948), football player for New York Giants Bill Swiacki (1948), player for New York Giants, member of the College Football Hall of Fame Lou Kusserow (1949), football player for Hamilton Tiger-Cats and New York Yanks John Azary (1951), basketball player, recipient of the Haggerty Award Jack Molinas (1953), NBA player for the Fort Wayne Pistons Jack Rohan (1953), head coach of the Columbia Lions men's basketball team 1961–1974, and 1990–1995 George Shaw (1953), Olympic triple jumper Richard Ballantine* (1967), cyclist and cycling advocate; son of Ian Ballantine '38 of Ballantine Books James Margolis (1958), Olympic fencer James Melcher (1961), Olympian fencer, president of Fencers Club and hedge fund manager Robert Contiguglia (1963), soccer player, former president of the United States Soccer Federation Peter Salzberg (1964), head coach of Vermont Catamounts men's basketball 1972–1981 Archie Roberts (1965), former football player for the Miami Dolphins and cardiac surgeon Jim McMillian (1968), NBA player for the Los Angeles Lakers, Buffalo Braves, New York Knicks and Portland Trail Blazers Dave Newmark (1968), NBA player for the Chicago Bulls; also played for Israeli team Hapoel Tel Aviv B.C. Marty Domres (1969), football player for San Diego Chargers and Baltimore Colts Heyward Dotson (1970), basketball player George Starke (1971), offensive lineman for the Washington Redskins Henry Bunis (1975), two-time All-American tennis player, runner-up in 1977 Chilean Open Rick Fagel (1975), professional tennis player Vitas Gerulaitis* (1975), champion tennis player Thomas Losonczy (1975), Olympic fencer, winner of the Congressional Gold Medal Alton Byrd (1979), basketball player Eric Fromm (1980), tennis player John Witkowski (1983), football player for Detroit Lions and Houston Oilers Gene Larkin (1984), member of the Minnesota Twins 1987 and 1991 World Series championship teams Amr Aly (1985), soccer player who won the Hermann Trophy as the top college player of the year 1984; member of the 1984 U.S. Olympic Soccer Team and indoor soccer team Los Angeles Lazers Stephen Trevor (1986), Olympic fencer Kyra Tirana Barry (1987), team leader for U.S. women's national wrestling team Caitlin Bilodeaux (1987), Olympic fencer Howard Endelman (1987), tennis player Phil Williamson (1987), tennis player for Antigua and Barbuda Bob Cottingham (1988), Olympic fencer Jon Normile (1989), Olympic fencer Frank Seminara (1989), Major League Baseball pitcher for the San Diego Padres and the New York Mets Tom Auth (1990), Olympic rower Christine Vardaros (1991), professional cyclist Ann Marsh (1994), Olympic fencer Ríkharður Daðason (1996), Icelandic soccer player Marcellus Wiley (1997), football player for the Buffalo Bills, San Diego Chargers and Dallas Cowboys Dan Kellner (1998), fencer Pellegrino Matarazzo (1999), head coach of VfB Stuttgart Matt Napoleon (1999), Olympic soccer goalkeeper Cristina Teuscher (2000), Olympic gold medalist swimmer Jedediah Dupree (2001), NCAA Champion fencer Veljko Urošević (2003), Serbian Olympic rower Fernando Perez (2004), outfielder for the Tampa Bay Rays Jeremiah Boswell (2005), professional basketball player for BC Sliven, KK Strumica, and KK Torus Delilah DiCrescenzo (2005), long-distance runner, inspiration and subject of the Grammy-nominated song Hey There Delilah Michael Quarshie (2005), Finnish American football player who played for the Oakland Raiders and Frankfurt Galaxy Lisa Nemec (2006), Croatian long-distance runner Miloš Tomić (2006), Serbian Olympic rower Erison Hurtault (2007), Dominican sprinter James Leighman Williams (2007), fencer who won silver in the 2008 Summer Olympics Emily Jacobson (2008), fencer İhsan Emre Vural (2008), Turkish rower for Galatasaray S.K. Sherif Farrag (2009), Egyptian-American Olympic fencer Nicholas la Cava (2009), Olympic rower Jeff Spear (2010), Olympic fencer Daria Schneider (2010), fencer Jeff Adams (2011), Houston Texans offensive tackle Nicole Ross (2011), Olympic fencer Isadora Cerullo (2013), Brazilian-American Olympic rugby player Katie Meili (2013), Olympic swimmer, Pan American Games and 2016 Summer Olympics gold medalist Josh Martin (2013), Kansas City Chiefs linebacker John Gregorek Jr. (2014), middle-distance runner David Najem (2014), American soccer player for New Mexico United and the Afghanistan national football team Nadia Eke (2015), Ghanaian triple jumper, African Championships gold medalist in 2016 Kristine Musademba (2015), figure skater Max Schnur (2015), tennis player playing on the ATP Challenger Tour Nzingha Prescod (2015), Olympic fencer Ramit Tandon (2015), professional squash player Jakub Buczek (2016), Canadian Olympic rower Sasha DiGiulian (2016), world champion climber Jacqueline Dubrovich (2016), Olympic fencer Maodo Lô (2016), German basketball player for Brose Bamberg Robb Paller (2016), American-Israeli Olympic baseball player Jeff Coby (2017), American basketball player for Xuventude Baloncesto Cameron Nizialek (2017), football player for Atlanta Falcons Akua Obeng-Akrofi (2018), Ghanaian sprinter Charlotte Buck (2018), Olympic rower Osama Khalifa (2018), #1 ranked college squash player in the U.S. for the 2016–17 season Camille Zimmerman (2018), American basketball player for Norrköping Dolphins Yasmeen Al-Dabbagh (2019), Saudi Arabian sprinter Jessica Antiles (2019), swimmer who won silver and bronze medals in the 2017 Maccabiah Games Dylan Castanheira (2019), soccer player, goalkeeper for Fort Lauderdale CF Sophie Whitehouse (2019), goalkeeper for Republic of Ireland women's national football team Mike Smith (2020), basketball player Anthony Jackie Tang (2020), Hong Kong tennis player John Tanguay (2020), rower who won a silver medal in the 2020 Summer Paralympics Dylan Geick* (2021), wrestler and internet personality Velavan Senthilkumar (2021), British Junior Open Squash champion and Asian Junior Squash champion Nastasya Generalova (2023), gymnast and model Olivia Giaccio (2024), Olympic freestyle skier Evita Griskenas (2024), rhythmic gymnast Camden Pulkinen (2024), figure skater Abbey Hsu (2024), basketball player
== Silver Book == The Silver Book, is formally titled Compendium of Terminology and Nomenclature of Properties in Clinical Laboratory Sciences. The original Silver Book was a publication of the IUPAC, but the second edition was published by the Royal Society of Chemistry.
In 1988, Bio-Synthesis helped in the synthesis and characterization of a new class of peptides with novel antimicrobial properties discovered at the NIH. In 1989, OCS became incorporated as Bio-synthesis, Inc. and moved its laboratories to Lewisville, Texas. In 1993, Bio-Synthesis was one of the first peptide synthesis companies to acquire a Finnigan MALDI-TOF mass spectrometer for the accurate quality control of synthetic peptides produced in-house. In 1994, Bio-synthesis pioneered the use of molecular methods for HLA analysis which is applied in organ matching for transplantation purposes. Later in the same year Bio-Synthesis held the first major HLA DNA typing workshop with the attendance of HLA laboratory directors from around the country in conjunction with University of North Texas in Denton Texas.
In order to easily determine when the filter is spent, Kelly and his team developed a mask equipped with a sensor composed of carbon nanofibers assembled into repeating structures called photonic crystals that reflect specific wavelengths of light. The sensors exhibit an iridescent color that changes when the fibers absorb toxins.
Sources: en.wikipedia.org
GSH is the reduced form of glutathione, with a free thiol group on cysteine. GSSG is the oxidized disulfide form, created when two GSH molecules become linked. The two forms exist together, and their balance is often reported as the GSH/GSSG ratio in laboratory studies.
Glutathione is synthesized inside cells from amino acids rather than being classified as an essential dietary nutrient. Dietary sources can provide glutathione or its precursors, but digestion and absorption alter what reaches tissues. Research continues on how dietary intake relates to cellular glutathione levels.
The liver has high glutathione concentrations and uses the compound in conjugation and antioxidant reactions. These reactions are relevant to the processing of drugs, pollutants, and normal metabolic byproducts. Studies often examine liver glutathione as a marker of oxidative stress or detoxification capacity.
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.