GSSG 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 2025-11-11. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| 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 |
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 is a tripeptide composed of glutamate, cysteine, and glycine. It contains an unusual gamma-glutamyl bond between glutamate and cysteine, which resists cleavage by many peptidases. The reduced form, GSH, carries a thiol group on cysteine and is the dominant intracellular form in most cells. Its structure allows it to participate in redox reactions and to serve as a sulfur donor. The oxidized form, GSSG, consists of two GSH molecules joined by a disulfide bond.
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.
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.
Urocanase (also known as imidazolonepropionate hydrolase or urocanate hydratase) is the enzyme (EC 4.2.1.49) that catalyzes the second step in the degradation of histidine, the hydration of urocanic acid to imidazol-4-one-5-propionic acid. Urocanase is coded for by the UROC1 gene, located on the third chromosome in humans. The protein itself is composed of 676 amino acids which then fold, producing the final product which has two identical subunits, making the enzyme a homodimer. To catalyze the hydrolysis of urocanate in the catabolic pathway of L-histidine the enzyme utilizes its two nicotinamide adenine dinucleotide (NAD+) groups. These act as electrophiles, attaching to the top carbon of the urocanate which leads to sigmatropic rearrangement of the urocanate molecule. This rearrangement allows for the addition of a water molecule, converting the urocanic acid into imidazol-4-one-5-propionic acid.
ATP hydrolysis by AAA ATPases is proposed to involve nucleophilic attack on the ATP gamma-phosphate by an activated water molecule, leading to movement of the N-terminal and C-terminal AAA subdomains relative to each other. This movement allows the exertion of mechanical force, amplified by other ATPase domains within the same oligomeric structure. The additional domains in the protein allow for regulation or direction of the force towards different goals.
232Th is the only primordial nuclide of thorium and makes up effectively all of natural thorium, with other isotopes of thorium appearing only in trace amounts as relatively short-lived decay products of uranium and thorium. The isotope decays by alpha decay with a half-life of 1.40×1010 years, over three times the age of the Earth and approximately the age of the universe. Its decay chain is the thorium series, eventually ending in lead-208. The remainder of the chain is quick; the longest half-lives in it are 5.75 years for radium-228 and 1.91 years for thorium-228, with all other half-lives totaling less than a week. 232Th is a fertile material able to absorb a neutron and undergo transmutation into the fissile nuclide uranium-233, which is the basis of the thorium fuel cycle. In the form of Thorotrast, a thorium dioxide suspension, it was used as a contrast medium in early X-ray diagnostics. Thorium-232 is now classified as carcinogenic.
Neutral Protamine Hagedorn (NPH) insulin, also known as isophane insulin, is an intermediate-acting insulin given to help control blood sugar levels in people with diabetes. The words refer to neutral pH (pH = 7), protamine a protein, and Hans Christian Hagedorn, the insulin researcher who invented this formulation. It is designed to improve the delivery of insulin, and is one of the earliest examples of engineered drug delivery. It is used by injection under the skin once to twice a day. Onset of effects is typically in 90 minutes and they last for 24 hours. Versions are available that come premixed with a short-acting insulin, such as regular insulin. The common side effect is low blood sugar. Other side effects may include pain or skin changes at the sites of injection, low blood potassium, and allergic reactions. Use during pregnancy is relatively safe for the fetus. NPH insulin is made by mixing regular insulin and protamine in exact proportions with zinc and phenol such that a neutral-pH is maintained and crystals form. There are human and pig insulin based versions. Protamine insulin was first created in 1936 and NPH insulin in 1946. It is on the World Health Organization's List of Essential Medicines. NPH is an abbreviation for "neutral protamine Hagedorn". In 2020, insulin isophane was the 221st most commonly prescribed medication in the United States, with more than 2 million prescriptions. In 2020, the combination of human insulin with insulin isophane was the 246th most commonly prescribed medication in the United States, with more than 1 million prescriptions.
Sources: en.wikipedia.org
=== Arjo === Arjo was founded in 1957 by Arne Johansson in the Swedish town of Eslöv. The company name consists of the first two letters of the first and last name of the company founder. Arjo initially functioned as a supplier of components and machine parts to medical device manufacturers. In 1972, the company developed the first height-adjustable bathtub and introduced it to the market. In 1993, the company's shares are listed on the Stockholm Stock Exchange and the London Stock Exchange. In 1995, the company merged with the Swedish Getinge Group, in whose "Extended Care" business area it continued to operate under its brand name. In 2004, Arjo took over the company BHM Medical and rounded off its range of passenger lifts with its Ceiling Lifts.
He appears as the lover of the Lady of the Lake, who bequeaths a powerful sword to Geralt. In the 2023 Warhammer 40,000 novel The Lion: Son of the Forest by Mike Brooks, the protagonist Lion El'Jonson (a character heavily inspired by King Arthur) encounters a wounded king fishing by a lake in a mysterious, alternate dimension. This figure serves as an allegory for the Fisher King, representing the setting's grievously wounded ruler, the Emperor of Mankind.
25 April Downing Street confirms the first UK evacuation flight carrying British citizens has left Sudan. High Court documents reveal that Prince William was paid a "very large sum" by News Group Newspapers, owners of The Sun, to settle historical phone-hacking claims. Data published by the Office for National Statistics indicates government borrowing for the year up to 31 March 2023 to be £139.2bn, less than the £152bn that had been forecast by the Office for Budget Responsibility prior to the 2023 budget. 26 April Andrew Bridgen is expelled from the Conservative Party after comparing COVID-19 vaccines to the Holocaust and being found to have breached lobbying rules. The first evacuation flight from Sudan lands in the UK. The Illegal Migration Bill passes its final stage in the House of Commons, with MPs voting 289–230 in favour of the bill. The UK's Competition and Markets Authority blocks Microsoft's £55bn deal to buy US video game company Activision Blizzard, citing concerns about reduced choice for gamers and reduced innovation; the move needed the approval of competition regulators in the United States, United Kingdom and European Union. 27 April Three days of fresh train strikes are called after both ASLEF and the RMT reject a pay offer from the Rail Delivery Group. The strikes dates are announced for 13 May 31 May and 3 June (ASLEF) and 13 May (RMT).
== In other animals == Demyelinating diseases/disorders have been found worldwide in various animals. Some of these animals include mice, pigs, cattle, hamsters, rats, sheep, Siamese kittens, and a number of dog breeds (including Chow Chow, Springer Spaniel, Dalmatian, Samoyed, Golden Retriever, Lurcher, Bernese Mountain Dog, Vizsla, Weimaraner, Australian Silky Terrier, and mixed breeds). Ziggy Star, a female northern fur seal, was treated at the Marine Mammal Center beginning in March 2014 and was noted as the first reported case of a demyelinating disease in a marine mammal. She was later transported to Mystic Aquarium & Institute for Exploration for lifelong care as an ambassador to the public. In 2017, she was the first seal treated for hydrocephalus.
== Formation of short chain fatty acids == The oral administration of glucose elicits a much greater rise in blood insulin levels and a much lower rise in blood glucose levels than those elicited by intravenous glucose infusions. This difference, termed the incretin effect, is due to the activation of FFAR2-bearing intestinal cells by the short chain fatty acids (SCFAs) that intestinal bacteria excrete. The microbiotas inside the small intestine and colon of animals and humans consist of a wide range of microorganisms and viruses. The microorganisms ingest the food their hosts consume including soluble dietary fibers, e.g., resistant starch, xanthan gum, and inulin, all three of which are resistant to the hosts' digestive enzymes. Certain microorganisms (e.g., anaerobic bacteria), ferment these dietary fibers to form and then excrete SCFAs (primarily acetic, propionic, and butyric acids). The relative levels of these three SCFAs in the intestines of humans are about 60:20:20, respectively. Intestinal SCFAs activate FFAR2-bearing cells in the nearby intestinal walls and also enter the blood circulation to activate FFAR2-bearing cells in distant tissues. SCFAs may also be made and released by the bacteria and/or host cells in tissue that contain bacterial infections.
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.
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.