This is a working overview of redox homeostasis, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-02-23 and is reviewed periodically as new material appears.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine, and it is the most abundant non-protein thiol in most living cells. The reduced form, GSH, carries a sulfhydryl group that can donate electrons, while the oxidized form, GSSG, forms when two GSH molecules link via a disulfide bond. The balance between these two forms helps define the cellular redox environment, and their ratio is often used as an indicator of oxidative stress. Because the sulfhydryl group is reactive, glutathione participates in many cellular processes, including detoxification and protein regulation.
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 is most stable as a dry powder stored cool and dry, but its thiol group is readily oxidized in solution. Aqueous preparations at neutral or alkaline pH lose GSH faster because the thiolate form reacts with dissolved oxygen and metal ions. Acidic conditions, chelating agents, and oxygen exclusion can slow oxidation, while repeated freeze-thaw cycles promote degradation. Light exposure and trace metals also contribute to loss. Laboratories typically validate stability for their own matrices because degradation rates depend on pH, temperature, concentration, and container materials.
Commercial glutathione is available in research-grade, food-grade, and supplement-grade forms, and purity specifications differ accordingly. Certificates of analysis commonly report identity by nuclear magnetic resonance or mass spectrometry, purity by HPLC, residual solvents, and heavy metals. Reference standards with assigned purity support calibration, while isotopically labeled glutathione can serve as an internal standard for mass spectrometry. For supplements, label claims may not be independently verified, and regulatory oversight varies by country. Verification often involves third-party testing for identity, potency, and contaminants.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C10H17N3O6S | Reduced form (GSH) |
| Molar mass | 307.32 g/mol | For GSH; GSSG is 612.63 g/mol |
| Appearance | White crystalline powder | Usually lyophilized |
| Solubility in water | Freely soluble (≥100 mg/mL) | pH dependent |
| Typical storage | -20 °C, desiccated | Protect from light and oxygen |
The Chinese Nationalist Air Force obtained the P-51 during the late Sino-Japanese War to fight against the Japanese. After the war, Chiang Kai-shek's Nationalist government used the planes against insurgent Communist forces. The Nationalists retreated to Taiwan in 1949. Pilots supporting Chiang brought most of the Mustangs with them, where the aircraft became part of the island's defense arsenal. People's Republic of China
=== Additional references === Gerngross T, Slater S (February 2003). "Biopolymers and the environment". Science. 299 (5608): 822–5, author reply 822–5. doi:10.1126/science.299.5608.822. PMID 12574603. S2CID 41354773. Gerngross TU (June 1999). "Can biotechnology move us toward a sustainable society?". Nat. Biotechnol. 17 (6): 541–4. doi:10.1038/9843. PMID 10385316. S2CID 36258380.
=== Dopaminergic control of the pars intermedia === The pituitary gland consists of three parts: the pars nervosa, the pars intermedia, and the pars distalis. The most critical structure to PPID, the pars intermedia, is regulated by the hypothalamus. The neurons of the hypothalamus innervate cells known as melanotropes within the pars intermedia, releasing dopamine which then binds to dopamine receptors on the melanotropes. The activation of these dopamine receptors leads to the inhibition of proopiomelanocortin (POMC) production in these cells. In PPID-affected horses, dopamine is not produced from these neurons, leading to dopamine levels about 10% of the level normally found in the pars intermedia. This is thought to be due to neurodegeneration of the neurons, secondary to free radical formation and oxidative stress. Without regulation from dopamine, the pars intermedia develops hyperplasia and adenoma formation, leading to gross enlargement and excessive production of POMC. These adenomas also have the potential to compress the hypothalamus and optic chiasm.
=== EC 1.21.98 With other, known, physiological acceptors === EC 1.21.98.1: cyclic dehypoxanthinyl futalosine synthase EC 1.21.98.2: dichlorochromopyrrolate synthase EC 1.21.98.3: anaerobic magnesium-protoporphyrin IX monomethyl ester cyclase EC 1.21.98.4: PqqA peptide cyclase
Sources: en.wikipedia.org
where V(x, t) is the voltage across the membrane at a time t and a position x along the length of the neuron, and where λ and τ are the characteristic length and time scales on which those voltages decay in response to a stimulus. Referring to the circuit diagram on the right, these scales can be determined from the resistances and capacitances per unit length.
=== Personality === Peng described Xi as hardworking and down-to-earth: "When he comes home, I've never felt as if there's some leader in the house. In my eyes, he's just my husband." In 1992, The Washington Post journalist Lena H. Sun had an interview with Xi, then CCP secretary of Fuzhou; Sun described Xi as considerably more at ease and confident than many officials his age, and said that he talked without consulting notes. He was described in a 2011 The Washington Post article by those who know him as "pragmatic, serious, cautious, hard-working, down to earth and low-key." He was described as a good hand at problem solving and "seemingly uninterested in the trappings of high office." The Chinese state media has also cast him as a fatherly figure and a man of the people, determined to stand up for Chinese interests.
=== Organ health === The Prospera test is the first assay with high sensitivity to both T-cell-mediated and antibody-mediated rejection. In December 2019, the test received final Medicare coverage. In 2020, Natera launched Renasight, a test to determine if there is a genetic cause for an individual's kidney disease and if there may be other at-risk relatives.
Sources: en.wikipedia.org
== January 4, 1982 (Monday) == The United States Postal Service inaugurated its new "electronic mail service", "E-COM" (Electronic Computer Originated Service)at 25 specially equipped U.S. post office locations. According to the USPS description, "a company's computer will send a message via a communications common carrier— such as long-distance telephone" to one of the 25 offices and "There, the message will be printed on paper, put in a distinctive blue-and-white E-COM envelope and delivered with regular mail." The service would be discontinued less than four years later, on September 2, 1985. U.S. National Security Adviser Richard V. Allen was fired by President Ronald Reagan in the wake of a report by a Japanese newspaper on November 13 that Allen had accepted a $1,000 payment from a Japanese magazine in return for arranging an interview of First Lady Nancy Reagan. Allen was replaced by deputy U.S. secretary of state William P. Clark. The nation of Brazil elevated its territory of Rondônia to statehood as its 23rd unidades federativa, with Porto Velho as its capital. A mudslide in the U.S. state of California killed at least 31 people, most of whom had been in homes buried in the town of Ben Lomond. President Reagan announced in a statement from the White House that the U.S. had submitted a draft of a treaty for the elimination of all medium-range American and Soviet nuclear missiles from Europe. In a statement, Reagan said "Such a treaty would be a major contribution to security, stability and peace.
Alcoholic liver disease (ALD, or alcoholic cirrhosis) develops in 10–20% of individuals who drink heavily for a decade or more. Alcohol seems to injure the liver by blocking the normal metabolism of protein, fats, and carbohydrates. This injury happens through the formation of acetaldehyde from alcohol. Acetaldehyde is reactive and leads to the accumulation of other reactive products in the liver. People with ALD may also have concurrent alcoholic hepatitis. Associated symptoms are fever, hepatomegaly, jaundice, and anorexia. AST and ALT blood levels are both elevated, but at less than 300 IU/liter, with an AST:ALT ratio > 2.0, a value rarely seen in other liver diseases. In the United States, 40% of cirrhosis-related deaths are due to alcohol. In non-alcoholic fatty liver disease (NAFLD), fat builds up in the liver and eventually causes scar tissue. This type of disorder can be caused by obesity, diabetes, malnutrition, coronary artery disease, and steroids. Though similar in signs to alcoholic liver disease, no history of notable alcohol use is found. Blood tests and medical imaging are used to diagnose NAFLD and NASH, and sometimes a liver biopsy is needed. Chronic hepatitis C, an infection with the hepatitis C virus, causes inflammation of the liver and a variable grade of damage to the organ. Over several decades, this inflammation and damage can lead to cirrhosis. Among people with chronic hepatitis C, 20–30% develop cirrhosis. Cirrhosis caused by hepatitis C and alcoholic liver disease are the most common reasons for liver transplant.
=== Safety === In general, somatostatin receptor antagonists were noted to be well tolerated. However, due to its mechanism of action, it may decrease the effectiveness of SSA therapy (Somatostatin Analogue Therapy), however other studies indicate SSA may not need to be stopped if somatostatin antagonists are used to label tumors instead of agonists. As somatostatin can cause inhibition of hormone production that uses it as a mediating hormone, it has an antiproliferative effect on cell tumors, especially in neuroendocrine tumors. Somatostatin analogue therapy uses longer-acting agonists than the endogenous somatostatin to extend the antiproliferative effects. Somatostatin receptor antagonists can bind to the receptors without activating them , antagonizing the therapeutic inhibitory effects of SSA therapy. Slow intravenous injection might be used until further safety data becomes available.
== External links == ImmPort - Gene summaries, ontologies, pathways, protein/protein interactions and more for genes involved in antigen processing and presentation antigen+presentation at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
Sources: en.wikipedia.org
Glutathione is a tripeptide of three amino acids: glutamate, cysteine, and glycine. The cysteine residue provides the sulfhydryl group that gives the molecule its reducing properties.
GSH is the reduced form, which contains a free sulfhydryl group. GSSG is the oxidized form, formed when two GSH molecules join through a disulfide bond. The ratio of GSH to GSSG is often used to assess cellular redox status.
No, glutathione is synthesized endogenously in most cells. It is not classified as an essential nutrient because the body can produce it from amino acid precursors. Dietary sources exist, but they are not required to maintain life.
The ratio depends on rapid separation or blocking of GSH before oxidation occurs. GSSG can be formed ex vivo if samples are not processed quickly in cold, acidic conditions. Even small delays can shift the apparent ratio, making standardized protocols essential.