This is a working overview of redox, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-11-06 and is reviewed periodically as new material appears.
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.
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.
| 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 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.
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.
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.
Glutathione is a small tripeptide built from glutamate, cysteine, and glycine. The peptide bond between glutamate and cysteine uses the gamma-carboxyl group, a linkage that resists ordinary peptidases. Cells make it in two ATP-dependent steps: gamma-glutamylcysteine synthetase joins glutamate and cysteine, then glutathione synthetase adds glycine. The pathway is feedback-inhibited by glutathione itself, so intracellular levels tend to stay within a narrow range. Because cysteine is often limiting, sulfur amino acid supply influences how much glutathione a cell can produce.
In its reduced form, glutathione carries a sulfhydryl group that can donate electrons. This property lets it act as a major cellular antioxidant and redox buffer. Glutathione peroxidase uses it to reduce hydrogen peroxide and lipid peroxides, while glutathione reductase regenerates the reduced form using NADPH. The ratio of reduced glutathione to glutathione disulfide is widely used as an indicator of oxidative stress, though the ratio changes with compartment, cell type, and sample handling. Oxidized glutathione can also form mixed disulfides with proteins, affecting their activity.
Glutathione supports detoxification by conjugating reactive electrophiles through glutathione S-transferases. The resulting conjugates are processed and exported, often after further metabolism. It also stores cysteine, transports amino acids across membranes through the gamma-glutamyl cycle, and assists in the maturation of iron-sulfur clusters and some prostaglandins. In plants, animals, and many microbes, the molecule appears in similar roles, but concentrations vary enormously between tissues. Liver, kidney, and red blood cells tend to contain high amounts, while blood plasma contains much less.
== Post-translational modifications == When protein folding into the mature, functional 3D state is complete, it is released from the ribosome but is not necessarily the end of the protein maturation pathway. A folded protein can still undergo further processing through post-translational modifications (PTMs). As of 2023 there are more than 650 known types of PTM. These modifications can alter protein activity, the ability of the protein to interact with other proteins and where the protein is found within the cell e.g. in the cell nucleus or cytoplasm. Through post-translational modifications, the diversity of proteins encoded by the genome is expanded by 2 to 3 orders of magnitude. There are four key classes of post-translational modification:
Studies of Sue found a broken and healed fibula and tail vertebrae, scarred facial bones and a tooth from another Tyrannosaurus embedded in a neck vertebra, providing evidence for aggressive behavior. In 1992, William Abler suggested that Tyrannosaurus may have had infectious saliva used to kill its prey. Abler observed that the serrations (tiny protuberances) on the cutting edges of the teeth are closely spaced, enclosing little chambers, which he argued trapped pieces of carcass with bacteria, giving Tyrannosaurus a deadly, infectious bite, as the Komodo dragon was mistakenly thought to have. Jack Horner and Don Lessem, in a 1993 popular book, questioned Abler's hypothesis, arguing that Tyrannosaurus's tooth serrations as more like cubes in shape than the serrations on a Komodo monitor's teeth, which are rounded. The basis for an infectious bite in Tyrannosaurus was further undermined when it was found Komodo dragons do not actually have an infectious bite nor hunt by biting prey and tracking it as it weakens. Tyrannosaurus probably primarily processed carcasses with lateral shakes of the head, like crocodilians. The head was not as maneuverable as the skulls of allosauroids, due to flat joints of the neck vertebrae. Studies on hadrosaur vertebrae from the Hell Creek Formation that were punctured by the teeth of what appears to be a late-stage juvenile Tyrannosaurus indicate that despite lacking the bone-crushing adaptations of the adults, young individuals were still capable of using the same bone-puncturing feeding technique.
Willem Vrolik, a Dutch anatomist who was also curator of the "Museum Vrolikianum", which made him privy to many specimens of bodies having birth defects, coined the term "osteogenesis imperfecta" in his bilingual Latin and Dutch language book on teratology, Illustrations of Human and Mammalian Embryogenesis, first published in 1849. Included is a description of the remains of an infant who had what is now known as perinatally fatal OI type II (as verified in a 1998 re-examination of the remains by Baljet et al.). The remains were first given to Vrolik's father, who could not make sense of them. Vrolik described poorly mineralized bones, bowed long bones, and fractures in various states of healing. Vrolik correctly determined that what he termed OI in the infant was not caused by secondary rickets, but a congenital abnormality causing primary osteopenia; he theorized this was due to a lack of "intrinsic generative energy".
Corneal cross-linking (CXL) with riboflavin (vitamin B2) and UV-A light is a surgical treatment for corneal ectasia such as keratoconus, PMD, and post-LASIK ectasia. It is used in an attempt to make the cornea stronger. According to a 2015 Cochrane review, there is insufficient evidence to determine if it is useful in keratoconus. In 2016, the US Food and Drug Administration approved riboflavin ophthalmic solution crosslinking based on three 12-month clinical trials.
Space Invaders, originally released for arcades in 1978, became a killer app when it was ported to the Atari VCS console in 1980, quadrupling sales of the three-year-old console. Star Raiders, released in 1980, was the first killer app computer game. BYTE named it the single most important reason for sales of Atari 400 and 800 computers. Another was Eastern Front (1941), released in 1981. In 1996, Computer Gaming World wrote that Wizardry: Proving Grounds of the Mad Overlord (1981) "sent AD&D fans scrambling to buy Apple IIs". The Famicom home port of Xevious is considered the console's first killer app, which caused system sales to jump by nearly 2 million units. Computer Gaming World stated that The Legend of Zelda on the Nintendo Entertainment System, Phantasy Star II on the Sega Genesis, and Far East of Eden for the NEC TurboGrafx-16 were killer apps for their consoles. The Super Mario, Final Fantasy, and Dragon Quest series were killer apps for Nintendo's Famicom and Super Famicom consoles in Japan. John Madden Football's popularity in 1990 helped the Genesis gain market share against the Super NES in North America. Sonic the Hedgehog, released in 1991, was hailed as a killer app as it revived sales of the three-year-old Genesis. Mortal Kombat helped pushed the sales of the Genesis due to being uncensored unlike the Nintendo version. Streets of Rage became a system seller for the Mega Drive/Genesis in the UK. Street Fighter II, originally released for arcades in 1991, became a system-seller for the Super NES when it was ported to the platform in 1992.
Sources: en.wikipedia.org
Things like ideologies, law, government, money and the economy are built on language; they exist because there are stories that billions of people believe. The current prevalence of misinformation suggests that an AI could use language to convince people to believe anything, even to take actions that are destructive. Geoffrey Hinton said in 2025 that modern AI is particularly "good at persuasion" and getting better all the time. He asks, "Suppose you wanted to invade the capital of the US. Do you have to go there and do it yourself? No. You just have to be good at persuasion." The opinions amongst experts and industry insiders are mixed, with sizeable fractions both concerned and unconcerned by risk from eventual superintelligent AI. Personalities such as Stephen Hawking, Bill Gates, and Elon Musk, as well as AI pioneers such as Geoffrey Hinton, Yoshua Bengio, Stuart Russell, Demis Hassabis, and Sam Altman, have expressed concerns about existential risk from AI. In May 2023, Geoffrey Hinton announced his resignation from Google in order to be able to "freely speak out about the risks of AI" without "considering how this impacts Google". He notably mentioned risks of an AI takeover, and stressed that in order to avoid the worst outcomes, establishing safety guidelines will require cooperation among those competing in use of AI. In 2023, many leading AI experts endorsed the joint statement that "Mitigating the risk of extinction from AI should be a global priority alongside other societal-scale risks such as pandemics and nuclear war".
In 1942, Allied repudiation of the Munich Agreement established the political and legal continuity of the First Republic and de jure recognition of Beneš's de facto presidency. The success of Operation Anthropoid—which resulted in the British-backed assassination of one of Hitler's top henchmen, Reichsprotektor of Bohemia and Moravia Reinhard Heydrich, by Jozef Gabčík and Jan Kubiš on 27 May—influenced the Allies in this repudiation. The Munich Agreement had been precipitated by the subversive activities of the Sudeten Germans. During the latter years of the war, Beneš worked toward resolving the German minority problem and received consent from the Allies for a solution based on a postwar transfer of the Sudeten German population. The First Republic had been committed to a Western policy in foreign affairs. The Munich Agreement was the outcome. Beneš determined to strengthen Czechoslovak security against future German aggression through alliances with Poland and the Soviet Union. The Soviet Union, however, objected to a tripartite Czechoslovak-Polish-Soviet commitment. In December 1943, Beneš's government concluded a treaty just with the Soviets. Beneš's interest in maintaining friendly relations with the Soviet Union was motivated also by his desire to avoid Soviet encouragement of a post-war communist coup in Czechoslovakia. Beneš worked to bring Czechoslovak communist exiles in Britain into cooperation with his government, offering far-reaching concessions, including the nationalization of heavy industry and the creation of local people's committees at the war's end.
Diallyl disulfide (DADS or 4,5-dithia-1,7-octadiene) is an organosulfur compound derived from garlic and a few other plants in the genus Allium. Along with diallyl trisulfide and diallyl tetrasulfide, it is one of the principal components of the distilled oil of garlic. It is a yellowish liquid which is insoluble in water and has a strong garlic odor. It is produced during the decomposition of allicin, which is released upon crushing garlic and other plants of the family Alliaceae. Diallyl disulfide has many of the health benefits of garlic, but it is also an allergen causing garlic allergy. Highly diluted, it is used as a flavoring in food. It decomposes in the human body into other compounds such as allyl methyl sulfide.
Hours after Palacios' statement, Free Peru's General Secretary Vladimir Cerrón said "When you lose faith in your militancy, you force yourself to look for strength with the mercenaries." Cerron also quoted Borges by saying "traitors are reliable because they never change." Afterward, El Comercio released a paper claiming that the Free Peru caucus voted as a split group nearly 50% of the time. On 29 November 2021, Vladimir Cerrón announced that Free Peru would hold an extraordinary national assembly on 5 December 2021, to determine the party's stance on the impeachment motion, the government, and other topics. On 6 December 2021, Free Peru concluded its extraordinary national assembly by announcing that it would vote unanimously against impeachment. Free Peru stated that it has "serious discrepancies" with the "caviar" government of Castillo, but also accused the pro-impeachment movement of being fascist and anti-democratic. Additionally, Free Peru also reaffirmed that it considered Cuba, Venezuela, and Bolivia to have democratic governments.
Sources: en.wikipedia.org
=== Anxiety disorders === KOR antagonists have demonstrated anxiolytic efficacy in preclinical stress models and early clinical evaluation. Early generation antagonists such as JDTic and nor-BNI produced anxiolytic-like effects in GAD, PTSD, and panic disorder models. However their long duration of action and off-target toxicities limited clinical development. Contemporary short-acting antagonists such as aticaprant are being evaluated for anxiety indications given their improved pharmacokinetic profiles and reduced toxicity burden.
At typical clinical doses used for Parkinson's disease, selegiline is a selective and irreversible inhibitor of monoamine oxidase B (MAO-B), increasing brain levels of dopamine. At higher doses, it loses its specificity for MAO-B and also inhibits monoamine oxidase A (MAO-A), which increases serotonin and norepinephrine levels in the brain as well. In addition to its MAOI activity, selegiline is a catecholaminergic activity enhancer (CAE) and enhances the impulse-mediated release of norepinephrine and dopamine in the brain. This action may be mediated by TAAR1 agonism. After administration, selegiline partially metabolizes into levomethamphetamine and levoamphetamine, which act as norepinephrine releasing agents (NRAs) and may contribute to its therapeutic and adverse effects as well. The levels of these metabolites are much lower with the ODT and transdermal patch forms of selegiline. Chemically, selegiline is a substituted phenethylamine and amphetamine, a derivative of methamphetamine, and the purified levorotatory enantiomer of deprenyl (the racemic mixture of selegiline and D-deprenyl). Deprenyl was discovered and studied as an antidepressant in the early 1960s by Zoltan Ecseri, József Knoll, and other colleagues at Chinoin Pharmaceutical Company in Hungary. Subsequently, selegiline was purified from deprenyl and was studied and developed itself. Selegiline was first introduced for medical use, to treat Parkinson's disease, in Hungary in 1977. It was subsequently approved in the United Kingdom in 1982 and in the United States in 1989.
This has resulted in an egg-shaped planet, likely to be destroyed within 400 million years. 14 August The World Health Organization (WHO) declares mpox a public health emergency of international concern for the second time in two years, following the spread of the virus in African countries. Human ageing is found to progress in two accelerated bursts from the ages of 44 and 60, rather than being a gradual and linear process. 16 August – The Planetary Habitability Laboratory publishes a report concluding that the Wow! signal was likely caused by a rare astrophysical event, the sudden brightening of a cold molecular cloud triggered by a stellar emission. 22 August – The first systematic analysis of 1,500 climate policy measures from 41 countries is published. Of the policy interventions that have been tried by 2022, it identifies 63 successful ones in terms of large trend breaks. The authors find that the introduction of a right combination of measures is crucial and that price-based instruments played a key role in these policy mixes. 23 August – BNT116, the world's first mRNA lung cancer vaccine, begins a Phase I clinical trial in seven countries. 29 August – The first global analysis estimating inadequate intakes of 15 micronutrients using dietary intake data is published, suggesting over half of the global population do not consume enough iodine (68%), vitamin E (67%), calcium (66%), iron (65%), riboflavin (55%), folate (54%), and vitamin C (53%).
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.
GSH is the reduced, thiol-containing form of glutathione, while GSSG is the oxidized disulfide dimer formed when two GSH molecules react. Cells maintain a high GSH-to-GSSG ratio under normal conditions. A shift toward GSSG is often interpreted as oxidative stress, though sample handling can affect the measured ratio.