This is a working overview of thiol, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-14. Anything still debated is marked as such rather than presented as settled.
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.
Synthesis occurs in two ATP-dependent steps: glutamate-cysteine ligase joins glutamate and cysteine to form gamma-glutamylcysteine, and glutathione synthetase adds glycine to complete the tripeptide. The pathway is feedback-inhibited by GSH and limited by cysteine availability, so cysteine supply often constrains production. Once formed, GSH participates in redox buffering, xenobiotic conjugation, and protein glutathionylation. Glutathione peroxidase uses GSH to reduce hydrogen peroxide and lipid peroxides, yielding GSSG, while glutathione reductase regenerates GSH using NADPH. Glutathione S-transferases conjugate electrophiles to GSH, supporting detoxification and excretion.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C10H17N3O6S | Tripeptide of glutamate, cysteine, and glycine. |
| Molar mass | 307.32 g/mol | Calculated from the molecular formula. |
| Appearance | White to off-white powder | Typically crystalline or lyophilized solid. |
| Solubility | Soluble in water; insoluble in ethanol | Aqueous solutions are acidic and prone to oxidation. |
| Typical storage | -20 °C, desiccated, protect from light | Reduce exposure to oxygen and moisture. |
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.
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.
Yonath was a member of the United States National Academy of Sciences; the American Academy of Arts and Sciences; the Israel Academy of Sciences and Humanities; the European Academy of Sciences and Art and the European Molecular Biology Organization. On 18 October 2014, Yonath was named an ordinary member of the Pontifical Academy of Sciences by Pope Francis. Her awards and honors included the following:
Octopuses are fished around the world and between 1988 and 1995, catches varied between 245,320 and 322,999 metric tons. The world catch peaked in 2007 at 380,000 tons, and had fallen by a tenth by 2012. Methods to capture octopuses include pots, trapping, trawling, snaring, drift fishing, spearing, hooking and catching by hands. Octopuses are also bycatch. Attempts to farm octopuses commercially are controversial. Octopus is eaten in many cultures, such as those on the Mediterranean and Asian coasts. The arms and other body parts are prepared in ways that vary by species and geography. Live octopuses or their wriggling pieces are consumed as san-nakji in Korean cuisine. If not prepared properly, however, the severed arms can choke the diner with their suction cups, causing at least one death in 2010. Animal welfare groups have objected to the live consumption of octopuses on the basis that they can experience pain.
An epitope, () also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The part of an antibody that binds to the epitope is called a paratope. Although epitopes are usually non-self proteins, sequences derived from the host that can be recognized (as in the case of autoimmune diseases) are also epitopes. The epitopes of protein antigens are divided into two categories, conformational epitopes and linear epitopes, based on their structure and interaction with the paratope. Conformational and linear epitopes interact with the paratope based on the 3-D conformation adopted by the epitope, which is determined by the surface features of the involved epitope residues and the shape or tertiary structure of other segments of the antigen. A conformational epitope is formed by the 3-D conformation adopted by the interaction of discontiguous amino acid residues. In contrast, a linear epitope is formed by the 3-D conformation adopted by the interaction of contiguous amino acid residues. A linear epitope is not determined solely by the primary structure of the involved amino acids. Residues that flank such amino acid residues, as well as more distant amino acid residues of the antigen affect the ability of the primary structure residues to adopt the epitope's 3-D conformation. 90% of epitopes are conformational.
In the above formula, the superscripts "ionized" each indicate the sum of concentrations of all ionized species in their respective phases. In addition, since log D is pH-dependent, the pH at which the log D was measured must be specified. In areas such as drug discovery—areas involving partition phenomena in biological systems such as the human body—the log D at the physiologic pH = 7.4 is of particular interest. It is often convenient to express the log D in terms of PI, defined above (which includes P0 as state I = 0), thus covering both un-ionized and ionized species. For example, in octanol–water:
Sources: en.wikipedia.org
vary as decreasing monotonic functions of temperature, and the enrichment of multiply D-substituted > multiply 13C-D-substituted > multiply 13C-substituted isotopologues for a same number of substitutions (as shown in this figure).
=== Norway === Reports from Norway have shown carisoprodol has addictive potential as a prodrug of meprobamate and/or potentiator of hydrocodone, oxycodone, codeine, and similar drugs. In May 2008 it was taken off the market in Norway.
=== Education === Humphreys graduated from Chickasha High School (Chickasha, Oklahoma) in 1948. He then attended Colorado College, graduating with his BA in 1952. He attended Seabury-Western Theological Seminary (in Evanston, Illinois), graduating with the MDiv degree in 1955. In 1965, he entered graduate school at Washington University to pursue a PhD in sociology. His dissertation adviser was Lee Rainwater. Humphreys obtained two pre-doctoral research fellowships from the National Institute of Mental Health to fund his dissertation research. He completed his dissertation in 1968, graduating with his PhD in that year. He published the dissertation as Tearoom Trade: Impersonal Sex in Public Places in 1970. His book won the C. Wright Mills Award from the Society for the Study of Social Problems in 1969. Due to the controversy around his research methods and the topic of his research, there was a failed attempt by the chancellor of Washington University to rescind his PhD.
=== Directed evolution === Directed evolution of an enzyme is a repetitive process of creating random genetic mutations, screening for a target phenotype, and selecting the most robust variant(s) for further modification. The ability of humankind to use directed evolution to optimize enzymes for biotechnological purposes is largely limited by the throughput of screening tools and methods and the simplicity of their use. Due to the iterative nature of directed evolution and the necessity for large libraries, directed evolution at the macroscale can be a costly endeavor. As such, performing experiments at the microscale through droplet-based microfluidics provides a significantly cheaper alternative to macroscopic equivalents. Various approaches price the directed evolution through droplet microfluidics under $40 for a screen of a 106–107 sized gene library, while the corresponding macroscale experiment is priced at approximately $15 million. Additionally, with screening times that range from 300 to 2000 droplets sorted per second, droplet-based microfluidics provides a platform for significantly accelerated library screening such that gene libraries of 107 can be sorted well within a day. Droplet-based microfluidic devices make directed evolution accessible and cost effective. Many different approaches to device construction of droplet-based microfluidic devices have been developed for directed evolution in order to have the capacity to screen a vast variety of different proteins, pathways, and genomes.
=== Phosphoenolpyruvate carboxykinase (PEPC-K) === Glyceroneogenesis can be regulated at two reaction pathways. First, it can be held at the decarboxylation of oxaloacetate to phosphoenolpyruvate. Secondly, the TCA cycle can affect glyceroneogenesis when the glutamate or substrates in the TCA cycle are being used as a precursor. Decarboxylation of oxaloacetate to phosphoenolpyruvate is catalyzed by PEPC-K, the essential enzyme which regulates glyceroneogenesis. Increases in PEPC-K levels or overexpression of the gene that codes for PEPC-K will increase glyceroneogenesis. Also, oxaloacetate can be decarboxylated to phosphoenolpyruvate when more PEPC-K can catalyze the reaction. Gene expression of PEPC-K can be suppressed by norepinephrine, glucocorticoids, and insulin. Norepinephrine is a neurotransmitter which decreases the activity of PEPC-K when the cell is in a cold environment. Glucocorticoids are steroid hormones involved in the reciprocal regulation of glyceroneogenesis in the liver and adipose tissues. Through a poorly-understood mechanism, they induce transcription of PEPC-K in the liver while decreasing transcription in adipose tissues. Insulin is a peptide hormone that causes cells to take in glucose. Through glyceroneogenesis, insulin down-regulates the expression of PEPC-K in both liver and adipose tissues.
Sources: en.wikipedia.org
This act was followed by reorganisational measures approved by the French parliament early in 1957 that ensured a large degree of self-government for individual territories. Upper Volta became an autonomous republic in the French community on 11 December 1958. Upper Volta achieved independence on 5 August 1960. The first president, Maurice Yaméogo, was the leader of the Voltaic Democratic Union (UDV). The 1960 constitution provided for election by universal suffrage of a president and a national assembly for five year terms; however, soon after coming to power, Yaméogo banned all political parties other than the UDV.
Anthropomorphised ants have often been used in fables, children's stories, and religious texts to represent industriousness and cooperative effort, such as in the Aesop fable The Ant and the Grasshopper. In the Quran, Sulayman is said to have heard and understood an ant warning other ants to return home to avoid being accidentally crushed by Sulayman and his marching army.[Quran 27:18], In parts of Africa, ants are considered to be the messengers of the deities. Some Native American mythology, such as the Hopi mythology, considers ants as the first animals. Ant bites are often said to have curative properties. The sting of some species of Pseudomyrmex is claimed to give fever relief. Ant bites are used in the initiation ceremonies of some Amazon Indian cultures as a test of endurance. In Greek mythology, the goddess Athena turned the maiden Myrmex into an ant when the latter claimed to have invented the plough, when in fact it was Athena's own invention.
Amyloid beta (Aβ, Abeta or beta-amyloid) denotes peptides of 36–43 amino acids that are the main component of the amyloid plaques found in the brains of people with Alzheimer's disease. The peptides derive from the amyloid-beta precursor protein (APP), which is cleaved by beta secretase and gamma secretase to yield Aβ in a cholesterol-dependent process and substrate presentation. Both neurons and oligodendrocytes produce and release Aβ in the brain, contributing to formation of amyloid plaques. Aβ molecules can aggregate to form flexible soluble oligomers which may exist in several forms. It is now believed that certain misfolded oligomers (known as "seeds") can induce other Aβ molecules to also take the misfolded oligomeric form, leading to a chain reaction akin to a prion infection. The oligomers are toxic to nerve cells. The other protein implicated in Alzheimer's disease, tau protein, also forms such prion-like misfolded oligomers, and there is some evidence that misfolded Aβ can induce tau to misfold. A study has suggested that APP and its amyloid potential is of ancient origins, dating as far back as early deuterostomes.
Other invertebrates may have no rigid structures but the epidermis may secrete a variety of surface coatings such as the pinacoderm of sponges, the gelatinous cuticle of cnidarians (polyps, sea anemones, jellyfish) and the collagenous cuticle of annelids. The outer epithelial layer may include cells of several types including sensory cells, gland cells and stinging cells. There may also be protrusions such as microvilli, cilia, bristles, spines and tubercles. Marcello Malpighi, the father of microscopical anatomy, discovered that plants had tubules similar to those he saw in insects like the silk worm. He observed that when a ring-like portion of bark was removed on a trunk a swelling occurred in the tissues above the ring, and he unmistakably interpreted this as growth stimulated by food coming down from the leaves, and being captured above the ring.
Sources: en.wikipedia.org
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.
No. It is a tripeptide made from three amino acids: glutamate, cysteine, and glycine. The gamma-glutamyl bond is unusual and distinguishes it from typical peptide linkages.
Most ingested glutathione is broken down in the gastrointestinal tract into its constituent amino acids. Some formulations may protect it from digestion, but intact absorption and delivery to specific tissues remain uncertain. Research continues on precursors and delivery methods.
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.