A practical reference on thiol: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-09-24 and is reviewed periodically as new material appears.
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.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. It occurs in nearly all living cells, with highest concentrations in liver, kidney, and red blood cells, and exists in reduced (GSH) and oxidized disulfide (GSSG) forms. The cysteine thiol group enables reversible oxidation and reduction reactions. This property makes glutathione a central participant in cellular redox balance. The balance between these forms is often used as an indicator of oxidative stress.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C10H17N3O6S | Reduced glutathione (GSH) |
| Molar mass | 307.32 g/mol | Calculated for C10H17N3O6S |
| Appearance | White to off-white powder | Typical solid form |
| Solubility | Water-soluble | Polar tripeptide |
| Common synonyms | GSH; L-glutathione | Gamma-glutamylcysteinylglycine |
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.
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 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.
Lechleiter had served as Lilly's president and chief operating officer since October 2005. In October 1998, Lilly formed a 50-50 joint venture with Icos, a Bothell, Washington-based biotechnology company, to develop and commercialize Tadalafil (Cialis), for the treatment of erectile dysfunction. Lilly agreed to pay Icos an upfront fee of $75 million.
The noradrenergic neurons in the brain form a neurotransmitter system, that, when activated, exerts effects on large areas of the brain. The effects are manifested in alertness, arousal, and readiness for action. Noradrenergic neurons (i.e., neurons whose primary neurotransmitter is norepinephrine) are comparatively few in number, and their cell bodies are confined to a few relatively small brain areas, but they send projections to many other brain areas and exert powerful effects on their targets. These noradrenergic cell groups were first mapped in 1964 by Annica Dahlström and Kjell Fuxe, who assigned them labels starting with the letter "A" (for "aminergic"). In their scheme, areas A1 through A7 contain the neurotransmitter norepinephrine (A8 through A14 contain dopamine). Noradrenergic cell group A1 is located in the caudal ventrolateral part of the medulla, and plays a role in the control of body fluid metabolism. Noradrenergic cell group A2 is located in a brainstem area called the solitary nucleus; these cells have been implicated in a variety of responses, including control of food intake and responses to stress. Cell groups A5 and A7 project mainly to the spinal cord. The most important source of norepinephrine in the brain is the locus coeruleus, which contains noradrenergic cell group A6 and adjoins cell group A4.
Repatriating the survivors of the 16 October strike on a semi-submersible to their home countries for prosecution avoids a civilian court challenge to continued detention without evidence, and a military court challenge to the legal justification for treating prisoners as unlawful combatants if they were not engaged in armed conflict.
Sources: en.wikipedia.org
Lisdexamphetamine was developed by Robert Oberlender at New River Pharmaceuticals, under the name NRP104, before being bought by Takeda Pharmaceuticals through its acquisition of Shire Pharmaceuticals, prior to market release. It was developed to create a longer-lasting and less-easily abused version of dextroamphetamine, as the requirement of conversion into dextroamphetamine via enzymes in the red blood cells delays its onset of action, regardless of the route of administration. In February 2007, the US Food and Drug Administration (FDA) approved lisdexamphetamine for the treatment of ADHD. In August 2009, Health Canada approved the marketing of lisdexamphetamine for prescription use. In January 2015, lisdexamphetamine was approved by the FDA for the treatment of binge eating disorder in adults. The FDA gave tentative approval to generic formulations of lisdexamphetamine in 2015. The expiration date for patent protection of lisdexamphetamine in the US was 24 February 2023. The Canadian patent expired 20 years from the filing date of 1 June 2004. Production quotas for 2016 in the United States were 29,750 kg.
=== Exceptions === Some jellyfish species, including Turritopsis dohrnii, Laodicea undulata, and Aurelia sp.1, are able to revert to the polyp stage even after reproducing (so-called reversible life cycle), rather than dying as in other jellyfish. Consequently, these species are considered biologically immortal and have no maximum lifespan. There may be no natural limit to the hydra's life span, but it is not yet clear how to estimate the age of a specimen. Flatworms, or Platyhelminthes, are known to be "almost immortal" as they have a great regeneration capacity, continuous growth, and binary fission type cellular division. Lobsters are sometimes said to be biologically immortal because they do not seem to slow down, weaken, or lose fertility with age. However, due to the energy needed for moulting, they cannot live indefinitely.
== Treatment == Often, treatment is not necessary, because episcleritis is a self-limiting condition. Artificial tears may be used to help with irritation and discomfort. More severe cases can be treated with either topical corticosteroids or oral non-steroidal anti-inflammatory drugs. Ketorolac, a topical NSAID, may be used, but it is not more effective than artificial tears and it causes more side effects.
Sources: en.wikipedia.org
where Q is the ion charge, n is the drift gas number density, μ is the reduced mass of the ion and the drift gas molecules, k is Boltzmann constant, T is the drift gas temperature, and σ is the collision cross-section between the ion and the drift gas molecules. Often, N is used instead of n for the drift gas number density, and Ω instead σ for the ion–neutral collision cross-section. This relation holds approximately at a low electric field limit, where the ratio of E/N is small, and thus the thermal energy of the ions is much greater than the energy gained from the electric field between collisions. With these ions having similar energies as the buffer gas molecules, diffusion forces dominate ion motion in this case. The ratio E/N is typically given in townsends (Td), and the transition between low- and high-field conditions is typically estimated to occur between 2 and 10 Td. When low-field conditions no longer prevail, the ion mobility itself becomes a function of the electric field strength, which is usually described empirically through the so-called alpha function:
=== Interaction with drugs === In vitro testing suggests that unidentified wolfberry phytochemicals in goji tea may inhibit metabolism of medications, such as those processed by the cytochrome P450 liver enzymes, including such drugs as warfarin.
== Signs and symptoms == Obesity is the chief symptom of HAIR-AN. In the majority of young women affected by HAIR-AN, hyperandrogenism leads to oily skin, acne, hirsutism, menstrual irregularities and, in some cases, androgenic alopecia, clitoromegaly, changes in muscle mass and deepening of the voice. Insulin resistance can be accompanied by normal or elevated levels of glucose. Symptoms of diabetes such as polydipsia, polyuria and weight loss may sometimes be present.
=== Cell movement === Actin is also involved in cell movement. Several different types of protrusions mediated directly or indirectly by actin are involved in cell migration in different ways, with the most important ones being lamellipodia, filopodia, invadopodia and blebs.
Sources: en.wikipedia.org
Glutathione is built from three amino acids: glutamate, cysteine, and glycine. The linkage involves the gamma-carboxyl group of glutamate rather than the alpha-carboxyl group, which is unusual for peptides. This structure protects the bond from some common peptidases.
It is present in nearly all cells, with notable amounts in the liver, kidneys, and red blood cells. The highest intracellular concentrations are usually in the millimolar range. Levels differ by tissue, age, and physiological state.
It is not classified as an essential nutrient because cells can synthesize it from amino acids. Dietary sources exist, but their contribution to tissue pools is not fully established. The body's production depends on enzyme activity and precursor availability.
GSH is the reduced thiol form, while GSSG is the disulfide-linked oxidized dimer. The GSH:GSSG ratio is used as a redox indicator, though the ratio can vary with sample handling and cell type.