thiol raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-09-15. Anything still debated is marked as such rather than presented as settled.
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 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.
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.
| 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.
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.
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.
Glutathione is present in most tissues, with especially high concentrations in the liver. It also serves as a cofactor for some enzymes and helps transport amino acids across cell membranes. In plants and microorganisms, glutathione contributes to stress responses and metal handling. The molecule is synthesized in two ATP-dependent steps, first producing gamma-glutamylcysteine and then adding glycine. Because cysteine availability often limits synthesis, dietary and metabolic factors can influence glutathione levels. Research continues to examine how these levels relate to health and disease.
=== External phylogeny === Animals are monophyletic, meaning they are derived from a common ancestor. Animals are the sister group to the choanoflagellates, with which they form the Choanozoa. Ros-Rocher and colleagues (2021) trace the origins of animals to unicellular ancestors, providing the external phylogeny shown in the cladogram. Uncertainty of relationships is indicated with dashed lines. The animal clade had certainly originated by 650 mya, and may have come into being as much as 800 mya, based on molecular clock evidence for different phyla.
=== Cardiac-valvular === Cardiac-valvular EDS (cvEDS) is characterized by three major criteria: severe progressive cardiac-valvular problems (affecting aortic and mitral valves), skin problems such as hyperextensibility, atrophic scarring, thin skin, and easy bruising, and joint hypermobility (generalized or restricted to small joints). Four minor criteria may aid in the diagnosis of cvEDS. cvEDS is an autosomal recessive disorder, inherited through variation in both alleles of the gene COL1A2.
Osteoporosis is a disease of bone where there is reduced bone mineral density, increasing the likelihood of fractures. Osteoporosis is defined in women by the World Health Organization as a bone mineral density of 2.5 standard deviations below peak bone mass, relative to the age and sex-matched average. This density is measured using dual energy X-ray absorptiometry (DEXA), with the term "established osteoporosis" including the presence of a fragility fracture. Osteoporosis is most common in women after menopause, when it is called "postmenopausal osteoporosis", but may develop in men and premenopausal women in the presence of particular hormonal disorders and other chronic diseases or as a result of smoking and medications, specifically glucocorticoids. Osteoporosis usually has no symptoms until a fracture occurs. For this reason, DEXA scans are often done in people with one or more risk factors, who have developed osteoporosis and are at risk of fracture. One of the most important risk factors for osteoporosis is advanced age. Accumulation of oxidative DNA damage in osteoblastic and osteoclastic cells appears to be a key factor in age-related osteoporosis. Osteoporosis treatment includes advice to stop smoking, decrease alcohol consumption, exercise regularly, and have a healthy diet. Calcium and trace mineral supplements may also be advised, as may Vitamin D. When medication is used, it may include bisphosphonates, Strontium ranelate, and hormone replacement therapy.
Sources: en.wikipedia.org
=== U.S. production ceases and resumes === The United States stopped producing bulk 238Pu with the closure of the Savannah River Site reactors in 1988. Since 1993, all of the 238Pu used in American spacecraft has been purchased from Russia. From 1992 to 1994, 10 kilograms were purchased by the US Department of Energy from Russia's Mayak Production Association. Via agreement with Minatom, the US must use plutonium for uncrewed NASA missions, and Russia must use the currency for environmental and social investment in the Chelyabinsk region, affected by long-term radioactive contamination such as the Kyshtym disaster. In total, 16.5 kilograms (36 lb) have been purchased, but Russia is no longer producing 238Pu, and their own supply is reportedly running low. In February 2013, a small amount of 238Pu was successfully produced by Oak Ridge's High Flux Isotope Reactor, and on December 22, 2015, they reported the production of 50 grams (1.8 ounces) of 238Pu. In March 2017, Ontario Power Generation (OPG) and its venture arm, Canadian Nuclear Partners, announced plans to produce 238Pu as a second source for NASA. Rods containing neptunium-237 will be fabricated by Pacific Northwest National Laboratory (PNNL) in Washington State and shipped to OPG's Darlington Nuclear Generating Station in Clarington, Ontario, Canada where they will be irradiated with neutrons inside the reactor's core to produce 238Pu.
==== Deductions for certain workers' meals ==== The law allows a tax deduction for restaurants and caterers for the cost of providing a free meal to workers while on shift. Companies can also take a tax deduction for the cost of free meals provided to workers on offshore oil rigs and gas platform workers. Companies that are required to provide meals to maritime crew under federal law may also take a tax deduction for the cost of those meals.
=== Feminism === The growth of popularity and access to TikTok has contributed to a growth in popularity of digital feminist movements and discourse originating from the platform. Digital spaces like TikTok enable marginalized communities and activists, such as feminists, to feel safer and have an easier place to engage in discussion and dialogue or build an identity which might otherwise be impossible due to circumstances. The momentum of digital feminist movements through platforms like TikTok have additionally encouraged many social media agents and marketing campaigns around the world to adopt some degree of feminism as a part of their online image or personal brand. TikTok's unique platform organization, of spontaneous peer-peer information sharing, has enabled its utilization for community-engaged, digital knowledge mobilization and exchange between social justice communities. However inversely enabled by the platform's organic potential, both feminist challenges and anti-feminist reinforcement of dominant social, hierarchical, and gender values are widespread and instigated through TikTok, and content labeled as anti-feminist is itself popularized on TikTok.
Sources: en.wikipedia.org
Mass spectrometer is in fact hyphenation between the separative instrument and a mass spectrometry instrument to get information on the molecular weight or atomic weight of the solute. In the advanced mass spectrometry technologies there is information on solutes structure and even chemical properties. The hyphenation between ultra high performance chromatography with high resolution mass spectrometers revolutionalized entire new scientific fields of research and application, such as toxicology, proteomics, lipidomics, genomics, metabolomics and metabonomics.
EMP, also known as estradiol normustine phosphate, is a combined estrogen ester and nitrogen mustard ester. It consists of estradiol, an estrogen, linked with a phosphate ester as well as an ester of normustine, a nitrogen mustard. In terms of its pharmacodynamic effects, EMP is a prodrug of estramustine, estromustine, and estradiol. As a prodrug of estradiol, EMP is an estrogen and hence an agonist of the estrogen receptors. EMP itself has only very weak affinity for the estrogen receptors. The medication is of about 91% higher molecular weight than estradiol due to the presence of its C3 normustine and C17β phosphate esters. Because EMP is a prodrug of estradiol, it may be considered to be a natural and bioidentical form of estrogen, although it does have additional cytostatic activity via estramustine and estromustine. EMP acts by a dual mechanism of action: 1) direct cytostatic activity via a number of actions; and 2) as a form of high-dose estrogen therapy via estrogen receptor-mediated antigonadotropic and functional antiandrogenic effects. The antigonadotropic and functional antiandrogenic effects of EMP consist of strong suppression of gonadal androgen production and hence circulating levels of androgens such as testosterone; greatly increased levels of sex hormone-binding globulin and hence a decreased fraction of free androgens in the circulation; and direct antiandrogenic actions in prostate cells. The free androgen index with oral EMP has been found to be on average 4.6-fold lower than with orchiectomy.
Sierra View Medical Center is a 167-bed, full-service acute care hospital located in Porterville, California. Founded in 1958, the hospital serves the Southern Sequoia region of California's Central Valley. Services include cancer care, an intensive-care unit and respiratory care. The hospital is a part of the Sierra View Local Healthcare District. It offers a wide range of health care services featuring state of the art technologies including Magnetic Resonance Imaging (MRI) and Computed Tomography (CT). The hospital is also home to the Roger S. Good Cancer Treatment Center, which hosts clinical trials of the University of California Los Angeles in oncology. In July 2007, the hospital opened a 32-station outpatient Dialysis Center. The hospital's Wound Healing Center is managed by Healogics. Sierra View Medical Center was awarded the Joint Commission's Gold Seal of Approval for Primary Stroke Centers in 2021, demonstrating compliance with high standards in quality improvement for patient outcomes. The hospital also received the organization's Pioneers in Quality award in 2017. Sierra View Medical Center received the Get With The Guidelines - Stroke GOLD PLUS with Target: Type 2 Diabetes Honor Roll from the American Heart Association. It is also the only hospital in Tulare County to be designated "Baby Friendly" following a World Health Organization and UNICEF-supported initiative aimed at promoting breastfeeding. The Wound Healing Center was awarded the Healogics Robert A. Warriner III Center of Excellence in 2018.
The enzyme can also act on putrescine, which has one extra CH2 in the diamine component, to give carboxyspermidine. Vibrio cholerae uses this enzyme in combination with carboxynorspermidine decarboxylase to make spermidine and norspermidine. This sequence is the dominant pathway to spermidine used by gut microbiota in humans.
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 form with a free thiol group, while GSSG is the oxidized disulfide-linked dimer. Most assays distinguish the two because their balance reflects redox conditions. The names are not interchangeable.