The short version of HPLC fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-03-29. Anything still debated is marked as such rather than presented as settled.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. The peptide bond between glutamate and cysteine uses the gamma-carboxyl group of glutamate rather than the alpha-carboxyl group. This unusual linkage protects the molecule from many common peptidases. The cysteine side chain carries a thiol group that can undergo reversible oxidation. Because of this thiol, glutathione participates in redox reactions and helps maintain the reducing environment inside most cells in living systems.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common name | Glutathione | Tripeptide of glutamate, cysteine, and glycine |
| Reduced form | GSH | Dominant intracellular thiol |
| Oxidized form | GSSG | Disulfide-linked dimer |
| Molar mass | 307.32 g/mol | For reduced glutathione |
| Functional motif | Gamma-glutamyl-cysteinyl-glycine | Gamma linkage resists many peptidases |
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.
Biosynthesis proceeds in two ATP-dependent steps. First, glutamate-cysteine ligase joins glutamate and cysteine. Second, glutathione synthetase adds glycine to the intermediate. The pathway is regulated by cysteine availability, enzyme expression, and feedback inhibition by glutathione itself. Liver tissue has a particularly high capacity for synthesis and export. Because the molecule is made inside cells, circulating glutathione reflects a balance of release, uptake, and breakdown rather than simple dietary supply.
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.
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.
== Side effects == The adverse effects include drowsiness, dizziness, confusion, constipation, anxiety, nausea, blurred vision, restlessness, decreased coordination, dry mouth, shallow breathing, hallucinations, irritability, problems with memory or concentration, tinnitus and trouble urinating. Chlorphenamine produces less sedation than other first-generation antihistamines. A large study on people 65 years old or older linked the development of Alzheimer's disease and other forms of dementia to the "higher cumulative" use of chlorphenamine and other first-generation antihistamines, due to their anticholinergic properties. Chlorphenamine is rated as a "high burden" anticholinergic by experts on a semi-subjective scale. This is inconsistent with the in vitro experiments showing low affinity to muscarinic acetylcholine receptors (see below).
==== Infectious or not ==== One manner of proving that a given disease is infectious, is to satisfy Koch's postulates (first proposed by Robert Koch), which require that first, the infectious agent be identifiable only in patients who have the disease, and not in healthy controls, and second, that patients who contract the infectious agent also develop the disease. These postulates were first used in the discovery that Mycobacteria species cause tuberculosis. However, Koch's postulates cannot usually be tested in modern practice for ethical reasons. Proving them would require experimental infection of a healthy individual with a pathogen produced as a pure culture. Conversely, even clearly infectious diseases do not always meet the infectious criteria; for example, Treponema pallidum, the causative spirochete of syphilis, cannot be cultured in vitro – however the organism can be cultured in rabbit testes. It is less clear that a pure culture comes from an animal source serving as host than it is when derived from microbes derived from plate culture. Epidemiology, or the study and analysis of who, why and where disease occurs, and what determines whether various populations have a disease, is another important tool used to understand infectious disease. Epidemiologists may determine differences among groups within a population, such as whether certain age groups have a greater or lesser rate of infection; whether groups living in different neighborhoods are more likely to be infected; and by other factors, such as gender and race.
The coffee tree produces fruit often referred to as a coffee cherry, but unlike the cherry, which contains a single pit, it most commonly contains two seeds with their flat sides together. The seeds are referred to as beans because of their appearance, though they are not true beans. A few coffee cherries, referred to as "peaberries" contain a single seed; they make up around 10% to 15% of all coffee beans. It is sometimes asserted that because the single bean does not need to share nutrients between two separated beans, it has a superior flavour profile with bright acidity, sweetness, and concentrated and complex flavours, but there is little evidence to support this; for example, peaberries may have been selected from high-quality beans. Coffee trees range from 5 to 10 m (16 to 33 ft) in height. As the tree gets older, it produces less fruit and slowly loses its resistance to pests and diseases. The coffee beans are in the seeds of fruits from trees and shrubs that originally grew naturally in African forests. Humans produce coffee by roasting, grinding and brewing the raw (green) coffee beans. Coffee plants are often grown in rows spaced apart depending on the desired density chosen by the farmer. Some farmers plant shade trees or cash-crop trees, such as orange trees, around them, or plant the coffee on the sides of hills to provide the conditions coffee needs to flourish.
Sources: en.wikipedia.org
== Calcium-deficient hydroxyapatite == Calcium-deficient (non-stoichiometric) hydroxyapatite, Ca10−x(PO4)6−x(HPO4)x(OH)2−x (where x is between 0 and 1) has a Ca/P ratio between 1.67 and 1.5. The Ca/P ratio is often used in the discussion of calcium phosphate phases. Stoichiometric apatite Ca10(PO4)6(OH)2 has a Ca/P ratio of 10:6 normally expressed as 1.67. The non-stoichiometric phases have the hydroxyapatite structure with cation vacancies (Ca2+) and anion (OH−) vacancies. The sites occupied solely by phosphate anions in stoichiometric hydroxyapatite, are occupied by phosphate or hydrogen phosphate, HPO2−4, anions. These calcium-deficient phases can be prepared by precipitation from a mixture of calcium nitrate and diammonium phosphate with the desired Ca/P ratio, for example, to make a sample with a Ca/P ratio of 1.6:
=== 2005 === 22 January Wave that Shook the World, an Equinox Special about the 2004 Indian Ocean earthquake and tsunami, preceded by a Dispatches Live Special on the same topic; the earthquake occurs in the Sunda Trench in Sumatra, the edge of the Sunda Plate for around four minutes; British geologist Bill McGuire (volcanologist) of UCL; engineering seismologist Thomas H. Heaton of Caltech; the earthquake had the strength of all the Earth's earthquakes in the previous five years; Barry Hirshorn of the Pacific Tsunami Warning Center; Simon Boxall of the National Oceanography Centre, Southampton; photographer Geoff Mackley; three-quarter of the deaths were in Sumatra; the 2004 Sri Lanka tsunami train wreck; Richard Gross of NASA's Airborne Science Program at JPL; the Cascadia subduction zone; the O. H. Hinsdale Wave Research Laboratory at Oregon State University. Produced by Martin Williams, directed by Lara Acaster, made by Pioneer Productions with Nova and WGBH. Shown on Nova on 29 March 2005 2 May Riddle of the Human Hobbits, an Equinox Special, a 3 ft 18,000 yr old female was discovered in Indonesia in 2004; the hominids were possibly alive 12,000 years ago, being 1 metre tall, on the Flores islands, east of Indonesia; Australians Mike Morwood, of the University of New England (Australia), and Bert Roberts of the University of Wollongong, with Thomas Sutikna of National Archaeology Research Institute (Indonesia); Leslie C.
Pompilidotoxins (PMTXs) are toxic substances that can only be found in the venom of several solitary wasps. This kind of wasp uses their venom to offensively capture prey and is relatively harmless to humans. This is in stark contrast to social insects that defend themselves and their colonies with their venom. The pompilidotoxin producing wasps are part of the Pompilinae subfamily which consists of fifty known genus groups of which only two groups are known to produce the toxin. Both groups produce different variants. The first notice of a pompilidotoxin variant was made by Konno et.al in 1997 after a survey was conducted of neurotoxins in solitary wasps that inhabit Japan. He purified and synthesised this toxin, now called α-pompilidotoxin from the solitary spider wasp (Anoplius samariensis). The second, closely related variant, β-pompilidotoxin, was found by Konno et.al. a year later in 1998 in another solitary wasp (Batozonellus maculifrons) In this year Konno et.al. also shed concrete light on the structure and function of these toxins. Anoplius samariensis is known to live distributed over the globe with reported cases in east-Asia, east and central Europe, and Russia. It produces the α-PMTX to act upon the nervous system of a stung victim. This way they can paralyse a wide range of spiders that will then be dragged to the wasp's nest that is located in the ground, in a cavity of a plant stem, or made from mud. The spider wasp lays its eggs on paralysed spiders so that the hatching larvae can feed on living prey.
Sources: en.wikipedia.org
Glutathione is a tripeptide made from glutamate, cysteine, and glycine. Its cysteine residue provides a thiol group that is central to its redox activity. The glutamate-cysteine bond forms through the gamma-carboxyl group of glutamate.
Reduced glutathione, GSH, can donate electrons and become oxidized to GSSG. The balance between these forms reflects the cell's redox environment. A shift toward GSSG is commonly interpreted as evidence of oxidative stress, though the ratio can vary by tissue and method.
Glutathione occurs in nearly all cell types, with notable amounts in the liver. It is also present in the lungs, kidneys, and red blood cells. Concentrations differ among tissues and change with age, diet, and disease states.
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.