Tietze assay comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-08-27. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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 made of glutamic acid, cysteine, and glycine. Its cysteine thiol group allows reversible oxidation and reduction, making it central to cellular redox chemistry. The reduced form, often abbreviated GSH, predominates inside most cells, while the oxidized disulfide form, GSSG, forms when two GSH molecules react. The ratio of GSH to GSSG is widely used as an indicator of oxidative stress in laboratory research, though it does not by itself diagnose a clinical condition.
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.
| Property | Value | Notes |
|---|---|---|
| Common name | Glutathione (reduced form) | Often abbreviated GSH |
| Chemical class | Tripeptide | Contains glutamate, cysteine, and glycine |
| Molecular formula | C10H17N3O6S | Refers to the reduced form |
| Molar mass | 307.32 g/mol | Calculated for C10H17N3O6S |
| Appearance | White to off-white powder | Typical laboratory-grade solid |
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.
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.
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.
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.
Interpreting glutathione measurements requires attention to pre-analytical variables. The GSSG concentration in a sample can rise artificially during storage or processing, making the GSH/GSSG ratio unreliable if not controlled. Reference ranges vary by specimen type, assay, and population, so comparisons across studies are difficult. Plasma glutathione is low and sensitive to hemolysis, while whole blood reflects primarily erythrocyte content. Many studies measure total glutathione rather than the reduced and oxidized forms separately, which limits conclusions about redox status.
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.
==== Limitations ==== When immature or abnormal white blood cells are present, automated differential results may be incorrect, necessitating a manual blood smear review. Overall, 10 to 25 percent of CBC samples are flagged for manual review by the analyzer. Although most abnormal samples are automatically flagged, some may be missed; conversely, analyzers may generate false positive flags when no abnormal cells are present. Hematology laboratories compensate for these issues by requiring a smear review when differential or CBC results fall outside certain numerical thresholds, regardless of the presence of analyzer flags. The sensitivity and specificity of analyzer flagging can be determined by comparing analyzer flags to manual differential results. The automated basophil count is notoriously unreliable, often underestimating counts in basophilia and producing falsely elevated results in the presence of abnormal cells. The manual differential is therefore considered the reference method for these cells. Analyzers may count nucleated red blood cells, giant and clumped platelets, and red blood cells containing abnormal hemoglobins (such as Hemoglobin S in sickle cell disease) as white blood cells, leading to faulty differential results. Automated differential counts on aged specimens may be incorrect due to cellular degeneration.
Metopon (5-methylhydromorphone, CAS number 124-92-5) is an opioid analogue that is a methylated derivative of hydromorphone which was invented in 1929 as an analgesic. Metopon is sometimes used in medicine. Although longer acting than hydromorphone, metopon is less potent and its oral bioavailability is fairly low. Generally, metopon has few advantages to distinguish it from other, more commonly used opioid analgesics, although it does have a slightly lower tendency to produce nausea and respiratory depression compared to morphine. In Canada, as of 1948, the hydrochloride of metopon (free base conversion ratio 0.891, molecular weight 335.8) was available only for oral administration for malignant pain and for maintenance of those habituated to morphine; the only dosage form available was singly scored 8 mg tablets. It was manufactured by Parke, Davis, & Co., and was only for sale to doctors and hospitals. Parke, Davis & Co. did not sell metopon to pharmacies. It is unknown whether metopon tablets are still manufactured and sold in Canada. Metopon tablets, ampoules, and suppositories are available in Switzerland, Austria, Germany, and other countries in Continental Europe and the drug is used in Patient Controlled Analgesia pumps for severe chronic pain in particular. Metopon is listed under Schedule II of the US Controlled Substances Act 1970, meaning it has an accepted medical use, but at this time it is not produced commercially and is seen only in laboratory research. It did see some use in medicine — oncology in particular — in the US in the 1950s.
α-Methylserotonin (αMS), also known as α-methyl-5-hydroxytryptamine (α-methyl-5-HT) or as 5-hydroxy-α-methyltryptamine (5-HO-αMT), is a tryptamine derivative closely related to the neurotransmitter serotonin (5-HT). It acts as a non-selective serotonin receptor agonist and has been used extensively in scientific research to study the function of the serotonin system.
=== Asthma === Developing asthma due to abdominal obesity is also a main concern. As a result of breathing at low lung volume, the muscles are tighter and the airway is narrower. Obesity causes decreased tidal volumes due to a reduction in chest expansion that is caused both by the weight on the chest itself and the effect of abdominal obesity on flattening the diaphragm. It is commonly seen that people who are obese breathe quickly and often, while inhaling small volumes of air. People with obesity are also more likely to be hospitalized for asthma. A study has stated that 75% of patients treated for asthma in the emergency room were either overweight or obese.
== Cell imaging == Chemical tags have been tailored for imaging technologies more so than fluorescent proteins because chemical tags can localize photosensitizers closer to the target proteins. Proteins can then be labeled and detected with imaging such as super-resolution microscopy, Ca2+-imaging, pH sensing, hydrogen peroxide detection, chromophore assisted light inactivation, and multi-photon light microscopy. In vivo imaging studies in live animals have been performed for the first time with the use of a monomeric protein derived from the bacterial haloalkane dehalogenase known as the Halo-tag. The Halo-tag covalently links to its ligand and allows for better expression of soluble proteins.
Sources: en.wikipedia.org
Greer (born 1945), American chemist notable for work on thermodynamics of fluids, polymer solutions and phase transitions François Auguste Victor Grignard (1871–1935), French chemist, 1912 Nobel Prize in Chemistry for his work on reactions important in the formation of carbon–carbon bonds Robert H. Grubbs (1942–2021), 2005 Nobel Prize in Chemistry for work on olefin metathesis Louis-Bernard Guyton de Morveau (1737–1816), French chemist known for establishing modern chemical nomenclature
=== 2000–2011: Established actor and diversification === In 2000, Carrey reteamed with the Farrelly brothers, who had previously directed him in Dumb and Dumber, for the black comedy film Me, Myself & Irene, a film that received mixed reviews but enjoyed box office success. Carrey played the role of state trooper Charlie Baileygates, who has multiple personalities and romances a woman portrayed by Renée Zellweger. That same year, Carrey starred in the second highest-grossing Christmas film of all time, How the Grinch Stole Christmas, playing the title character, for which he received both praise and criticism from critics alongside a Golden Globe nomination. For his next feature film, Carrey starred opposite Jennifer Aniston and Morgan Freeman in Tom Shadyac's international hit comedy Bruce Almighty (2003). Carrey played a television newsman who unexpectedly receives God's omnipotent abilities when the deity decides to take a vacation. The film received mixed reviews upon release but still became a financial success, earning over $484 million worldwide, and going on to become the seventeenth highest-grossing live action comedy of all time. In 2004, Carrey starred in Eternal Sunshine of the Spotless Mind. The film received critical acclaim upon release. Critics highly praised Carrey's portrayal of Joel Barish, in addition to the performance of his co-star Kate Winslet, who was nominated for an Oscar.
30 August – Nicky Gavron, 82, British politician, deputy mayor of London (2000–2003, 2004–2008). 3 September – Flora Fraser, 21st Lady Saltoun, 93, Scottish peer, member of the House of Lords (1979–2014). 18 September – Malcolm Mitchell-Thomson, 3rd Baron Selsdon, 86, British peer, banker and businessman, member of the House of Lords (1963–2021). 1 October – Michael Ancram, 13th Marquess of Lothian, 79, British politician and peer, three-times MP, member of the House of Lords (since 2010). 2 October – Herman Ouseley, Baron Ouseley, 79, Guyanese-born British civil rights activist and politician, member of the House of Lords (2001–2019). 4 October – Alexander Leitch, Baron Leitch, 76, British businessman and life peer, member of the House of Lords (since 2004). 7 October – Hugh Cholmondeley, 5th Baron Delamere, 90, British peer, member of the House of Lords (1979–1999). 12 October – Alex Salmond, 69, Scottish politician, first minister (2007–2014). 20 October – Paul White, Baron Hanningfield, 84, British politician and life peer, member of the House of Lords (since 1998). 4 November – Robin Renwick, Baron Renwick of Clifton, 86, British diplomat and life peer, ambassador to the United States (1991–1995). 6 November – Anna Lo, 74, Northern Irish politician, MLA (2007–2016). Sir John Nott, 92, British politician, MP (1966–1983) and defence secretary (1981–1983). 20 November – John Prescott, Baron Prescott, 86, British politician, deputy prime minister (1997–2007), first secretary of state (2001–2007), and MP (1970–2010).
What we have got is the smoking gun - the thing that caused his illness and was given to him with malice." Subsequently, French and Russian teams claimed that the elevated 210Po levels were not the result of deliberate poisoning, and did not cause Arafat's death. It has also been suspected that Russian businessman Roman Tsepov was killed with polonium. He had symptoms similar to Litvinenko's.
Sources: en.wikipedia.org
One or more of the disulfide bonds that join the heavy chains in the hinge region are preserved, so the two Fab regions of the antibody remain joined together, yielding a divalent molecule (containing two antibody binding sites), hence the designation F(ab')2. The light chains remain intact and attached to the heavy chain. The Fc fragment is digested into small peptides. Fab fragments are generated by cleavage of IgG with papain instead of pepsin. Papain cleaves IgG above the hinge region containing the disulfide bonds that join the heavy chains, but below the site of the disulfide bond between the light chain and heavy chain. This generates two separate monovalent (containing a single antibody binding site) Fab fragments and an intact Fc fragment. The fragments can be purified by gel filtration, ion exchange, or affinity chromatography. Fab and F(ab')2 antibody fragments are used in assay systems where the presence of the Fc region may cause problems. In tissues such as lymph nodes or spleen, or in peripheral blood preparations, cells with Fc receptors (macrophages, monocytes, B lymphocytes, and natural killer cells) are present, which can bind the Fc region of intact antibodies, causing background staining in areas that do not contain the target antigen. Use of F(ab')2 or Fab fragments ensures that the antibodies are binding to the antigen and not Fc receptors. These fragments may also be desirable for staining cell preparations in the presence of plasma, because they are not able to bind complement, which could lyse the cells.
There are as many mass-balance equations as there are reagents, A, B..., so if the equilibrium constant values are known, there are n mass-balance equations in n unknowns, [A], [B]..., the so-called free reagent concentrations. Solution of these equations gives all the information needed to calculate the concentrations of all the species. Thus, the importance of equilibrium constants lies in the fact that, once their values have been determined by experiment, they can be used to calculate the concentrations, known as the speciation, of mixtures that contain the relevant species.
== Ecology == Cercopagis pengoi is eurythermal and euryhaline, being able to tolerate a wide range of temperature and salinity. It is a pelagic species, found in a higher abundance further from the shore and from the bottom. It is a generalist feeder which preys on various species in both micro- and mesozooplankton (i.e. cladocerans, copepods, rotifers). The size of prey ranges from its own body size to seventeen times smaller. Prey is captured using thoracopods I, then retained by thoracopods II-IV, and crushed by its cuticle by mandibles, finally C. pengoi sucks the prey body contents. Fishhook waterfleas reproduce asexually during the summer, which produces a quick rise in population. When conditions are inhospitable, C. pengoi will undergo sexual reproduction, producing resting eggs that can over-winter and repopulate the lake quickly in the spring. Resting eggs can withstand desiccation (extreme dryness), freeze-drying, and ingestion by fish.
The Ebers Papyrus is among the oldest and most important medical papyri of Ancient Egypt. Written c. 1550 BC, it was likely copied from a series of much earlier texts, and contains a passage from the First Dynasty (c. 3400 BC). The document is named after Georg Ebers, who purchased the document in 1872 in the city of Luxor, the site of Thebes (known to Ancient Egyptians as Waset). Thebes was the most venerated city of Ancient Egypt in its heyday during the Middle Kingdom and New Kingdom. The Ebers Papyrus is thought to contain the first known medical reference to diabetes, by the phrase: "...to eliminate urine which is too asha". The crucial word asha can mean both "plentiful" and "often". It is unclear whether the condition described was excessive urine (polyuria), which may have been symptomatic of diabetes, or increased frequency of urine, very often due to urinary tract infection. The following mixture was prescribed for treatment: "A measuring glass filled with Water from the Bird pond, Elderberry, Fibres of the asit plant, Fresh Milk, Beer-Swill, Flower of the Cucumber, and Green Dates". Urinary troubles in the adult were also corrected with "rectal injections of olive oil, honey, sweet beer, sea salt, and seeds of the wonderfruit".
=== Metal binding interactions === Binding metal ions to protein and other components of biological material is one of the most popular uses of ITC, since ovotransferrin to ferric iron binding study published by Lin et al. from MicroCal Inc. This is due to some of the metal ions utilized in biological systems having d10 electron configuration which cannot be studied with other common techniques such as UV-vis spectrophotometry or electron paramagnetic resonance. It is also closely related to biochemical and medicinal studies due to the large abundance of metal binding enzymes in biological systems.
Sources: en.wikipedia.org
Glutathione is a sulfur-containing tripeptide made from glutamate, cysteine, and glycine. It is found in most cells and participates in redox balance and detoxification reactions.
No. It is a tripeptide assembled from three amino acids. The term amino acid applies to the individual building blocks, not to the assembled molecule.
It is present in many tissues, with especially high amounts in liver. Intracellular concentrations are generally much higher than those found in blood plasma.
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.