A practical reference on derivatization: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-08-25. Anything still debated is marked as such rather than presented as settled.
In living systems, glutathione occurs in millimolar concentrations in many cell types, while extracellular levels are generally much lower. The liver holds a substantial share of the body's total pool, and the molecule participates in reduction, detoxification, and amino acid transport. It also serves as a cofactor for enzymes such as glutathione peroxidase and glutathione S-transferase. Because the cysteine residue supplies a reactive thiol, glutathione can donate electrons and become oxidized. Cells regenerate reduced glutathione through glutathione reductase using NADPH.
Commercial glutathione is produced by microbial fermentation or chemical synthesis, then purified. Reduced and oxidized grades are offered separately, with purity specifications often exceeding 98 percent. The compound appears in foods such as fresh fruits, vegetables, and meats, although cooking and processing can lower amounts. Oral, topical, and inhaled forms are discussed in research and consumer contexts, but absorption and tissue delivery remain active areas of study. Regulatory status varies by country and intended use.
Quality control for glutathione focuses on identity, purity, and oxidation state. Certificates of analysis may report assay value, water content, and the presence of GSSG or other impurities. Chromatographic purity is often expressed as a percentage of peak area. Reference standards help laboratories compare results across instruments and batches. Because glutathione is a small, polar molecule, separation from cysteine, gamma-glutamylcysteine, and related thiols can be challenging. Verification often combines more than one analytical technique.
Measuring glutathione requires attention to sample preparation because the molecule oxidizes readily. Blood, tissue, and cell samples are often treated with acid to precipitate proteins and stabilize the thiol. Without such steps, GSH can convert to GSSG or form mixed disulfides during storage. Analytical methods include spectrophotometric assays, high-performance liquid chromatography, and mass spectrometry. Each approach has different sensitivity, specificity, and susceptibility to interference from related compounds in complex matrices.
For solid glutathione, storage conditions affect shelf life. The reduced form is typically kept cool, dry, and protected from air and light. Moisture can promote oxidation, while elevated temperatures accelerate degradation. Suppliers often specify storage at or below freezing, sometimes under inert gas. Solutions are less stable than powders and may require preparation shortly before use. Buffers and chelating agents can slow oxidation, but they do not eliminate it. Published stability data vary with matrix, pH, and container.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C10H17N3O6S | Reduced glutathione (GSH) |
| Molar mass | 307.32 g/mol | Oxidized dimer GSSG is 612.63 g/mol |
| Appearance | White to off-white crystalline powder | Typical purified solid |
| Solubility | Freely soluble in water; practically insoluble in ethanol | Polarity reflects multiple ionizable groups |
| Common synonyms | GSH; L-glutathione; γ-glutamylcysteinylglycine | 'Reduced' distinguishes it from GSSG |
For solid glutathione reagents, storage at low temperature and protection from moisture and light are typical precautions. Aqueous solutions can oxidize over time, and pH affects stability; alkaline conditions generally promote thiol oxidation. Some protocols prepare fresh solutions, while others use antioxidants or chelators to limit metal-catalyzed oxidation. Purity and counterion content can vary among commercial preparations, affecting concentration calculations. Certificates of analysis and validated assays help verify identity and purity.
Measuring glutathione in biological samples requires attention to oxidation, because GSH can convert to GSSG after sample collection. Blood and plasma samples are often treated with acid or alkylating agents to preserve the reduced form. Without stabilization, apparent GSH concentrations can fall while GSSG rises. Differences in sample type, handling delay, and deproteinization method can produce results that are not comparable across studies. Reporting preanalytical details is therefore important for interpreting findings.
Several techniques are used for quantification. Enzymatic recycling assays rely on glutathione reductase and a colorimetric or fluorescent readout, offering sensitivity for total glutathione. High-performance liquid chromatography can separate GSH from GSSG and other thiols, often with UV, fluorescence, or electrochemical detection. Mass spectrometry provides structural confirmation and can quantify low-abundance species when paired with separation. Each approach has trade-offs in specificity, throughput, and equipment requirements, so method selection depends on the research question and available instrumentation.
Stability depends on pH, temperature, oxygen exposure, and trace metals. Aqueous solutions of reduced glutathione are susceptible to oxidation, especially when neutral or alkaline and exposed to air. Transition metal ions can catalyze thiol oxidation, so chelators and inert atmospheres are sometimes used in research settings. Standards are typically stored cold and desiccated, with limited freeze-thaw cycles. Questions remain about how closely in vitro stability data reflect the behavior of glutathione within intact cells and tissues.
Measuring glutathione requires attention to oxidation during sample handling, because GSH in biological samples can convert to GSSG or form mixed disulfides with proteins after collection. Acidic extraction, rapid cooling, and chelating agents are commonly used to limit such changes. Analytical methods usually distinguish free reduced glutathione, total glutathione, and protein-bound forms. Because these forms have different stability and reactivity, reported values depend heavily on the preparation protocol. No single preparation is universally suitable for every biological matrix or analytical goal.
==== Increase in cancer risk ==== The IARC concluded that if unprocessed red meat does cause cancer, there is a 17% higher risk of colorectal cancer for every 100 g of unprocessed red meat consumed daily. It found an 18% higher risk of colorectal cancer for every 50 g of processed red meat consumed daily. A 2021 umbrella review reported an increase of 11–51% risk of multiple cancer per 100g/d increment of red meat, and an increase of 8–72% risk of multiple cancer per 50g/d increment of processed meat. A 2022 Burden of Proof study analyzed data from epidemiological evidence (not mechanistic evidence) and found that each 100 g of unprocessed red meat consumed per day would increase colorectal cancer risk by at least 6% and breast cancer by at least 3%. The Burden of Proof methodology was later criticized for systematically under-estimating levels of risk.
April 3 – A United States Air Force F-15E Strike Eagle is shot down over Iran during combat operations. Both crew members are later rescued. During the rescue mission, an A-10 Thunderbolt II is also hit and crashes, though its pilot ejects safely and is recovered. April 4 – 2025–26 NHL season: In ice hockey, the Buffalo Sabres clinched the Stanley Cup playoffs for the first time since the 2010–11 season, ending their 14-year Stanley Cup playoff drought. April 5 Trump posts an expletive-laden message on Truth Social threatening to destroy Iranian power plants and bridges if Iran does not reopen the Strait of Hormuz, writing: "Open the Fuckin' Strait, you crazy bastards, or you'll be living in Hell – JUST WATCH!" The 2026 NCAA Division I women's basketball championship game is held at the Mortgage Matchup Center in Phoenix, Arizona, in which the UCLA Bruins beat the South Carolina Gamecocks 79–51 to win their first title. April 6 The crew of Artemis II breaks the record for the furthest humans have ever been from Earth, reaching a maximum distance of 252,757 miles (406,773 km) as they travel around the far side of the Moon. The Supreme Court vacates a federal appeals court ruling that upheld former Trump advisor Steve Bannon's criminal conviction for contempt of Congress for defying a subpoena from the January 6th Committee. The DOJ moves to formally dismiss Bannon's convictions.
Francium is a chemical element; it has symbol Fr and atomic number 87. It is extremely radioactive; its most stable isotope, francium-223 (originally called actinium K after the natural decay chain in which it appears), has a half-life of only 22 minutes. It is the second-most electropositive element, behind only caesium, and is the second rarest naturally occurring element (after astatine). Francium's isotopes decay quickly into astatine, radium, and radon. The electronic structure of a francium atom is [Rn] 7s1; thus, the element is classed as an alkali metal. As a consequence of its extreme instability, bulk francium has never been seen. Because of the general appearance of the other elements in its periodic table column, it is presumed that francium would appear as a highly reactive metal if enough could be collected together to be viewed as a bulk solid or liquid. Obtaining such a sample is highly improbable since the extreme heat of decay resulting from its short half-life would immediately vaporize any viewable quantity of the element. Francium was discovered by Marguerite Perey in France (from which the element takes its name) on January 7, 1939. Before its discovery, francium was referred to as eka-caesium or ekacaesium because of its conjectured existence below caesium in the periodic table. It was the last element first discovered in nature, rather than by synthesis. Outside the laboratory, francium is extremely rare, with trace amounts found in uranium ores, where the isotope francium-223 (in the family of uranium-235) continually forms and decays.
The biguanide class of antidiabetic medications, which also includes the withdrawn agents phenformin and buformin, originates from research on Goat's rue (Galega officinalis) also known as Galega, French lilac, Italian fitch, Spanish sainfoin, Pestilenzkraut, or Professor-weed. (The plant should not be confused with plants in the genus Tephrosia which are highly toxic and sometimes also called Goat's rue.) Galega officinalis has been used in folk medicine for several centuries. G. officinalis itself does not contain biguanide medications which are chemically synthesized compounds composed of two guanidine molecules joined together and designed to be less toxic than the plant-derived parent compound galegine (isoamylene guanidine). Metformin was first described in the scientific literature in 1922, by Emil Werner and James Bell, as a product in the synthesis of N,N-dimethylguanidine. In 1929, Slotta and Tschesche discovered its sugar-lowering action in rabbits, finding it the most potent biguanide analog they studied. This result was ignored, as other guanidine analogs such as the synthalins, took over and were themselves soon overshadowed by insulin. Interest in metformin resumed at the end of the 1940s. In 1950, metformin, unlike some other similar compounds, was found not to decrease blood pressure and heart rate in animals. That year, Filipino physician Eusebio Y. Garcia used metformin (he named it Fluamine) to treat influenza; he noted the medication "lowered the blood sugar to minimum physiological limit" and was not toxic.
Brain levels of endogenous trace amines are several hundred-fold below those for the classical neurotransmitters noradrenaline, dopamine, and serotonin, but their rates of synthesis are equivalent to those of noradrenaline and dopamine and they have a very rapid turnover rate. Endogenous extracellular tissue levels of trace amines measured in the brain are in the low nanomolar range. These low concentrations arise because of their very short half-life. Because of the pharmacological relationship between phenethylamine and amphetamine, the original paper and both reviews suggest that phenethylamine plays a prominent role in mediating the mood-enhancing euphoric effects of a runner's high, as both phenethylamine and amphetamine are potent euphoriants. Skydiving has also been shown to induce a marked increase in urinary phenethylamine concentrations.
Sources: en.wikipedia.org
This reflected a new PLAN tactic of laying anti-personnel mines parallel to their anti-tank mines to kill policemen or soldiers either engaging in preliminary mine detection or inspecting the scene of a previous blast. In 1972, South Africa acknowledged that two more policemen had died and another three had been injured as a result of mines. The proliferation of mines in the Caprivi and other rural areas posed a serious concern to the South African government, as they were relatively easy for a PLAN cadre to conceal and plant with minimal chance of detection. Sweeping the roads for mines with hand held mine detectors was possible, but too slow and tedious to be a practical means of ensuring swift police movement or keeping routes open for civilian use. The SADF possessed some mine clearance equipment, including flails and ploughs mounted on tanks, but these were not considered practical either. The sheer distances of road vulnerable to PLAN sappers every day was simply too vast for daily detection and clearance efforts. For the SADF and the police, the only other viable option was the adoption of armoured personnel carriers with mine-proof hulls that could move quickly on roads with little risk to their passengers even if a mine was encountered. This would evolve into a new class of military vehicle, the mine resistant and ambush protected vehicle (MRAP). By the end of 1972, the South African police were carrying out most of their patrols in the Caprivi Strip with mineproofed vehicles.
The first step of transcription for some negative, single-stranded RNA viruses is cap snatching, in which the first 10 to 20 residues of a host cell RNA are removed (snatched) and used as the 5′ cap and primer to initiate the synthesis of the nascent viral mRNA. The viral RNA-dependent RNA polymerase (RdRp) can then proceed to transcribe positive-sense viral mRNA using the negative-sense viral RNA as a template. Cap-snatching also explains why some viral mRNA have 5' terminal extensions of 10-20 nucleotides that are not encoded for in the genome. Examples of viruses that engage in cap-snatching include influenza viruses (Orthomyxoviridae), Lassa virus (Arenaviridae), hantaan virus (Hantaviridae) and rift valley fever virus (Phenuiviridae). Most viruses snatch 15-20 nucleotides except for the families Arenaviridae and Nairoviridae and the genus Thogotovirus (Orthomyxoviridae) which use a shorter strand. In the influenza virus, cap snatching occurs in the nucleus of the cell. The cap snatching endonuclease function is contained in the PA subunit of the RNA polymerase. In Arenaviridae and Bunyavirales, cap-snatching takes place in the cytoplasm.
Bacteria (particularly those that are catalase-positive) Staphylococcus aureus. Serratia marcescens. Listeria species. E. coli. Klebsiella species. Pseudomonas cepacia, a.k.a. Burkholderia cepacia. Nocardia. Fungi Aspergillus species. Aspergillus has a propensity to cause infection in people with CGD and of the Aspergillus species, Aspergillus fumigatus seems to be most common in CGD. Candida species. Patients with CGD can usually resist infections of catalase-negative bacteria but are susceptible to catalase-positive bacteria. Catalase is an enzyme that catalyzes the breakdown of hydrogen peroxide in many organisms. In infections caused by organisms that lack catalase (catalase-negative), the host with CGD is successfully able to "borrow" hydrogen peroxide being made by the organism and use it to fight off the infection. In infections by organisms that have catalase (catalase-positive), this "borrowing mechanism" is unsuccessful because the enzyme catalase first breaks down any hydrogen peroxide that would be borrowed from the organism. Therefore in the CGD patient, hydrogen peroxide cannot be used to make oxygen radicals to fight infection, leaving the patient vulnerable to infection by catalase-positive bacteria.
Portal is a single-player first-person action/puzzle game that was first available as a part of The Orange Box as one of its three original new games. The game consists primarily of a series of puzzles, solved by creating portals which the player and simple objects can pass through in order to reach an exit point, under the supervision of an AI-programmed robot named GLaDOS. The portal system and the unusual physics it creates are the emphasis of the game. Portal was a surprise favorite of The Orange Box, receiving widespread praise and several Game of the Year awards.
Bacteria also use contact-dependent signaling, notably to limit their growth. Signaling molecules used by multicellular organisms are often called pheromones. They can have such purposes as alerting against danger, indicating food supply, or assisting in reproduction.
Sources: en.wikipedia.org
== Uses == In February 2010, the Food and Drug Administration of the United States approved Xiaflex for the treatment of Dupuytren's contracture. It is the first approved nonsurgical treatment for this condition. In a case of Dupuytren's contracture, collagen accumulates in the palmar fascia of the hands, so that the fingers cannot be straightened. A similar phenomenon occurs in Peyronie's disease, a contracture of the penis.
== Causes == Disease: Infections including an anorectal abscess and inflammatory diseases including Crohn's disease and ulcerative colitis can result in fistulas. Fistulas to the anus may occur in hidradenitis suppurativa. In women, fistulas can also occur following pelvic infection and inflammation.
Viscosity - The Feynman Lectures on Physics Fluid properties – high accuracy calculation of viscosity for frequently encountered pure liquids and gases Fluid Characteristics Chart – a table of viscosities and vapor pressures for various fluids Gas Dynamics Toolbox – calculate coefficient of viscosity for mixtures of gases Glass Viscosity Measurement – viscosity measurement, viscosity units and fixpoints, glass viscosity calculation Kinematic Viscosity – conversion between kinematic and dynamic viscosity Physical Characteristics of Water – a table of water viscosity as a function of temperature Calculation of temperature-dependent dynamic viscosities for some common components Artificial viscosity Viscosity of Air, Dynamic and Kinematic, Engineers Edge
Carlos Manuel de Céspedes was either initiated or introduced to the concept of Freemasonry during his time studying in Spain the 1840's, but as well, he studied what secret societies he could of the entire Mediterranean region from Syria to Turkey on his travels. After the death of Narciso López, in 1851, de Céspedes wrote the original version of La Bayamesa with the poet José Fornaris. In 1867, de Céspedes joined Estrella Tropical Lodge No. 19, in the town of Bayamo. Most records indicate that this was his initiation. On August 13, 1867, a meeting was held at Estrella Tropical Lodge No. 19 to discuss the revolution against the Spanish. After the meeting, Francisco Maceo Osorio turned to Perucho Figueredo, and said to him: "...now it's your turn, who are a musician, to compose our own Marseillaise." Figueredo finished the instrumental composition the next day, on August 14. On October 20, 1868, Figueredo finished the lyrics of the current version of Cuba's national anthem as the revolutionary troops entered Bayamo.
Sources: en.wikipedia.org
It is a tripeptide rather than a full protein. Proteins generally contain many amino acids joined by alpha-peptide bonds, while glutathione has three residues and an unusual gamma-glutamyl linkage. That structure affects how enzymes recognize and break it down.
GSH is the reduced form with a free thiol group. GSSG is the oxidized disulfide dimer formed when two GSH molecules react. The GSH-to-GSSG ratio is used in research as one indicator of cellular redox conditions.
Yes, it is present in many animal and plant tissues, including meats, some vegetables, and fruits. Heat, storage, and processing can reduce its content, so measured amounts vary widely.
Common methods include spectrophotometric enzyme cycling assays, HPLC with UV or fluorescence detection, and LC-MS/MS. Detection often requires derivatization because glutathione lacks a strong chromophore. Method choice depends on the sample type and the required sensitivity.