Everything below concerns GSSG. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-08-25. Numbers and descriptions here follow the published literature rather than marketing material.
Glutathione is most stable as a dry powder stored cool and dry, but its thiol group is readily oxidized in solution. Aqueous preparations at neutral or alkaline pH lose GSH faster because the thiolate form reacts with dissolved oxygen and metal ions. Acidic conditions, chelating agents, and oxygen exclusion can slow oxidation, while repeated freeze-thaw cycles promote degradation. Light exposure and trace metals also contribute to loss. Laboratories typically validate stability for their own matrices because degradation rates depend on pH, temperature, concentration, and container materials.
Commercial glutathione is available in research-grade, food-grade, and supplement-grade forms, and purity specifications differ accordingly. Certificates of analysis commonly report identity by nuclear magnetic resonance or mass spectrometry, purity by HPLC, residual solvents, and heavy metals. Reference standards with assigned purity support calibration, while isotopically labeled glutathione can serve as an internal standard for mass spectrometry. For supplements, label claims may not be independently verified, and regulatory oversight varies by country. Verification often involves third-party testing for identity, potency, and contaminants.
Quantifying glutathione requires distinguishing GSH from GSSG and preventing oxidation during sample preparation. Common approaches include the enzymatic recycling assay, often called the Tietze method, which measures total glutathione after converting GSSG to GSH. HPLC with ultraviolet or fluorescence detection and LC-MS/MS can separate and quantify both forms, sometimes after derivatization of the thiol group. Blood, plasma, and tissue samples differ in matrix and baseline concentrations, so method validation must account for recovery, linearity, and interference. No single assay is universally standard.
Storage conditions strongly influence glutathione stability. The solid reduced form is commonly kept desiccated at or below minus twenty degrees Celsius, protected from light and moisture. Aqueous solutions are less stable because the thiol group reacts with dissolved oxygen, and oxidation accelerates at neutral or alkaline pH. Acidic solutions and oxygen-free handling can slow degradation, but repeated freeze-thaw cycles should be avoided. Researchers often verify concentration before use, because apparent losses can arise from oxidation or water uptake.
Measuring glutathione in biological samples requires attention to oxidation and matrix effects. High-performance liquid chromatography with ultraviolet or fluorescence detection can separate reduced and oxidized forms after derivatization. Liquid chromatography with tandem mass spectrometry offers higher specificity and can quantify glutathione alongside related thiols. Because glutathione can oxidize during sample handling, many protocols use rapid acidification with metaphosphoric acid or sulfosalicylic acid. Internal standards help correct for losses during extraction and analysis.
| Property | Value | Notes |
|---|---|---|
| Typical assay | Enzymatic recycling assay (Tietze) | Measures total glutathione after reduction of GSSG. |
| Separation method | HPLC or LC-MS/MS | Can quantify GSH and GSSG separately with appropriate standards. |
| Solid storage | -20 °C, desiccated, protect from light | Dry powder is more stable than aqueous solutions. |
| Solution storage | Acidic pH, -80 °C, aliquot | Reduce oxygen exposure and freeze-thaw cycling. |
| Oxidation product | Glutathione disulfide (GSSG) | Formed by thiol oxidation; often measured as a stress marker. |
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.
Glutathione reference materials are sensitive to oxygen, light, and elevated temperature. Solid material is typically stored desiccated at -20 °C or below, while solutions require tighter control because thiol oxidation proceeds faster in liquid form. Aqueous solutions are often prepared fresh, kept cold, and protected from air; some protocols add acid or chelating agents to slow metal-catalyzed oxidation. Repeated freeze-thaw cycles can accelerate degradation and should be avoided. Stability data vary by matrix, so laboratories usually verify performance with their own storage conditions.
Quality control for glutathione measurements includes calibration with authenticated standards, internal standards where available, blank correction, and spike recovery checks. Because glutathione can form during sample processing or degrade before analysis, pre-analytical handling is a major source of variability. Interlaboratory comparisons often show differences in reported values due to method-specific calibration and detection principles. Interpretive thresholds are context-dependent, and no single reference range applies across all tissues or matrices. Researchers generally report both reduced and oxidized forms, along with the method and sample handling details.
Quantification of glutathione in biological or food samples commonly uses liquid chromatography coupled to ultraviolet, fluorescence, electrochemical, or mass spectrometric detection. Because the thiol group oxidizes readily, samples are often acidified or derivatized immediately after collection to stabilize reduced glutathione. Enzymatic recycling assays and colorimetric kits offer higher throughput but generally lower specificity than chromatographic methods. Mass spectrometry can distinguish glutathione from related thiols and allow simultaneous measurement of oxidized forms. Reported concentrations depend strongly on sample type, extraction procedure, and analytical platform.
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.
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.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine, and it is the most abundant non-protein thiol in most living cells. The reduced form, GSH, carries a sulfhydryl group that can donate electrons, while the oxidized form, GSSG, forms when two GSH molecules link via a disulfide bond. The balance between these two forms helps define the cellular redox environment, and their ratio is often used as an indicator of oxidative stress. Because the sulfhydryl group is reactive, glutathione participates in many cellular processes, including detoxification and protein regulation.
Glutathione is synthesized in two ATP-dependent steps. First, gamma-glutamylcysteine synthetase links glutamate and cysteine; second, glutathione synthetase adds glycine to form the complete tripeptide. The pathway is feedback-inhibited by GSH itself, which helps maintain steady intracellular levels. Tissues vary widely in glutathione content, with the liver typically containing the highest concentrations, followed by the kidneys, lungs, and erythrocytes. Because cysteine is often limiting, its availability influences synthesis rates, and regulation of this pathway varies by cell type.
Glutathione serves as a cofactor for several enzymes, including glutathione peroxidase and glutathione S-transferase. These enzymes help reduce hydrogen peroxide and lipid peroxides, and they conjugate reactive electrophiles for excretion. The molecule also acts as a reservoir for cysteine, an amino acid that is prone to oxidation. In addition, glutathione participates in the metabolism of nitric oxide, leukotrienes, and prostaglandins. Its roles extend to cell signaling, apoptosis, and the regulation of protein function through S-glutathionylation.
== Ribozymes and the origin of life == RNA can also act as a hereditary molecule, which encouraged Walter Gilbert to propose that in the distant past, the cell used RNA as both the genetic material and the structural and catalytic molecule rather than dividing these functions between DNA and protein as they are today; this hypothesis is known as the "RNA world hypothesis" of the origin of life. Since nucleotides and RNA (and thus ribozymes) can arise by inorganic chemicals, they are candidates for the first enzymes, and in fact, the first "replicators" (i.e., information-containing macro-molecules that replicate themselves). An example of a self-replicating ribozyme that ligates two substrates to generate an exact copy of itself was described in 2002. The discovery of the catalytic activity of RNA solved the "chicken and egg" paradox of the origin of life, solving the problem of origin of peptide and nucleic acid central dogma. According to this scenario, at the origin of life, all enzymatic activity and genetic information encoding was done by one molecule: RNA. Ribozymes have been produced in the laboratory that are capable of catalyzing the synthesis of other RNA molecules from activated monomers under very specific conditions, these molecules being known as RNA polymerase ribozymes. The first RNA polymerase ribozyme was reported in 1996, and was capable of synthesizing RNA polymers up to 6 nucleotides in length.
=== Keratinization of sulcular epithelium === Although the inherent nature of the sulcular epithelium is non-keratinised, studies have discovered the potentiality of sulcular epithelium to keratinise under certain environmental conditions. It was shown that when exposed to the environment of the gingival surface, the sulcular epithelium develops into a keratinised squamous epithelium similar to that on the regular outer surface of the gingiva.
=== Formation of four bonds === This is a general method that is able to give good yields for substituted imidazoles. In essence, it is an adaptation of the Debus method called the Debus-Radziszewski imidazole synthesis. The starting materials are substituted glyoxal, aldehyde, amine, and ammonia or an ammonium salt.
=== Thin films === Gold nanoparticles capped with organic ligands, such as alkanethiol molecules, can self-assemble into large monolayers (>cm2). The particles are first prepared in organic solvent, such as chloroform or toluene, and are then spread into monolayers either on a liquid surface or on a solid substrate. Such interfacial thin films of nanoparticles have close relationship with Langmuir-Blodgett monolayers made from surfactants. The mechanical properties of nanoparticle monolayers have been studied extensively. For 5 nm spheres capped with dodecanethiol, the Young's modulus of the monolayer is on the order of GPa. The mechanics of the membranes are guided by strong interactions between ligand shells on adjacent particles. Upon fracture, the films crack perpendicular to the direction of strain at a fracture stress of 11
Amin al-Husayni, as chairman Jamal al-Husayni, as vice-chairman Husayin al-Khalidi Emile al-Ghury Ahmed Hilmi Abd al-Baqi The United Kingdom government called the 1946–47 London Conference on Palestine in an attempt to bring peace to its Mandate territory, which began on 9 September 1946. The conference was boycotted by the AHE as well as the Jewish Agency, but was attending by Arab League states, which argued against any partition.
Sources: en.wikipedia.org
==== Fatty acids ==== There has been a growing interest in the role of long-chain omega-3 polyunsaturated fatty acids to reduce inflammation and alleviate the symptoms of RA. Metabolism of omega-3 polyunsaturated fatty acids produces docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which inhibit pro-inflammatory eicosanoids and cytokines (TNF-a, IL-1b, and IL-6), decreasing both lymphocyte proliferation and reactive oxygen species. These studies showed evidence for significant clinical improvements on RA in inflammatory status and articular index. Gamma-linolenic acid, an omega-6 fatty acid, may reduce pain, tender joint count, and stiffness, and is generally safe. For omega-3 polyunsaturated fatty acids (found in fish oil, flax oil and hemp oil), a meta-analysis reported a favorable effect on pain, although confidence in the effect was considered moderate. The same review reported less inflammation but no difference in joint function. A review examined the effect of marine oil omega-3 fatty acids on pro-inflammatory eicosanoid concentrations; leukotriene4 (LTB4) was lowered in people with rheumatoid arthritis but not in those with non-autoimmune chronic diseases. Fish consumption has no association with RA. A fourth review limited inclusion to trials in which people eat ≥2.7 g/day for more than three months. The use of pain relief medication was decreased, but improvements in tender or swollen joints, morning stiffness, and physical function were unchanged.
=== Temperature === Conversion of both CO and CO2 to CH4 starts at a catalyst temperature below 300°C, but the conversion is incomplete and peak tailing is evident. At around 340°C, conversion is complete, as indicated by area measurements, but some tailing limits the peak height. At 360-380°C, tailing is eliminated and there is little change in peak height up to 400°C. Operating temperatures for various methanizers range from 350-400°C. Although carbonization of CO has been reported at temperatures above 350°, it is rather a rare phenomenon.
== Classification of fuzzy complexes == Structural ambiguity in protein complexes covers a wide spectrum. In a polymorphic complex, the protein adopts two or more different conformations upon binding to the same partner, and these conformations can be resolved. Clamp, flanking and random complexes are dynamic, where ambiguous conformations interchange with each other and cannot be resolved. Interactions in fuzzy complexes are usually mediated by short motifs. Flanking regions are tolerant to sequence changes as long as the amino acid composition is maintained, for example in case of linker histone C-terminal domains and H4 histone N-terminal domains.
A crystal structure of the serotonin 5-HT2B receptor bound to LSD reveals an extracellular loop that forms a "lid" over the diethylamide end of the binding cavity and "traps" LSD in the binding pocket, which explains the slow rate of LSD unbinding from serotonin receptors. The related lysergamide lysergic acid amide (LSA) that lacks the diethylamide moiety is far less potent in comparison. Moreover, a specific residue in the binding pocket is partially responsible for the prolonged action of LSD, and this residue is found in the human protein but not in the receptors of rodents. LSD is an extraordinarily potent psychoactive drug and is among the most potent psychedelics known in humans. The very high potency of LSD in producing psychedelic-like effects is also the case in animals, including rodents and monkeys. It is unclear why LSD is so potent. The affinity and activational potency of LSD at the human serotonin 5-HT2A receptor in vitro is unremarkable compared to other psychedelics such as DOI and DOB. There is no evidence for its greater potency being related to pharmacokinetics or metabolism. It appears that the N,N-diethylamide moiety of LSD fits into a sterically constrained region of the serotonin 5-HT2A receptor that specifically accommodates this moiety. LSD, like other psychedelics, has been found to increase the expression of genes related to synaptic plasticity and hence to have psychoplastogenic effects. This appears to be mediated by serotonin 5-HT2A receptor agonism.
== Awards == Wennemers work was recognized by the Leonidas Zervas Award of the European Peptide Society (2010), the Pedler Award of the Royal Society of Chemistry (2016), the Inhoffen Medal (2017), the Netherlands Scholar Award for Supramolecular Chemistry (2019), the Arthur C. Cope Scholar Award of the American Chemical Society (2021), the Scoffone Prize of the Italian Peptide Society (2022), and the Vincent du Vigneaud Award of the American Peptide Society (2023). She also won ths 2020 Spark Award (invention) and the 2023 Golden Owl Award (teaching) from the ETH Zurich. Wennemers was awarded the Emil Fischer Medal by the German Chemical Society on September 7, 2026, for her pioneering work on synthetic peptides, becoming the first woman to win the award in its 114-year history.
Sources: en.wikipedia.org
Bats are the only mammals that can truly fly. They fly through the air at a constant speed by moving their wings up and down (usually with some fore-aft movement as well). Because the animal is in motion, there is some airflow relative to its body which, combined with the velocity of the wings, generates a faster airflow moving over the wing. This generates a lift force vector pointing forwards and upwards, and a drag force vector pointing rearwards and upwards. The upwards components of these counteract gravity, keeping the body in the air, while the forward component provides thrust to counteract both the drag from the wing and from the body as a whole. The wings of bats are much thinner and consist of more bones than those of birds, allowing bats to maneuvere more accurately and fly with more lift and less drag. By folding the wings inwards towards their body on the upstroke, they use 35% less energy during flight than birds. The membranes are delicate, ripping easily; however, the tissue of the bat's membrane is able to regrow, such that small tears can heal quickly. The surface of their wings is equipped with touch-sensitive receptors on small bumps called Merkel cells, also found on human fingertips. These sensitive areas are different in bats, as each bump has a tiny hair in the center, making it even more sensitive and allowing the bat to detect and collect information about the air flowing over its wings, and to fly more efficiently by changing the shape of its wings in response.
== Names == The term lean refers to the tendency for users to have difficulty standing up straight and walking while under the influence of the drug. "Purple drank" references the mixture's typically purple hue, as the cough syrups employed are often purple in color, and the African-American Vernacular English term "drank" for an alcoholic beverage. Other names include "syrup/sizzurp", "surp/zurp", "jelly", "Tussin/Tuss'", "Barre", "Wock", "Act", "Texas tea", "mud", "dirty Sprite", and "tsikuni". In areas where lean had not yet been introduced, codeine-based cough syrup mixed with antihistamine pills was called "juice and beans". Lean is also sometimes referred to by color in slang, usually purple (usually shortened to "purp"), but can also be red, green, or yellow based on the ingredients used.
Picking up where A Loner left off, Saddiction (2025) saw the band further explore the sonic aspects and the post-punk and cold wave facets of their influences. It spawned several singles, including "2 am Thoughts". Their lyrics generally explore dark and gloomy themes, set against the backdrop of urban landscapes, primarily in Paris and its suburbs. Their discography demonstrates a gradual transition towards a clean singing voice. Hangman's Chair suspended their activities in November 2025 for an indefinite period.
=== Fabrication and misrepresentation === As early as 2000, Hari was criticised by Ben Elton in the letters page of Varsity for inaccuracies including stating that only Jews can be Israeli citizens. In addition to plagiarism, Hari was found to have fabricated elements of stories. In one of the stories for which he won the 2008 Orwell Prize, he reported on atrocities in the Central African Republic, stating that French soldiers told him that "Children would bring us the severed heads of their parents and scream for help, but our orders were not to help them." However, an NGO worker who translated for Hari said that the quotation was invented and that Hari exaggerated the extent of the devastation in the CAR. In his apology after his plagiarism was exposed, Hari said that other staff of the NGO had supported his version of events. In a 2010 article about military robots, Hari falsely claimed that former Japanese prime minister Junichiro Koizumi was attacked by a factory robot and was nearly killed. Hari falsely claimed that a large globe erected for the Copenhagen climate summit was "covered with corporate logos" for McDonald's and Carlsberg, with "the Coke brand ... stamped over Africa".
Sources: en.wikipedia.org
The ratio depends on rapid separation or blocking of GSH before oxidation occurs. GSSG can be formed ex vivo if samples are not processed quickly in cold, acidic conditions. Even small delays can shift the apparent ratio, making standardized protocols essential.
Enzymatic recycling assays measure total glutathione, while HPLC and LC-MS/MS can resolve GSH and GSSG separately. Derivatization or thiol-blocking reagents are sometimes used to stabilize and detect the compounds. Method choice depends on the sample type and required specificity.
Dry glutathione powder is typically stored at -20 °C in a desiccated container protected from light. Solutions should be prepared fresh, kept acidic or frozen, and avoid repeated freeze-thaw cycles. Stability should be confirmed for each specific laboratory condition.
Chromatographic methods can separate the two forms before detection. Enzymatic assays often measure total glutathione first and then use a separate procedure to estimate the oxidized fraction. The difference between total and oxidized amounts provides an indirect estimate of the reduced form.