A practical reference on tetrapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-08-22. Anything still debated is marked as such rather than presented as settled.
In its supplied form epitalon is a white to off-white powder, usually lyophilized and often hygroscopic. It dissolves readily in water and in aqueous buffers, and it is commonly handled as the acetate or trifluoroacetate salt to improve stability during purification and drying. The amide backbone is labile in aqueous media, so solutions are less durable than the dry solid. Handling notes in the chemical literature therefore emphasize keeping the powder dry, cool and shielded from light until it is dissolved.
Epitalon is a synthetic tetrapeptide whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography with ultraviolet detection, frequently near 214 nanometers where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the observed molecular mass and helps separate the intact peptide from truncated or modified forms. Amino acid analysis or tandem mass spectrometry can establish residue order. Purity is commonly quoted as an area percentage, yet such values are method-dependent, and comparisons between laboratories require matching column, gradient and detection wavelength.
Laboratory handling begins with dissolution of the lyophilized powder in water or a suitable aqueous buffer. The dry solid is the more stable form, so stock solutions are generally prepared only when required and kept cold afterwards. Repeated freezing and thawing of a solution is avoided because it encourages aggregation and gradual loss of the intact chain. Diluents and containers are selected to limit adsorption of a short peptide onto plastic surfaces and to reduce microbial growth in aqueous preparations.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic tetrapeptide | Four residues, linear chain |
| Residue sequence | Ala-Glu-Asp-Gly | Single-letter form AEDG |
| Calculated mass | 390.3 daltons | Value for the free, uncharged form |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility | Freely soluble in water | Often handled as a salt form |
Proposed mechanisms centre on cell-culture observations rather than a defined receptor interaction. Several reports describe increased expression of the telomerase catalytic subunit after exposure of cultured human cells, and the authors attributed the effect to short peptide fragments entering the nucleus and influencing gene transcription. No receptor for the tetrapeptide has been identified, and the free peptide is expected to be degraded rapidly by plasma peptidases. Whether any measurable fraction reaches intact tissues after administration remains an unresolved question rather than an established finding.
The published literature is dominated by a small number of research groups, much of it in Russian-language journals, and independent replication outside those groups is limited. Studies are typically small, use cultured cells or rodent models, and report endpoints that differ between papers, which makes comparison difficult. Large randomised human trials have not appeared in the indexed literature. Questions about absorption, distribution and clearance are therefore still treated as open in reviews that mention the compound.
Epitalon is a synthetic tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. Its design traces to epithalamin, a peptide fraction prepared from bovine pineal gland extracts that researchers in Saint Petersburg began investigating in the 1970s. The compound has a molecular formula of C14H22N4O9 and a nominal molecular mass near 390 daltons. It holds no approved drug status in the United States or the European Union, and material sold under this name is generally offered as a research chemical rather than a finished pharmaceutical product.
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
Epitalon is a synthetic tetrapeptide with the amino acid sequence alanine-glutamate-aspartate-glycine, abbreviated Ala-Glu-Asp-Gly or AEDG. It was developed by the Russian researcher Vladimir Khavinson and colleagues during work on peptide bioregulators derived from the pineal gland. The compound is short enough to be produced by standard solid-phase peptide synthesis and is typically handled as a lyophilized white powder. Its small size distinguishes it from larger pineal peptides such as epithalamin, a complex extract from which the tetrapeptide was conceptually derived.
The four residues give epitalon a molecular formula of C14H22N4O9 and a molecular weight near 390.35 daltons. The presence of two acidic residues, glutamate and aspartate, makes the free peptide strongly acidic, while the alanine and glycine ends provide neutral, nonpolar character. This combination produces a molecule with substantial water solubility. Because there are no cysteine, methionine, or tryptophan residues, the peptide lacks the most common oxidation-sensitive side chains, which simplifies handling compared with many longer peptides.
Storage and handling follow conventional peptide practice. Lyophilized epitalon is typically kept refrigerated or frozen, protected from moisture and light, and allowed to equilibrate to room temperature before opening to avoid condensation. Once dissolved, aqueous solutions are usually stored cold and used within a short period, since dilute peptide solutions can support microbial growth and may slowly degrade. The absence of cysteine and methionine reduces, but does not eliminate, oxidation concerns during long-term storage.
Regulatory status varies by country and is not harmonized. Epitalon is not an approved drug in major Western jurisdictions. In some countries it is sold as a research chemical, and in others it has appeared in products marketed for other categories. This inconsistent status means that purity, labeling accuracy, and documentation differ widely between suppliers, and verification of identity and purity through independent analysis is the usual way buyers assess a given lot.
The type II and XI collagenopathies are a group of disorders that affect connective tissue, the tissue that supports the body's joints and organs. These disorders are caused by defects in type II or type XI collagen. Collagens are complex molecules that provide structure, strength, and elasticity to connective tissue. Type II and type XI collagen disorders are grouped together because both types of collagen are components of the cartilage found in joints and the spinal column, the inner ear, and the jelly-like substance that fills the eyeball (the vitreous). The type II and XI collagenopathies result in similar clinical features.
Hide glue also functions as its own clamp. Once the glue begins to gel, it pulls the joint together. Violin makers may glue the center seams of top and back plates together using a rubbed joint rather than using clamps. This technique involves coating half of the joint with hot hide glue, and then rubbing the other half against the joint until the hide glue starts to gel, at which point the glue becomes tacky. At this point the plate is set aside without clamps, and the hide glue pulls the joint together as it hardens. Hide glue regains its working properties after cooling if it is reheated. This property can be used when the glue's open time does not allow the joint to be glued normally. For example, a cello maker may not be able to glue and clamp a top to the instrument's ribs in the short one-minute open time available. Instead, the builder will lay a bead of glue along the ribs, and allow it to cool. The top is then clamped to the ribs. Moving a few inches at a time, the maker inserts a heated palette knife into the joint, heating the glue. When the glue is liquefied, the palette knife is removed, and the glue cools, creating a bond. A similar process can be used to glue veneers to a substrate. The veneer and/or the substrate is coated with hot hide glue. Once the glue is cold, the veneer is positioned on the substrate. A hot object such as a clothes iron is applied to the veneer, liquefying the underlying glue. When the iron is removed, the glue cools, bonding the veneer to the substrate. Hide glue joints do not creep under loads.
Often this irregular shape is due to their many centers of ossification or because they contain bony sinuses. The bones of the spine, pelvis, and some bones of the skull are irregular bones. Examples include the ethmoid and sphenoid bones.
Most synthesis routines yield a mix of actinide isotopes as oxides, from which a given isotope of curium needs to be separated. An example procedure could be to dissolve spent reactor fuel (e.g. MOX fuel) in nitric acid, and remove the bulk of the uranium and plutonium using a PUREX (Plutonium – URanium EXtraction) type extraction with tributyl phosphate in a hydrocarbon. The lanthanides and the remaining actinides are then separated from the aqueous residue (raffinate) by a diamide-based extraction to give, after stripping, a mixture of trivalent actinides and lanthanides. A curium compound is then selectively extracted using multi-step chromatographic and centrifugation techniques with an appropriate reagent. Bis-triazinyl bipyridine complex has been recently proposed as such reagent which is highly selective to curium. Separation of curium from the very chemically similar americium can also be done by treating a slurry of their hydroxides in aqueous sodium bicarbonate with ozone at elevated temperature. Both americium and curium are present in solutions mostly in the +3 valence state; americium oxidizes to soluble Am(IV) complexes, but curium stays unchanged and so can be isolated by repeated centrifugation. Metallic curium is obtained by reduction of its compounds. Initially, curium(III) fluoride was used for this purpose. The reaction was done in an environment free of water and oxygen, in an apparatus made of tantalum and tungsten, using elemental barium or lithium as reducing agents.
== Antivenom == Antivenom, or antivenin, is commonly used to treat the effects of local and systemic pit viper envenomations. The first step in the production of crotaline antivenom is collecting ("milking") the venom of a live rattlesnake—usually from the western diamondback (Crotalus atrox), eastern diamondback (Crotalus adamanteus), South American rattlesnake (Crotalus durissis terrificus), or fer-de-lance (Bothrops atrox). The extracted venom is then diluted and injected into horses, goats, or sheep, whose immune systems produce antibodies that protect from the toxic effects of the venom. These antibodies accumulate in the blood, which is then extracted and centrifuged to separate the red blood cells. The resulting serum is purified into a lyophilized powder, which is packaged for distribution and later use by human patients. Because antivenom is derived from animal antibodies, people generally display an allergic response during infusion, known as serum sickness.
Sources: en.wikipedia.org
Liu Wenhui (simplified Chinese: 刘文辉; traditional Chinese: 劉文輝; pinyin: Liú Wénhuī; Wade–Giles: Liu Wen-hui; 10 January 1895 – 24 June 1976) was a Chinese general and warlord of Sichuan and Xikang provinces (Sichuan clique). At the beginning of his career, he was aligned with the Kuomintang (KMT), commanding the Sichuan-Xikang Defence Force from 1927 to 1929. In 1929, he became Sichuan governor before being ousted by a coalition of warlords in 1933; from there, he controlled the western part of Sichuan province, then known as Xikang, ruling the area as a personal fiefdom. He maintained his autonomy from the Nationalist government and pursued development programs in the province, which he funded through the trade of opium and by maintaining cordial relations with Chiang Kai-shek during the Second Sino-Japanese War. In 1949 he defected to the Communist forces of Mao Zedong, and went on to hold high office in the new People's Republic of China, serving as Minister of Forestry (1959–1967), member of the National People's Congress, member of the National Committee of the Chinese People's Political Consultative Conference, and member of the Central Committee of the Revolutionary Committee of the Chinese Kuomintang.
Yamni Nigam FRES is a British entomologist. She is a professor at Swansea University. Her scientific research focuses on the immune system of insects and invertebrates. She has a particular interest in wound healing and maggot (larval) therapy. Nigam additionally lectures on anatomy, physiology and pathophysiology within the School of Health & Social Care in the Faculty of Medicine, Health & Life - science at Swansea University.
The two substrates of this enzyme are (+)-trans-carveol and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are (+)-carvone, reduced NADH, and a proton. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (+)-trans-carveol:NAD+ oxidoreductase. This enzyme is also called carveol dehydrogenase. This enzyme participates in monoterpenoid biosynthesis and the degradation of the terpenes limonene and pinene.
== Career == D'Abo made her screen debut in the low-budget science fiction horror film Xtro (1982), playing Analise Mercier, a French au pair, who becomes a human incubator for an alien. She appeared in the film Until September (1984) and had small roles in television mini-series based on Sidney Sheldon's novels Master of the Game (1984) and If Tomorrow Comes. She also appeared in Oscar winner Taylor Hackford's film White Nights (1985) and in an uncredited role as a woman pouring champagne to Klaus Maria Brandauer at a hunting party in the Oscar winning Out of Africa (1985), directed by Oscar winner Sydney Pollack. Other credits include Arthur the King (1985). She worked on the French stage in Lyon playing Varinia in Spartacus directed by Jacques Weber in 1981, played Roxane in Cyrano de Bergerac at the Grenier de Toulouse in 1982, then worked in a 1987 French TV movie, Les Idiots (The Idiots), written by Gérard Brach, with Jean Carmet and Jean-Pierre Marielle. D'Abo had a starring role in The Living Daylights (1987) as Kara Milovy, the sweet and vulnerable Czechoslovak cellist and would-be sniper who falls for James Bond. As a tie-in with the film, she also appeared in a Bond-themed Playboy cover and multi-page pictorial in the September 1987 issue, but later said in an interview with People magazine that "I wouldn't do those pictures now... I've learned a lot since then". She featured in the music video to the 1987 single 'So the Story Goes' by British band Living in a Box.
Sources: en.wikipedia.org
== Research directions == The approach of screening the soil for useful compounds using genomics has been done by others, and is likely to continue to be pursued as a method to further explore primary metabolites and secondary metabolites made by microorganisms. As of February 2018, the malacidins had not been tested on humans. At the time of their discovery it was unknown whether the discovery would lead to any new antibiotic drugs; showing that a potential drug is safe and effective takes years of work and millions of dollars, and the scientists said at the time that they had no plans to try to develop a drug based on the work. In the 2018 paper, malacidins were shown to kill only Gram-positive bacteria and not Gram-negative bacteria. They were, however, able to kill multidrug-resistant pathogens, including bacteria resistant to vancomycin in the laboratory, and methicillin-resistant Staphylococcus aureus (MRSA) skin infections in an animal wound model. Brady, Hover, and two other authors disclosed in the 2018 paper that they had "competing financial interests, as they are employees or consultants of Lodo Therapeutics." Lodo was founded in 2016 out of Brady's laboratory, to discover new chemicals in nature as starting points for drug discovery.
Protein phosphorylation is highly conserved in pathways central to cell survival, such as cell cycle progression relying on cyclin-dependent kinases (CDKs), but individual phosphorylation sites are often flexible. Targets of CDK phosphorylation often have phosphosites in disordered segments, which are found in non-identical locations even in close species. Conversely, targets of CDK phosphorylation in structurally defined regions are more highly conserved. While CDK activity is critical for cell growth and survival in all eukaryotes, only very few phosphosites show strong conservation of their precise positions. Positioning is likely to be highly important for phosphates that allosterically regulate protein structure, but much more flexible for phosphates that interact with phosphopeptide-binding domains to recruit regulatory proteins.
On June 7, after winning the election, Ford said that the "very first item" on his agenda would be to cancel the federal carbon tax and provincial cap-and-trade programs in order to prevent motorists from being "gouged at the pumps". According to a June 28, 2018 article in The Economist, Ontario, with "Canada's second-highest public debt per person and a growing budget deficit", Ford's "poleaxing of cap and trade" would result in C$2.8bn worth of pollution permits owned by companies that could result in lawsuits. The article said that Ontario would lose C$2bn a year from the sale of pollution permits under its cap-and-trade program, which represents 1.3% of Ontario's revenue. In November 2018, the Ford government announced that it was eliminating three provincial watchdog groups, including the Environmental Commissioner of Ontario (ECO), to cut costs. Then Environmental Commissioner of Ontario (ECO), Dianne Saxe, had just submitted her 4-volume, 339-page 2018 Environmental Protection Report, entitled "Back to Basics, to the Legislative Assembly of Ontario. Saxe was a "vocal critic" of the Ford government's "actions on climate change"—"their vow to fight a federal carbon tax, pulling out of more than 700 renewable energy contracts and moving to end the Ontario Green Energy Act." Bill 57, also known as the Restoring Trust, Transparency and Accountability Act transferred the Environmental Commissioner Officer's duties to the Auditor General of Ontario.
== Further reading == Viana, Raquel V.; Wallis, Carole L. (2011). "3. Good clinical laboratory practice (GCLP) for molecular based tests used in diagnostic laboratories". In Akyar, Isin (ed.). Wide Spectra of Quality Control. BoD – Books on Demand. pp. 29–52. ISBN 978-953-307-683-6.
== History == L.W. Alvarez and Robert Cornog of the United States first used an accelerator as a mass spectrometer in 1939 when they employed a cyclotron to demonstrate that 3He was stable; from this observation, they immediately and correctly concluded that the other mass-3 isotope, tritium (3H), was radioactive. In 1977, inspired by this early work, Richard A. Muller at the Lawrence Berkeley Laboratory recognised that modern accelerators could accelerate radioactive particles to an energy where the background interferences could be separated using particle identification techniques. He published the seminal paper in Science showing how accelerators (cyclotrons and linear) could be used for detection of tritium, radiocarbon (14C), and several other isotopes of scientific interest including 10Be; he also reported the first successful radioisotope date experimentally obtained using tritium. His paper was the direct inspiration for other groups using cyclotrons (G. Raisbeck and F. Yiou, in France) and tandem linear accelerators (D. Nelson, R. Korteling, W. Stott at McMaster). K. Purser and colleagues also published the successful detection of radiocarbon using their tandem at Rochester. Soon afterwards the Berkeley and French teams reported the successful detection of 10Be, an isotope widely used in geology. Soon the accelerator technique, since it was more sensitive by a factor of about 1,000, virtually supplanted the older "decay counting" methods for these and other radioisotopes. In 1982, AMS labs began processing archaeological samples for radiocarbon dating
Sources: en.wikipedia.org
The peptide contains four residues in the order alanine, glutamate, aspartate and glycine, abbreviated AEDG. The chain is linear and held together by three peptide bonds. Its calculated mass for the uncharged free form is about 390.3 daltons.
Epithalamin refers to a crude preparation derived from bovine pineal tissue, which contains many components. Epitalon is a single synthetic tetrapeptide identified from that material and produced by chemical synthesis. The two names are sometimes confused because early reports treated the synthetic peptide as an active fragment of the extract.
It has been registered for clinical use in Russia, where it is associated with a small family of short peptides. In most other jurisdictions it is not an approved medicine and is traded as a research chemical. Regulatory status varies by country and changes over time.
The dry powder is typically held at -20 degrees Celsius or lower, protected from light and moisture. Allowing a sealed vial to reach room temperature before opening reduces condensation on its contents. Conditions stated on a supplier certificate of analysis take precedence over general guidance.