If you have been reading about tetrapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-04-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
Laboratory work has examined effects on telomerase activity in cultured cells, on melatonin rhythms in animals, and on markers of oxidative stress. Some experiments report measurable changes while others show none, and the reported findings rest largely on small studies. The absence of large independent trials means the generality of these results is unresolved rather than settled. Review articles occasionally apply the label geroprotector, a term that reflects a research hypothesis about ageing rather than an established clinical finding.
Epitalon is the common name for a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, usually abbreviated AEDG. All four residues are proteinogenic amino acids, and the free peptide has a calculated mass near 390 grams per mole. Because the chain is short and carries no modifications, it is assembled readily by solid-phase synthesis and is distributed mainly as a freeze-dried solid for laboratory work. Catalogue listings use the spellings epitalon, epithalone, and simply AEDG, and the three refer to the same sequence.
The compound is generally presented as a synthetic fragment of epithalamin, a pineal gland extract investigated in the former Soviet Union from the 1970s onward. Vladimir Khavinson and colleagues in Saint Petersburg developed short peptides modelled on such extracts, and epitalon became the most widely cited of those sequences. Most primary reports appeared in Russian-language journals or in proceedings with limited international circulation. Independent replication in laboratories outside that network remains sparse, and much repeated secondary material traces back to a small number of originating groups.
Solubility is high in water, phosphate-buffered saline and normal saline, a pattern that follows from the two acidic residues in the chain. The peptide dissolves poorly in non-polar solvents such as hexane or chloroform. Stock solutions are often prepared in water first and then diluted into the buffer of interest. Because the molecule is small and hydrophilic, filtration through a low-protein-binding membrane is usually straightforward, and visible particulates are uncommon in freshly made solutions.
Identity and purity are established with reversed-phase high-performance liquid chromatography and mass spectrometry. The chromatogram shows the main peak and any truncated or oxidised by-products, while the mass spectrum confirms the expected 390 dalton mass. Amino acid analysis can corroborate composition when a sample's origin is uncertain. Counterion content, particularly residual trifluoroacetate from purification, is frequently reported alongside purity because it shifts the net mass of the solid.
Reference material is normally supplied as a lyophilised powder in a sealed vial. Product literature typically recommends storage at minus twenty degrees Celsius or colder, protected from light and moisture. Freeze-thaw cycling is usually avoided because repeated condensation can introduce water into the vial. Working solutions are commonly prepared fresh, aliquoted, and kept cold for short periods rather than stored at ambient temperature. Labelling the date of opening helps track how long a vial has been in use.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Computed for the free acid of Ala-Glu-Asp-Gly |
| Molecular mass | About 390.35 g/mol | Free peptide; salt forms shift the value |
| Appearance | White to off-white solid | Typical of short peptides after freeze-drying |
| Solubility class | Freely soluble in water | Aqueous buffers are also commonly used |
| Common synonyms | Epitalon, epithalone, AEDG | AEDG is the single-letter sequence |
Residue composition is the property that most cleanly separates verified material from mislabelled samples. Alanine, glutamate, aspartate and glycine appear in that order from the N-terminus, and the two acidic residues sit in the middle of the chain. Because the peptide is short, it can be produced by solid-phase synthesis and characterised by mass spectrometry without ambiguity. Any reported sample whose measured mass departs substantially from 390 daltons is a different compound or a degraded mixture rather than epitalon.
Epitalon is a synthetic tetrapeptide whose four residues are alanine, glutamate, aspartate and glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9 and its monoisotopic mass is near 390.35 daltons. The peptide carries two acidic side chains, so it is neutral to negatively charged in most aqueous buffers. Published reference summaries usually list it under both spellings, epitalon and epithalon, and treat the two names as the same material.
Material sold for research use varies widely in documented quality. A useful verification package includes a certificate of analysis that states peptide content rather than only net weight, the chromatographic method and column used, and a mass spectrum consistent with the expected mass. Independent testing by a third-party laboratory is occasionally reported. Statements of identity resting only on a supplier label provide little assurance, and the gap between nominal mass and actual peptide content can be substantial once counterions and residual water are counted.
Peptides of this size are generally stable as dry solids but degrade in solution over time. The principal routes are hydrolysis of the peptide backbone and oxidation, with hydrolysis favoured by elevated temperature and extreme pH. Aqueous solutions held at room temperature can show measurable loss of purity within days, while frozen aliquots are considerably more durable. Because the sequence contains neither cysteine nor methionine, oxidation is less of a concern than for many other peptides, but pH control during handling still matters.
Chemically, the molecule consists of four amino acid residues joined by three peptide bonds, with a free N-terminal amino group and a free C-terminal carboxyl group. Its molecular formula is C14H22N4O9, and its monoisotopic mass is approximately 390 daltons. The acidic glutamate and aspartate side chains give the peptide a net negative charge near neutral pH, a property that shapes its chromatographic behaviour and solubility profile. No disulfide bridges or other post-translational modifications are present, so the primary sequence alone defines the structure.
Most experimental work has been carried out in cell culture and animal models. Several reports describe changes in telomerase activity and proliferation in cultured cells, while rodent studies have examined lifespan, melatonin rhythm and reproductive endpoints. Human data remain limited, and much of the published clinical material consists of small trials with incomplete reporting of methods and controls. Whether the cell and animal findings translate into measurable effects in people is an open question, and the mechanistic basis of the reported telomerase changes is not fully established.
Purity assessment of peptide reagents normally relies on reversed-phase high-performance liquid chromatography. A gradient of acetonitrile in water with trifluoroacetic acid, paired with a C18 stationary phase, separates the target tetrapeptide from truncated sequences and deletion analogues. Detection at 214 nanometres exploits absorbance of the peptide backbone, since the molecule contains no aromatic residue. Results are expressed as a percentage of total peak area. Values above ninety-five percent are typical for research-grade material, although reporting conventions vary between suppliers.
Identity confirmation uses mass spectrometry, usually electrospray ionisation in positive mode or matrix-assisted laser desorption. The protonated free peptide produces a signal near three hundred and ninety-one daltons, while salt adducts shift that value slightly. Tandem mass spectrometry or amino acid analysis supplies sequence-level confirmation, which a single mass measurement cannot. Peptides containing aspartate can cyclise into succinimide intermediates that hydrolyse to isoaspartate isomers of identical mass. Because those isomers are difficult to separate chromatographically, identity and purity results carry more weight when interpreted together.
Storage practice centres on limiting moisture, oxygen, and repeated temperature cycling. Freeze-dried powder is generally held desiccated at minus twenty degrees Celsius or colder and protected from light. Reconstituted solutions are markedly less stable, and the aspartate-glycine junction is prone to succinimide formation at neutral to mildly alkaline pH. Portioning material into single-use aliquots reduces degradation compared with repeated freeze-thaw cycles. Stability data specific to this tetrapeptide remain scarce, so most handling guidance is extrapolated from general peptide chemistry rather than measured directly.
=== Radionuclides with half-lives of 104 years to 108 years === Ordered by half-life. Some of these are known to have been present in the early Solar System (marked "ESS", meaning the first few million years of the Solar System's history) from an excess of their decay products.
Biological differences in fractionation stem not only from biochemical differences between different molecules, but also from physiological differences between different organisms. For example, the δDs of multiple leaf wax molecules are enriched in shrubs (median ~ −90‰) relative to trees (median ~ −135‰), which themselves are enriched relative to both C3 (median ~ −160‰) and C4 grasses (median ~ −140‰). Between individual species, substantial variation in δD has been documented. Other physiological factors that contribute to variable leaf wax δD values include the seasonal timing of leaf development, response to external stress or environmental variability, and the presence or absence of stomata It can be difficult to distinguish between physiological factors and environmental factors, when many physiological adaptations are directly related to environment. Several environmental factors have been shown to contribute to leaf wax δD variability, in addition to environmental effects on the δD of source water. Humidity is known to impact lipid δD at moderate humidity levels, but not at particularly high (>80%) or low (<40%) humidity levels, and a broad trend of enriched δDs, meaning smaller εl/w, is seen in arid regions. Temperature and sunlight intensity, both correlated to latitude, have strong effects on the rates of metabolism and transpiration, and by extension on εl/w. Also, the average chain length of leaf wax molecules varies with geographic latitude, and εl/w has been shown to increase with increasing chain length.
It was also in the Basque Country where a higher percentage of negative votes was registered (23.5%). A different situation to that of Catalonia, where the level of participation was similar to that of the rest of Spain, and the positive votes exceeded 90%.
A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. The tests are classified by speciality field, conveying in which ward of a hospital or by which specialist doctor these tests are usually performed. The ICD-10-CM is generally the most widely used standard by insurance companies and hospitals who have to communicate with one another, for giving an overview of medical tests and procedures. It has over 70,000 codes. This list is not exhaustive but might be useful as a guide, even though it is not yet categorized consistently and only partly sortable.
Sources: en.wikipedia.org
Naltrexone/bupropion, sold under the brand name Contrave among others, is a fixed-dose combination medication for the management of chronic obesity in adults in combination with a reduced-calorie diet and increased physical activity. It contains naltrexone, an opioid antagonist, and bupropion, an aminoketone atypical antidepressant. It is taken by mouth. Both component medications have individually demonstrated some evidence of effectiveness in promoting weight loss, and the combination has been shown to produce some synergistic effects on weight. In September 2014, a sustained release formulation of the drug was approved for marketing in the United States under the brand name Contrave. The combination, sold under the brand name Mysimba, was subsequently approved by the European Medicines Agency for medical use in the European Union in the spring of 2015. It was approved in Canada under the Contrave brand name in 2018.
== Available forms == κ-Bungarotoxin naturally occurs in Bungarus multicinctus venom glands[11]. The polypeptide consists of 66 amino acids and is cross-linked by five disulfide bonds. This is similar to LS-III, a venom purified from Laticauda semifasciata[12]. κ-Bungarotoxin can form heterodimers, thereby creating κ-2-Bungarotoxin and κ-3-Bungarotoxin. These differences are also observed globally. Though both κ-2- and κ-3-bungarotoxin are derived from Bungarus multicinctus venom, these are prevalent in the province of Guangdong, China, whereas κ-bungarotoxin is found in the Taiwanese B. multicinctus. These forms might have an evolutionary advantage in each specific region. Another form of κ-bungarotoxin is the α-bungarotoxin. κ-Bungarotoxin exhibits a 47% structural homology to α-bungarotoxin, but has an even shorter COOH-terminal than LS-III. α-Bungarotoxin also consists of the amino acid tryptanophyl, which is not present in κ-bungarotoxin. α-Bungarotoxin binds with a 200 times stronger affinity to nicotinic receptors than κ-bungarotoxin. Lastly, β-bungarotoxin also resembles the bungarotoxin family. β-Bungarotoxin is a potent inhibitor of the transport system for choline on the presynaptic terminal. It differs in the fact that β-bungarotoxin does not bind to a receptor, but binds enzymatically. β-Bungarotoxin will bind to voltage-gated potassium channels, after which phospholipase A2-mediated destruction of membrane phospholipids occurs in the nerves.
== Applications == PEDOT:PSS has the highest efficiency among conductive organic thermoelectric materials (ZT~0.42) and thus can be used in flexible thermoelectric generators. Yet its largest application is as a transparent, conductive polymer with high ductility. For example, AGFA coats 200 million photographic films per year with a thin, extensively-stretched layer of virtually transparent and colorless PEDOT:PSS as an antistatic agent to prevent electrostatic discharges during production and normal film use, independent of humidity conditions, and as electrolyte in polymer electrolytic capacitors. PEDOT:PSS is commonly used in organic light emitting diode (OLED) and organic solar cell for hole injection or hole extraction to improve carrier transport. If organic compounds, including high boiling solvents like methylpyrrolidone, dimethyl sulfoxide, sorbitol, ionic liquids and surfactants, are added conductivity increases by many orders of magnitude. This makes it also suitable as a transparent electrode, for example in touchscreens, organic light-emitting diodes, flexible organic solar cells and electronic paper to replace the traditionally used indium tin oxide (ITO). Owing to the high conductivity (up to 4600 S/cm), it can be used as a cathode material in capacitors replacing manganese dioxide or liquid electrolytes. It is also used in organic electrochemical transistors.
=== Type 2 diabetes === Type 2 diabetes, also known as non insulin dependent diabetes and as chronic hyperglycemia, is caused primarily by genetics and the development of metabolic syndrome. The beta cells can still secrete insulin but the body has developed a resistance and its response to insulin has declined. It is believed to be due to the decline of specific receptors on the surface of the liver, adipose, and muscle cells which lose their ability to respond to insulin that circulates in the blood. In an effort to secrete enough insulin to overcome the increasing insulin resistance, the beta cells increase their function, size and number. Increased insulin secretion leads to hyperinsulinemia, but blood glucose levels remain within their normal range due to the decreased efficacy of insulin signaling. However, the beta cells can become overworked and exhausted from being overstimulated, leading to a 50% reduction in function along with a 40% decrease in beta-cell volume. At this point, not enough insulin can be produced and secreted to keep blood glucose levels within their normal range, causing overt type 2 diabetes.
=== Clinical trials === PL9643, an ophthalmic solution, is being tested in phase 3 clinical trials to determine safety and efficacy in patients with dry eye. PL9643 activates MC1R, MC3R, MC4R and MC5R. Completed Phase 2 studies demonstrated positive results for the treatment of dry eye disease. Dersimelagon (MT-7117) is an orally administered MC1R agonist being tested in phase 3 clinical trials to evaluate safety and tolerability in patients with erythropoietic protoporphyria or X-linked protoporphyria. Resomelagon (AP1189) is an orally administered MC1R and MC3R agonist being tested in three phase 2 clinical trials to study safety and efficacy in patients with rheumatoid arthritis and idiopathic membranous nephropathy.
Sources: en.wikipedia.org
== Polysomes == Translation is carried out by more than one ribosome simultaneously. Because of the relatively large size of ribosomes, they can only attach to sites on mRNA 35 nucleotides apart. The complex of one mRNA and a number of ribosomes is called a polysome or polyribosome.
Self was concerned that NAA had not ever designed a fighter, insisting they obtain the drawings and study the wind-tunnel test results for the P-40, before presenting them with detailed design drawings based on the agreed concept. NAA purchased the drawings and data from Curtiss for £56,000, confirming the purchase with the British Purchasing Commission. The commission approved the resulting detailed design drawings, signing the commencement of the Mustang project on 4 May 1940, and firmly ordering 320 on 29 May 1940. Prior to this, NAA only had a letter of intent for an order of 320 aircraft. Curtiss engineers accused NAA of plagiarism. The British Purchasing Commission stipulated armament of four .303 in (7.7 mm) machine guns (as used on the Tomahawk), a unit cost of no more than $40,000, and delivery of the first production aircraft by January 1941. In March 1940, 320 aircraft were ordered by Freeman, who had become the executive head of the Ministry of Aircraft Production (MAP) and the contract was promulgated on 24 April. The NA-73X, which was designed by a team led by lead engineer Edgar Schmued, followed the best conventional practice of the era, designed for ease of mass manufacturing. The design included several new features. One was a wing designed using laminar flow airfoils, which were developed co-operatively by NAA and the National Advisory Committee for Aeronautics (NACA). These airfoils generated low drag at high speeds.
CH2=CHCH3 + 1/2 O2 + CH3CO2H → CH2=CHCH2O2CCH3 + H2O Hydrolysis of this acetate gives allyl alcohol. In alternative fashion, propylene can be oxidized to acrolein, which upon hydrogenation gives the alcohol. In principle, allyl alcohol can be obtained by dehydrogenation of propan-1-ol.
== History == 2C-B was first synthesized and evaluated by American chemist Alexander Shulgin in 1974. He described the properties and effects of 2C-B in humans, along with those of 2C-D, in the scientific literature in 1975. Shulgin proposed 2C-B and 2C-D for use in psychedelic-assisted psychotherapy. However, it was reportedly abandoned for such purposes due to gastrointestinal side effects and lack of entactogenic effects. 2C-B was Shulgin's favorite psychedelic of his own creations, though he has said that he only tried it a few times.
Sources: en.wikipedia.org
It is a four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine. The chain is unmodified and contains only standard proteinogenic residues, which makes it straightforward to produce by solid-phase synthesis and to characterise by standard peptide methods.
Epitalon and epithalon both circulate, and the difference reflects transliteration of a name coined in Russian-language publications. Reference to the extract it derives from, epithalamin, explains the shared stem. Databases and suppliers are inconsistent, so a search for one spelling alone may miss relevant entries.
No. Epithalamin is a multi-component preparation obtained from pineal tissue, and its exact composition is not fully characterised. Epitalon is a single defined tetrapeptide described as a short synthetic counterpart of that extract, so the two are related in origin but not interchangeable in identity.
Sealed lyophilised powder is normally kept at minus twenty degrees Celsius or below, away from light and moisture. Vials are allowed to reach room temperature before opening to limit condensation. Repeated warming and cooling of the same vial is discouraged.