A practical reference on Tetrapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
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.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. It was designed at the St. Petersburg Institute of Bioregulation and Gerontology as a short, chemically defined analogue of epithalamin, a fraction obtained from bovine pineal tissue. Small peptide bioregulators of this type formed a long-running line of work there from the 1980s onward. Because the molecule is produced by solid-phase synthesis rather than extraction, its composition is exact and its purity can be measured directly.
The most frequently cited proposed action is induction of telomerase, the enzyme that adds repeat sequences to chromosome ends. Cell-culture work from the originating group reported higher telomerase reverse transcriptase expression and measurable telomere elongation in human somatic cells after exposure. How a four-residue peptide would reach nuclear gene regulation is not established, and no cell-surface receptor or uptake route has been identified. Additional reports describe changes in melatonin secretion, antioxidant enzyme activity and lipid peroxidation in aged animals, but these findings remain mechanistically unconnected to the telomerase observation.
Published evidence comes mainly from Russian-language journals and from a single research group, with small sample sizes and limited independent replication. A few laboratories outside that group have examined related peptides and reported weaker or absent telomerase effects, so the central claim is best described as contested rather than settled. Rodent studies report modest changes in some ageing markers and in survival, but designs vary and control conditions are often sparse. No large randomised trial in humans has been published, and long-term safety data in healthy populations are correspondingly thin.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised and often hygroscopic |
| Solubility class | Freely soluble in water | Poor solubility in non-polar solvents |
| Typical storage temperature | -20 degrees Celsius or colder | Sealed, desiccated, protected from light |
| Typical analytical method | Reversed-phase HPLC with mass spectrometry | Establishes purity and confirms mass |
| Common salt form | Trifluoroacetate or acetate | Counterion reported alongside purity values |
Dissolution is usually performed in water or a suitable aqueous buffer, and the resulting liquid is divided into single-use portions before freezing. Freeze-thaw cycling is a recognised source of loss for short peptides, since each cycle can encourage aggregation or adsorption onto container walls. Working solutions are generally kept cold and used within a short window, although published stability data specific to epitalon are thin. Containers should be marked with concentration and date, and solutions examined for cloudiness before use.
Identity is normally established by reversed-phase high-performance liquid chromatography combined with mass spectrometry, a pairing that separates components and confirms molecular mass at once. Purity is quoted as a percentage from the chromatogram, and figures above ninety-five percent are a frequent commercial specification. Amino acid analysis or sequencing supplies further confirmation when required. Because many short peptides behave similarly under chromatography, retention time alone does not establish sequence; the mass measurement is what separates one tetrapeptide from another, and certificates should report both.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and its calculated monoisotopic mass is approximately 390.35 daltons. The compound does not occur naturally as a free peptide; it is produced by solid-phase peptide synthesis. Because it contains two acidic residues and no basic residues, the neutral form carries a net negative charge at physiological pH. This charge profile influences how the peptide behaves in solution and during chromatographic analysis.
Laboratory-grade epitalon is typically supplied as a lyophilized powder. Purity is commonly assessed with reverse-phase high-performance liquid chromatography, often paired with mass spectrometry to confirm molecular identity. Amino acid analysis and peptide mapping can provide additional confirmation of sequence. Certificates of analysis for research materials frequently report purity above 95 percent, although the methods behind such figures vary between suppliers. The absence of a pharmacopeial monograph means that no single standardized assay defines the compound, so reported results depend on the analytical protocol chosen.
Storage recommendations center on limiting moisture, heat, and light. The dry powder is generally kept at minus 20 degrees Celsius, and some suppliers recommend minus 80 degrees for long-term archival. Once dissolved, solutions are usually aliquoted and frozen to avoid repeated freeze-thaw cycles, which can promote aggregation or degradation. Aqueous stability depends on pH and concentration, and buffered saline is often preferred over plain water for biological work. Stability data specific to epitalon remain limited, so general peptide-handling practices are applied by analogy rather than from product-specific validation.
== External links == Gastric+inhibitory+polypeptide at the U.S. National Library of Medicine Medical Subject Headings (MeSH) King MW (16 November 2006). "Gastrointestinal Hormones and Peptides". Indiana University – Purdue University Indianapolis School of Medicine. Archived from the original on 6 December 2007. Retrieved 1 October 2006. Overview of all the structural information available in the PDB for UniProt: P09681 (Gastric inhibitory polypeptide) at the PDBe-KB.
=== United States and Canada === Methadone is a Schedule I controlled substance in Canada and Schedule II in the United States, with an ACSCN of 9250 and a 2014 annual aggregate manufacturing quota of 31,875 kilos for sale. Methadone intermediate is also controlled, under ACSCN 9226 also under Schedule II, with a quota of 38,875 kilos. In most countries of the world, methadone is similarly restricted. The salts of methadone in use are the hydrobromide (free base conversion ratio 0.793), hydrochloride (0.894), and HCl monohydrate (0.850). Methadone is also regulated internationally as a Schedule I controlled substance under the United Nations Single Convention on Narcotic Drugs of 1961.
The primary purpose of packaging space food is preserving and containing the food. However, the packaging must also be light-weight, easy to dispose of and useful in the preparation of the food for consumption. The packaging also includes a bar-coded label, which allows for the tracking of an astronaut's diet. The labels also specify the food's preparation instructions in both English and Russian. Many foods from the Russian space program are packaged in cans and tins. These are heated through electro-resistive (ohmic) methods, opened with a can-opener, and the food inside consumed directly. Russian soups are hydrated and consumed directly from their packages. NASA space foods are packaged in retort pouches or employ freeze drying. They are also packaged in sealed containers which fit into trays to keep them in place. The trays include straps on the underside, allowing astronauts to attach the tray to an anchor point such as their legs or a wall surface and include clips for retaining a beverage pouch or utensils in the microgravity environment.
Sources: en.wikipedia.org
Rick Stein's Food Heroes Christmas Special, BBC TV, December 2005. 2 half-hour episodes, also aired as a 1-hour programme. Betjeman and Me: Rick Stein's Story, August 2006 Rick Stein and the Japanese Ambassador, BBC Two, 2006 Rick Stein in Du Maurier Country, BBC Two, May 2007 Fishy Treats and Simple Eats, Japanese Food Network, Autumn 2007 Rick Stein's Mediterranean Escape, BBC Two, 8 August 2007. 6 episodes Rick Stein's Memoirs of a Seafood Chef, BBC Two, 7 January 2009 Who Do You Think You Are?, BBC TV, 16 February 2009 Rick Stein's Far Eastern Odyssey, BBC Two, July 2009. 6 episodes Rick Stein's Christmas Odyssey, BBC Two, December 2009 Rick Stein's Food of the Italian Opera, BBC HD, June 2010 Rick Stein's Cornish Christmas, BBC Two, December 2010 Rick Stein's Spain, BBC Two, July 2011. 4 episodes Rick Stein Tastes The Blues, BBC Four, November 2011 Rick Stein's Spanish Christmas, BBC Two, December 2011 Rick Stein's India, BBC Two, June 2013. 6 episodes Rick Stein's German Bite, BBC Two, August 2013 (Also referred to as The German Odyssey) Rick Stein: From Venice to Istanbul, BBC Two, August 2015. 7 episodes A Cook Abroad, BBC Two, 2 March 2015 (episode 5: Rick Stein's Australia) Rick Stein's Taste of Shanghai, BBC Two, February 2016 Rick Stein's Long Weekends, BBC Two, May 2016. 10 episodes Rick Stein's Road to Mexico, BBC Two, November 2017. 7 episodes Talking Books, BBC 2018 Rick Stein's Secret France, BBC Two, Autumn 2019. 6 episodes Pointless Celebrities, BBC One, 28 November 2020 Rick Stein's Cornwall, BBC Two, January 2021.
The insulin concentration in blood increases after meals and gradually returns to basal levels during the next 1–2 hours. However, the basal insulin level is not stable. It oscillates with a regular period of 3-6 min. After a meal the amplitude of these oscillations increases but the periodicity remains constant. The oscillations are believed to be important for insulin sensitivity by preventing downregulation of insulin receptors in target cells. Such downregulation underlies insulin resistance, which is common in type 2 diabetes. It would therefore be advantageous to administer insulin to diabetic patients in a manner mimicking the natural oscillations. The insulin oscillations are generated by pulsatile release of the hormone from the pancreas. Insulin originates from beta cells located in the islets of Langerhans. Since each islet contains up to 2000 beta cells and there are one million islets in the pancreas it is apparent that pulsatile secretion requires sophisticated synchronization both within and among the islets of Langerhans.
The catalytic cycle begins with coordination of the Cu(I) species to the olefin, followed by oxidative addition at the γ position and an allylic shift to displace the leaving group. This generates a Cu(III) allyl complex intermediate. Finally, reductive elimination yields the final product and regenerates Cu(I). A Cu(III) intermediate has not been confirmed by isolation from allylic substitutions, but Cu(III) intermediates have been isolated before, thus providing credence to the proposed mechanism. If reductive elimination does not occur fast enough, the γ allyl complex can isomerize to the α allyl complex and yield the α substituted isomer as a byproduct. This side pathway can be prevented by using electron withdrawing ligands on copper, typically a cyanide or halide ligand, which promote reductive elimination.
Reducing information asymmetry: Price information affects competitive markets' efficiency because it impacts price dispersion, arbitrage, and farmer and consumer welfare. Since the marginal cost of digitally delivering information approaches zero, digital agriculture has the potential to spread price information. Aker and Fafchamps find that the introduction of mobile phone coverage in Niger reduced spatial price dispersion for agri-food products, especially for remote markets and perishable goods. Similarly, price information provided by Internet kiosks ("e-choupals") in India led to an increase in farmers' net profits as traders lost monopsony power. Other examples of digital platforms for price information include MFarm and Esoko. Matching buyers and sellers: E-commerce lowers the search costs of matching buyers and sellers, potentially shortening the value chain. Rather than go through dozens of intermediaries, farmers can sell directly to consumers. Market access services can also solve the matching problem without necessarily hosting online transactions. For example, Esoko sends market information (prices for specific commodities, market locations, etc.) to agents and farmers, connecting them to commodity buyers. All of these matching platforms help smallholders coordinate with buyers and enter both regional and global value chains. Finally, digital technologies can also facilitate matching in financial and input markets, not just producer-to-consumer output sales.
Sources: en.wikipedia.org
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.
Reversed-phase HPLC establishes purity and separation from related peptides, and mass spectrometry confirms the molecular mass. Amino acid analysis can verify residue composition. No single method proves identity on its own, so the results are read together.
Yes. Residual trifluoroacetate or acetate from purification adds mass and can shift the value obtained by certain assays. Purity figures are therefore meaningful only when the counterion form is stated. Reporting both peptide content and salt form gives a clearer picture.
No. Epithalamin is a peptide-containing extract of bovine pineal glands, while epitalon is a single synthetic tetrapeptide. The extract contains many peptides and other tissue components, so its composition varies between batches in ways that a synthesised sequence does not.