If you have been reading about Epitalon 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 2025-10-24. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Calculated from the four residues with three water losses |
| Molecular mass | About 390.35 g/mol | Monoisotopic mass near 390.14, used for mass-spectrometric identification |
| Peptide sequence | Ala-Glu-Asp-Gly | Single-letter form AEDG; no disulfide bonds or modified residues |
| Appearance | White to off-white solid | Supplied as a dried powder |
| Isoelectric point | Around 4 | Estimated from aspartate and glutamate side-chain pKa values |
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.
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.
Lyophilised epitalon is generally held at minus twenty degrees Celsius in a sealed container kept dry and dark. Cooler conditions are sometimes recommended for long-term archives. The solid takes up moisture readily enough that repeated opening of a vial introduces water, so dividing a batch into smaller portions before storage lowers degradation risk. Aqueous solutions are less durable than the dry powder and are usually prepared shortly before use, then kept cold and shielded from light to slow hydrolysis and oxidation.
Verification of research-grade material involves comparing a supplier chromatogram against an in-house reference, checking the observed mass against the calculated value, and where possible confirming residue order by tandem mass spectrometry or enzymatic peptide mapping. Purity claims should be read alongside the method used to obtain them, because detection wavelength and integration settings alter the result. Batch-specific data, rather than a generic grade statement, is the informative part of a certificate.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
Stability depends strongly on pH, temperature and the presence of oxygen and trace metals. Cleavage of the backbone proceeds faster under neutral to alkaline conditions, whereas acidic solutions tend to slow that reaction. The aspartate and glutamate side chains can undergo deamidation or imide formation over time, generating closely related impurities. Published stability data specific to epitalon are sparse, so the usable life of a given solution is best regarded as an open question that depends on buffer composition, concentration and storage temperature.
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.
=== Soundtrack === The soundtrack for The Orange Box consists of music that Valve employees composed for Half-Life 2: Episode One, Half-Life 2: Episode Two, Portal, and Team Fortress 2. It also includes the original version and an exclusive remix of "Still Alive", both by Jonathan Coulton. It was released on December 21, 2007, and is sold by the official Valve Store, Amazon.com, and digital music services such as iTunes, Napster, and eMusic. A more-complete version of this soundtrack that also includes music files from Half-Life and Half-Life 2 was released on Steam as part of the Audiosurf package. "Still Alive" was subsequently released as a free downloadable song for the rhythm game Rock Band on March 31, 2008.
==== Kerogens and coals ==== The first stage that sedimentary organic matter (SOM) experiences after deposition is diagenesis. During diagenesis, biological decomposition can alter the DHR of organics. Several experimental studies have shown that some biodegraded materials become slightly enriched in D (less than 50‰). Most organics become kerogen by the end of diagenesis. Generally, δD of kerogen spans a wide range. Many factors contribute to the kerogen we observe in geologic records, including:
== Molecular Structure of EAATs == Like all glutamate transporters, EAATs are trimers, with each protomer consisting of two domains : the central scaffold domain (Figure 1A, wheat) and the peripheral transport domain (Figure 1A, blue). The transport conformational path is as follows. First, the outward facing conformation occurs (OF, open) which allows the glutamate to bind. Then the HP2 region closes after uptake (OF, closed) and the elevator like movement carries the substrate to the intracellular side of the membrane. It worth nothing that this elevator motion consists of several yet to be categorized/identified conformational changes. After the elevator motion brings the substrate to the IC side of the membrane, EAAT adopts the inward facing (IF, closed) state in which the transport domain is lowered, but the HP2 gate is still closed with the glutamate still bound to the transporter. Lastly, the HP2 gate opens and the glutamate diffuses into the cytoplasm of the cell.
Maximum speed: 440 mph (710 km/h, 383 kn) Cruise speed: 362 mph (583 km/h, 315 kn) Stall speed: 100 mph (160 km/h, 87 kn) Range: 1,650 mi (2,660 km, 1,434 nmi) with external tanks Service ceiling: 41,900 ft (12,800 m) Rate of climb: 3,200 ft/min (16 m/s) Lift-to-drag: 14.6 Wing loading: 39 lb/sq ft (190 kg/m2) Power/mass: 0.162 / 0.187 hp/lb (0.266 / 0.307 kW/kg) (without / with WEP) Recommended Mach limit 0.8 Armament
Sources: en.wikipedia.org
=== Sample preparation === Conducting and semi-conducting samples may be directly analyzed after being formed into electrodes. Non-conductive samples are first powdered, mixed with a conducting powder (usually high purity graphite or silver), homogenized, and then formed into electrodes. Even liquids can be analyzed if they are frozen or after impregnating a conducting powder. Sample homogeneity is important for reproducibility.
It was nominated for numerous awards and won "Best VR/AR" at the 2020 Game Awards. Valve acknowledged that the audience for VR games was limited, and Gabe Newell, Valve's president, described Alyx as a long-term investment into new technologies. As of 2024, it had sold more than two million copies. In 2026, Valve ported Alyx to its standalone Steam Frame headset.
==== Endocrine actions ==== Valproic acid has been found to be an antagonist of the androgen and progesterone receptors, and hence as a nonsteroidal antiandrogen and antiprogestogen, at concentrations much lower than therapeutic serum levels. In addition, the drug has been identified as a potent aromatase inhibitor, and suppresses estrogen concentrations. These actions are likely to be involved in the reproductive endocrine disturbances seen with valproic acid treatment. Valproic acid has been found to directly stimulate androgen biosynthesis in the gonads via inhibition of histone deacetylases and has been associated with hyperandrogenism in women and increased 4-androstenedione levels in men. High rates of polycystic ovary syndrome and menstrual disorders have also been observed in women treated with valproic acid.
A multiple-sequence FASTA format, or multi-FASTA format, would be obtained by concatenating several single-sequence FASTA files in one file. This does not imply a contradiction with the format as only the first line in a FASTA file may start with a ";" or ">", forcing all subsequent sequences to start with a ">" in order to be taken as separate sequences (and further forcing the exclusive reservation of ">" for the sequence definition line). Thus, the examples above would be a multi-FASTA file if taken together. Modern bioinformatics programs that rely on the FASTA format expect the sequence headers to be preceded by ">". The sequence is generally represented as "interleaved", or on multiple lines as in the above example, but may also be "sequential", or on a single line. Running different bioinformatics programs may require conversions between "sequential" and "interleaved" FASTA formats.
"World War II Fighter Aerodynamics." EAA Sport Aviation, January 1999. Leffingwell, Randy (and David Newhardt, photography). Mustang: 40 Years. St. Paul, Minnesota: Crestline (Imprint of MBI Publishing Company), 2003. ISBN 0-7603-2122-1. Liming, R.A. Mathematics for Computer Graphics. Fallbrook, California: Aero Publishers, 1979. ISBN 978-0-8168-6751-6. Liming, R.A. Practical Analytic Geometry With Applications to Aircraft. New York: The MacMillan Company, 1944. Loftin, LK, Jr. Quest for Performance: The Evolution of Modern Aircraft, NASA SP-468. Archived 13 June 2006 at the Wayback Machine Washington, D.C.: NASA History Office. Retrieved: 22 April 2006. Lowe, Malcolm V. North American P-51 Mustang (Crowood Aviation Series). Ramsbury, Wiltshire, UK: Crowood Press, 2009. ISBN 978-1-86126-830-3. Loving, George. Woodbine Red Leader: A P-51 Mustang Ace in the Mediterranean Theater. New York: Ballantine Books, 2003. ISBN 0-89141-813-X. Matricardi, Paolo. Aerei militari: Caccia e Ricognitori(in Italian). Milan: Mondadori Electa, 2006. Mietelski, Michał, Samolot myśliwski Mustang Mk. I-III wyd. I (in Polish). Warsaw: Wydawnictwo Ministerstwa Obrony Narodowej, 1981. ISBN 83-11-06604-3. Miller, Donald L. Eighth Air Force: The American Bomber Crews in Britain. London: Aurum Press, 2007. ISBN 978-1-84513-221-7. Munson, Kenneth. Caccia e aerei da attacco e addestramento dal 1946 ad oggi(in Italian). Torino: Editrice S.A.I.E., 1969. No ISBN. O'Leary, Michael. P-51 Mustang: The Story of Manufacturing North American's Legendary World War II Fighter in Original Photos.
Sources: en.wikipedia.org
=== Homologous recombination === Another method of cloning without the use of ligase is by DNA recombination, for example as used in the Gateway cloning system. The gene, once cloned into the cloning vector (called entry clone in this method), may be conveniently introduced into a variety of expression vectors by recombination.
Increasing temperature, which evens out the Boltzmann population of states. Conversely, low temperature NMR can sometimes yield better results than room-temperature NMR, providing the sample remains liquid. Saturation of the sample with energy applied at the resonant radiofrequency. This manifests in both CW and pulsed NMR; in the first case (CW) this happens by using too much continuous power that keeps the upper spin levels completely populated; in the second case (pulsed), each pulse (that is at least a 90° pulse) leaves the sample saturated, and four to five times the (longitudinal) relaxation time (5T1) must pass before the next pulse or pulse sequence can be applied. For single pulse experiments, shorter RF pulses that tip the magnetization by less than 90° can be used, which loses some intensity of the signal, but allows for shorter recycle delays. The optimum there is called an Ernst angle, after the Nobel laureate. Especially in solid state NMR, or in samples containing very few nuclei with spin (diamond with the natural 1% of carbon-13 is especially troublesome here) the longitudinal relaxation times can be on the range of hours, while for proton-NMR they are often in the range of one second. Non-magnetic effects, such as electric-quadrupole coupling of spin-1 and spin-3/2 nuclei with their local environment, which broaden and weaken absorption peaks. 14N, an abundant spin-1 nucleus, is difficult to study for this reason. High-resolution NMR instead probes molecules using the rarer 15N isotope, which has spin-1/2.
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Fourth, TFEU article 106(1) requires that the state may not grant special or exclusive rights for undertakings that distort competition, and states that (2) competition law applies to services of general economic interest, unless it obstructs their tasks in law or fact (e.g. in providing public services). Under TFEU art 107(1) no state aid that distorts competition is allowed, but aid is allowed (2) for individual consumers, without discrimination, and (3) for economic development, particularly to tackle underemployment. The Procurement Directive 2014/24/EU, on government procurement in the EU sets standards for open tenders when outsourcing public services to private companies.
Sources: en.wikipedia.org
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.
It is not recognised as an endogenous peptide hormone. The four-residue sequence can appear inside larger proteins and in digestive fragments of dietary protein, but no dedicated pathway producing it as a signalling molecule has been identified.
Several cell-culture reports describe increased telomerase activity after treatment, measured by enzyme assays or by transcript levels. Results differ between cell types and laboratories, and measured telomere lengthening has been reported in some studies but not in others, which leaves the physiological relevance open.
Reversed-phase high-performance liquid chromatography is run alongside mass spectrometry. The chromatogram separates components and gives a purity figure, while the mass spectrum confirms that the measured molecular mass matches the expected sequence. Neither measurement on its own is treated as sufficient.