The short version of AEDG fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-11-06. Anything still debated is marked as such rather than presented as settled.
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.
Documentation accompanying research peptides usually includes a certificate of analysis listing the batch number, purity figure, and test methods applied. Buyers comparing suppliers should check whether the reported purity refers to chromatographic area or to a mass-balance calculation, because the two are not equivalent. Counter-ion content, residual solvents, and water content are sometimes omitted from such certificates even though they affect the actual peptide mass present. Independent verification through a second laboratory is the most direct way to confirm that a supplied material matches its label.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Freeze-dried solid |
| Solubility class | Freely soluble in water | Aqueous buffers also suitable |
| Typical storage temperature | Minus 20 degrees Celsius or colder | Desiccated and light protected |
| Typical analytical method | RP-HPLC with UV detection | 214 nm on C18 column |
| Identity confirmation | Electrospray mass spectrometry | Sequence verified separately |
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.
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
Epitalon is a synthetic linear tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and the calculated mass is approximately 390.35 g/mol. The compound is made by solid-phase peptide synthesis rather than extracted from tissue, although early work described it as a short fragment of a peptide fraction obtained from bovine pineal extract. In the research literature the spelling epitalon and the variant epithalone both appear, while AEDG is the standard code used in peptide nomenclature.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
Human data are limited to small studies, often without the randomization, blinding, or control groups expected in contemporary clinical research. Reported outcomes have included changes in melatonin levels, immune markers, and subjective measures, but sample sizes were generally too small to support firm conclusions. Some reviews treat the peptide as promising while noting methodological weaknesses; others question whether the observed effects are specific. The compound is frequently discussed in longevity-focused communities, where enthusiasm often outpaces the published evidence. Separating established findings from speculation is therefore important when reading summaries of this research.
Epitalon emerged from research conducted in Saint Petersburg by Vladimir Khavinson and colleagues, who studied short peptides as potential regulators of aging. The work built on epithalamin, a pineal gland extract reported to influence neuroendocrine function. Epitalon was designed as a synthetic counterpart with a defined sequence, allowing reproducible experiments that extracts could not support. Early publications described effects on melatonin rhythms and lifespan in animal models. These findings circulated mainly in Russian-language journals during the 1990s, which limited their visibility among English-speaking researchers.
The most widely cited claim is that epitalon activates telomerase and thereby extends telomere length. Supporting evidence comes largely from cultured human cells, where treatment was associated with increased telomerase activity and delayed replicative senescence. Telomerase activation is a biologically consequential effect, since the enzyme is largely silenced in most somatic cells. However, the route by which a short peptide would reach and act on the enzyme's regulatory machinery has not been established. Independent replication in human trials is scarce, so the link between cell-culture observations and whole-body aging remains an open question.
== Biography == Meldal received B.S. and PhD degrees in chemical engineering from Technical University of Denmark (DTU); his PhD work was supervised by Klaus Bock and focused on the synthetic chemistry of carbohydrates. From 1983 to 1988 he was a postdoctoral fellow in organic chemistry, first at the DTU, next at the MRC Laboratory of Molecular Biology at Cambridge University and then at the University of Copenhagen. In 1996 he was appointed assistant professor at DTU. Since 1998 he has led the synthesis group in the Department of Chemistry of the Carlsberg Laboratory. Meldal developed several technological techniques and instruments for peptide synthesis near the start of his career. He developed the multiple-column synthesis used in peptide and organic synthesis instruments, as well as for assembling large split-mix libraries. He first presented the cycloaddition of acetylenes and azides used in peptide and protein conjugations, in polymers and in material sciences. Meldal's group has then showed this reaction to be orthogonal to the majority of functional group chemistries. More recently Meldal has developed an optical encoding technique and has focused on the merger of organic chemistry and peptide chemistry on solid support. He has devised a range of novel methods for the generation of N-acyl iminium ions in which combinatorial libraries of these compounds are generated and screened for substances with activity toward G protein-coupled receptors in cell-based on-bead screening.
=== Tutorials and educational websites === "An Introduction to Proteins" from HOPES (Huntington's Disease Outreach Project for Education at Stanford) Proteins: Biogenesis to Degradation – The Virtual Library of Biochemistry and Cell Biology
Animals are categorised into ecological groups depending on their trophic levels and how they consume organic material. Such groupings include carnivores (further divided into subcategories such as piscivores, insectivores, ovivores, etc.), herbivores (subcategorised into folivores, graminivores, frugivores, granivores, nectarivores, algivores, etc.), omnivores, fungivores, scavengers/detritivores, and parasites. Interactions between animals of each biome form complex food webs within that ecosystem. In carnivorous or omnivorous species, predation is a consumer–resource interaction where the predator feeds on another organism, its prey, who often evolves anti-predator adaptations to avoid being fed upon. Selective pressures imposed on one another lead to an evolutionary arms race between predator and prey, resulting in various antagonistic/competitive coevolutions. Almost all multicellular predators are animals. Some consumers use multiple methods; for example, in parasitoid wasps, the larvae feed on the hosts' living tissues, killing them in the process, but the adults primarily consume nectar from flowers. Other animals may have very specific feeding behaviours, such as hawksbill sea turtles which mainly eat sponges.
238U(22Ne,xn)260−xNo (x=4,5,6) This reaction was first studied in 1964 at FLNR. The team were able to detect decays from 252Fm and 250Fm. The 252Fm activity was associated with an ~8 s half-life and assigned to 256102 from the 4n channel, with a yield of 45 nb. They were also able to detect a 10 s spontaneous fission activity also tentatively assigned to 256102. Further work in 1966 on the reaction examined the detection of 250Fm decay using chemical separation and a parent activity with a half-life of ~50 s was reported and correctly assigned to 254102. They also detected a 10 s spontaneous fission activity tentatively assigned to 256102. The reaction was used in 1969 to study some initial chemistry of nobelium at the FLNR. They determined eka-ytterbium properties, consistent with nobelium as the heavier homologue. In 1970, they were able to study the SF properties of 256No. In 2002, Patin et al. reported the synthesis of 256No from the 4n channel but were unable to detect 257No. The cross section values for the 4-6n channels have also been studied at the FLNR.
"Climate Changes Faster Than Species Can Adapt, Rattlesnake Study Finds", Science Daily, Dec. 05, 2011 Justin's Rattlesnake Bite "Rattlesnake" . New International Encyclopedia. 1905. "Rattlesnake" . Encyclopædia Britannica (11th ed.). 1911.
Sources: en.wikipedia.org
In organic chemistry, secondary amino acids are amino acids which do not contain the amino group −NH2 but are rather a secondary amine (>NH). Secondary amino acids can be classified to cyclic acids, such as proline, and acyclic N-substituted amino acids. In nature, proline, hydroxyproline, pipecolic acid and sarcosine are well-known secondary amino acids. Proline is the only proteinogenic secondary amino acid; all other secondary amino acids are non-proteinogenic. Hydroxyproline is incorporated into proteins by hydroxylation of proline. Pipecolic acid, a heavier analog of proline, is found in efrapeptin. Sarcosine is a N-methylated glycine in which the methyl group is used in many biochemical reactions. Azetidine-2-carboxylic acid is a smaller homolog of proline that is found in plants.
Protein methods are the techniques used to study proteins. There are experimental methods for studying proteins (e.g., for detecting proteins, for isolating and purifying proteins, and for characterizing the structure and function of proteins, often requiring that the protein first be purified). Computational methods typically use computer programs to analyze proteins. However, many experimental methods (e.g., mass spectrometry) require computational analysis of the raw data.
Nevertheless, Essendon went on to win the 1942 Premiership with Western Australian Wally Buttsworth in irrepressible form at centre half-back. Essendon won the 1942 Premiership by defeating Richmond in the grand final, 19.18 (132) to 11.13 (79). The match was played at Princes Park in front of 49,000 spectators. Essendon lost the 1943 grand final to Richmond by 5 points, finished 3rd in 1944, and dropped to 8th in 1945. After World War II, Essendon enjoyed great success. In the five years immediately after the war, Essendon won three premierships (1946, 1949, 1950) and were runners-up twice (1947, 1948). In 1946, Essendon were clearly the VFL's supreme force, topping the ladder after the home-and-away games and surviving a drawn second semi-final against Collingwood to make it through to the grand final a week later with a score of 10.16 (76) to 8.9 (57). In the grand final against Melbourne, Essendon set a grand final record score of 22.18 (150) to Melbourne 13.9 (87), featuring a 7-goal performance by centre half-forward Gordon Lane. Rover Bill Hutchinson, and defenders Wally Buttsworth, Cec Ruddell and Harold Lambert were among the best players. Essendon lost the 1947 Grand Final to Carlton by a single point despite recording 30 scoring shots to 21. The following year, Essendon tied with Melbourne in the 1948 grand final, kicking 7.27 to Melbourne's 10.9, before losing the replay 13.11 (89) to 7.8 (50).
Hari, Johann (2015). Chasing the Scream: The First and Last Days of the War on Drugs. London; New York: Bloomsbury. ISBN 978-1-62040-890-2. Blanchard, Michael; Chin, Gabriel J. (1998). "Identifying the Enemy in the War on Drugs: A Critique of the Developing Rule Permitting Visual Identification of Indescript White Powders in Narcotics Prosecutions". American University Law Review (47): 557. SSRN 1128945. Daniel Burton-Rose, The Celling of America: An Inside Look at the U.S. Prison Industry. Common Courage Press, 1998. Stephanie R. Bush-Baskette, "The War on Drugs as a War on Black Women", in Meda Chesney-Lind and Lisa Pasko (eds.), Girls, Women, and Crime: Selected Readings. Sage, 2004. Chin, Gabriel (2002). "Race, the War on Drugs and the Collateral Consequences of Criminal Conviction". Gender, Race & Justice (6): 253. SSRN 390109. Alexander Cockburn and Jeffrey St. Clair, Whiteout: The CIA, Drugs and the Press. New York: Verso, 1998. Mitchell Earlywine, Understanding Marijuana: A New Look at the Scientific Evidence. New York: Oxford University Press, 2005. Kathleen J. Frydl, The Drug Wars in America, 1940–1973. New York: Cambridge University Press, 2013. Nunn, Kenneth B. (2002). "Race, Crime and the Pool of Surplus Criminality: Or Why the War on Drugs Was a War on Blacks". Gender, Race & Justice. 6 (6): 381. Tony Payan, "A War that Can't Be Won." Tucson: The University of Arizona Press, 2013. Preston Peet, Under the Influence: The Disinformation Guide to Drugs. The Disinformation Company, 2004. Thomas C.
The rRNA molecules are thought responsible for its enzymatic activity, as no amino-acid residues lie within 18Å of the enzyme's active site, and, when the majority of the amino-acid residues in the ribosome were stringently removed, the resulting ribosome retained its full peptidyl transferase activity, fully able to catalyze the formation of peptide bonds between amino acids. A pseudo 2 fold symmetry of the region surrounding the peptidyl transferase center (PTC) led to the hypothesis of the Proto-Ribosome, that a vestige of an ancient dimeric molecule from the RNA world is functioning within the ribosome. An RNA molecule derived from the 23S ribosomal RNA sequence for this region has been synthesized in the lab in 2022 to test the proto-ribosome hypothesis. It was able to dimerize and to form peptide bonds. A much shorter RNA molecule has been synthesized in the laboratory in 1999 with the ability to form peptide bonds, and it has been suggested that rRNA has evolved from a similar molecule. tRNA is suggested to have also evolved from RNA molecules that began to catalyze amino acid transfer (also see the discussion of amino acid-RNA ligation above). The current core of the ribosome, the PTC, may also have evolved from the concatenation of five proto-tRNAs. A RNP world-type hypothesis is that the tRNA acceptor stem and the catalytic domain of the aaRS came earlier than the genetic code and the PTC.
Sources: en.wikipedia.org
Reversed-phase high-performance liquid chromatography with ultraviolet detection at 214 nanometres is the usual approach. Peak area percentage provides a purity figure relative to other components in the sample. Mass spectrometry is then applied to confirm identity.
Aspartate can cyclise into a succinimide intermediate that later hydrolyses back as isoaspartate. Both forms share the same molecular mass, so mass spectrometry alone cannot tell them apart. This shapes how purity data should be interpreted.
Freeze-dried material is normally kept desiccated below minus twenty degrees Celsius and shielded from light. Solutions are prepared shortly before use and held cold. Repeated thawing is avoided because it accelerates aggregation and degradation.
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.