tetrapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-07-06. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Amino acid sequence | Ala-Glu-Asp-Gly | Linear tetrapeptide, also written AEDG |
| Molecular mass | About 390.35 g/mol | Value calculated from the sequence |
| Appearance | White to off-white powder | Lyophilised material forms a loose cake |
| Solubility | Freely soluble in water | Also dissolves in isotonic saline |
| Storage | -20 °C, desiccated | Aliquot solutions to avoid freeze–thaw cycling |
The compound is generally described as a synthetic analogue of a fragment isolated from a pineal gland extract. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology introduced it during the 1980s and 1990s while studying short peptides from animal tissue. The original extract, called epithalamin, is a heterogeneous mixture, whereas epitalon is a single defined sequence. That distinction matters because findings reported for the extract are not automatically findings about the pure tetrapeptide, and claims about broader biological effects remain a separate question from the chemical identity described here.
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 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.
The compound is described in the literature as a derivative of epithalamin, a preparation obtained from bovine pineal tissue. Work on this peptide family was carried out mainly by a research group in Saint Petersburg beginning in the 1980s, and the substance was later registered for clinical use in Russia under the name Epitalon. Outside that region it is generally treated as a research chemical rather than an approved medicine. Statements about its biological activity rest on a relatively small number of studies, and independent replication remains limited.
== Afferent inputs == The PVN receives afferent inputs from many brain regions and different parts of the body, by hormonal control. Among these, inputs from neurons in structures adjacent to the anterior wall of the third ventricle (the "AV3V region") carry information about the electrolyte composition of the blood, and about circulating concentrations of such hormones as angiotensin and relaxin, to regulate the magnocellular neurons. Inputs from the brainstem (the nucleus of the solitary tract) and the ventrolateral medulla carry information from the heart and stomach. Inputs from the hippocampus to the CRH neurones are important regulators of stress responses. Inputs from neuropeptide Y-containing neurons in the arcuate nucleus coordinate metabolic regulation (via TRH secretion) with regulation of energy intake. Specifically, the projections from the arcuate nucleus seem to exert their effect on appetite via MC4R-expressing oxytocinergic cells of the PVN. Inputs from suprachiasmatic nucleus about levels of lighting (circadian rhythms). Inputs from glucose sensors within the brain stimulate release of vasopressin and corticotropin-releasing hormone from parvocellular neurosecretory cells.
Therefore, before agreeing to any surgical procedure, the plastic surgeon evaluates and considers the woman's mental health to determine if breast implants can positively affect her self-esteem and sexual functioning.
=== Hematopoietic stem cell transplantation === Hematopoietic stem cell transplantation (HSCT) involves replacing the dysfunctional stem cells from a person with sickle cell disease with healthy cells from a well-matched donor. Finding a well matched donor is essential to the process' success. Different types of donors may be suitable, including umbilical cord blood, human leukocyte antigen (HLA) matched relatives, or HLA-matched donors who are not related to the person being treated. Risks associated with HSCT can include graft-versus-host disease, failure of the graft, and other toxicity related to the transplant.
=== Inference === Variant genetic codes used by an organism can be inferred by identifying highly conserved genes encoded in that genome, and comparing its codon usage to the amino acids in homologous proteins of other organisms. For example, the program FACIL infers a genetic code by searching which amino acids in homologous protein domains are most often aligned to every codon. The resulting amino acid (or stop codon) probabilities for each codon are displayed in a genetic code logo. As of January 2022, the most complete survey of genetic codes is done by Shulgina and Eddy, who screened 250,000 prokaryotic genomes using their Codetta tool. This tool uses a similar approach to FACIL with a larger Pfam database. Despite the NCBI already providing 27 translation tables, the authors were able to find new 5 genetic code variations (corroborated by tRNA mutations) and correct several misattributions. Codetta was later used to analyze genetic code change in ciliates.
==== Nuclear disarmament and 1983 election ==== One of Heseltine's main jobs was to campaign against the Campaign for Nuclear Disarmament (CND), which had grown in size from 3,000 to 10,000 in three years amid public disquiet about the deployment of Trident and Cruise missiles, and the hawkish rhetoric often employed by Thatcher and US president Ronald Reagan. Nott had had little interest in campaigning and had left the matter to the minister of state, Peter Blaker, Heseltine's contemporary from Oxford. Heseltine put together a small group of seven civil servants called Defence Section 19 (DS19) to brief MPs and other opinion formers, and argue the case for Britain to have nuclear weapons. Some, both in the civil service and out of it, had qualms about using civil servants for what amounted to a political campaigning role. Opinion polls showed the public to be opposed to Trident and Cruise missiles, but also opposed to unilateral ("one-sided" as Heseltine insisted on calling it) disarmament, so Heseltine steered the debate away from the former and towards the latter. At the advice of John Ledlie Heseltine visited at the US Air Base at RAF Greenham Common, and after long prior discussion Heseltine insisted on wearing a combat jacket (not, as was often wrongly asserted, a Flak jacket; Ledlie does not accept Heseltine's later claim that he was simply handed it by a military figure to protect his coat from the rain). The jacket was a gift to cartoonists and he wore it on several subsequent visits to military bases.
Sources: en.wikipedia.org
Chest radiography can show pneumothorax, and is indicated if there is chest discomfort or breathing difficulty Computed tomography (CT) scans and magnetic resonance imaging (MRI) may be indicated when there is severe headache or severe back pain after diving. CT is the most sensitive method to evaluate for pneumothorax. It can be used where barotrauma-related pneumothorax is suspected and chest radiograph findings are negative. Echocardiography can be used to detect the number and size of gas bubbles in the right side of the heart.
==== Dol ==== The dol (from the Latin word for pain, dolor) is a unit of measurement for pain. James D. Hardy, Herbert G. Wolff, and Helen Goodell of Cornell University proposed the unit based on their studies of pain during the 1940s and 1950s. They defined one dol to equal a just-noticeable difference in pain. The unit never came into widespread use and other methods are now used to assess the level of pain experienced by patients.
The temperature gradient gel electrophoresis (TGGE) or temperature gradient capillary electrophoresis (TGCE) method is based on the principle that partially denatured DNA is more restricted and travels slower in a porous material such as a gel. This property allows for the separation of DNA by melting temperature. To adapt these methods for SNP detection, two fragments are used; the target DNA which contain the SNP polymorphic site being interrogated and an allele-specific DNA sequence, referred to as the normal DNA fragment. The normal fragment is identical to the target DNA except potentially at the SNP polymorphic site, which is unknown in the target DNA. The fragments are denatured and then reannealed. If the target DNA has the same allele as the normal fragment, homoduplexes will form that will have the same melting temperature. When run on the gel with a temperature gradient, only one band will appear. If the target DNA has a distinct allele, four products will form following the reannealing step; homoduplexes consisting of target DNA, homoduplexes consisting of normal DNA and two heterduplexes of each strand of target DNA hybridized with the normal DNA strand. These four products will have distinct melting temperatures and will appear as four bands in the denaturing gel.
Moore supports a balance between securing the United States' borders and creating pathways to citizenship for those already in the country. In June 2023, Moore said that he supported efforts to strengthen the federal temporary protected status policy for immigrants living in the United States. In June 2024, after a man who had entered the United States illegally was arrested in connection with the murder of Rachel Morin, Moore blamed congressional inaction on the issue of immigration as well as conditions at the Mexico–United States border for Morin's killing. In June 2023, after multiple Republican governors sent members of their state national guards to the southern border, Moore told WRC-TV that he did not support sending members of the Maryland National Guard to the border. In January 2025, he declined to say if he would deploy Maryland National Guard members at the southern border if asked by the federal government. Moore also advised local jurisdictions to "follow the Constitution" when cooperating with federal immigration efforts. In May 2025, he signed into law the Maryland Values Act, which prohibits federal law enforcement from conducting immigration actions at sensitive locations. In April 2025, Moore condemned the Trump administration's deportation of Kilmar Abrego Garcia on the grounds of inadequate due process, saying that "no one should be deported to the very county where a judge determined they will face persecution" and calling on the federal government to "correct" their error.
Sources: en.wikipedia.org
It is a synthetic tetrapeptide. Its sequence was derived from research on peptide fractions of bovine pineal extract, and the intact AEDG sequence has not been demonstrated as an abundant free peptide in human tissue.
AEDG is the one-letter code for the four amino acids alanine, glutamate, aspartate and glycine in that order. The same molecule is written in three-letter form as Ala-Glu-Asp-Gly.
Identity is normally confirmed by mass spectrometry against the calculated mass of roughly 390.35 g/mol. Purity is then estimated by reversed-phase high-performance liquid chromatography with ultraviolet detection.
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine–glutamate–aspartate–glycine, also written AEDG. It was developed in Russian gerontology research and is studied for proposed effects on telomerase, melatonin regulation, and neuroendocrine function. It is not an approved pharmaceutical in the United States or the European Union.