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 2025-12-07. Where a claim depends on a specific study, the study is described rather than over-claimed.
The four residues give epitalon a molecular formula of C14H22N4O9 and a molecular weight near 390.35 daltons. The presence of two acidic residues, glutamate and aspartate, makes the free peptide strongly acidic, while the alanine and glycine ends provide neutral, nonpolar character. This combination produces a molecule with substantial water solubility. Because there are no cysteine, methionine, or tryptophan residues, the peptide lacks the most common oxidation-sensitive side chains, which simplifies handling compared with many longer peptides.
The proposed relationship between epitalon and pineal function is a central part of its background. Khavinson's group reported that short peptides corresponding to regions of larger pineal proteins could influence gene expression in cells. Epitalon was framed as a synthetic analogue of an active fragment rather than a direct isolation product. Whether the tetrapeptide reproduces the effects of the parent extract is an open question, because comparative studies are limited and the parent extract itself is not a single defined substance.
（TG:@pojiaai）Epitalon is a synthetic linear tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. It emerged from work on epithalamin, a peptide fraction prepared from bovine pineal tissue, and was designed as a short, chemically defined analogue of that extract. Early publications came mainly from Russian laboratories studying pineal peptides and aging-related endpoints. The compound appears in the literature under several spellings, including epithalon and epithalone, which complicates systematic searching. Its small size makes solid-phase assembly and routine analytical characterization straightforward.
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.
| Property | Value | Notes |
|---|---|---|
| Amino acid sequence | Ala-Glu-Asp-Gly | Tetrapeptide, often abbreviated AEDG |
| Molecular formula | C14H22N4O9 | Free peptide, unmodified termini |
| Molecular weight | ~390.35 Da | Calculated for the free acid form |
| Appearance | White to off-white powder | Typical lyophilized product form |
| Solubility class | Freely soluble in water | Two acidic residues dominate ionic character |
Oscar Tiegs' scientific interests and contributions ranged from the physiological analysis of nervous and muscular action to invertebrate embryology, his studies being comparable to the very best work the last century. He repeatedly turned from one area of research to another, only to return again. He was a dedicated practiser of descriptive morphology during a period when the majority of biologists were turning to experimentation. Typically, even his first research paper, was to describe something unusually interesting, namely that the male of the echiuroid worm exhibits a greater degree of degeneration than other species, the tissues fusing with those of its female partner and the host. He briefly made some helminthological investigations, for example with hookworm, and monogeneans before moving to the newly created Department of Zoology at the University of Adelaide in 1922.
=== Triggers === Several environmental factors have been postulated to modify illness susceptibility or induce disease; the most persuasive of these is the role of female sex hormones, as evidenced by the disease's significant female-to-male ratio and other data. Furthermore, investigations indicate that Epstein–Barr virus, retroviruses, or other viruses may play a role in causing disease in some patients. Cytomegalovirus has also been proposed as capable of eliciting anti-RNP antibody responses in the absence of illness. Environmental exposure to vinyl chloride has been linked to the development of an MCTD-like condition.
volatility A material quality which describes how readily a substance vaporizes. At a given temperature and pressure, a substance with high volatility is more likely to exist as a gas, while a substance with low volatility is more likely to exist as a liquid or solid; equivalently, less volatile substances will more readily condense from a gaseous state than highly volatile ones.
Sources: en.wikipedia.org
An aptamer against a-amanitin (the toxin that causes lethal Amanita poisoning) has been developed, an example of an aptamer against a mushroom target. Aptamer applications can be roughly grouped into sensing, therapeutic, reagent production, and engineering categories. Sensing applications are important in environmental, biomedical, epidemiological, biosecurity, and basic research applications, where aptamers act as probes in assays, imaging methods, diagnostic assays, and biosensors. In therapeutic applications and precision medicine, aptamers can function as drugs, as targeted drug delivery vehicles, as controlled release mechanisms, and as reagents for drug discovery via high-throughput screening for small molecules and proteins. Aptamers have application for protein production monitoring, quality control, and purification. They can function in molecular engineering applications as a way to modify proteins, such as enhancing DNA polymerase to make PCR more reliable. Because the affinity of the aptamer also affects its dynamic range and limit of detection, aptamers with a lower affinity may be desirable when assaying high concentrations of a target molecule. Affinity chromatography also depends on the ability of the affinity reagent, such as an aptamer, to bind and release its target, and lower affinities may aid in the release of the target molecule. Hence, specific applications determine the useful range for aptamer affinity.
==== Analytical chemistry ==== Often there are chemical species present or necessary at one stage of sample processing that will interfere with the analysis. For example, some air monitoring is performed by drawing air through a small glass tube filled with sorbent particles that have been coated with a chemical to stabilize or derivatize the analyte of interest. The coating may be of such a concentration or characteristics that it would damage the instrumentation or interfere with the analysis. If the sample can be extracted from the sorbent using a nonpolar solvent (such as toluene or carbon disulfide), and the coating is polar (such as HBr or phosphoric acid) the dissolved coating will partition into the aqueous phase. Clearly the reverse is true as well, using polar extraction solvent and a nonpolar solvent to partition a nonpolar interferent. A small aliquot of the organic phase (or in the latter case, polar phase) can then be injected into the instrument for analysis.
Formylation reactions are a form of electrophilic aromatic substitution and therefore work best with electron-rich starting materials. Phenols are a common substrate, as they readily deprotonate to excellent phenoxide nucleophiles. Other electron-rich substrates, such as mesitylene, pyrrole, or fused aromatic rings can also be expected to react. Benzene will react under aggressive conditions, but deactivated rings such as pyridine are difficult to formylate effectively. Many formylation reactions will select only the ortho product (e.g. salicylaldehyde), attributed to attraction between the phenoxide and the formylating reagent. Ionic interactions have been invoked for the cationic nitrogen centres in the Vilsmeier–Haack reaction and Duff reaction, and the electron-deficient carbene in the Reimer-Tiemann reaction; coordination to high oxidation metals has been invoked in the Casiraghi and Rieche formylations (cf. Kolbe–Schmitt reaction). The direct reaction between phenol and paraformaldehyde is possible via the Casiraghi formylation, but other methods apply masked forms of formaldehyde, in part to limit the formation of phenol formaldehyde resins. Aldehydes are strongly deactivating and as such phenols typically only react once. However certain reactions, such as the Duff reaction, can give double addition. Formylation can be applied to other aromatic rings. As it generally begins with nucleophilic attack by the aromatic group, the electron density of the ring is an important factor. Some aromatic compounds, such as pyrrole, are known to formylate regioselectively.
Sources: en.wikipedia.org
Due to a mass die-off of trees throughout California that could increase the risk of wildfires, Newsom declared a state of emergency on March 22, 2019, in preparation for the 2019 wildfire season. After declaring another state of emergency on August 18, 2020, he reported that the state was battling 367 known fires, many sparked by intense thunderstorms on August 16–17. His request for assistance via issuance of a federal disaster declaration in the wake of six major wildfires was first rejected by the Trump administration, but accepted after Trump spoke to Newsom.
== Autoproteolysis == Autoproteolysis takes place in some proteins, whereby the peptide bond is cleaved in a self-catalyzed intramolecular reaction. Unlike zymogens, these autoproteolytic proteins participate in a "single turnover" reaction and do not catalyze further reactions post-cleavage. Examples include cleavage of the Asp-Pro bond in a subset of von Willebrand factor type D (VWD) domains and Neisseria meningitidis FrpC self-processing domain, cleavage of the Asn-Pro bond in Salmonella FlhB protein, Yersinia YscU protein, as well as cleavage of the Gly-Ser bond in a subset of sea urchin sperm protein, enterokinase, and agrin (SEA) domains. In some cases, the autoproteolytic cleavage is promoted by conformational strain of the peptide bond.
Malignancies can develop in the glabrous and hair-bearing parts of the vulva. Based on the cellular origin and histology, vulvar cancers are classified into squamous cell carcinomas, melanomas, basal cell carcinomas, adenocarcinomas, sarcomas and invasive extramammary Paget's disease. Squamous cell carcinomas represent the most common variant of vulvar cancers and account for approximately 75%. These are usually found in the labia, particularly the labia majora. The second most common vulvar cancer is basal cell carcinoma, which rarely spreads to regional lymph nodes or distant organs. The third most common subtype is vulvar melanoma. Studies have shown that vulvar melanomas appear to have a different tumor biology and mutational characteristics compared to skin melanomas, which has a direct impact on the medical treatment of vulvar melanomas. Signs and symptoms of vulvar cancer can include: itching, or bleeding; skin changes including rashes, sores, lumps or ulcers, and changes in vulvar skin coloration. Pelvic pain might also occur especially during urinating and sex. However, a significant proportion remains asymptomatic in early disease stages, often delaying its diagnosis. As such, 32% of women with vulvar melanoma already have regional involvement or distant metastases at the time of diagnosis, which significantly impacts prognosis. Surgery (with or without removal of regional lymph nodes) is usually the primary treatment modality.
Sources: en.wikipedia.org
Epitalon is a synthetic tetrapeptide composed of four amino acids: alanine, glutamate, aspartate, and glycine. It is written as Ala-Glu-Asp-Gly. The free peptide has a molecular weight of about 390 daltons and is normally supplied as a lyophilized powder.
No. Epitalon is chemically synthesized, not extracted. It was designed as a short synthetic fragment conceptually related to larger pineal peptides studied in the same research tradition, particularly the extract known as epithalamin. The two are distinct materials with different compositions.
The term bioregulator is used in this research tradition for short peptides proposed to influence gene expression or cell function. Epitalon is grouped with other synthetic short peptides under this label. The term reflects a proposed mechanism rather than an established drug classification.
It is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, often abbreviated AEDG. The molecule is linear and contains no modified residues, so it is fully described by its sequence.