This is a working overview of tetrapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-28 and is reviewed periodically as new material appears.
The molecule is a short, linear, hydrophilic peptide that dissolves readily in water or aqueous buffer. Its principal chemical liabilities are hydrolytic rather than oxidative, since it contains no cysteine, methionine, or tryptophan residues. The aspartate–glycine step is a recognised site for aspartimide formation under mildly acidic or basic conditions, generating isoaspartate and succinimide-related products over time. Desiccated lyophilised powder held at −20 °C is comparatively stable, whereas dilute solutions degrade faster and are best frozen as single-use aliquots rather than thawed repeatedly.
No pharmacopoeial monograph exists for this peptide, so quality rests on the supplier's internal specifications and on whatever independent testing a purchaser arranges. Certificates of analysis differ widely in which tests they report and in the limits applied. The counter-ion introduced during purification, commonly acetate or trifluoroacetate, changes the net peptide content of a given mass of powder, so two samples of equal weight may not contain equal amounts of the active sequence. Third-party laboratories can verify purity, identity, residual solvents, and counter-ion content for a fee, which makes documentation more informative than labelling.
Verification of a sample usually begins with reversed-phase high-performance liquid chromatography, which resolves the peptide from truncated sequences and other impurities and expresses purity as a percentage of total peak area. Mass spectrometry by electrospray ionisation or matrix-assisted laser desorption supplies an independent check, because the measured mass can be compared against the theoretical value for AEDG. Amino acid analysis or tandem mass spectrometry sequencing can confirm residue order. Each of these methods answers a different question: a purity figure does not establish identity, and an identity match does not establish how much of the material is intact peptide.
Epitalon is a synthetic tetrapeptide whose four residues are alanine, glutamate, aspartate and glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9 and its monoisotopic mass is near 390.35 daltons. The peptide carries two acidic side chains, so it is neutral to negatively charged in most aqueous buffers. Published reference summaries usually list it under both spellings, epitalon and epithalon, and treat the two names as the same material.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Electrospray or MALDI mass spectrometry | Observed mass compared with theoretical 390.35 Da |
| Purity specification | 95 percent or greater by RP-HPLC | Common convention for research-grade peptide |
| Counter-ion | Acetate or trifluoroacetate | Affects net peptide content of a weighed sample |
| Solution storage | −80 °C as single-use aliquots | Repeated freeze–thaw cycles accelerate loss |
| Main degradation route | Aspartimide formation at Asp-Gly | Produces isoaspartate and related species |
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.
Identity and purity of epitalon samples are normally established by reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, combined with mass spectrometry. The mass spectrum confirms the expected molecular ion and can reveal truncated or oxidised by-products. Amino acid analysis after acid hydrolysis verifies that the four residues are present in the expected ratio. Certificates typically report a purity figure taken from chromatographic peak area, expressed as a percentage of total integrated signal.
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.
Interest in epitalon is usually discussed within the broader field of short peptide bioregulators, a category that includes other synthetic di-, tri-, and tetrapeptides studied by the same research group. These compounds share a common rationale: that small fragments of tissue-derived proteins can retain biological activity and can be produced reproducibly. The category as a whole remains outside mainstream pharmacological consensus, and epitalon specifically has a limited presence in independent, non-Russian research literature, which shapes how its evidence base is described.
Regulatory treatment differs by country. No formulation of epitalon holds a marketing authorisation as a medicine in the United States or the European Union, where material sold for laboratory use is handled as a research chemical and is not intended for human consumption. In Russia, several short peptide preparations from the same institute's peptide series are registered medicinal products, and epitalon appears in that national context. Elsewhere it is frequently offered as a cosmetic ingredient, a category with lighter requirements. Advertising claims about longevity or disease prevention are restricted in most jurisdictions, which limits how sellers describe the compound.
Freeze-dried epitalon is normally kept at minus twenty degrees Celsius in a sealed, desiccated container, protected from light. Short excursions at ambient temperature during shipping are generally tolerated, but repeated warming and cooling cycles encourage moisture uptake, which shortens shelf life. Once dissolved, the peptide is far less stable than the solid: aqueous solutions are subject to hydrolysis and to deamidation at the aspartate and glutamate residues. Working solutions are therefore held refrigerated and used within days, and repeated freezing and thawing of the same vial is best avoided.
== Further reading == Wolfram-Schauerte, Maik; Pozhydaieva, Nadiia; Grawenhoff, Julia; Welp, Luisa M.; Silbern, Ivan; Wulf, Alexander; Billau, Franziska A.; Glatter, Timo; Urlaub, Henning; Jäschke, Andres; Höfer, Katharina (August 16, 2023). "A viral ADP-ribosyltransferase attaches RNA chains to host proteins". Nature. 620 (7976): 1054–1062. Bibcode:2023Natur.620.1054W. doi:10.1038/s41586-023-06429-2. PMC 10468400. PMID 37587340.
=== 2018 === In April 2018, RTL started broadcasting its own UHD channel in Germany. First available at Astra 19.2°E, the Channel shows UHD productions, Formula 1, Football and Deutschland sucht den Superstar. Satellite operator SES broadcast an 8K television signal via its satellite system for the first time in May 2018. The 8K demonstration content, with a resolution of 7680 × 4320 pixels, a frame rate of 60 fps, and 10 bpc color depth, was encoded in HEVC and transmitted at a rate of 80 Mbit/s via the Astra 3B satellite during SES's Industry Days conference in Luxembourg. In June 2018, fuboTV broadcast the 2018 FIFA World Cup live in 4K and HDR10 becoming the first OTT streaming service to do so. Quarter, Semi and Final matches were available on many popular streaming devices including Apple TV, Chromecast Ultra, Fire TV, Roku and Android TVs. Content was streamed at 60 frames per second using HLS and DASH. Video was sent in fragmented MP4 containers delivering HEVC encoded video. On December 1, 2018, NHK launched BS8K, a broadcast channel transmitting at 8K resolution.
== Screening == Initial screening for CIP/CIM may be performed using an objective scoring system for muscle strength. The Medical Research Council (MRC) score is one such tool, and sometimes used to help identify CIP/CIM patients in research studies. The MRC score involves assessing strength in 3 muscle groups in the right and left sides of both the upper and lower extremities. Each muscle tested is given a score of 0–5, giving a total possible score of 60. An MRC score less than 48 is suggestive of CIP/CIM. However, the tool requires that patients be awake and cooperative, which is often not the case. Also, the screening tool is non-specific, because it does not identify the cause a person's muscle weakness. Once weakness is detected, the evaluation of muscle strength should be repeated several times. If the weakness persists, then a muscle biopsy, a nerve conduction study (electrophysiological studies), or both should be performed.
Sources: en.wikipedia.org
Berg did not complete his final step due to the pleas of several fellow investigators, including Robert Pollack, who feared the biohazards associated with the last step. The SV40 was known to cause cancer tumors to develop in mice. Additionally, the E. coli bacterium (although not the strain used by Berg) inhabited the human intestinal tract. For these reasons, the other investigators feared that the final step would create cloned SV40 DNA that might escape into the environment and infect laboratory workers. These workers could then become cancer victims. Concern about this potential biohazard, along with others, caused a group of leading researchers to send a letter to the president of the National Academy of Sciences (NAS). In this letter, they requested that he appoint an ad hoc committee to study the bio-safety ramifications of this new technology. This committee, called the Committee on Recombinant DNA molecules of the National Academy of Science, U.S.A., held in 1974, concluded that an international conference was necessary to resolve the issue and that until that time, scientists should halt experiments involving recombinant DNA technology.
One of the challenges of in vitro modelling of complex tissues is the difficulty of co-culturing different cell types. Co-culturing of different cell types can be achieved at the onset of levitation, either by mixing different cell types before levitation, or by magnetically guiding 3D cultures in an invasion assay format. Co-culturing in a realistic tissue architecture is important for accurately modeling in-vivo conditions. One example is increasing the accuracy of cellular assays, as shown in the figure on the right. In the figure, the human GBM cells and normal human astrocytes (NHA) are cultured separately and then magnetically guided together (left, time 0). Invasion of GBM into NHA in 3D culture provides an assay for basic cancer biology and drug screening (right, 12h to 252h). Magnetic levitation has shown potential for maintaining cell viability and simulating in vivo conditions. However, its scalability and efficacy in comparison to traditional culturing methods have been topics of discussion.
mRNA-based disease diagnosis technologies are diagnostic procedures using messenger RNAs. as molecular diagnostic tools to discover the relationships between patient's DNAs and their specific biological features. The mRNA-based disease diagnosis technologies have been applied to medical field widely in recent years, especially on early diagnosis of tumors (such as renal cell carcinoma, hepatocellular carcinoma, breast cancer and prostate cancer). The technology can be applied to various types of samples depending on how easily the samples are accessible and whether the samples reliably contain the mRNA that related to specific diseases. For example, in hepatocellular carcinoma, the tumor tissues excised during the operation are a good resource for mRNA-based test to analysis. Among those most commonly used samples, blood sample is one of the most easily accessible via minimally invasive method. degenerative diseases . Blood has been used in early diagnosis of some cancers, such as non-small lung cancer and neuroendocrine tumors.
The FAO GM Foods Platform is a web platform where participating countries can share information on their assessments of the safety of genetically modified (recombinant-DNA) foods and feeds based on the Codex Alimentarius. It also allows for sharing of assessments of low-level GMO contamination (LLP, low-level presence). The platform was set up by the Food and Agriculture Organization of the United Nations, and was launched at the FAO headquarters in Rome on 1 July 2013. The information uploaded to the platform is freely available to be read. Agerskovgruppen Global Aquaculture Alliance
Sources: en.wikipedia.org
Mass spectrometry provides the identity check, because the observed mass is compared with the theoretical mass of the AEDG sequence. Chromatography separates and quantifies impurities but does not by itself prove which peptide is present. The two techniques are normally used together.
Yes. Trifluoroacetate and acetate ions remain associated with the peptide after purification, so a weighed quantity of powder contains less peptide than the nominal mass suggests. Certificates that report net peptide content rather than raw weight are more directly comparable between suppliers.
Dilute aqueous solutions are less stable than the dry powder and are usually aliquoted and frozen to avoid repeated freeze–thaw cycles. Lyophilised material is best stored desiccated at −20 °C, protected from light. Working solutions are typically prepared fresh from a frozen aliquot.
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.