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 2025-10-04 and is reviewed periodically as new material appears.
Material sold for research use varies widely in documented quality. A useful verification package includes a certificate of analysis that states peptide content rather than only net weight, the chromatographic method and column used, and a mass spectrum consistent with the expected mass. Independent testing by a third-party laboratory is occasionally reported. Statements of identity resting only on a supplier label provide little assurance, and the gap between nominal mass and actual peptide content can be substantial once counterions and residual water are counted.
Peptides of this size are generally stable as dry solids but degrade in solution over time. The principal routes are hydrolysis of the peptide backbone and oxidation, with hydrolysis favoured by elevated temperature and extreme pH. Aqueous solutions held at room temperature can show measurable loss of purity within days, while frozen aliquots are considerably more durable. Because the sequence contains neither cysteine nor methionine, oxidation is less of a concern than for many other peptides, but pH control during handling still matters.
Typical storage for the lyophilized powder is −20 °C or lower, in a sealed container protected from light and moisture. Hygroscopic material should be allowed to equilibrate to room temperature before the vial is opened, which limits condensation on the contents. Working solutions are commonly divided into single-use aliquots and frozen to avoid repeated freeze-thaw cycles. Dilute solutions are more prone to adsorption onto plastic surfaces and to loss during filtration, so procedures that minimize transfers and use low-binding labware are preferable.
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.
Discussions in the literature often conflate three distinct entities: the pineal extract epithalamin, the isolated tetrapeptide AEDG, and commercial preparations sold under similar names. Reviews citing older Russian-language studies sometimes omit detail on purity, route of administration and control groups, which makes cross-study comparison difficult. Researchers working with the compound generally note the need for independent replication, standardized enzyme assays, and clearer reporting of peptide identity. These caveats are relevant when weighing claims that appear in secondary sources rather than in primary reports.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized solid |
| Solubility | Freely soluble in water | Also dissolves in polar organic solvents |
| Typical storage temperature | −20 °C or below | Sealed, desiccated, protected from light |
| Primary purity assay | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray ionization commonly used |
Purity assessment of peptide reagents normally relies on reversed-phase high-performance liquid chromatography. A gradient of acetonitrile in water with trifluoroacetic acid, paired with a C18 stationary phase, separates the target tetrapeptide from truncated sequences and deletion analogues. Detection at 214 nanometres exploits absorbance of the peptide backbone, since the molecule contains no aromatic residue. Results are expressed as a percentage of total peak area. Values above ninety-five percent are typical for research-grade material, although reporting conventions vary between suppliers.
Identity confirmation uses mass spectrometry, usually electrospray ionisation in positive mode or matrix-assisted laser desorption. The protonated free peptide produces a signal near three hundred and ninety-one daltons, while salt adducts shift that value slightly. Tandem mass spectrometry or amino acid analysis supplies sequence-level confirmation, which a single mass measurement cannot. Peptides containing aspartate can cyclise into succinimide intermediates that hydrolyse to isoaspartate isomers of identical mass. Because those isomers are difficult to separate chromatographically, identity and purity results carry more weight when interpreted together.
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.
Epitalon is a synthetic tetrapeptide with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
Literature searches for this compound must account for several spelling variants. Indexing databases contain epitalon, epithalon, epithalone, and AEDG, and relevant records are scattered across Russian-language and English-language journals that do not consistently cross-cite. Early publications describe the parent extract as a mixture of many peptides, whereas later work addresses the single synthetic tetrapeptide. That shift in nomenclature complicates comparison between studies, because extract data and tetrapeptide data are sometimes cited interchangeably. A search strategy omitting the alternate spellings will return an incomplete set of references.
Reported biological findings come mainly from cell culture and rodent experiments. Those studies describe changes in telomerase catalytic subunit expression, melatonin rhythm amplitude, and antioxidant enzyme activity after peptide exposure. Human data are sparse and consist of small trials with limited blinding and inconsistent endpoints. The proposed mechanisms remain hypotheses rather than established facts, and there is no consensus on whether effects observed in animals carry over to people. Independent replication outside the original research groups is limited, which is a recognised gap in the published literature.
Dehydroascorbic acid (DHA) is the major oxidized form of ascorbic acid (vitamin C). It is actively imported into the endoplasmic reticulum of cells via glucose transporters. It is trapped therein by reduction back to ascorbic acid by glutathione and other thiols. The (free) chemical radical semidehydroascorbic acid (SDA) also belongs to the group of oxidized ascorbic acids.
Robinson and another colleague, Pauling founded the Institute of Orthomolecular Medicine in Menlo Park, California, which was soon renamed the Linus Pauling Institute of Science and Medicine. Pauling directed research on vitamin C, but also continued his theoretical work in chemistry and physics until his death. In his last years, he became especially interested in the possible role of vitamin C in preventing atherosclerosis and published three case reports on the use of lysine and vitamin C to relieve angina pectoris. During the 1990s, Pauling put forward a comprehensive plan for the treatment of heart disease using lysine and vitamin C. In 1996, a website was created expounding Pauling's treatment which it referred to as Pauling Therapy. Proponents of Pauling Therapy believe that heart disease can be treated and even cured using only lysine and Vitamin C and without drugs or heart operations. Pauling's work on vitamin C in his later years generated much controversy. He was first introduced to the concept of high-dose vitamin C by biochemist Irwin Stone in 1966. After becoming convinced of its worth, Pauling took 3 grams of vitamin C every day to prevent colds. Excited by his own perceived results, he researched the clinical literature and published Vitamin C and the Common Cold in 1970. He began a long clinical collaboration with the British cancer surgeon Ewan Cameron in 1971 on the use of intravenous and oral vitamin C as cancer therapy for terminal patients.
On March 10, 2014, the first Dunkin' Donuts/Baskin-Robbins combination store in Southern California opened in Ramona. This is Dunkin' Donuts' third California shop to open, following shops in Barstow and on Camp Pendleton. Since March 2014, Dunkin' Donuts has opened several additional locations throughout California, including the Los Angeles area. Dunkin' Donuts shops opened in the San Francisco Bay Area in Walnut Creek, Half Moon Bay, and American Canyon in 2016, as well as South San Francisco and Fremont, in 2017.
The Marxist-Leninist leadership of the Soviet Union intensely debated foreign policy issues and changed directions several times. Even after Stalin assumed dictatorial control in the late 1920s, there were debates, and he frequently changed positions. During the country's early period, it was assumed that Communist revolutions would break out soon in every major industrial country, and it was the Russian responsibility to assist them. The Comintern was the weapon of choice. A few revolutions did break out, but they were quickly suppressed (the longest lasting one was in Hungary)—the Hungarian Soviet Republic—lasted only from 21 March 1919 to 1 August 1919. The Russian Bolsheviks were in no position to give any help. By 1921, Lenin, Trotsky, and Stalin realized that capitalism had stabilized itself in Europe and there would not be any widespread revolutions anytime soon. It became the duty of the Russian Bolsheviks to protect what they had in Russia, and avoid military confrontations that might destroy their bridgehead. Russia was now a pariah state, along with Germany. The two came to terms in 1922 with the Treaty of Rapallo that settled long-standing grievances. At the same time, the two countries secretly set up training programs for the illegal German army and air force operations at hidden camps in the USSR. Moscow eventually stopped threatening other states, and instead worked to open peaceful relationships in terms of trade, and diplomatic recognition.
Sources: en.wikipedia.org
=== Mass Spectrometry === Mass spec techniques are essential in nuclear forensics analysis. Mass spec can provide elemental and isotopic information. Mass spec also requires less sample mass relative to counting techniques. For nuclear forensic purposes it is essential that the mass spectrometry offers excellent resolution in order to distinguish between similar analytes, e.g. 235U and 236U. Ideally, mass spec should offer excellent resolution/mass abundance, low backgrounds, and proper instrumental function.
== Honors and awards == In December 2010 he was acknowledged in his individual capacity, as the "Cold Chain Personality of the Year" by an expert panel hosted by KPMG-Supply Chain Leadership Council. The award was in appreciation for individual contributions to the industry and for aligning focus on the socio-economic fabric in India. In 2012 he was applauded with the "Exemplary Thought Leadership Award" by the ICE Centre of Excellence in India. In 2014 he won the prestigious Agribusiness Leadership Award at the annual Agriculture Leadership Summit in New Delhi. In 2016, ISHRAE lauded him as honorary lifetime member, their first ever. He is expert member of the Empowered Committee in the Ministry of New & Renewable Energy for implementation of Montreal Protocol and on the Global Advisory Committee of the International Solar Alliance (ISA) In India, he is recognised as one among the few eminent persons from the private sector who have shifted over to public service by taking on specialist advisory roles in government. His authored documents are frequently cited in the cold chain domain. He is recipient of various recognition and achievement awards from the cold chain industry in India.
== Nutrition == Plain kefir is 87% water, 7% carbohydrates, 4% protein, and 1% fat (table). In a reference amount of 100 g (3.5 oz), kefir provides 52 calories of food energy, and contains moderate amounts (10-19% of the Daily Value, DV) of vitamin A, vitamin B12, riboflavin, and calcium (table). Kefir contains byproducts of the fermentation process, including carbon dioxide and ethanol.
Sources: en.wikipedia.org
The powder is normally kept at −20 °C or below in a sealed, moisture-protected container. Letting the vial reach room temperature before opening helps prevent condensation on the contents.
Reversed-phase HPLC with ultraviolet detection is the usual approach, often paired with mass spectrometry. Together the two methods address both chromatographic purity and molecular identity.
Differences arise from the analytical method, the detection wavelength, and whether the number refers to the peptide or to total powder mass. Counterion and water content can lower the actual peptide fraction considerably.
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.