The short version of counterion fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-09-20. Anything still debated is marked as such rather than presented as settled.
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.
The compound is generally presented as a synthetic fragment of epithalamin, a pineal gland extract investigated in the former Soviet Union from the 1970s onward. Vladimir Khavinson and colleagues in Saint Petersburg developed short peptides modelled on such extracts, and epitalon became the most widely cited of those sequences. Most primary reports appeared in Russian-language journals or in proceedings with limited international circulation. Independent replication in laboratories outside that network remains sparse, and much repeated secondary material traces back to a small number of originating groups.
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.
Solubility is high in water, phosphate-buffered saline and normal saline, a pattern that follows from the two acidic residues in the chain. The peptide dissolves poorly in non-polar solvents such as hexane or chloroform. Stock solutions are often prepared in water first and then diluted into the buffer of interest. Because the molecule is small and hydrophilic, filtration through a low-protein-binding membrane is usually straightforward, and visible particulates are uncommon in freshly made solutions.
Identity and purity are established with reversed-phase high-performance liquid chromatography and mass spectrometry. The chromatogram shows the main peak and any truncated or oxidised by-products, while the mass spectrum confirms the expected 390 dalton mass. Amino acid analysis can corroborate composition when a sample's origin is uncertain. Counterion content, particularly residual trifluoroacetate from purification, is frequently reported alongside purity because it shifts the net mass of the solid.
Reference material is normally supplied as a lyophilised powder in a sealed vial. Product literature typically recommends storage at minus twenty degrees Celsius or colder, protected from light and moisture. Freeze-thaw cycling is usually avoided because repeated condensation can introduce water into the vial. Working solutions are commonly prepared fresh, aliquoted, and kept cold for short periods rather than stored at ambient temperature. Labelling the date of opening helps track how long a vial has been in use.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Computed for the free acid of Ala-Glu-Asp-Gly |
| Molecular mass | About 390.35 g/mol | Free peptide; salt forms shift the value |
| Appearance | White to off-white solid | Typical of short peptides after freeze-drying |
| Solubility class | Freely soluble in water | Aqueous buffers are also commonly used |
| Common synonyms | Epitalon, epithalone, AEDG | AEDG is the single-letter sequence |
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 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.
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.
Reversed-phase high-performance liquid chromatography is the standard approach for assessing purity, usually with ultraviolet detection near 214 nm, where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the molecular mass and helps reveal truncation or deletion byproducts. Amino acid analysis can verify composition, and counterion content is sometimes measured because peptides purified with trifluoroacetic acid retain variable amounts of that salt. Purity figures reported without a stated method and detection wavelength are difficult to interpret.
The final withdrawal of the Mustang from USAF placed hundreds of P-51s onto the civilian market. The rights to the Mustang design were purchased from North American by the Cavalier Aircraft Corporation, which attempted to market the surplus Mustang aircraft in the US and overseas. In 1967 and again in 1972, the USAF procured batches of remanufactured Mustangs from Cavalier, most of them destined for air forces in South America and Asia that were participating in the Military Assistance Program (MAP). These aircraft were remanufactured from existing original F-51D airframes fitted with new V-1650-7 engines, a new radio, tall F-51H-type vertical tails, and a stronger wing that could carry six 12.7 mm (0.50 in) machine guns and a total of eight underwing hardpoints. Two 1,000-pound (450 kg) bombs and six 127 mm (5 in) rockets could be carried. They all had an original F-51D-type canopy but carried a second seat for an observer behind the pilot. One additional Mustang was a two-seat, dual-control TF-51D (67-14866) with an enlarged canopy and only four wing guns. Although these remanufactured Mustangs were intended for sale to South American and Asian nations through the MAP, they were delivered to the USAF with full USAF markings. They were, however, allocated new serial numbers (67-14862/14866, 67-22579/22582 and 72-1526/1541). The last US military use of the F-51 was in 1968 when the US Army employed a vintage F-51D (44-72990) as a chase aircraft for the Lockheed YAH-56 Cheyenne armed helicopter project.
By using life cycle assessment tools he demonstrated the shortcomings of bioplastics and similar biomass based technologies intended as a substitute for the petrochemical processes used today. His main findings showed that changing from petrochemical to biomass-based processes often worsens their environmental impact and increases the emissions of carbon dioxide when compared to conventional processes based on fossil fuel stocks. With the recent mandate to increase biofuel content in the United States this area of research has become increasingly important, but to date has failed to guide public policy in the United States. Arguably, Gerngross' most important biotechnological contribution consisted of humanizing the glycosylation machinery in yeast to produce human therapeutic proteins, including antibodies, with fully human carbohydrate structures. Much of this work was conducted at Glycofi, Inc., a Lebanon, New Hampshire biotechnology startup company that was acquired in 2006 by Merck in a record-setting $400 million transaction. His work has been frequently cited in the popular press including The Times (London), CNN, Scientific American, BBC, The Guardian, The Economist, New Scientist, Nature Biotechnology and the Los Angeles Times. He has most recently been covered by the Boston Globe, CNBC, First Rounders, Evaluate Pharma, STAT and numerous others.
Pituitary pars intermedia dysfunction (PPID), or equine Cushing's disease, is an endocrine disease affecting the pituitary gland of horses. It is most commonly seen in older animals, and is classically associated with the formation of a long, wavy coat (hirsutism) and chronic laminitis.
=== EC 1.21.4 With a disulfide as acceptor === EC 1.21.4.1: D-proline reductase (dithiol) EC 1.21.4.2: glycine reductase EC 1.21.4.3: sarcosine reductase EC 1.21.4.4: betaine reductase EC 1.21.4.5: tetrachlorohydroquinone reductive dehalogenase
Sources: en.wikipedia.org
== Global Research Infrastructure == Widespread interest and funding for research on regenerative medicine has prompted institutions in the United States and around the world to establish departments and research institutes that specialize in regenerative medicine including: The Department of Rehabilitation and Regenerative Medicine at Columbia University, the Institute for Stem Cell Biology and Regenerative Medicine at Stanford University, the Center for Regenerative and Nanomedicine at Northwestern University, the Wake Forest Institute for Regenerative Medicine, and the British Heart Foundation Centers of Regenerative Medicine at the University of Oxford. In China, institutes dedicated to regenerative medicine are run by the Chinese Academy of Sciences, Tsinghua University, and the Chinese University of Hong Kong, among others.
The medical uses of estradiol cypionate are the same as those of estradiol and other estrogens. Examples of indications for the drug include hormone therapy and hormonal contraception. In regard to the latter, estradiol cypionate has been used in combination with medroxyprogesterone acetate as a combined injectable contraceptive. Along with estradiol valerate, estradiol undecylate, and estradiol benzoate, estradiol cypionate is used as a form of high-dose estrogen therapy in feminizing hormone therapy for transgender women. The medication has been used to induce puberty in girls with delayed puberty due to hypogonadism. Estradiol cypionate is usually used at a dosage of 1 to 5 mg by intramuscular injection every 3 to 4 weeks in the treatment of menopausal symptoms such as hot flashes and vaginal atrophy, at a dosage of 1.5 to 2 mg by intramuscular injection once a month in the treatment of female hypoestrogenism due to hypogonadism, and at a dosage of 2 to 10 mg by intramuscular injection once every 1 or 2 weeks for hormone therapy in transgender women. The doses used to induce puberty in girls are 0.2 to 2.5 mg per month, gradually increased over a period of 4 years.
The crossover video game Lego Dimensions, which incorporates the use of Lego minifigures with a special gamepad, includes Portal-themed elements, as first demonstrated during its Electronic Entertainment Expo 2015 trailer. A Portal-themed level appears as part of the main story campaign, with GLaDOS playing a significant role in the game's plot. A Chell minifigure was released that comes packaged with buildable sentry turret and companion cube; the figure unlocks an additional level and open-world area based on the series when used in-game. The Portal levels include Easter eggs based on Doug Rattmann hiding himself away. The game also features a new song written by Jonathan Coulton and performed by Ellen McLain that plays over the end credits. The series' main antagonist, GLaDOS, was included as the dealer in Poker Night 2. This game features Portal themed unlockables such as playing cards, table and room. Wheatley is also featured as a bargaining chip. A Portal based pinball table for Zen Pinball 2, Pinball FX2, and Pinball FX3 was developed by Zen Studios in collaboration with Valve. GLaDOS guest stars in Defense Grid: The Awakening in a full-story expansion. A cosmetic set based on the Companion Cube was released as a visual replacement for the "Io" character in Valve's multiplayer online battle arena game, Dota 2. P-Body is a playable character in the Windows release of Super Bomberman R.
== Critical reception == Thomas's work and stature as a poet have been much debated by critics and biographers since his death. Critical studies have been clouded by Thomas's personality and mythology, especially his drunken persona and death in New York. When Seamus Heaney gave an Oxford lecture on the poet he opened by addressing the assembly, "Dylan Thomas is now as much a case history as a chapter in the history of poetry", querying how "Thomas the Poet" is one of his forgotten attributes. The Poetry Archive notes that "Dylan Thomas's detractors accuse him of being drunk on language as well as whiskey, but whilst there's no doubt that the sound of language is central to his style, he was also a disciplined writer who re-drafted obsessively". David Holbrook, who has written three books about Thomas, stated in his 1962 publication Llareggub Revisited, "the strangest feature of Dylan Thomas's notoriety—not that he is bogus, but that attitudes to poetry attached themselves to him which not only threaten the prestige, effectiveness and accessibility to English poetry but also destroyed his true voice and, at last, him." Holbrook's negative evaluation of Thomas's work, based on an ad hominem psychoanalytic reading, is rejected by Rhian Barfoot as reductive and outdated viewed in the context of more recent psychoanalytic theory as found in the work of Lacan and Kristeva, where the emphasis on the semiotic and the materiality of language is seen as corresponding to Thomas's poetic style and thus supportive of a positive critical evaluation of his work.
== Notable people == Captain John Macgregor Skinner (1761–1832) moved to Holyhead from the US in 1793. Master on packet ships between Holyhead and Dublin but was washed overboard. The town erected an obelisk in his honour and his house is an exhibit at the Holyhead Maritime Museum. John Walpole Willis (1793–1877), a Welsh-born judge, and a judge of the Supreme Court of New South Wales, born in Holyhead Sir Ralph Champneys Williams (1848–1927) colonial governor of the Windward Islands & Newfoundland, born in Holyhead Lillie Goodisson (1860–1947), a Welsh Australian nurse and a pioneer of family planning in New South Wales, born in Holyhead Francis Dodd (1874–1949), a British portrait painter, landscape artist and printmaker, born in Holyhead
Sources: en.wikipedia.org
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.
Epitalon and epithalon both circulate, and the difference reflects transliteration of a name coined in Russian-language publications. Reference to the extract it derives from, epithalamin, explains the shared stem. Databases and suppliers are inconsistent, so a search for one spelling alone may miss relevant entries.
No. Epithalamin is a multi-component preparation obtained from pineal tissue, and its exact composition is not fully characterised. Epitalon is a single defined tetrapeptide described as a short synthetic counterpart of that extract, so the two are related in origin but not interchangeable in identity.
Sealed lyophilised powder is normally kept at minus twenty degrees Celsius or below, away from light and moisture. Vials are allowed to reach room temperature before opening to limit condensation. Repeated warming and cooling of the same vial is discouraged.