counterion is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2025-12-03. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| 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.
Harman trademarked the phrase "It's finger lickin' good", which eventually became the company slogan. He also introduced the "bucket meal" in 1957 (14 pieces of chicken, five bread rolls and a pint of gravy in a cardboard bucket). Serving their signature meal in a paper bucket was to become an iconic feature of the company. By 1963, there were 600 KFC restaurants, making the company the largest fast food operation in the United States. KFC popularized chicken in the fast food industry, diversifying the market by challenging the dominance of the hamburger. With significant growth in tow, the fledgling Kentucky Fried Chicken decided in 1964 that they would begin offering franchise opportunities beyond the Atlantic, and landed on the United Kingdom as its entry point into Europe. As such, the first British KFC eatery opened its doors at 92 Fishergate in Preston, Lancashire, on May 1, 1965, and still operates today. Pat Grace met with Sanders at his holiday home near Toronto, Canada, and agreed to franchise the brand in Ireland. In 1970 Grace returned to Ireland after a number of years in Canada to open his first Kentucky Fried Chicken restaurants in Phibsboro shopping center in Dublin. Eventually he opened another six restaurants located in Dublin, Limerick and Cork. After disagreements over cost cutting with KFC management in the early 1980s, the Irish restaurants were renamed to Pat Grace's Famous Fried Chicken reportedly retaining the original recipe. These stores were closed in the late 1980s.
=== Special edition === On June 26, 2007, Stone Sour released a special edition version of the album with six previously unreleased tracks and a bonus DVD. The DVD included a full concert performance by the band from October 2006 in Moscow and the music videos for "30/30-150", "Through Glass", and "Sillyworld". When talking about the special edition, vocalist Taylor said, "We really wanted to do something which was really cool," saying that it shows the band's different musical elements and them in their live element, which he says "people really gravitate towards". In addition to this, Stone Sour released a live album of their concert in Moscow exclusively on iTunes, entitled Live in Moscow.
Henri Poincaré laid the seeds for the discovery of radioactivity through his interest in and studies of X-rays, which significantly influenced physicist Henri Becquerel. Radioactivity was discovered in 1896 by Becquerel while working with phosphorescent materials. These materials glow in the dark after exposure to light, and Becquerel suspected that the glow produced in cathode-ray tubes by X-rays might be associated with phosphorescence. He wrapped a photographic plate in black paper and placed various phosphorescent salts on it. All results were negative until he used uranium salts. The uranium salts caused a blackening of the plate in spite of the plate being wrapped in black paper. In 1897, Marie Curie began studying the radiation emitted by uranium compounds. Curie named the radiation rayons de Becquerel, "Becquerel Rays" and showed that these rays were a property of atoms. While X-rays were produced using electrical energy, the source of energy for radiation was a mystery. In 1899, Julius Elster and Hans Geitel performed key experiments to find the energy source for radioactivity, excluding extraction of energy from air by measurements in a vacuum and extraction of energy from outer space by measurements 300m down a mine in the Harz mountains. If the atoms themselves were the source of energy, this meant the seemingly immutable atoms must be altered when emitting the rays. In 1900 Curie summarized the puzzle of radioactivity as a choice between two equally unlikely possibilities: either energy was not conserved or chemical elements could be transmuted.
=== Vesicle trafficking === This particular domain, the Vitellogenin lipid transport domain, is also found in the Microsomal triglyceride transfer protein (MTTP) and in Apolipoprotein B. It aids cell trafficking and export of cargo.
Sources: en.wikipedia.org
== Biosynthetic mechanism == Hyaluronic acid (HA) is a linear glycosaminoglycan (GAG), an anionic, gel-like, polymer, found in the extracellular matrix of epithelial and connective tissues of vertebrates. It is part of a family of structurally complex, linear, anionic polysaccharides. The carboxylate groups present in the molecule make it negatively charged, therefore allowing for successful binding to water, and making it valuable to cosmetic and pharmaceutical products. HA consists of repeating β4-glucuronic acid (GlcUA)-β3-N-acetylglucosamine (GlcNAc) disaccharides, and is synthesized by hyaluronan synthases (HAS), a class of integral membrane proteins that produce the well-defined, uniform chain lengths characteristic to HA. There are three existing types of HASs in vertebrates: HAS1, HAS2, HAS3; each of these contribute to elongation of the HA polymer. For an HA capsule to be created, this enzyme must be present because it polymerizes UDP-sugar precursors into HA. HA precursors are synthesized by first phosphorylating glucose by hexokinase, yielding glucose-6-phosphate, which is the main HA precursor. Then, two routes are taken to synthesize UDP-n-acetylglucosamine and UDP-glucuronic acid which both react to form HA. Glucose-6-phosphate gets converted to either fructose-6-phosphate with hasE (phosphoglucoisomerase), or glucose-1-phosphate using pgm (α-phosphoglucomutase), where those both undergo different sets of reactions. UDP-glucuronic acid and UDP-n-acetylglucosamine get bound together to form HA via hasA (HA synthase).
== Prognosis == A typical patient with severe McLeod syndrome that begins in adulthood lives for an additional 5 to 10 years. Patients with cardiomyopathy have elevated risk for congestive heart failure and sudden cardiac death. The prognosis for a normal life span is often good in some patients with mild neurological or cardiac sequelae.
The harm from smoking comes from the many toxic chemicals in the natural tobacco leaf and those formed in smoke from burning tobacco. A 2024 study estimated that each cigarette reduces life expectancy by 20 minutes, while other studies estimate that each one reduces life expectancy by about 11 minutes on average. Humans continue to smoke because nicotine, the primary psychoactive chemical in cigarettes, is highly addictive. Cigarettes, like narcotics, have been described as "strategically addictive", with their addictive properties being a core component of the business strategy. About half of smokers die from a smoking-related cause. Smoking harms nearly every organ of the body. Smoking leads most commonly to diseases affecting the heart, liver, and lungs, being a major risk factor for heart attacks, strokes, chronic obstructive pulmonary disease (COPD) (including emphysema and chronic bronchitis), and cancer (particularly lung cancer, cancers of the larynx and mouth, and pancreatic cancer). It also causes peripheral vascular disease and hypertension. The incidence of erectile dysfunction is approximately 85 percent higher in men who smoke compared to men who do not smoke. Children born to women who smoke during pregnancy are at higher risk of congenital disorders, cancer, respiratory disease, and sudden death. Starting smoking earlier in life and smoking cigarettes higher in tar content increases the risk of these diseases.
Rinck PA (ed.). "MRI: A Peer-Reviewed, Critical Introduction". European Magnetic Resonance Forum (EMRF)/The Round Table Foundation (TRTF). A Guided Tour of MRI: An introduction for laypeople National High Magnetic Field Laboratory The Basics of MRI. Underlying physics and technical aspects. Video: What to Expect During Your MRI Exam from the Institute for Magnetic Resonance Safety, Education, and Research (IMRSER) Royal Institution Lecture – MRI: A Window on the Human Body A Short History of Magnetic Resonance Imaging from a European Point of View How MRI works explained simply using diagrams Real-time MRI videos: Biomedizinische NMR Forschungs GmbH. Paul C. Lauterbur, Genesis of the MRI (Magnetic Resonance Imaging) notebook, September 1971 (all pages freely available for download in variety of formats from Science History Institute Digital Collections at digital.sciencehistory.org) Images showing early MRI scans and the development of the MRI scanner from the archives of University of Nottingham Manuscripts and Spcial Collections Archive collections relating to the development of MRI at the University of Nottingham, including the papers of Nobel Prize winner Sir Peter Mansfield
=== Transitional National Legislative Assembly (2016–2021) === As a result of a peace agreement that came into effect in 2015, a Transitional National Legislative Assembly was formed with 400 members. The membership is as follows:
Sources: en.wikipedia.org
Norbornenes were selected as dipolarophiles due to their balance between strain-promoted reactivity and stability. The drawbacks of this reaction include the cross-reactivity of the nitrile oxide due to strong electrophilicity and slow reaction kinetics.
== Technique == Multiple methods for analysis of BUN and creatinine have evolved over the years. Most of those in current use are automated and give clinically reliable and reproducible results. There are two general methods for the measurement of urea nitrogen. The diacetyl, or Fearon, reaction develops a yellow chromogen with urea, and this is quantified by photometry. It has been modified for use in autoanalyzers and generally gives relatively accurate results. It still has limited specificity, however, as illustrated by spurious elevations with sulfonylurea compounds, and by colorimetric interference from hemoglobin when whole blood is used. In the more specific enzymatic methods, the enzyme urease converts urea to ammonia and carbonic acid. These products, which are proportional to the concentration of urea in the sample, are assayed in a variety of systems, some of which are automated. One system checks the decrease in absorbance at 340 nm when the ammonia reacts with alpha-ketoglutaric acid. The Astra system measures the rate of increase in conductivity of the solution in which urea is hydrolyzed. Even though the test is now performed mostly on serum, the term BUN is still retained by convention. The specimen should not be collected in tubes containing sodium fluoride because the fluoride inhibits urease. Also chloral hydrate and guanethidine have been observed to increase BUN values.
=== Ghrelin/growth hormone secretagogue receptor === Adenosine is an endogenous agonist of the ghrelin/growth hormone secretagogue receptor. However, while it is able to increase appetite, unlike other agonists of this receptor, adenosine is unable to induce the secretion of growth hormone and increase its plasma levels.
== Further reading == Behar, Howard with Janet Goldstein. (2007). It's Not About the Coffee: Leadership Principles from a Life at Starbucks, 208 pages. ISBN 1-59184-192-5. Clark, Taylor. (2007). Starbucked: A Double Tall Tale of Caffeine, Commerce and Culture. 336 pages. ISBN 0-316-01348-X. Michelli, Joseph A. (2006). The Starbucks experience: 5 principles for turning ordinary into extraordinary, 208 pages. ISBN 0-07-147784-5. Pendergrast, Mark (2001) [1999]. Uncommon Grounds: The History of Coffee and How It Transformed Our World. London: Texere. ISBN 1-58799-088-1. Schultz, Howard. and Dori Jones Yang. (1997). Pour Your Heart Into It: How Starbucks Built a Company One Cup at a Time, 350 pages. ISBN 0-7868-6315-3. Simon, Bryant. (2009). Everything but the Coffee: Learning about America from Starbucks. 320 pages. ISBN 0-520-26106-2. Media Archived at Ghostarchive and the Wayback Machine: "How Starbucks Became An $80B Business". CNBC. January 10, 2019. Archived at Ghostarchive and the Wayback Machine: "Why Starbucks Failed In Australia". CNBC. June 26, 2018. Archived at Ghostarchive and the Wayback Machine: "Why Starbucks Is Struggling In South Africa". CNBC. October 23, 2019.
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.