The short version of Deamidation fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
Documentation accompanying research peptides usually includes a certificate of analysis listing the batch number, purity figure, and test methods applied. Buyers comparing suppliers should check whether the reported purity refers to chromatographic area or to a mass-balance calculation, because the two are not equivalent. Counter-ion content, residual solvents, and water content are sometimes omitted from such certificates even though they affect the actual peptide mass present. Independent verification through a second laboratory is the most direct way to confirm that a supplied material matches its label.
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.
Published evidence comes mainly from Russian-language journals and from a single research group, with small sample sizes and limited independent replication. A few laboratories outside that group have examined related peptides and reported weaker or absent telomerase effects, so the central claim is best described as contested rather than settled. Rodent studies report modest changes in some ageing markers and in survival, but designs vary and control conditions are often sparse. No large randomised trial in humans has been published, and long-term safety data in healthy populations are correspondingly thin.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. It was designed at the St. Petersburg Institute of Bioregulation and Gerontology as a short, chemically defined analogue of epithalamin, a fraction obtained from bovine pineal tissue. Small peptide bioregulators of this type formed a long-running line of work there from the 1980s onward. Because the molecule is produced by solid-phase synthesis rather than extraction, its composition is exact and its purity can be measured directly.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Freeze-dried solid |
| Solubility class | Freely soluble in water | Aqueous buffers also suitable |
| Typical storage temperature | Minus 20 degrees Celsius or colder | Desiccated and light protected |
| Typical analytical method | RP-HPLC with UV detection | 214 nm on C18 column |
| Identity confirmation | Electrospray mass spectrometry | Sequence verified separately |
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography with ultraviolet detection, frequently near 214 nanometers where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the observed molecular mass and helps separate the intact peptide from truncated or modified forms. Amino acid analysis or tandem mass spectrometry can establish residue order. Purity is commonly quoted as an area percentage, yet such values are method-dependent, and comparisons between laboratories require matching column, gradient and detection wavelength.
Laboratory handling begins with dissolution of the lyophilized powder in water or a suitable aqueous buffer. The dry solid is the more stable form, so stock solutions are generally prepared only when required and kept cold afterwards. Repeated freezing and thawing of a solution is avoided because it encourages aggregation and gradual loss of the intact chain. Diluents and containers are selected to limit adsorption of a short peptide onto plastic surfaces and to reduce microbial growth in aqueous preparations.
Stability depends strongly on pH, temperature and the presence of oxygen and trace metals. Cleavage of the backbone proceeds faster under neutral to alkaline conditions, whereas acidic solutions tend to slow that reaction. The aspartate and glutamate side chains can undergo deamidation or imide formation over time, generating closely related impurities. Published stability data specific to epitalon are sparse, so the usable life of a given solution is best regarded as an open question that depends on buffer composition, concentration and storage temperature.
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.
Human data are limited to small studies, often without the randomization, blinding, or control groups expected in contemporary clinical research. Reported outcomes have included changes in melatonin levels, immune markers, and subjective measures, but sample sizes were generally too small to support firm conclusions. Some reviews treat the peptide as promising while noting methodological weaknesses; others question whether the observed effects are specific. The compound is frequently discussed in longevity-focused communities, where enthusiasm often outpaces the published evidence. Separating established findings from speculation is therefore important when reading summaries of this research.
Epitalon emerged from research conducted in Saint Petersburg by Vladimir Khavinson and colleagues, who studied short peptides as potential regulators of aging. The work built on epithalamin, a pineal gland extract reported to influence neuroendocrine function. Epitalon was designed as a synthetic counterpart with a defined sequence, allowing reproducible experiments that extracts could not support. Early publications described effects on melatonin rhythms and lifespan in animal models. These findings circulated mainly in Russian-language journals during the 1990s, which limited their visibility among English-speaking researchers.
The most widely cited claim is that epitalon activates telomerase and thereby extends telomere length. Supporting evidence comes largely from cultured human cells, where treatment was associated with increased telomerase activity and delayed replicative senescence. Telomerase activation is a biologically consequential effect, since the enzyme is largely silenced in most somatic cells. However, the route by which a short peptide would reach and act on the enzyme's regulatory machinery has not been established. Independent replication in human trials is scarce, so the link between cell-culture observations and whole-body aging remains an open question.
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.
Epitalon is a synthetic tetrapeptide with the amino acid sequence alanine-glutamate-aspartate-glycine, abbreviated Ala-Glu-Asp-Gly or AEDG. It was developed by the Russian researcher Vladimir Khavinson and colleagues during work on peptide bioregulators derived from the pineal gland. The compound is short enough to be produced by standard solid-phase peptide synthesis and is typically handled as a lyophilized white powder. Its small size distinguishes it from larger pineal peptides such as epithalamin, a complex extract from which the tetrapeptide was conceptually derived.
==== United nations ==== The UN Commission on Narcotic Drugs added 2C-B to Schedule II of the Convention on Psychotropic Substances in March 2001. 2C-B is a scheduled drug in most jurisdictions. The following is a partial list of territories where the substance has been scheduled.
An insulin pump delivers insulin subcutaneously. The insulin pump body itself can also contain the algorithm used in an AID system, or it can connect via Bluetooth with a separate mobile device (such as a phone) to send data and receive commands to adjust insulin delivery. Algorithm The algorithm for each AID system differs. In commercial systems (see below), little is known about the details of how the control algorithm works. In open source systems, the code and algorithm are openly available. In general, all algorithms do the same basic functionality of taking in CGM data and based on predicted glucose level's and the user's personal settings (for basal rates, insulin sensitivity, and carbohydrate ratio, for example) then recommends insulin dosing to help bring or maintain glucose levels in target range. Depending on the system, users may have the ability to adjust the target for the system, and may have different settings to ask the system to give more or less insulin in general.
The United States Environmental Protection Agency (EPA) maintains and approves test methods, which are approved procedures for measuring the presence and concentration of physical, chemical and biological contaminants; evaluating properties, such as toxic properties, of chemical substances; or measuring the effects of substances under various conditions. The methods in the Agency index are known as EPA Methods. There are other types of methods such as the ASTM and United States Pharmacopeia, but the EPA Methods are developed through a regulatory process involving public notice, comment and revision and are legally binding whereas ASTM methods are developed through a consensus process and compliance is voluntary. These methods are developed to help standardize and achieve the EPA mission to protect the environment and human health.
93Zr is a radioisotope of zirconium with a half-life of 1.61 million years, decaying through emission of a low-energy beta particle. 73% of decays populate an excited state of niobium-93, which decays with a half-life of 13.9 years (almost entirely by internal conversion, emitting no gamma ray) to the stable ground state of 93Nb, while the remaining 27% of decays directly populate the ground state. It is one of the 7 long-lived fission products. The low specific activity and low energy of its radiation limit the radioactive hazards of this isotope, and its insolubility makes it unlikely to escape a waste repository; all these are shared with palladium-107. Nuclear fission produces it at a fission yield of 6.3% (thermal neutron fission of 235U), one of the most abundant fission products. Nuclear reactors usually contain large amounts of zirconium as fuel rod cladding (see zircalloy), and neutron irradiation of 92Zr also produces some 93Zr, though this is limited by 92Zr's low neutron capture cross section of 0.22 barns. Indeed, one of the primary reasons for using zirconium in fuel rod cladding is its low cross section. 93Zr also has a low neutron capture cross section of 0.7 barns. Most fission zirconium consists of other isotopes; the other isotope with a significant neutron absorption cross section is 91Zr with a cross section of 1.24 barns. 93Zr is a less attractive candidate for disposal by nuclear transmutation than are 99Tc and 129I.
In December 2007, Takeda submitted a New Drug Application (NDA) for alogliptin to the United States Food and Drug Administration (FDA), after positive results from Phase III clinical trials. In September 2008, the company also filed for approval in Japan, winning approval in April 2010. The company also filed a marketing authorisation application elsewhere outside the United States, which was withdrawn in June 2009 needing more data. The first NDA failed to gain approval and was followed by a pair of NDAs (one for alogliptin and a second for a combination of alogliptin and pioglitazone) in July 2011. In 2012, Takeda received a negative response from the FDA on both of these NDAs, citing a need for additional data.
Sources: en.wikipedia.org
== Adverse effects == In the United States, manufacturers of dietary supplements are required to demonstrate safety of their products before approval is granted for commerce. Despite this caution, numerous adverse effects have been reported, including muscle cramps, hair loss, joint pain, liver disease, and allergic reactions, with 29% of the adverse effects resulting in hospitalization, and 20% in serious injuries or illnesses. The potential for adverse effects also occurs when individuals consume more than the necessary daily amount of vitamins or minerals that are needed to maintain normal body processes and functions. The incidence of adverse effects reported to the FDA were due to "combination products" that contain multiple ingredients, whereas dietary supplements containing a single vitamin, mineral, lipid product, and herbal product were less likely to cause adverse effects related to excess supplementation. Among general reasons for the possible harmful effects of dietary supplements are: a) absorption in a short time, b) manufacturing quality and contamination, and c) enhancing both positive and negative effects at the same time. The incidence of liver injury from herbal and dietary supplements is about 16–20% of all supplement products causing injury, with the occurrence growing globally over the early 21st century.
where K is the area of the quadrilateral and s is its semiperimeter. For a tangential quadrilateral with given sides, the inradius is maximum when the quadrilateral is also cyclic (and hence a bicentric quadrilateral). In terms of the tangent lengths, the incircle has radius
=== Sex differences === Differences in sex determination are controlled by sex chromosomes. Sex hormonal releases have a significant effect on sexual dimorphisms (phenotypic differentiation of sexual characteristics) of the brain. Recent studies seem to suggest that regulating these dimorphisms has implications for understanding normal and abnormal brain function. Sexual dimorphisms may be significantly influenced by sex-based brain gene expression which varies from species to species. Animal models such as rodents, Drosophila melanogaster, and Caenorhabditis elegans, have been used to observe the origins and/or extent of sex bias in the brain versus the hormone-producing gonads of an animal. With the rodents, studies on genetic manipulation of sex chromosomes resulted in an effect on one sex that was completely opposite of the effect in the other sex. For example, a knockout of a particular gene only resulted in anxiety-like effects in males. With studies on D. menlanogaster it was found that a large brain sex bias of expression occurred even after the gonads were removed, suggesting that sex bias could be independent of hormonal control in certain aspects. Observing sex-biased genes has the potential for clinical significance in observing brain physiology and the potential for related (whether directly or indirectly) neurological disorders. Examples of diseases with sex biases in development include Huntington's disease, cerebral ischemia, and Alzheimer's disease.
=== Elimination === Severe cases require hemodialysis, which is the most rapid method of removing potassium from the body. These are typically used if the underlying cause cannot be corrected swiftly while temporising measures are instituted or there is no response to these measures. Loop diuretics (furosemide, bumetanide, torasemide) and thiazide diuretics (e.g., chlortalidone, hydrochlorothiazide, or chlorothiazide) can increase kidney potassium excretion in people with intact kidney function. Potassium can bind to a number of agents in the gastrointestinal tract. Sodium polystyrene sulfonate (Kayexalate) was approved for this use decades ago, and can be given by mouth or rectally. Sodium polystyrene sulfonate given with sorbitol was uncommonly but convincingly associated with colonic necrosis; this combination is no longer used. Patiromer is taken by mouth and works by binding free potassium ions in the gastrointestinal tract and releasing calcium ions for exchange, thus lowering the amount of potassium available for absorption into the bloodstream and increasing the amount lost via the feces. The net effect is a reduction of potassium levels in the blood serum. Sodium zirconium cyclosilicate is a medication that binds potassium in the gastrointestinal tract in exchange for sodium and hydrogen ions. Onset of effects occurs in one to six hours. It is taken by mouth.
In India, most universities and nearly all research institutions are public. Some private undergraduate colleges exist but most are engineering schools that are affiliated with public universities. Private schools can be partially aided by the national or state governments. India also has an "open" public university, the Indira Gandhi National Open University which offers distance education. In terms of the number of enrolled students, it is now the largest university in the world with over four million students.
Sources: en.wikipedia.org
Iron–sulfur clusters are complexes of iron and sulfur atoms held within proteins by cysteinyl residues. They play both structural and functional roles, including electron transfer, redox sensing, and as structural modules.
== Classification == The MEROPS protease database includes the following ten families of asparagine peptide lyases, which are included in 6 different clans of proteases. Proteolytic enzymes are classified into families based on sequence similarity. Each family includes proteolytic enzymes with homologous sequences and common catalytic type. Clans are groups of proteolytic enzymes families with related structures, where catalytic type is not conserved.
The majority were sailors (particularly those who were English), taken with their ships, but others were fishermen and coastal villagers. However, most of these captives were people from lands close to Africa, particularly Spain and Italy. This eventually led to the bombardment of Algiers by an Anglo-Dutch fleet in 1816.
According to the author of the study there were 137 such events in Thailand during this period. Other ASEAN nations ranked in the study were Myanmar, ranked 3; Philippines, 5; and Vietnam, 8. Climate Change Performance Index (CCPI) 2017: Of 58 nations responsible for about 90% of global energy-related CO2 emissions, Thailand was ranked 42d in taking "action on climate protection" (1=best, 61=worst), earning an assessment of "poor". Other ASEAN nations ranked were Indonesia, 22 "good"; Malaysia, 44, "poor"; and Singapore, 54, "very poor". Global Climate Risk Index 2017: Thailand ranked number 10 of 180 nations most affected by "...weather-related loss events..." during the period 1996-2015 (1=most affected, 180=least affected) according to Germanwatch. Other ASEAN nations ranked in the top 10 were Myanmar, 2; Philippines, 5; and Vietnam, 8. Climate Central: Thailand is ranked seventh (higher number=lower risk) on the "Top 20 Most At-Risk Countries" for exposure to sea level rise and coastal flooding. It estimates the number of "People living on land that will be below sea level or chronic flood levels by the end of the century, assuming current emissions trends continue, and medium sensitivity of sea level to warming." In Thailand, eight million persons, or 12% of the population, are "at-risk" according to the study. Six of ASEAN's ten member-states are on the at-risk list. Climate Change Performance Index 2016: Thailand ranked 49 of 61 (1=best, 61=worst) countries, putting it in the "Very Poor" performance category.
== Career == She completed her secondary education at the Reformed College of Debrecen, graduating in 1971. She earned her medical degree summa cum laude from the University of Debrecen Medical School in 1977. Between 1977 and 1982, she worked at the Department of Anatomy, Histology and Embryology of the University of Debrecen Medical School. Then, from 1982 to 1993, she was a staff member of the Department of Clinical Chemistry. She held research fellowships at the State University of New York (1988), Thomas Jefferson University in Philadelphia (1989–1990), and Gifu University in Japan (1992). She obtained the Doctor of the Hungarian Academy of Sciences (D.Sc.) degree in 1992. In 1993, she was appointed full professor and director of the Department of Public Health and Epidemiology (later the Department of Preventive Medicine), a position she held until 2017. From 2005 to 2012 she served as the founding dean of the Faculty of Public Health at the University of Debrecen, and between 2007 and 2013 she was the vice-president responsible for medical specialization and postgraduate training of the Medical and Health Science Centre. From 2021 to 2024, she was a visiting professor at Semmelweis University and senior adviser to the Epidemiology and Surveillance Centre. Since November 2024, she has been a professor at the Institute of Preventive Medicine and Public Health of Semmelweis University.
Sources: en.wikipedia.org
Reversed-phase high-performance liquid chromatography with ultraviolet detection at 214 nanometres is the usual approach. Peak area percentage provides a purity figure relative to other components in the sample. Mass spectrometry is then applied to confirm identity.
Aspartate can cyclise into a succinimide intermediate that later hydrolyses back as isoaspartate. Both forms share the same molecular mass, so mass spectrometry alone cannot tell them apart. This shapes how purity data should be interpreted.
Freeze-dried material is normally kept desiccated below minus twenty degrees Celsius and shielded from light. Solutions are prepared shortly before use and held cold. Repeated thawing is avoided because it accelerates aggregation and degradation.
No. Epithalamin is a peptide-containing extract of bovine pineal glands, while epitalon is a single synthetic tetrapeptide. The extract contains many peptides and other tissue components, so its composition varies between batches in ways that a synthesised sequence does not.