Deamidation comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-10-26. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9, and its calculated molar mass is approximately 390.35 grams per mole. The compound is a short fragment related to a peptide fraction isolated from bovine pineal gland extracts, and it is normally supplied as a lyophilised powder intended for laboratory research. It is not a registered pharmaceutical product in most countries.
The peptide emerged from research carried out in Saint Petersburg from the late 1980s onward, where investigators searched for shorter active fragments of a pineal preparation known as epithalamin. The name epitalon was chosen to reflect that parent extract. Early reports described effects on neuroendocrine markers and on the lifespan of laboratory animals. Much of that work appeared in Russian-language journals, with English translations following later, which affects how readily the original protocols can be assessed by outside groups.
| 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 |
Animal and clinical reports appear mainly in Russian-language journals from the 1990s and 2000s, covering endpoints such as melatonin rhythm, lifespan in aged rodents, and retinal function. Many of these papers involve small groups, lack blinding or placebo comparison, and are difficult to retrieve through indexed databases. Review articles published in English generally summarise the claims without reanalysing the underlying data. Because no large randomised trial exists, the clinical importance of these reported effects stays unresolved and is properly described as an open question.
No national medicines regulator has approved epitalon as a therapeutic product. It is generally distributed as a research chemical, and in some jurisdictions selling peptides for human consumption without approval is restricted or prohibited. Certificates of analysis accompanying commercial material vary in which tests are performed, and independent verification of identity and purity is uncommon. Statements about anti-ageing or disease-prevention benefits on vendor pages are marketing claims rather than regulatory findings, a distinction that shapes how the compound is discussed in scientific and popular sources alike.
The most frequently cited laboratory finding is that AEDG increased telomerase activity and extended telomere length in cultured human somatic cells. That work used fetal fibroblast strains and reported changes in enzyme activity alongside altered division counts. Replication by unrelated groups has been limited, and the published record is largely a single-laboratory series rather than a multi-centre programme. The result supports a hypothesis about peptide influence on gene expression in cell culture; it does not by itself establish an effect on telomere length in living animals or in people.
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.
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.
A centenarian is a person who has reached the age of 100. Because life expectancies at birth worldwide are well below 100, the term is invariably associated with longevity. The United Nations estimated that there were 316,600 living centenarians worldwide in 2012, and 573,000 in 2020, almost quadruple the 2000 estimate of 151,000. As world population and life expectancy continue to increase, the number of centenarians is expected to increase substantially in the 21st century. According to the Office of National Statistics in the United Kingdom, one-third of babies born in the country in 2013 are expected to live to 100. According to a 1998 United Nations demographic survey, Japan is expected to have 272,000 centenarians by 2050; other sources suggest that the number could be closer to 1 million. The incidence of centenarians in Japan was one per 3,522 people in 2008. In Japan (as in most countries), the population of centenarians is highly skewed towards women. Japan in fiscal year 2016 had 57,525 female centenarians, while there were 8,167 males, a ratio of 7:1. The increase of centenarians was even more skewed, at 11.6:1.
== Other hydroxylations == The function of the remainder of the hydroxylated E2 metabolites (6α-, 6β-, 7α-, 12β-, 15α-, 15β-, and 16β-OHE2) remain to be elucidated. Some of these metabolites, such as 15α-OHE2, are excreted in relatively large amounts in pregnant women, possibly serving as an indicator of good fetal health.
The prognosis for visual restoration and maintenance of ocular health with corneal transplants is generally very good. Risks for failure or guarded prognoses are multifactorial. The type of transplant, the disease state requiring the procedure, the health of the other parts of the recipient eye and even the health of the donor tissue may all confer a more or less favorable prognosis. The majority of corneal transplants result in significant improvement in visual function for many years or a lifetime. In cases of rejection or transplant failure, the surgery can generally be repeated.
Sources: en.wikipedia.org
In 2000, Shaw et al. demonstrated that circulating 3α-diol mediates prostate development in tammar wallaby pouch young via conversion to DHT in target tissues. Tammar wallaby pouch young do not show sexually dimorphic circulating levels of T and DHT during prostate development which suggests that another androgenization mechanism was responsible. While 3α-diol's androgen receptor binding affinity is five orders of magnitude lower than DHT (3α-diol is nearly inactive at the androgen receptor), it was known that 3α-diol can be oxidized back to DHT via the action of a number of dehydrogenases. In 2003, Wilson et al. demonstrated that 5α-reductase expression in target tissues enabled a novel pathway from 17OHP to 3α-diol without T or A4 as an intermediate. In 2004, Mahendroo et al. demonstrated that an overlapping novel pathway is operating in mouse testes, generalizing what had been demonstrated in tammar wallaby. The term "backdoor pathway" was coined by Auchus in 2004 and was described as 5α-reduction of 17α-hydroxyprogesterone (17OHP) which is a first step in a pathway that ultimately leads to the production of dihydrotestosterone (DHT). and defined as a route to DHT that: (1) bypasses conventional intermediates androstenedione (A4) and T; (2) involves 5α-reduction of C21 pregnanes to C19 androstanes; and (3) involves the 3α-oxidation of 3α-diol to DHT. The backdoor pathway explains how androgens are produced under certain normal and pathological conditions in humans when the classical androgen pathway cannot fully explain the observed consequences.
=== Pilonidal sinus === Pilonidal sinus (PNS): a sinus tract, or small channel, that may originate from the source of infection and open to the surface of the skin. Material from the cyst drains through the pilonidal sinus. A pilonidal cyst is usually painful, but if it is a draining sinus, the pressure is relieved and the patient might not feel pain.
=== Regulation by CRISPRi === Recent genome-wide CRISPR interference (CRISPRi) screens have identified genes whose selective inhibition modulates specific components of the SASP during inflammation-induced senescence, such as that triggered by interleukin-6 (IL-6). These approaches have helped distinguish molecular regulators of replicative senescence from those involved in inflammatory senescence, providing new targets for studying aging-related pathways. SASP has been reduced through inhibition of p38 mitogen-activated protein kinases and janus kinase. The protein hnRNP A1 (heterogeneous nuclear ribonucleoprotein A1) antagonizes cellular senescence and induction of the SASP by stabilizing Oct-4 and sirtuin 1 mRNAs.
=== Population === Like modern humans, Neanderthals probably descended from a very small population with an effective population—the number of individuals who can bear or father children—of 3,000 to 12,000 approximately. Neanderthals maintained this low population, proliferating weakly harmful genes due to the reduced effectivity of natural selection. Archaeological evidence suggests that the initial Cro-Magnon population was approximately 10 times higher than Neanderthals. Compared to Cro-Magnons, Neanderthals may have been at a demographic disadvantage due to a lower fertility rate, a higher infant mortality rate, or a combination of the two. In a sample of 206 Neanderthals, based on the abundance of young and mature adults in comparison to other age demographics, about 80% of them above the age of 20 died before reaching 40. This high mortality rate was probably due to their high-stress environment. Infant mortality was estimated to have been very high for Neanderthals, about 43% in northern Eurasia.
Sources: en.wikipedia.org
Explorations of artificial materials for manipulating electromagnetic waves began at the end of the 19th century. Some of the earliest structures that may be considered metamaterials were studied by Jagadish Chandra Bose, who in 1898 researched substances with chiral properties. Karl Ferdinand Lindman studied wave interaction with metallic helices as artificial chiral media in the early twentieth century. In the late 1940s, Winston E. Kock from AT&T Bell Laboratories developed materials that had similar characteristics to metamaterials. In the 1950s and 1960s, artificial dielectrics were studied for lightweight microwave antennas. Microwave radar absorbers were researched in the 1980s and 1990s as applications for artificial chiral media. Negative-index materials were first described theoretically by Victor Veselago in 1967. He proved that such materials could transmit light. He showed that the phase velocity could be made anti-parallel to the direction of Poynting vector. This is contrary to wave propagation in naturally occurring materials. In 1995, John M. Guerra fabricated a sub-wavelength transparent grating (later called a photonic metamaterial) having 50 nm lines and spaces, and then coupled it with a standard oil immersion microscope objective (the combination later called a super-lens ) to resolve a grating in a silicon wafer also having 50 nm lines and spaces. This super-resolved image was achieved with illumination having a wavelength of 650 nm in air.
There are six conditionally essential amino acids whose synthesis can be limited under special pathophysiological conditions, such as prematurity in the infant or individuals in severe catabolic distress: arginine, cysteine, glycine, glutamine, proline and tyrosine. Dietary sources of protein include grains, legumes, nuts, seeds, meats, dairy products, fish, and eggs.
The van Deemter equation in chromatography, named for Jan van Deemter, relates the variance per unit length of a separation column to the linear mobile phase velocity by considering physical, kinetic, and thermodynamic properties of a separation. These properties include pathways within the column, diffusion (axial and longitudinal), and mass transfer kinetics between stationary and mobile phases. In liquid chromatography, the mobile phase velocity is taken as the exit velocity, that is, the ratio of the flow rate in ml/second to the cross-sectional area of the ‘column-exit flow path.’ For a packed column, the cross-sectional area of the column exit flow path is usually taken as 0.6 times the cross-sectional area of the column. Alternatively, the linear velocity can be taken as the ratio of the column length to the dead time. If the mobile phase is a gas, then the pressure correction must be applied. The variance per unit length of the column is taken as the ratio of the column length to the column efficiency in theoretical plates. The van Deemter equation is a hyperbolic function that predicts that there is an optimum velocity at which there will be the minimum variance per unit column length and, thence, a maximum efficiency. The van Deemter equation was the result of the first application of rate theory to the chromatography elution process.
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== Formulation == Dakin's original solution contained sodium hypochlorite (0.4% to 0.5%), prepared by treating calcium hypochlorite with sodium carbonate ("washing soda"). The solution left after removal of the insoluble calcium carbonate still contained some soda. Boric acid (4%) was then added as a buffering agent to maintain a pH of between 9 and 10. Dakin found that alkalinity outside this range was too irritating. The solution, while unstable, remains effective for at least a week, if made to the correct pH. Other formulations have been developed over time. In 1916, Marcel Daufresne substituted sodium bicarbonate for Dakin's boric acid as buffering agent. This formulation is the basis of current commercial products. The concentration chosen by Dakin (0.5%) was the maximum highest concentration found tolerable to the skin. It is the concentration recommended by the U.S. Centers for Disease Control (CDC) as a household disinfectant. In one study, bactericidal effects of sodium hypochlorite solution were observed at concentrations as low as 0.025%, without any tissue toxicity in vivo or in vitro. It recommended that concentration be adopted as a "modified Dakin's solution" for wound dressing. Currently, various concentrations are sold for wound cleansing including Anasept (0.057%), 1/4 strength Dakin's (0.125%), and Di-Dak-Sol or Dakin's Wound Cleanser (0.0125%) which is 1/40 strength.
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 synthetic tetrapeptide built from alanine, glutamate, aspartate and glycine. The four residues are joined by standard peptide bonds, giving a linear chain rather than a branched structure.