If you have been reading about counterion and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Linear tetrapeptide | Four residues joined by three peptide bonds |
| Sequence | Ala-Glu-Asp-Gly | Commonly abbreviated AEDG |
| Molecular formula | C14H22N4O9 | Free acid form |
| Monoisotopic mass | Approximately 390 Da | Matches values reported from mass spectrometry |
| Net charge near neutral pH | Negative | Contributed by glutamate and aspartate side chains |
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and its calculated monoisotopic mass is approximately 390.35 daltons. The compound does not occur naturally as a free peptide; it is produced by solid-phase peptide synthesis. Because it contains two acidic residues and no basic residues, the neutral form carries a net negative charge at physiological pH. This charge profile influences how the peptide behaves in solution and during chromatographic analysis.
Laboratory-grade epitalon is typically supplied as a lyophilized powder. Purity is commonly assessed with reverse-phase high-performance liquid chromatography, often paired with mass spectrometry to confirm molecular identity. Amino acid analysis and peptide mapping can provide additional confirmation of sequence. Certificates of analysis for research materials frequently report purity above 95 percent, although the methods behind such figures vary between suppliers. The absence of a pharmacopeial monograph means that no single standardized assay defines the compound, so reported results depend on the analytical protocol chosen.
Storage recommendations center on limiting moisture, heat, and light. The dry powder is generally kept at minus 20 degrees Celsius, and some suppliers recommend minus 80 degrees for long-term archival. Once dissolved, solutions are usually aliquoted and frozen to avoid repeated freeze-thaw cycles, which can promote aggregation or degradation. Aqueous stability depends on pH and concentration, and buffered saline is often preferred over plain water for biological work. Stability data specific to epitalon remain limited, so general peptide-handling practices are applied by analogy rather than from product-specific validation.
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.
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.
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.
The four residues give epitalon a molecular formula of C14H22N4O9 and a molecular weight near 390.35 daltons. The presence of two acidic residues, glutamate and aspartate, makes the free peptide strongly acidic, while the alanine and glycine ends provide neutral, nonpolar character. This combination produces a molecule with substantial water solubility. Because there are no cysteine, methionine, or tryptophan residues, the peptide lacks the most common oxidation-sensitive side chains, which simplifies handling compared with many longer peptides.
Because sites of protein-protein interaction have often been found to be flanked by prolines, the presence of the two prolines in this ‘finger’ of the structure indicates a possible interaction site. A short polypeptide of eight amino acid residues, containing this sequence, was indeed found to block the L-type calcium channels, though with a lesser activity. These interacting amino acids are also found in two other L-type calcium channel blocking proteins, C10S2C2 and S4C8. Although both of these toxins are members of the three-fingered family, the three-fingered structure is probably not a requirement for channel blocking: other snake toxins, including dendrotoxin, have similar effects on various channels, but do not show the three-fingered structure.
== Role in disease == Granzyme B has a normal concentration of 20-40 pg/ml in the blood plasma while retaining 70% activity and elevated concentrations of granzyme B are found in a number of disease states. Granzyme B can generate autoantigens by cleaving in disordered regions and linker regions of antigens exposing new epitopes and this can cause the development of autoimmune diseases. Granzyme B release with perforin from CD8+ T cells can cause heart and kidney transplant rejection through killing of allogeneic endothelial cells. The destruction of insulin producing β cells in pancreatic islets is mediated by T cells and granzyme B contributing to Type 1 Diabetes. Granzyme B can also mediate the death of cells after spinal cord injury and is found at elevated levels in rheumatoid arthritis. Chronic obstructive pulmonary disease (COPD) has been attributed to granzyme B secreted from NK and T cells causing the apoptosis of bronchial epithelial cells. Matrix destabilisation and remodelling by granzyme B is also linked to asthma pathogenesis. Granzyme B can kill melanocytes causing the skin condition vitiligo and granzyme B overexpression is found in contact dermatitis, lichen sclerosus and lichen planus cases. Cytotoxic cells expressing granzyme B have been identified close to hair follicles linking a possible role in hair loss. The ECM remodelling properties of granzyme B have also implicated its involvement in left ventricular remodelling, which increases the subsequent chances of myocardial infarction.
a chiral stationary phase or a chiral additive in the mobile phase. The chiral stationary phase can be prepared by mixing chirally pure reagents such as L-amino acid, or brucine, or a chiral ligand exchange reagent with silica gel slurry, or by impregnation of the TLC plate in the solution of a chiral reagent. The principle can also be applied to chemically modify the stationary phase before making the plate via bonding of the chiral moieties of interest to the reactive groups of the layer material.
Sources: en.wikipedia.org
Major intrinsic proteins (MIPs) comprise a large superfamily of transmembrane protein channels that are grouped together on the basis of homology. The MIP superfamily includes three subfamilies: aquaporins, aquaglyceroporins and S-aquaporins.
The mendelevium separated by this method has the advantage of being free of organic complexing agent compared to the resin column; the disadvantage is that mendelevium then elutes very late in the elution sequence, after fermium. Another method to isolate mendelevium exploits the distinct elution properties of Md2+ from those of Es3+ and Fm3+. The initial steps are the same as above, and employs HDEHP for extraction chromatography, but coprecipitates the mendelevium with terbium fluoride instead of lanthanum fluoride. Then, 50 mg of chromium is added to the mendelevium to reduce it to the +2 state in 0.1 M hydrochloric acid with zinc or mercury. The solvent extraction then proceeds, and while the trivalent and tetravalent lanthanides and actinides remain on the column, mendelevium(II) does not and stays in the hydrochloric acid. It is then reoxidized to the +3 state using hydrogen peroxide and then isolated by selective elution with 2 M hydrochloric acid (to remove impurities, including chromium) and finally 6 M hydrochloric acid (to remove the mendelevium). It is also possible to use a column of cationite and zinc amalgam, using 1 M hydrochloric acid as an eluant, to effect the reduction. Thermochromatographic chemical isolation could be achieved using the volatile mendelevium hexafluoroacetylacetonate: the analogous fermium compound is known and similar.
For services to Online Safety. Nathaniel Timothy Hepburn. Director and Chief Executive, Charleston. For services to the Arts. Ian Leslie Hewitt. Lately Chairman, All England Lawn Tennis Club. For services to Tennis and to Charity. Dr. Alison Maynard Hill. Chair, Bikeability Trust, and Chair, Cyclox. For services to Cycling. Daniel Peter Hill. Director, Daddys with Angels. For charitable services to Bereaved Families. Nicholas Andrew Hill. National Conservation Projects Manager. For services to Heritage. Martyn Paul Hillier. Founder, Micropub Association. For services to Business and to Hospitality. Geraldine Hills. Founder, Manchester Parent Champions. For services to Children and Young People with Special Educational Needs and Disabilities. Stuart William Hogg. For services to Rugby Union Football. Paul Hollywood. Baker and Television Presenter. For services to Baking and to Broadcasting. Helen Holtam. Tutor, Friends of Erlestoke Prison, Origami Inside. For services to Prisoners. Glennis Edith Hooper. For Charitable Services to People with Breast Cancer. Susan Hornby. Co-Founder and Head Teacher, The Bridge School Malvern. For services to Disadvantaged Children. Helen Housby. For services to Netball. Joslyn Hoyte-Smith. Chair, GB Olympians Association. For services to Athletics. Ian Russell Hughes. Director of Policy, Local Government Association. For services to Local Government. Air Commodore Paul Jonathan Hughesdon. Lately Director of Welfare, Royal Air Force Benevolent Fund. For services to Veterans. Christopher Neil Hunter Gordon. Chairman, Resources for Autism.
Sources: en.wikipedia.org
The traditional kava beverage is prepared through aqueous extraction of the fresh or dried roots of the Piper methysticum plant. When using fresh roots, the outer layer is typically peeled before the root is either chewed or mechanically ground into a fine, fibrous pulp, which is then mixed with water. For dried roots, the material is finely ground, placed in a porous cloth, and infused in water. The resulting brew is usually consumed immediately after preparation, often from a communal bowl. Traditional and recreational preparation of kava beverage involves macerating, grinding, or pounding fresh or dried rhizome/root (1.0–1.5 g) and mixing it with water or coconut milk (100–150 mL) to form an emulsion, which is then agitated and strained through cloth or bark filters into a communal bowl. The resulting drink is grey and slightly pungent, with fresh rhizome/root producing a stronger and more complex beverage than dried forms due to the retention of volatile compounds. In Vanuatu, fresh root is commonly used, while in non-Pacific countries, kava is typically prepared from dried root powder soaked in water (about one tablespoon per cup) for 30 minutes before straining. On Pohnpei in Micronesia, preparation also includes mixing the kava root with the fibrous bark of Hibiscus tiliaceus before pressing.
Peukert argued that societies that have reached "classical modernity" are characterized by advanced capitalist economic organization and mass production, by the "rationalization" of culture and society, massive bureaucratization of society, the "spirit of science" assuming a dominant role in popular discourses, and the "social disciplining" and "normalization" of the majority of ordinary people. Peukert was greatly influenced by the theories of Max Weber, but unlike many other scholars, who saw Weber attempting to rebut Karl Marx, he viewed Weber's principal intellectual opponent as Friedrich Nietzsche. Peukert wrote that for Weber, the principal problems of modern Germany were: The increasing "rationalization" of everyday life via bureaucratization and secularism had led to a "complete demystification of the world". The popularity of the "spirit of science" had led to a misguided belief that science could solve all problems within the near-future. Contrary to the "Bielefeld School", Peukert argued by the time of the Weimar Republic, Germany had broken decisively with the past, and had become a thoroughly "modern" society in all its aspects. Peukert argued that the very success of German modernization inspired by the "dream of reason" meant the contradictions and problems of "classical modernity" were felt more acutely in Germany than elsewhere. For Peukert, the problems of "classical modernity" were:
=== Hepatocellular carcinoma === Hepatocellular carcinoma is the most common primary liver cancer, and the most common cause of death in people with cirrhosis. Screening using an ultrasound with or without cancer markers such as alpha-fetoprotein can detect this cancer and is often carried out for early signs which has been shown to improve outcomes.
Sources: en.wikipedia.org
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.
The compound came out of work on epithalamin, a peptide preparation derived from pineal tissue, conducted largely in Russian laboratories. Later studies in other countries examined it mainly in cell cultures and animal models.
The tetrapeptide sequence is a synthetic construct rather than a described circulating peptide. It was derived by analogy to peptide fractions obtained from tissue extracts, not isolated from blood or tissue as such.
The dry powder is typically held at -20 degrees Celsius or lower, protected from light and moisture. Allowing a sealed vial to reach room temperature before opening reduces condensation on its contents. Conditions stated on a supplier certificate of analysis take precedence over general guidance.