freeze-drying raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
Identity is normally established by reversed-phase high-performance liquid chromatography combined with mass spectrometry, a pairing that separates components and confirms molecular mass at once. Purity is quoted as a percentage from the chromatogram, and figures above ninety-five percent are a frequent commercial specification. Amino acid analysis or sequencing supplies further confirmation when required. Because many short peptides behave similarly under chromatography, retention time alone does not establish sequence; the mass measurement is what separates one tetrapeptide from another, and certificates should report both.
Short peptides such as AEDG are normally supplied as a freeze-dried solid and are kept dry, cold, and shielded from light. Holding at minus twenty degrees Celsius is common for the long term, while a refrigerator suffices for brief periods before use. The material takes up moisture to some degree, so containers should stay sealed and be allowed to reach room temperature before opening, which limits condensation on the contents. Repeated warming and cooling of a single container is discouraged because it admits water and can lower the amount of intact peptide.
Dissolution is usually performed in water or a suitable aqueous buffer, and the resulting liquid is divided into single-use portions before freezing. Freeze-thaw cycling is a recognised source of loss for short peptides, since each cycle can encourage aggregation or adsorption onto container walls. Working solutions are generally kept cold and used within a short window, although published stability data specific to epitalon are thin. Containers should be marked with concentration and date, and solutions examined for cloudiness before use.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four constituent residues |
| Molecular mass | About 390.35 Da | Monoisotopic value, confirmed by mass spectrometry |
| Residue sequence | Ala-Glu-Asp-Gly | Read from the N-terminus to the C-terminus |
| Common synonyms | Epithalon; AEDG | Both forms appear in reference catalogues |
| Net charge near neutral pH | Negative | Two acidic side chains give a low isoelectric point |
The compound is described in the literature as a derivative of epithalamin, a preparation obtained from bovine pineal tissue. Work on this peptide family was carried out mainly by a research group in Saint Petersburg beginning in the 1980s, and the substance was later registered for clinical use in Russia under the name Epitalon. Outside that region it is generally treated as a research chemical rather than an approved medicine. Statements about its biological activity rest on a relatively small number of studies, and independent replication remains limited.
In its supplied form epitalon is a white to off-white powder, usually lyophilized and often hygroscopic. It dissolves readily in water and in aqueous buffers, and it is commonly handled as the acetate or trifluoroacetate salt to improve stability during purification and drying. The amide backbone is labile in aqueous media, so solutions are less durable than the dry solid. Handling notes in the chemical literature therefore emphasize keeping the powder dry, cool and shielded from light until it is dissolved.
Epitalon is a synthetic tetrapeptide whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
Stability of the tetrapeptide follows ordinary peptide chemistry rather than any unusual structural feature. The aspartate-glycine pair is prone to aspartimide formation under mildly basic or neutral conditions, and deamidation can follow, altering both mass and chromatographic retention. Dry lyophilised powder kept at or below minus twenty degrees Celsius is the usual handling recommendation, with repeated freeze-thaw cycles avoided. Once dissolved in neutral aqueous buffer, degradation proceeds over days to weeks depending on pH and temperature, while acidic conditions generally slow the aspartimide route. A formal stability-indicating study has not been published in the indexed literature.
Epitalon is a synthetic linear tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and the calculated mass is approximately 390.35 g/mol. The compound is made by solid-phase peptide synthesis rather than extracted from tissue, although early work described it as a short fragment of a peptide fraction obtained from bovine pineal extract. In the research literature the spelling epitalon and the variant epithalone both appear, while AEDG is the standard code used in peptide nomenclature.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
== Management == As of July 2025, there are no clear guidelines for treating Type 5 diabetes. Some evidence suggests that very small amounts of insulin combined with oral medications may be most effective. It is crucial to differentiate Type 5 diabetes from Type 1 diabetes, as administering too much insulin can quickly be fatal. The diet for patients should include significantly higher amounts of protein and fewer carbohydrates, with special attention paid to correcting micronutrient deficiencies.
== Formation == The 82nd Division was constituted during World War I on 5 August 1917 as an infantry division in the National Army. It was organized and formally activated on 25 August 1917 at Camp Gordon, Georgia. At the time, the division consisted entirely of newly conscripted soldiers. Original enlisted men assigned to the division came from Alabama, Georgia, and Tennessee. In October 1917, nearly all of them were transferred to fill shortages in National Guard and National Army units, principally the 30th, 31st, and 81st Divisions, which were training at other camps in the Southern United States. Replacements for them were received mostly from Camp Devens, Massachusetts, Camp Dix, New Jersey, Camps Lee and Meade, Virginia, and Camp Upton, New York, the men hailing from New England and the Mid-Atlantic states. In the spring, 5,000 more replacements for transfers made over the winter were assigned from Fort Devens, Camp Gordon, Camp Upton, Camp Dodge, Iowa, and Camp Travis, Texas, along with a contingent of men from Alabama, Georgia, and Tennessee. The citizens of Atlanta held a contest to give a nickname to the new division. In April 1918, Major General Eben Swift, the commanding general, chose "All American" to reflect the unique composition of the 82nd—it had soldiers from all 48 states in the Union. The bulk of the division was two infantry brigades, each commanding two regiments. The 163rd Brigade commanded the 325th Infantry Regiment and the 326th Infantry Regiment along with the 320th Machine Gun Battalion.
=== Manganese electrolysis === During the electrowinning of manganese, the addition of selenium dioxide decreases the power necessary to operate the electrolysis cells. China is the largest consumer of selenium dioxide for this purpose. For every tonne of manganese, an average 2 kg selenium oxide is used.
Drug development is the process of bringing a new pharmaceutical drug to the market once a lead compound has been identified through the process of drug discovery. It includes preclinical research on microorganisms and animals, filing for regulatory status, such as via the United States Food and Drug Administration for an investigational new drug to initiate clinical trials on humans, and may include the step of obtaining regulatory approval with a new drug application to market the drug. The entire process—from concept through preclinical testing in the laboratory to clinical trial development, including Phase I–III trials—to approved vaccine or drug typically takes more than a decade.
== C == CAICISS – Coaxial impact collision ion scattering spectroscopy CARS – Coherent anti-Stokes Raman spectroscopy CBED – Convergent beam electron diffraction CCM – Charge collection microscopy CDI – Coherent diffraction imaging CE – Capillary electrophoresis CET – Cryo-electron tomography CL – Cathodoluminescence CLSM – Confocal laser scanning microscopy COSY – Correlation spectroscopy Cryo-EM – Cryo-electron microscopy Cryo-SEM – Cryo-scanning electron microscopy CV – Cyclic voltammetry
Sources: en.wikipedia.org
== History == The US Food and Drug Administration (FDA) approved serdexmethylphenidate/dexmethylphenidate based on evidence from one clinical trial of 150 participants with attention deficit hyperactivity disorder 6 to 12 years of age (Study 1). The four-week trial was conducted at five sites in the United States. The safety and tolerability of serdexmethylphenidate/dexmethylphenidate was examined in an open-label trial of 238 participants with attention deficit hyperactivity disorder 6 to 12 years of age (Study 2). The 12-month trial was conducted at 18 sites in the United States.
=== April === 1 April Biochemists report finishing the complete sequence of the human genome. A study shows that, contrary to widespread belief, body sizes of mammal extinction survivors of the dinosaur-times extinction event were the first to evolutionarily increase, with brain sizes increasing later in the Eocene. 4 April The Intergovernmental Panel on Climate Change (IPCC) releases the third and final part of its Sixth Assessment Report on climate change, warning that greenhouse gas emissions must peak before 2025 at the latest and decline 43% by 2030, in order to likely limit global warming to 1.5 °C (2.7 °F). Researchers announce a new technique for accelerating the development of vaccines and other pharmaceutical products by up to a million times, using much smaller quantities based on DNA nanotechnology. Alzheimer's disease (AD) research progress:A study reports 42 new genes linked to an increased risk of AD. Researchers report a potential primary mechanism of sleep disturbance as an early-stage effect of neurodegenerative diseases. Researchers identify several genes associated with changes in brain structure over lifetime and potential AD therapy-targets (5 Apr).
== Interfaces == The interface between a liquid phase technique (HPLC) with a continuously flowing eluate, and a gas phase technique carried out in a vacuum was difficult for a long time. The advent of electrospray ionization changed this. Currently, the most common LC–MS interfaces are electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo-ionization (APPI). These are newer MS ion sources that facilitate the transition from a high pressure environment (HPLC) to high vacuum conditions needed at the MS analyzer. Although these interfaces are described individually, they can also be commercially available as dual ESI/APCI, ESI/APPI, or APCI/APPI ion sources. Various deposition and drying techniques, including moving belts, were used in the past, but the most common of these was the off-line MALDI deposition. A new approach still under development, called direct-EI LC–MS interface, couples a nano HPLC system and an electron ionization equipped mass spectrometer.
== Structure == Factor XIII of human blood is a heterotetramer of two A and two B linear polypeptides or "units". A units are potentially catalytic; B units are not. A units form a dimeric center. Non-covalently bound B units form a ring-like structure around the center. B units are removed when XIII is activated to XIIIa. Dimers containing only A units also occur within cells such as platelets. Large quantities of singular B units (monomers) also occur within blood. These dimers and monomers are not known to participate in coagulation, whereas the tetramers do. A units have a mass of about 83 kDa, 731 amino acid residues, 5 protein domains (listed from the N-terminal to C-terminal, residue numbers are in brackets):
Sources: en.wikipedia.org
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.
No. The two spellings refer to the same tetrapeptide, and the difference reflects transliteration from Russian. Laboratories and catalogues use both forms interchangeably. The material is also indexed as AEDG, taken from the one-letter codes of its residues.
Epithalamin is a mixed preparation derived from animal pineal tissue and contains many peptides. Epitalon is one synthetic sequence chosen for study from that broader mixture. Statements about one do not transfer directly to the other.
Reversed-phase high-performance liquid chromatography is run alongside mass spectrometry. The chromatogram separates components and gives a purity figure, while the mass spectrum confirms that the measured molecular mass matches the expected sequence. Neither measurement on its own is treated as sufficient.