If you have been reading about tetrapeptide 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.
Last reviewed on 2025-08-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
（TG:@pojiaai）Epitalon is a synthetic linear tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. It emerged from work on epithalamin, a peptide fraction prepared from bovine pineal tissue, and was designed as a short, chemically defined analogue of that extract. Early publications came mainly from Russian laboratories studying pineal peptides and aging-related endpoints. The compound appears in the literature under several spellings, including epithalon and epithalone, which complicates systematic searching. Its small size makes solid-phase assembly and routine analytical characterization straightforward.
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.
| Property | Value | Notes |
|---|---|---|
| Amino acid sequence | Ala-Glu-Asp-Gly | Tetrapeptide, often abbreviated AEDG |
| Molecular formula | C14H22N4O9 | Free peptide, unmodified termini |
| Molecular weight | ~390.35 Da | Calculated for the free acid form |
| Appearance | White to off-white powder | Typical lyophilized product form |
| Solubility class | Freely soluble in water | Two acidic residues dominate ionic character |
== V == V3 loop – vaccination – vaccine – vaccinia – vaginal candidiasis – valley fever – variable region – varicella zoster virus (VZV) – vector – vertical transmission – viral burden – viral core – viral culture – viral envelope – viral load – viremia – viricide – virion – virology – virus – visceral
Differential cross section measurements were commonly made, for example, to study the structure of the atomic nucleus by scattering from them nucleons, such as neutrons. It is important to distinguish between differential light scattering and dynamic light scattering, both of which are referred to by the initials DLS. The latter refers to a technique that is quite different, measuring the fluctuation of scattered light due to constructive and destructive interference, the frequency being linked to the thermal motion, Brownian motion of the molecules or particles in solution or suspension. A MALS measurement requires a set of ancillary elements. Most important among them is a collimated or focused light beam (usually from a laser source producing a collimated beam of monochromatic light) that illuminates a region of the sample. In modern instruments, the beam is generally plane-polarized perpendicular to the plane of measurement, though other polarizations may be used especially when studying anisotropic particles. Earlier measurements, before the introduction of lasers, were performed using focused, though unpolarized, light beams from sources such as Hg-arc lamps. Another required element is an optical cell to hold the sample being measured. Alternatively, cells incorporating means to permit measurement of flowing samples may be employed. If single-particles scattering properties are to be measured, a means to introduce such particles one-at-a-time through the light beam at a point generally equidistant from the surrounding detectors must be provided.
=== Pseudomonas syringae pv. tomato strain DC3000, its derivatives, and its tomato host === As its name suggests, P. syringae pv. tomato DC3000 (Pst DC3000) is virulent to tomato (Solanum lycopersicum). However, the tomato cultivar Rio Grande-PtoR (RG-PtoR), harboring the resistance gene Pto, recognizes key effectors secreted by Pst DC3000, making it resistant to the bacteria. Studying the interactions between the Pto-expressing tomato lines and Pst DC3000 and its pathovars is a powerful system for understanding plant-microbe interactions. Like other plants, the tomato has a two-tier pathogen defense system. The first and more universal line of plant defense, pattern-triggered immunity (PTI), is activated when plant pattern recognition receptors (PRRs) on the cell surface bind to pathogen-associated molecular patterns (PAMPs). The other branch of plant immunity, effector-triggered immunity (ETI), is triggered when intracellular (Nucleotide-binding site, Leucine-rich repeat) NB-LRR proteins bind to an effector, a molecule specific to a particular pathogen. ETI is generally more severe than PTI, and when a threshold of defense activation is reached, it can trigger a hypersensitive response (HR), which is purposeful death of host tissue to prevent the spread of infection. Two key effectors secreted by Pst DC3000 are AvrPto and AvrPtoB, which initiate ETI by binding the Pto/Prf receptor complex in Pto-expressing tomato lines like RG-PtoR.
Sources: en.wikipedia.org
=== Freeze drying (lyophilized) === Donkey milk can be freeze-dried to preserve the biological quality of the milk, and so preserve its nutritional, functional, and cosmetic properties. This is possible because in freeze drying the milk is frozen and brought under vacuum at low temperatures. During this process, the water is removed by sublimation. The result is approximately ten percent of dry matter that is called lyophilized (or freeze-dried) donkey milk. This powder is easy to reconstitute. The lyophilized product has to be packaged without any oxygen. It has a shelf life of two years. Normally it is produced from pasteurized donkey milk so it is ready to use. Analysis of freeze-dried donkey's milk has demonstrated that the natural colour, flavours, nutrients, and bioactive substances of fresh donkey milk are retained. Spray-drying is another way to dry products, in which the milk is heated and vitamins and other important bioactive substances may get lost. In contrast, Freeze-drying does not require chemical preservatives and can be either consumed directly or re-hydrated easily. However, this method for is costly, and is practiced only by a few companies. This product is easy to find in Italy, where it was for the first time put on the market.
natural vs synthetic, e.g. glycine vs caprolactam, respectively polar vs nonpolar, e.g. vinyl acetate vs ethylene, respectively cyclic vs linear, e.g. ethylene oxide vs ethylene glycol, respectively By type of polymer they form:
Later, on April 28, 1950, Joliot-Curie would be dismissed from the military and civilian Atomic Energy Commission for political reasons. Young communist militants (UJRF) were also accused of sabotage actions like the famous Henri Martin affair and the case of Raymonde Dien, who was jailed one year for having blocked an ammunition train, with the help of other militants, in order to prevent the supply of French forces in Indochina in February 1950. The dockworkers across France also struck, in numbers of more than 35,000, in protest of the war. Similar actions against trains occurred in Roanne, Charleville, Marseille, and Paris. Even ammunition sabotage by PCF agents has been reported, such as grenades exploding in the hands of legionaries. These actions became such a cause for concern by 1950 that the French Assembly voted a law against sabotage between March 2–8. At this session tension was so high between politicians that fighting ensued in the assembly following communist deputies' speeches against the Indochinese policy. This month saw the French navy mariner and communist militant Henri Martin arrested by military police and jailed for five years for sabotage and propaganda operations in Toulon's arsenal. On May 5 communist Ministers were dismissed from the government, marking the end of Tripartism. A few months later on November 11, 1950, the French Communist Party leader Maurice Thorez went to Moscow.
Sources: en.wikipedia.org
== Effects on global climate == In climate change science, ENSO is known as one of the internal climate variability phenomena. The other two main ones are Pacific decadal oscillation and Atlantic multidecadal oscillation. La Niña impacts the global climate and disrupts normal weather patterns, which can lead to intense storms in some places and droughts in others. El Niño events cause short-term (approximately 1 year in length) spikes in global average surface temperature while La Niña events cause short term cooling. Therefore, the relative frequency of El Niño compared to La Niña events can affect global temperature trends on decadal timescales.
Enzymatic specificity provides useful insight into enzyme structure, which ultimately determines and plays a role in physiological functions. Specificity studies also may provide information of the catalytic mechanism. Specificity is important for novel drug discovery and the field of clinical research, with new drugs being tested for its specificity to the target molecule in various rounds of clinical trials. Drugs must contain as specific as possible structures in order to minimize the possibility of off-target affects that would produce unfavorable symptoms in the patient. Drugs depend on the specificity of the designed molecules and formulations to inhibit particular molecular targets. Novel drug discovery progresses with experiments involving highly specific compounds. For example, the basis that drugs must successfully be proven to accomplish is both the ability to bind the target receptor in the physiological environment with high specificity and also its ability to transduce a signal to produce a favorable biological effect against the sickness or disease that the drug is intended to negate.
=== Contamination === Any addition of carbon to a sample of a different age will cause the measured date to be inaccurate. Contamination with modern carbon causes a sample to appear to be younger than it really is: the effect is greater for older samples. If a sample that is 17,000 years old is contaminated so that 1% of the sample is modern carbon, it will appear to be 600 years younger; for a sample that is 34,000 years old, the same amount of contamination would cause an error of 4,000 years. Contamination with old carbon, with no remaining 14C, causes an error in the other direction independent of age – a sample contaminated with 1% old carbon will appear to be about 80 years older than it truly is, regardless of the date of the sample.
Sources: en.wikipedia.org
Epitalon is a synthetic tetrapeptide composed of four amino acids: alanine, glutamate, aspartate, and glycine. It is written as Ala-Glu-Asp-Gly. The free peptide has a molecular weight of about 390 daltons and is normally supplied as a lyophilized powder.
No. Epitalon is chemically synthesized, not extracted. It was designed as a short synthetic fragment conceptually related to larger pineal peptides studied in the same research tradition, particularly the extract known as epithalamin. The two are distinct materials with different compositions.
The term bioregulator is used in this research tradition for short peptides proposed to influence gene expression or cell function. Epitalon is grouped with other synthetic short peptides under this label. The term reflects a proposed mechanism rather than an established drug classification.
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.