The short version of Tetrapeptide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-24 and is reviewed periodically as new material appears.
Storage practice centres on limiting moisture, oxygen, and repeated temperature cycling. Freeze-dried powder is generally held desiccated at minus twenty degrees Celsius or colder and protected from light. Reconstituted solutions are markedly less stable, and the aspartate-glycine junction is prone to succinimide formation at neutral to mildly alkaline pH. Portioning material into single-use aliquots reduces degradation compared with repeated freeze-thaw cycles. Stability data specific to this tetrapeptide remain scarce, so most handling guidance is extrapolated from general peptide chemistry rather than measured directly.
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.
The published literature is dominated by a small number of research groups, much of it in Russian-language journals, and independent replication outside those groups is limited. Studies are typically small, use cultured cells or rodent models, and report endpoints that differ between papers, which makes comparison difficult. Large randomised human trials have not appeared in the indexed literature. Questions about absorption, distribution and clearance are therefore still treated as open in reviews that mention the compound.
Epitalon is a synthetic tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. Its design traces to epithalamin, a peptide fraction prepared from bovine pineal gland extracts that researchers in Saint Petersburg began investigating in the 1970s. The compound has a molecular formula of C14H22N4O9 and a nominal molecular mass near 390 daltons. It holds no approved drug status in the United States or the European Union, and material sold under this name is generally offered as a research chemical rather than a finished pharmaceutical product.
Proposed mechanisms centre on cell-culture observations rather than a defined receptor interaction. Several reports describe increased expression of the telomerase catalytic subunit after exposure of cultured human cells, and the authors attributed the effect to short peptide fragments entering the nucleus and influencing gene transcription. No receptor for the tetrapeptide has been identified, and the free peptide is expected to be degraded rapidly by plasma peptidases. Whether any measurable fraction reaches intact tissues after administration remains an unresolved question rather than an established finding.
| 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 |
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.
Verification of a sample usually begins with reversed-phase high-performance liquid chromatography, which resolves the peptide from truncated sequences and other impurities and expresses purity as a percentage of total peak area. Mass spectrometry by electrospray ionisation or matrix-assisted laser desorption supplies an independent check, because the measured mass can be compared against the theoretical value for AEDG. Amino acid analysis or tandem mass spectrometry sequencing can confirm residue order. Each of these methods answers a different question: a purity figure does not establish identity, and an identity match does not establish how much of the material is intact peptide.
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.
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.
Numerous stimuli are able to alter melanogenesis, or the production of melanin by cultured melanocytes, although the method by which it works is not fully understood. Increased melanin production is seen in conditions where adrenocorticotropic hormone (ACTH) is elevated, such as Addison's and Cushing's disease. This is mainly a consequence of alpha-MSH being secreted along with the hormone associated with reproductive tendencies in primates. Alpha-MSH is a cleavage product of ACTH that has an equal affinity for the MC1 receptor on melanocytes as ACTH. Melanosomes are vesicles that package the chemical inside a plasma membrane. The melanosomes are organized as a cap protecting the nucleus of the keratinocyte. When ultraviolet rays penetrate the skin and damage DNA, thymidine dinucleotide (pTpT) fragments from damaged DNA will trigger melanogenesis and cause the melanocyte to produce melanosomes, which are then transferred by dendrites to the top layer of keratinocytes.
As early as 1960, ZAPU's predecessor, the National Democratic Party (NDP), had established informal contacts with the Soviet Union and Czechoslovakia, and discussed the possibility of obtaining military training in Eastern Europe for its members. In July 1962, Nkomo visited Moscow and discussed plans for a ZAPU-led armed uprising in Rhodesia. He made formal requests for Soviet funding and arms for ZIPRA, explaining that "for these purposes ZAPU needs arms, explosives, revolvers...the party also needs money to bribe persons who guard important installations, to carry out sabotage". The Soviets agreed to supply ZAPU with limited funds beginning in 1963, and increased its level of financial support after UDI. In 1963, ZIPRA also made its first formal request to the Soviet Union for military training. The Soviets began training ZIPRA militants in guerrilla warfare in early 1964. Nkomo's public endorsement of a violent strategy confirmed white politicians' opposition to ZAPU and fed their negative attitudes towards black nationalists at large. In response to the formation of ZIPRA, the Rhodesian government banned ZAPU, driving that party's supporters underground. It also passed draconian security legislation restricting the right to assembly and granting the security forces broad powers to crack down on suspected political subversives. For the first time, the death sentence was also introduced for any act of politically inspired terrorism which involved arson or the use of explosives.
The chemical and thermal dynamics in hydrothermal vents makes such environments highly suitable thermodynamically for chemical evolution processes to take place. Therefore, thermal energy flux is a permanent agent and is hypothesized to have contributed to the evolution of the planet, including prebiotic chemistry. Günter Wächtershäuser proposed the iron-sulfur world theory and suggested that life might have originated at hydrothermal vents. Wächtershäuser proposed that an early form of metabolism predated genetics. By metabolism he meant a cycle of chemical reactions that release energy in a form that can be harnessed by other processes. It has been proposed that amino acid synthesis could have occurred deep in the Earth's crust and that these amino acids were subsequently shot up along with hydrothermal fluids into cooler waters, where lower temperatures and the presence of clay minerals would have fostered the formation of peptides and protocells. This is an attractive hypothesis because of the abundance of CH4 (methane) and NH3 (ammonia) present in hydrothermal vent regions, a condition that was not provided by the Earth's primitive atmosphere. A major limitation to this hypothesis is the lack of stability of organic molecules at high temperatures, but some have suggested that life would have originated outside of the zones of highest temperature. There are numerous species of extremophiles and other organisms currently living immediately around deep-sea vents, suggesting that this is indeed a possible scenario.
=== Occurrence in cereals === The alkylresorcinols alkyl chain, present in cereals, ranges from 15 to 25 carbon atoms. ARs have been reported to be present in high amounts in rye, wheat, and triticale, and in low concentrations in barley, maize, oat, and millet, while no information is at present available for Khorasan wheat. They are most abundant in the bran fractions (2600-4100 μg/g; 0.1-0.3% of dry weight), whereas they are in trace amounts in strachy endosperm and germ. They can also be found in rice, though not in the edible parts of the rice plant. Their presence in the endosperm (the part of cereal grain that is used to make white flour), means that alkylresorcinols can be used as 'biomarkers' for people who eat foods containing wholegrain wheat and rye, rather than cereal products based on white flour. Moreover, they were thought to have anti-nutritive properties (e.g. decreasing growth of pigs and chickens fed rye), but this theory has been discredited, and a number of animal studies have demonstrated that they have no obvious negative effect on animals or humans, while recent studies suggest they may have some health benefits as activators of the enzyme SIRT3, with the 17-carbon homologue 5-heptadecylresorcinol showing strongest activity.
=== Nutritive === It maintains the vitality of the surrounding cells. (PDL is heavily anastomosed). There are three principal sources of blood vessels which are apical vessels, perforating vessels and gingival vessels. Apical vessels originate from vessels that supply the pulp. Perforating vessels originate from lamina dura and the vessels perforate the socket wall (cribriform plate). Gingival vessels are derived from the gingival tissue. Outer layers of blood supply in PDL may help in mechanical suspension and support of the tooth while inner layers of blood vessels supply surrounding PDL tissues.
Sources: en.wikipedia.org
=== Other uses === The distinctive dried seed heads, which resemble the spouts of watering cans, are widely sold throughout the world for decorative purposes and for dried flower arranging. A unique fabric called lotus silk, from the lotus plant fibres, is produced only at Inle Lake, Myanmar, and in Siem Reap, Cambodia. This thread is used for weaving special robes for Buddha images called kya thingan (lotus robe).
1 March to 14 August Operation Kentucky Jumper was a clear and search operation conducted by the 101st Airborne Division, 9th Infantry Division and ARVN 3rd Regiment, 1st Division in Thừa Thiên Province. The operation resulted in 317 PAVN/VC killed for the loss of 61 U.S. killed.
== Applications == The efficacy of hydrogel dressings has been assessed on various wound types. There is some evidence to suggest that hydrogels are effective dressings for chronic wounds including pressure ulcers, diabetic ulcers, and venous ulcers although the results are uncertain. Hydrogels have been shown to accelerate healing in partial and full thickness burn wounds of varying size. Other studies have shown that hydrogel dressings accelerate healing in radioactive skin injuries and dog bite wounds. Hydrogel dressings decrease the healing time of traumatic skin injuries by an average 5.28 days and reduce the pain reported by patients.
=== Alcoholism === Alcoholism has been shown to produce sleep with less slow wave sleep and less delta power, while increasing stage 1 and REM incidence in both men and women. In long-term alcohol abuse, the influences of alcohol on sleep architecture and reductions in delta activity have been shown to persist even after long periods of abstinence.
The Port of Hong Kong, located by the South China Sea, is a deepwater seaport dominated by trade in containerised manufactured products. A key factor in the economic development of Hong Kong, the natural shelter and deep waters of Victoria Harbour provide ideal conditions for berthing and the handling of all types of vessels. It is one of the busiest ports in the world, in the three categories of shipping movements, cargo handled, and passengers carried. This makes Hong Kong a Large-Port Metropolis. The Star Ferry operates two lines across Victoria Harbour for its 53,000 daily passengers. Ferries also serve outlying islands inaccessible by other means. Smaller kai-to boats serve the most remote coastal settlements. Ferry travel to Macau and mainland China is also available. Junks, once common in Hong Kong waters, are no longer widely available and are used privately and for tourism. The large size of the port gives Hong Kong the classification of Large-Port Metropolis.
Sources: en.wikipedia.org
τν is the spectral optical depth in frequency, and τλ is the spectral optical depth in wavelength. Although absorbance is properly unitless, it is sometimes reported in "absorbance units", or AU. Many people, including scientific researchers, wrongly state the results from absorbance measurement experiments in terms of these made-up units.
adenosine diphosphate (ADP) A nucleoside diphosphate consisting of adenosine attached to two consecutive phosphate groups via high-energy ester bonds. ADP can be phosphorylated to produce ATP and thus is a precursor for its synthesis; it can also be dephosphorylated into AMP.
In February 1917, revolution broke out in Russia in which workers, soldiers and peasants established soviets, the monarchy was forced into exile fell and a provisional government was formed until the election of a constituent assembly. Alexander Kerensky, a Russian lawyer and revolutionary, became a key political figure in the Russian Revolution of 1917. After the February Revolution, Kerensky joined the newly formed Russian Provisional Government, first as Minister of Justice, then as Minister of War and after July as the government's second Minister-Chairman. A leader of the moderate socialist Trudovik faction of the Socialist Revolutionary Party known as the Labour Group, Kerensky was also the vice-chairman of the powerful Petrograd Soviet. After failing to sign a peace treaty with the German Empire to exit from World War I which led to massive popular unrest against the government cabinet, Kerensky's government was overthrown on 7 November by the Bolsheviks led by Vladimir Lenin in the October Revolution. Soon after the October Revolution, the Russian Constituent Assembly elected Socialist-Revolutionary leader Victor Chernov as President of a Russian Republic, but it rejected the Bolshevik proposal that endorsed the Soviet decrees on land, peace and workers' control and acknowledged the power of the Soviets of Workers', Soldiers' and Peasants' Deputies.
Inflammatory abnormalities are a large group of disorders that underlie a vast variety of human diseases. The immune system is often involved with inflammatory disorders, as demonstrated in both allergic reactions and some myopathies, with many immune system disorders resulting in abnormal inflammation. Non-immune diseases with causal origins in inflammatory processes include cancer, atherosclerosis, and ischemic heart disease. Examples of disorders associated with inflammation include:
=== Semi-chisel saw chains === The semi-chisel chain has teeth with rounded corners formed by a radius between the top and side plates. While slower than full chisel in softwood, it retains an acceptable cutting sharpness longer, making it the preferred choice for dirtier wood, hard or dry wood, frozen wood or stump work, all of which would rapidly degrade full chisel chain. They are similar to the full chisel design but have a small 45 degree chamfer between the plates rather than a radius. Performance is similar to full chisel. Semi chisel chains have a lower kick-back risk. These chains are available for consumer, semi-pro and professional saws.
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 heterogeneous peptide fraction obtained from pineal gland extract and contains many components. Epitalon is a single synthetic tetrapeptide with the sequence Ala-Glu-Asp-Gly. Researchers synthesised the shorter peptide while attempting to identify active sequences within the extract.