Heptapeptide is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-01-20. Where a claim depends on a specific study, the study is described rather than over-claimed.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Many skin conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscles and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square metres, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues. The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers by diffusion from the dermis since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis.
=== Organoeinsteinium compounds === Einsteinium's high radioactivity has a potential use in radiation therapy, and organometallic complexes have been synthesized in order to deliver einsteinium to an appropriate organ in the body. Experiments have been performed on injecting einsteinium citrate (as well as fermium compounds) to dogs. Einsteinium(III) was also incorporated into β-diketone chelate complexes, since analogous complexes with lanthanides previously showed strongest UV-excited luminescence among metallorganic compounds. When preparing einsteinium complexes, the Es3+ ions were 1000 times diluted with Gd3+ ions. This allowed reducing the radiation damage so that the compounds did not disintegrate during the 20 minutes required for the measurements. The resulting luminescence from Es3+ was much too weak to be detected. This was explained by the unfavorable relative energies of the individual constituents of the compound that hindered efficient energy transfer from the chelate matrix to Es3+ ions. Similar conclusion was drawn for americium, berkelium and fermium. Luminescence of Es3+ ions was however observed in inorganic hydrochloric acid solutions as well as in organic solution with di(2-ethylhexyl)orthophosphoric acid. It shows a broad peak at about 1064 nanometers (half-width about 100 nm) which can be resonantly excited by green light (ca. 495 nm wavelength). The luminescence has a lifetime of several microseconds and the quantum yield below 0.1%.
== Cultural Award of the State of Hesse (2009) == In 2009, following a temporary revocation of the award, Kermani received the Hesse Cultural Award — along with Cardinal Karl Lehmann; the former president of the Church of Hesse-Nassau; Peter Steinacker; and the vice president of the Central Council of Jews, Salomon Korn. That year's ceremony was held under the theme of interreligious tolerance. The prize was offered to Kermani on March 20, 2009, after the originally intended recipient, Fuat Sezgin, had declined to accept it on the grounds that his co-recipient, Salomon Korn, supported Israel's military actions. On May 13, 2009, Kermani learned that the award intended for him had been revoked. He went on, however, to describe how this view had been shaken by what he described as the aesthetic experience: "For the first time, I thought: I — not just 'one' — I could believe in a cross." On April 24, 2009, Lehmann stated in a letter to Hesse's Minister President Roland Koch that Lehmann "cannot accept the award under these circumstances". Commentators described Lehmann's tone as "subtly ... defamatory", "smug", "mean-spirited", and "condescending"; Kermani, too, found it "defamatory". In the end, after a conversation with Kermani, Lehmann and Steinacker decided to accept the award jointly. The award was ultimately presented to the four laureates on November 26, 2009. At the ceremony, Minister President Koch apologized to Kermani. Kermani donated his prize money to Franz Meurer, the pastor of the Catholic parish of St. Theodor in Cologne-Vingst.
Sources: en.wikipedia.org
Cyclophosphamide (Cytoxan, Procytox), Doxorubicin (Adriamycin) and Vincristine (Oncovin) Paclitaxel (Taxol) Irinotecan (Camptosar) Guidelines recommended as of 2018 that patients who relapse > 6 months from initial therapy should be retreated with the original chemotherapy regimen. For patients who relapse in < 6 months, single-agent chemotherapy either topotecan second-line therapy, or paclitaxel can be used.
=== Gray hair === Low levels of catalase may play a role in the graying process of human hair. Hydrogen peroxide is naturally produced by the body and broken down by catalase. Hydrogen peroxide can accumulate in hair follicles and if catalase levels decline, this buildup can cause oxidative stress and graying. These low levels of catalase are associated with old age. Hydrogen peroxide interferes with the production of melanin, the pigment that gives hair its color.
Agrobacterium tumefaciens, a soil rhizosphere bacterium, can attach to plant cells and infect them with a callus-inducing Ti plasmid by horizontal gene transfer, causing a callus infection called crown gall disease. Schell and Van Montagu (1977) hypothesised that the Ti plasmid could be a natural vector for introducing the Nif gene responsible for nitrogen fixation in the root nodules of legumes and other plant species. Today, genetic modification of the Ti plasmid is one of the main techniques for introduction of transgenes to plants and the creation of genetically modified crops.
Louis Szathmary (born Lajos István Szathmáry II June 2, 1919 – October 4, 1996) was a Hungarian-American chef, writer, and public personality. A pioneering force in the food service profession, he is best known for heading the Chicago restaurant The Bakery and writing the New York Times bestseller The Chef's Secret Cookbook. Szathmary's involvement with the early frozen food industry, his numerous cookbooks and articles and his persona established him as an icon in the culinary arts industry.
Sources: en.wikipedia.org
A childhood friend of Charmaine's named Tracey Giles, who had lived in the upper flat at 25 Midland Road, would later recollect an incident in which she had entered the Wests' flat unannounced only to see Charmaine, naked and standing on a chair, gagged and with her hands bound behind her back with a belt, as Rose stood alongside the child with a large wooden spoon in her hand. According to Giles, Charmaine had been "calm and unconcerned", while Anne Marie had been standing by the door with a blank expression on her face. Hospital records later revealed that Charmaine had received treatment for a severe puncture wound to her left ankle in the casualty unit of Gloucestershire Royal Hospital on 28 March 1971. This incident was explained by Rose as having resulted from a household accident.
== Organoleptic characteristics == The organoleptic characteristics of edible insects vary between species and are influenced by environment. For instance, aquatic edible insects such as water boatmen (family Corixidae) and dragonfly larvae have a fish flavor, while diving beetles taste more like clams. Environment is not always a predictor of flavor, as terrestrial edible insects may also exhibit fish-like flavors (e.g. crickets, grasshoppers). Over 400 volatile compounds responsible for the aroma and flavor of edible insects have been identified. Pheromone chemicals contribute to pungent aromas and flavors in some species and the presence of organic acids (like formic acid in ants) makes some species taste sour. Organoleptic characteristics are dependent on the development stage of the insect (egg, larva, pupa, nymph, or adult) and may change significantly as an insect matures. For example, texture can change from soft to crunchy as an insect develops from larva to adult due to increasing exoskeletal chitin. Cooking method is considered the strongest influence on the final flavor of edible insects. Wet-cooking methods such as scalding or steaming remove pheromones and odor compounds, resulting in a milder flavor, while dry-cooking methods such as frying and roasting introduce more complex flavors. The table below provides common flavor descriptors for a selection of edible insects. Flavors will vary with preparation method (e.g. raw, dried, fried, etc.). Insect development stage is provided when possible.
STE20/SPS1-related proline-alanine-rich protein kinase is an enzyme that in humans is encoded by the STK39 gene. This gene encodes a serine/threonine kinase that is thought to function in the cellular stress response pathway. The kinase is activated in response to hypotonic stress, leading to phosphorylation of several cation-chloride-coupled cotransporters. The catalytically active kinase specifically activates the p38 MAP kinase pathway, and its interaction with p38 decreases upon cellular stress, suggesting that this kinase may serve as an intermediate in the response to cellular stress. Some studies suggest that this gene might be linked to high blood pressure.
General Public were an English new wave band, formed in Birmingham in 1983, by vocalists Dave Wakeling and Ranking Roger of the Beat, and which also included former members of Dexys Midnight Runners, the Specials, and the Clash. They are best remembered for their hits "Tenderness" (1984) and "I'll Take You There" (1994).
=== Predatory vs. defensive bites === Snake bites are classified as either predatory or defensive. During defensive strikes, the rate of venom expulsion and total volume of venom expelled is much greater than during predatory strikes. Defensive strikes can have 10 times as much venom volume expelled at 8.5 times the flow rate. This can be explained by the snake's need to quickly subdue a threat. While employing similar venom expulsion mechanics, predatory strikes are quite different from defensive strikes. Snakes usually release the prey shortly after the envenomation allowing the prey to run away and die. Releasing prey prevents retaliatory damage to the snake. The venom scent allows the snake to relocate the prey once it is deceased. The amount of venom injected has been shown to increase with the mass of the prey animal. Larger venom volumes allow snakes to effectively kill larger prey while remaining economical during strikes against smaller prey. This is an important skill as venom is a metabolically expensive resource.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.