A practical reference on heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-06-06 and is reviewed periodically as new material appears.
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.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
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.
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.
=== Brand names === Janssen's patent on risperidone expired in December 2003, opening the market for cheaper generic versions from other companies, and Janssen's exclusive marketing rights expired in June 2004 (the result of a pediatric extension). It is available under many brand names worldwide. Risperidone is available as a tablet, an oral solution, and an ampule, which is a depot injection. Brand names include Risperdal, Risperdal Consta, Risperdal M-Tab, Risperdal Quicklets, Risperlet, Okedi, and Perseris.
25 Jan&1 Sep) mimicking neurons' communication, is reported. 9 November IBM unveils its 433-qubit 'Osprey' quantum processor, the successor to its Eagle system. A study shows that 50+ aged users of the dietary program SNAP "had about 2 fewer years of cognitive aging over a 10-year period compared with non-users" despite it having nearly no conditions for the sustainability and healthiness of the food products purchased with the coupons (or coupon-credits). 10 November A study describes how one may eventually be able to detect (distinguish) wormholes, suggesting they may have never been observed because they appear very similar to black holes. Notable software developments: After domain seizures of Z-Library by copyright law enforcement and moves toward dark web and IPFS technologies by its content providers, the open source shadow library UI Anna's Archive – which also provides access to a full copy of Z-Library content and scientific articles – is established by a team of archivists, essentially providing the largest human book and literature library. News outlets report about the development of a post-editing model using GPT-3 that improves machine translations after identification of current translation problems (8 Nov/25 Oct). The largest global inventory and interactive map of greenhouse gas emission sources is released by Climate TRACE (9 Nov).
A protein called divalent metal transporter 1 (DMT1), which can transport several divalent metals across the plasma membrane, then transports iron across the enterocyte's cell membrane into the cell. If the iron is bound to heme, it is instead transported across the apical membrane by heme carrier protein 1 (HCP1). Heme is then catabolized by microsomal heme oxygenase into biliverdin, releasing Fe2+. These intestinal lining cells can then either store the iron as ferritin, which is accomplished by Fe2+ binding to apoferritin (in which case the iron will leave the body when the cell dies and is sloughed off into feces), or the cell can release it into the body via the only known iron exporter in mammals, ferroportin. Hephaestin, a ferroxidase that can oxidize Fe2+ to Fe3+ and is found mainly in the small intestine, helps ferroportin transfer iron across the basolateral end of the intestine cells. Upon release into the bloodstream, Fe3+ binds transferrin and circulates to tissues. In contrast, ferroportin is post-translationally repressed by hepcidin, a 25-amino acid peptide hormone. The body regulates iron levels by regulating each of these steps. For instance, enterocytes synthesize more Dcytb, DMT1 and ferroportin in response to iron deficiency anemia. Iron absorption from diet is enhanced in the presence of vitamin C and diminished by excess calcium, zinc, or manganese.
The body of 18-year-old Hannah Lynch, daughter of Mike Lynch, is recovered from the Bayesian, making her the seventh and final victim of the sinking. Storm Lilian brings disruption to much of the UK, with gusts of up to 70 mph in some regions. The Energy Price Cap is set to rise by 10% in October, with the average household price for gas and electricity increasing by £149 per year. A report by the United Nations urges the UK to take measures to curb race hate speech, including by politicians. 24–26 August – Eight people are stabbed during the Notting Hill Carnival, with a total of 334 people being arrested during the event. 24 August Data from the Office for National Statistics shows the number of those aged 16–24 not in employment, education or training rose to 872,000 during the period of April to June 2024. British athletes Helene Raynsford and Gregor Ewan light the Paralympic Flame at Stoke Mandeville, ahead of its journey to Paris for the 2024 Summer Paralympics. 25 August EE, one of the UK's largest mobile phone networks, advises parents not to give primary school age children smartphones after receiving an increase in the number of requests for guidance from parents. A British Reuters employee named as Ryan Evans is confirmed as having been killed in a missile attack on a hotel in Ukraine the previous day. 26 August A major incident is declared as a fire engulfs a block of flats in Dagenham, east London, which had "known" safety issues. More than 100 people are evacuated, with two taken to hospital.
Sources: en.wikipedia.org
DNA → RNA → protein Some critics thought that by using the word "dogma", Crick was implying that this was a rule that could not be questioned, but all he really meant was that it was a compelling idea without much solid evidence to support it. In his thinking about the biological processes linking DNA genes to proteins, Crick made explicit the distinction between the materials involved, the energy required, and the information flow. Crick was focused on this third component (information) and it became the organising principle of what became known as molecular biology. Crick had by this time become a highly influential theoretical molecular biologist. Proof that the genetic code is a degenerate triplet code finally came from genetics experiments, some of which were performed by Crick. The details of the code came mostly from work by Marshall Nirenberg and others who synthesised synthetic RNA molecules and used them as templates for in vitro protein synthesis. Nirenberg first announced his results to a small audience in Moscow at a 1961 conference. Crick's reaction was to invite Nirenberg to deliver his talk to a larger audience.
Counter-Strike – A team-based tactical first-person shooter game involving rounds of combat between two teams, counter-terrorists and terrorists. Counter-Strike was later released commercially by Valve as a standalone game. Day of Defeat – A World War II first-person shooter, originally a mod and later a commercially released game. Deathmatch Classic – An official mod by Valve that updates the multiplayer gameplay from id Software's Quake, featuring enhanced textures, models, and lighting. It was released on June 7, 2001, and included in an update to Half-Life a month later. OS X and Linux ports of the Windows game were released through Steam in August 2013. Deathmatch Plus – A mod split off from Oz Deathmatch. The mod has a "Lights Out" mode that turns off all the bright lights in a map. Also includes night vision goggles, a silenced machine gun and hand grenades can be exchanged for cluster bombs. CNET Gamecenter placed it on its list of top 10 Half-Life mods, comparing it to Oz Deathmatch, saying that the mod is easier to use and the grappling hook is better but the night vision mode is worse. Earth's Special Forces – Third-person fighting oriented game based on the anime Dragon Ball Z. In development since at least 2000, when early alpha versions were released, the mod features fast-paced 3D melee combat, shooting energy attacks, flight mechanics, character transformations, and multiple game modes. Each playable character has unique abilities, along with distinct strengths and weaknesses.
Peristalsis is the rhythmic contraction of muscles that begins in the esophagus and continues along the wall of the stomach and the rest of the gastrointestinal tract. This initially results in the production of chyme which when fully broken down in the small intestine is absorbed as chyle into the lymphatic system. Most of the digestion of food takes place in the small intestine. Water and some minerals are reabsorbed back into the blood in the large intestine. The waste products of digestion (feces) are excreted from the rectum via the anus.
Having personally experienced a confused night action off Guadalcanal, Lee was not enthusiastic about a night engagement with Japanese surface forces, believing that his crews were not adequately trained for it. Shortly after learning Lee's opinion, Mitscher requested permission from Spruance to move TF 58 west during the night, to reach a launch position at dawn that would allow for a maximum aerial assault on the enemy force. Spruance considered for an hour, then refused Mitscher's request. Mitscher's staff was disappointed with Spruance's decision. Burke later commented: "We knew we were going to have hell slugged out of us in the morning. We knew we couldn't reach them. We knew they could reach us." Spruance's decision was influenced by his orders from Nimitz, who had made it clear that the protection of the invasion fleet was the primary mission of TF 58. Spruance had concerns that the Japanese would attempt to draw his main fleet away from the Marianas with a diversionary force while slipping an attack force in to destroy the landing fleet. Locating and destroying the Japanese fleet was not his primary objective, and he was unwilling to allow the main strike force of the Pacific Fleet to be drawn westward, away from the amphibious forces. Mitscher accepted the decision without comment. Spruance's decision in this matter, although subsequently criticized, was certainly justified; by this point in the war, it was well known that Japanese operational plans frequently relied on the use of decoys and diversionary forces.
They have two sets of teeth, including one set of larger sharp, teeth coming out of the mandibular and premaxillary bones to grasp and control the prey. The other set of teeth, located posteriorly and connected to the hyomandibular bone, is made up of pharyngeal tooth patches, which are used for sorting out nutrients and grinding down larger pieces of food. Another three bones make up the lower jaw: the dentary, the angular, and the surangular. The cranial surface of the skull is made up of the nasals, the antorbital, the lacrimal, the parietal, the intertemporal, the post parietal, the supratemporal, the extra scapular, the post temporal, and the opercular. The entirety of the skull is attached to the girdle through another set of bones.
Sources: en.wikipedia.org
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.