A practical reference on heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-06. Anything still debated is marked as such rather than presented as settled.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
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.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by RP-HPLC | Area percentage of the main peak |
| Identity confirmation | Electrospray ionization mass spectrometry | Observed mass compared with the theoretical value near 751.9 Da |
| Recommended dry storage | -20 °C, desiccated | -80 °C for multi-year archival material |
| Solution handling | Prepare fresh; avoid long storage | Sterile filtration reduces microbial load |
| Common synonyms | TKPRPGP; TP-7 | Sequence code and laboratory designation used interchangeably |
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
=== Decontamination === Treatment of a recently ingested poison may involve gastric decontamination to decrease absorption. Gastric decontamination can involve activated charcoal, gastric lavage, whole bowel irrigation, or nasogastric aspiration. Routine use of emetics (syrup of Ipecac), cathartics or laxatives are no longer recommended. Activated charcoal is the treatment of choice to prevent poison absorption. It is usually administered when the patient is in the emergency room or by a trained emergency healthcare provider such as a Paramedic or EMT. However, charcoal is ineffective against metals such as sodium, potassium, and lithium, and alcohols and glycols; it is also not recommended for ingestion of corrosive chemicals such as acids and alkalis. Cathartics were postulated to decrease absorption by increasing the expulsion of the poison from the gastrointestinal tract. There are two types of cathartics used in poisoned patients; saline cathartics (sodium sulfate, magnesium citrate, magnesium sulfate) and saccharide cathartics (sorbitol). They do not appear to improve patient outcome and are no longer recommended. Emesis (i.e. induced by ipecac) is no longer recommended in poisoning situations, because vomiting is ineffective at removing poisons. Gastric lavage, commonly known as a stomach pump, is the insertion of a tube into the stomach, followed by administration of water or saline down the tube. The liquid is then removed along with the contents of the stomach. Lavage has been used for many years as a common treatment for poisoned patients.
Plaques on house exteriors inform pedestrians where a well-known personality once lived. Often, these plaques are dedicated to Soviet celebrities little known outside Russia (and similarly, for decorated generals and revolutionaries, little known inside Russia). In addition, Moscow contains many "museum houses" dedicated to famous Russian writers, composers, and artists. Moscow's skyline is rapidly modernizing, with several new towers being constructed. In recent years, the city administration has been widely criticized for the widespread destruction of many historical buildings. As much as a third of historic Moscow has been destroyed during the past few years to make space for luxury apartments and hotels. Other historical buildings—including landmarks such as the 1930 Moskva hotel and the 1913 department store Voyentorg—have been razed and rebuilt, with an inevitable loss in historical value. Critics blame the government for not enforcing conservation laws: during the last 12 years, more than 50 buildings with monument status were torn down, several of these dating back to the 17th century. In addition, some critics wonder if the funds used for reconstructing razed buildings could not be used to renovate decaying structures—such as many works of architect Konstantin Melnikov, as well as the Mayakovskaya metro station. Some organizations, such as the Moscow Architecture Preservation Society and Save Europe's Heritage, are trying to attract international public attention to these problems.
Selenium and zinc are commonly referred to as antioxidant minerals, but these chemical elements have no antioxidant action themselves, but rather are required for the activity of antioxidant enzymes, such as glutathione reductase and superoxide dismutase.
=== Screening === Two main approaches exist for the finding of new bioactive chemical entities from natural sources. The first is sometimes referred to as random collection and screening of material, but the collection is far from random. Biological (often botanical) knowledge is often used to identify families that show promise. This approach is effective because only a small part of the earth's biodiversity has ever been tested for pharmaceutical activity. Also, organisms living in a species-rich environment need to evolve defensive and competitive mechanisms to survive. Those mechanisms might be exploited in the development of beneficial drugs. A collection of plant, animal and microbial samples from rich ecosystems can potentially give rise to novel biological activities worth exploiting in the drug development process. One example of successful use of this strategy is the screening for antitumor agents by the National Cancer Institute, which started in the 1960s. Paclitaxel was identified from Pacific yew tree Taxus brevifolia. Paclitaxel showed anti-tumour activity by a previously undescribed mechanism (stabilization of microtubules) and is now approved for clinical use for the treatment of lung, breast, and ovarian cancer, as well as for Kaposi's sarcoma. Early in the 21st century, Cabazitaxel (made by Sanofi, a French firm), another relative of taxol has been shown effective against prostate cancer, also because it works by preventing the formation of microtubules, which pull the chromosomes apart in dividing cells (such as cancer cells). Other examples are: 1.
Sources: en.wikipedia.org
=== Discontinuation === The British National Formulary recommends a gradual withdrawal when discontinuing antipsychotics to avoid acute withdrawal syndrome or rapid relapse. Symptoms of withdrawal commonly include nausea, vomiting, and loss of appetite. Other symptoms may include restlessness, increased sweating, and trouble sleeping. Less commonly, there may be a feeling of the world spinning, numbness, or muscle pains. Symptoms generally resolve after a short period of time. There is tentative evidence that discontinuation of antipsychotics can result in psychosis. It may also result in reoccurrence of the condition that is being treated. Rarely, tardive dyskinesia can occur when the medication is stopped.
=== 1999—2003: First Michelin stars === After four years, the Fat Duck was awarded its first Michelin star in the 1999 list. Blumenthal worked with the physics professor Peter Barham of the University of Bristol, and developed a menu of dishes through experimentation such as slow-cooked lamb which avoids shocking the fibres in the meat and causing them to seize. By 2000, techniques were being used such as cooking vegetables in mineral water after discovering that the levels of calcium in tap water causes their discolouration, and freezing cuttlefish to break down the molecules and increase their tenderness. In 2001, the Fat Duck was awarded a second Michelin star and was named restaurant of the year by the AA. In 2002, Blumenthal opened a second restaurant in Bray, the Riverside Brasserie, selling many of the Fat Duck's earlier dishes at reduced prices. The critic Jay Rayner gave it a positive review, calling it "truly stunning value", with the best lemon tart he had ever tasted.
==== Reagent coflow prior to droplet formation ==== Reagents can be added at the time of droplet formation through a "co-flow" geometry. Reagent streams are pumped in separate channels and join at the interface with a channel containing the continuous phase, which shears and creates droplets containing both reagents. By changing the flow rates in reagent channels, reagent ratios within a droplet can be controlled.
Sources: en.wikipedia.org
=== Judaism === In Judaism, animal blood may not be consumed even in the smallest quantity (Leviticus 3:17 and elsewhere); this is reflected in Jewish dietary laws (Kashrut). Blood is purged from meat by rinsing and soaking in water (to loosen clots), salting and then rinsing with water again several times. Eggs must also be checked and any blood spots removed before consumption. Although blood from fish is biblically kosher, it is rabbinically forbidden to consume fish blood to avoid the appearance of breaking the Biblical prohibition. Another ritual involving blood involves the covering of the blood of fowl and game after slaughtering (Leviticus 17:13); the reason given by the Torah is: "Because the life of the animal is [in] its blood" (ibid 17:14). In relation to human beings, Kabbalah expounds on this verse that the animal soul of a person is in the blood, and that physical desires stem from it. Likewise, the mystical reason for salting temple sacrifices and slaughtered meat is to remove the blood of animal-like passions from the person. By removing the animal's blood, the animal energies and life-force contained in the blood are removed, making the meat fit for human consumption.
=== In-source fragmentation === Often, the ionization process is sufficiently violent to leave the resulting ions with sufficient internal energy to fragment within the mass spectrometer. If the product ions persist in their non-equilibrium state for a moderate amount of time before auto-dissociation this process is called metastable fragmentation. Nozzle-skimmer fragmentation refers to the purposeful induction of in-source fragmentation by increasing the nozzle-skimmer potential on usually electrospray based instruments. Although in-source fragmentation allows for fragmentation analysis, it is not technically tandem mass spectrometry unless metastable ions are mass analyzed or selected before auto-dissociation and a second stage of analysis is performed on the resulting fragments. In-source fragmentation can be used in lieu of tandem mass spectrometry through the utilization of enhanced in-source fragmentation annotation (EISA) technology which generates fragmentation that directly matches tandem mass spectrometry data. Fragments observed by EISA have higher signal intensity than traditional fragments which suffer losses in the collision cells of tandem mass spectrometers. EISA enables fragmentation data acquisition on MS1 mass analyzers such as time-of-flight and single quadrupole instruments. In-source fragmentation is often used in addition to tandem mass spectrometry (with post-source fragmentation) to allow for two steps of fragmentation in a pseudo MS3-type of experiment.
== α-Ketoglutarates: glutamate, glutamine, proline, arginine == Most amino acids are synthesized from α-ketoacids, and later transaminated from another amino acid, usually glutamate. The enzyme involved in this reaction is an aminotransferase.
Sources: en.wikipedia.org
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.
A reported purity value reflects the share of the main peak in one chromatographic run and says nothing about identity. Confirming that the expected sequence is present requires a separate measurement such as mass spectrometry. Purity and identity are distinct questions.
A mass spectrum reports the molecular masses present in a sample and shows whether they match the value expected for selank, near 751.9 Da. It also flags common artifacts such as truncation or adduct formation. It does not establish correct stereochemistry or complete sequence order on its own.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.