The short version of Heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-19 and is reviewed periodically as new material appears.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
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.
Relative bioavailability is one of the measures used to assess bioequivalence (BE) between two drug products. For FDA approval, a generic manufacturer must demonstrate that the 90% confidence interval for the ratio of the mean responses (usually of AUC and the maximum concentration, Cmax) of its product to that of the "brand name drug" is within the limits of 80% to 125%. Where AUC refers to the concentration of the drug in the blood over time t = 0 to t = ∞, Cmax refers to the maximum concentration of the drug in the blood. When Tmax is given, it refers to the time it takes for a drug to reach Cmax. While the mechanisms by which a formulation affects bioavailability and bioequivalence have been extensively studied in drugs, formulation factors that influence bioavailability and bioequivalence in nutritional supplements are largely unknown. As a result, in nutritional sciences, relative bioavailability or bioequivalence is the most common measure of bioavailability, comparing the bioavailability of one formulation of the same dietary ingredient to another.
{\displaystyle {\begin{aligned}&{\frac {dS}{dt}}=-{\frac {\beta IS}{N}},\\[6pt]&{\frac {dI}{dt}}={\frac {\beta IS}{N}}-\gamma I-\mu I,\\[6pt]&{\frac {dR}{dt}}=\gamma I,\\[6pt]&{\frac {dD}{dt}}=\mu I,\end{aligned}}}
For example, before combat missions Fallschirmjäger soldiers received the "Combat Ration for Paratroopers", which contained tins of cheese and ham, an energy bar, crispbread, candy drops, powdered milk, and instant coffee. The standard Schutzstaffel (SS) ration, designed to last for four days, consisted of 25 ounces (710 g) of Graubrot, 6–10 ounces (170–280 g) of canned meat (sometimes in the form of sausage), five ounces (140 g) of vegetables, one-half ounce (14 g) of butter, margarine, jam, or hazelnut paste, coffee, and six cigarettes (despite the SS's strong anti-smoking stance). Some other special supplements were given, including leberwurst. Regions invaded and occupied by Nazi forces were stripped of their food to feed Germans and starve local populations. As a result, soldiers could eat a variety of foods depending on availability. When in static positions German soldiers could eat well while rationing for frontline soldiers was sometimes hampered by supply issues. For example, a German soldier who fought in Crimea, which presented a logistical challenge due to a long and vulnerable land route, described the food he and his comrades received during this period as consisting of one warm meal a day, typically cabbage soup with a piece of tomato, with the addition of half a loaf of bread, some fat, cheese, and hard honey every second day. However, when the same soldier was billeted in a Russian village, he described the food as including a midday meal of borscht with bread and a large evening meal of potatoes, other vegetables, eggs, and meat.
== Challenges with peptide identification == Peptides that are degenerate (shared by two or more proteins in the database) makes it difficult to unambiguously identify the protein to which they belong. Additionally, some proteome samples of vertebrates have a large number of paralogs, and alternative splicing in higher eukaryotes can result in many identical protein subsequences. Moreover, many proteins are naturally (co- or post-translational) or artificially (sample preparation artefacts) modified. This further challenges the identification of the peptide sequence by means of conventional database matching approaches. Together with peptide fragmentation spectra of poor quality or high complexity (due to co-isolation or sensitivity limitations), this leaves in a conventional shotgun proteomics experiment many sequencing spectra unidentified.
=== Physics === Candlepower (cp), a measure of luminous intensity Centipoise (cP), a unit of viscosity CP symmetry, in particle physics, the product of charge conjugation and parity Cp, the specific heat capacity at constant pressure Pressure coefficient (Cp), a parameter for studying the flow of fluids Center of pressure (fluid mechanics), the point where the total sum of a pressure field acts on a body
Sources: en.wikipedia.org
== See also == Labor unions in the United States Norris–La Guardia Act Wagner Act Jurisdictional strike Solidarity action Chauffeurs, Teamsters, and Helpers Local No. 391 v. Terry, 494 U.S. 558 (1990) 5 to 2 on §185 of LMRA 1947, holding that a plaintiff is entitled to trial by jury if the trade union denies representation
Unlike soil, hydroponic nutrient solutions do not have cation-exchange capacity (CEC) from clay particles or organic matter. The absence of CEC and soil pores means the pH, oxygen saturation, and nutrient concentrations can change much more rapidly in hydroponic setups than is possible in soil. Selective absorption of nutrients by plants often imbalances the amount of counterions in solution. This imbalance can rapidly affect solution pH and the ability of plants to absorb nutrients of similar ionic charge (see article membrane potential). For instance, nitrate anions are often consumed rapidly by plants to form proteins, leaving an excess of cations in solution. This cation imbalance can lead to deficiency symptoms in other cation based nutrients (e.g. Mg2+) even when an ideal quantity of those nutrients are dissolved in the solution. Depending on the pH or on the presence of water contaminants, nutrients such as iron can precipitate from the solution and become unavailable to plants. Routine adjustments to pH, buffering the solution, or the use of chelating agents is often necessary. Unlike soil types, which can vary greatly in their composition, hydroponic solutions are often standardized and require routine maintenance for plant cultivation. Under controlled laboratory conditions hydroponic solutions are periodically pH adjusted to near neutral (pH 6.0) and are aerated with oxygen.
During the time leading up to the passing of the laws, there was fierce opposition to them, above all by the Free Democratic Party, the rising West German student movement, a group calling itself Notstand der Demokratie ("Democracy in Crisis") and members of the Campaign against Nuclear Armament. A key event in the development of open democratic debate occurred in 1967, when the Shah of Iran, Mohammad Reza Pahlavi, visited West Berlin. Several thousand demonstrators gathered outside the Opera House where he was to attend a special performance. Supporters of the Shah (later known as Jubelperser), armed with staves and bricks attacked the protesters while the police stood by and watched. A demonstration in the centre was being forcibly dispersed when a bystander named Benno Ohnesorg was shot in the head and killed by a plainclothes policeman. (It has now been established that the policeman, Kurras, was a paid spy of the East German security forces.) Protest demonstrations continued, and calls for more active opposition by some groups of students were made. In a massive campaign against the protesters, the press, especially the tabloid Bild-Zeitung newspaper, described these as a massive disruption to life in Berlin. Protests against the US intervention in Vietnam, mingled with anger over the vigour with which demonstrations were repressed led to mounting militance among the students at the universities in Berlin.
Three different arrangements of iron atoms in solid iron are observed at ordinary pressures. These allotropes are conventionally denoted α, γ, δ, and ε. As molten iron cools past its freezing point of 1538 °C, it crystallizes into its δ allotrope, which has a body-centered cubic (bcc) crystal structure. As it cools further to 1394 °C, it changes to its γ-iron allotrope, a face-centered cubic (fcc) crystal structure, or austenite. At 912 °C and below, the crystal structure again becomes the bcc α-iron allotrope. In the transition from body-centered to face centered, the crystal expands along one axis and contracts along the other two axis, resulting in a net reduction of volume of about 0.41 percent.
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (also known as PhIP) is one of the most abundant heterocyclic amines (HCAs) found in cooked meat. PhIP is formed at high temperatures from the reaction between creatine or creatinine (found in muscle meats), amino acids, and sugar. PhIP formation increases with the temperature and duration of cooking and also depends on the method of cooking and the variety of meat being cooked. The U.S. Department of Health and Human Services National Toxicology Program has declared PhIP as "reasonably anticipated to be a human carcinogen". International Agency for Research on Cancer (IARC), part of World Health Organization, has classified PhIP as IARC Group 2B carcinogen (i.e., possibly carcinogenic to humans). There is sufficient evidence in experimental animals, as well as in vitro models, for the carcinogenicity of PhIP.
Sources: en.wikipedia.org
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
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.