If you have been reading about heptapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
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.
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.
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.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
One reason why it is important to study the nature of UCMs is that some have been shown to contain toxic components, but only a small range of known petrogenic toxicants, such as the USEPA list of 16 polycyclic aromatic hydrocarbons (PAHs), tend to be routinely monitored in the environment. Analysis of the hydrocarbon fraction of crude oils by GC reveals a complex mixture containing many thousands of individual components. Components that are resolved by GC have been extensively studied e.g. However, despite the application of many analytical techniques the remaining components have, until very recently, proved difficult to separate due to the large numbers of co-eluting compounds. Gas chromatograms of mature oils have prominent n-alkane peaks which distract attention from the underlying unresolved complex mixture (UCM) of hydrocarbons often referred to as the ‘hump’. Processes such as weathering and biodegradation result in a relative enrichment of the UCM component by removal of resolved components and the creation of new compounds. It has been shown that both resolved and unresolved components of oils are subject to concurrent biodegradation, i.e. it is not a sequential process, but due to the recalcitrant nature of some components, the rates of biodegradation of individual compounds greatly varies. The UCM fraction often represents the major component of hydrocarbons within hydrocarbon-polluted sediments (see reference therein) and biota e.g.
== Distribution and habitat == Clown loaches are native to the islands of Sumatra and Borneo in Indonesia. Clear stream environments provide the optimal habitat for clown loaches, but biannual monsoon flooding forces the fish to move into flooded flood plains, or murky or blackwater rivers or lakes, for 7–8 months of the year, and clown loaches are commonly found in the flood plains of hilly areas. Breeding adults migrate to smaller waterways to spawn annually. In its native habitat, the fish is found in water with a temperature range of 25 to 30 °C (77 to 86 °F), a pH between 5.0 and 8.0, and water hardness between 5 and 12 dH.
Annie-Laurie Ala von Auersperg (born 1958), co-founder of the National Center for Victims of Crime, who married financier Ralph H. Isham, son of diplomat Heyward Isham. Alexander Georg von Auersperg (born 1959), co-founder of the National Center for Victims of Crime, who married investment banker Nancy Louise Weinberg. The Auerspergs were divorced in 1965. At that time, Sunny's net worth was over $75 million. Alfred Auersperg died in 1992 after lingering in an irreversible coma for nine years following a 1983 car accident in Austria. On June 6, 1966, Sunny married Claus von Bülow, a former aide to oilman J. P. Getty, at the Brick Presbyterian Church in New York City. His maternal grandfather, whose surname he took, was Frits Toxwerdt von Bülow, Justice Minister of Denmark in the government of Klaus Berntsen (1910–1913) and also came from a noble background. Together, they had a daughter:
=== Acute exposures === In case reports of humans intentionally or accidentally ingesting high concentrations of copper salts (doses usually not known but reported to be 20–70 grams of copper), a progression of symptoms was observed including abdominal pain, headache, nausea, dizziness, vomiting and diarrhea, tachycardia, respiratory difficulty, hemolytic anemia, hematuria, massive gastrointestinal bleeding, liver and kidney failure, and death. Episodes of acute gastrointestinal upset following single or repeated ingestion of drinking water containing elevated levels of copper (generally above 3–6 mg/L) are characterized by nausea, vomiting, and stomach irritation. These symptoms resolve when copper in the drinking water source is reduced. Three experimental studies were conducted that demonstrate a threshold for acute gastrointestinal upset of approximately 4–5 mg/L in healthy adults, although it is not clear from these findings whether symptoms are due to acutely irritant effects of copper and/or to metallic, bitter, salty taste. In an experimental study with healthy adults, the average taste threshold for copper sulfate and chloride in tap water, deionized water, or mineral water was 2.5–3.5 mg/L. This is just below the experimental threshold for acute gastrointestinal upset.
Sources: en.wikipedia.org
The NBOMe drugs, primarily 25I-NBOMe, were encountered as novel recreational drugs by 2010, and by 2012 had eclipsed other psychedelics like LSD and psilocybin-containing mushrooms in popularity, at least for a time. Various NBOMes, such as 25I-NBOMe, became Schedule I controlled substances in the United States in 2013.
In 2000, Wesley Enoch wrote and directed a modern adaptation titled Black Medea, which was first produced by Sydney Theatre Company's Blueprint at the Wharf 2 Theatre, Sydney, on 19 August 2000. Nathan Ramsay played the part of Jason, Tessa Rose played Medea, and Justine Saunders played the Chorus. Medea is re-characterised as an indigenous woman transported from her homeland to the city and about to be abandoned by her abusive social-climbing husband. Tom Lanoye (2001) used the story of Medea to bring up modern problems (such as migration and man vs. woman), resulting in a modernized version of Medea. His version also aims to analyze ideas such as the love that develops from the initial passion, problems in the marriage, and the "final hour" of the love between Jason and Medea. Roger Kirby's 2004 adaptation of the play, Medea in Jerusalem, was set in modern day Israel, and featured an Israeli-Jewish Jason and a Palestinian Medea who opts to turn her children into suicide bombers after being divorced by Jason. It premiered at the Rattlestick Playwrights Theatre in New York City. Kristina Leach adapted the story for her play The Medea Project, which had its world premiere at the Hunger Artists Theatre Company in 2004 and placed the story in a modern-day setting. Peter Stein directed Medea in Epidaurus 2005. Irish playwright Marina Carr's By the Bog of Cats is a modern re-telling of Euripides' Medea. In November 2008, Theatre Arcadia, under the direction of Katerina Paliou, staged Medea at the Bibliotheca Alexandrina (University of Alexandria, Egypt).
== See also == Estradiol dibutyrate/hydroxyprogesterone heptanoate/testosterone caproate Estradiol diundecylate/hydroxyprogesterone heptanoate/testosterone cyclohexylpropionate Estrapronicate/hydroxyprogesterone heptanoate/nandrolone undecanoate Progesterone/hydroxyprogesterone heptanoate/α-tocopherol palmitate
Sources: en.wikipedia.org
Holyhead's cliffs are used for coasteering, a water sport which involves jumping off cliffs at different heights. Holyhead is the start and finish point of the Anglesey Coastal Path. Holyhead was officially twinned with Greystones, County Wicklow on 20 January 2012, and this is celebrated on a new road sign.
class I "fish-like" – hydrophilic odorants class II "tetrapod-specific" – more hydrophobic compounds In the current scheme, class I corresponds to alpha and beta while class II corresponds to gamma. Gamma is not actually tetrapod specific: it's just present in many more copies in tetrapods.
Sokolniki Park—in the 18th century, the home of the tsar's falconers well outside Moscow—became contiguous with the expanding city during the later 19th century and was developed into a municipal park in 1878. The suburban Savyolovsky Rail Terminal was built in 1902. In January 1905, the institution of the City Governor, or Mayor, was officially introduced; Alexander Adrianov became Moscow's first official mayor. When Catherine II assumed power in 1762, observers depicted the city's filth and the smell of sewage as symptoms of the disorderly lifestyles of lower-class Russians recently arrived from the farms. Elites called for improved sanitation, which became part of Catherine's plans for increased control over social life. National political and military successes from 1812 through 1855 calmed her critics and validated efforts to produce a more enlightened and stable society. The poor state of public health was discussed less often. However, in the wake of Russia's failures in the Crimean War in 1855–1856, confidence in the state's ability to maintain order in the slums eroded; therefore, demands for improved public health put this issue back on the public agenda. In 1903, the Moskvoretskaya water supply was completed.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.