peptide stability raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-02-27 and is reviewed periodically as new material appears.
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.
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.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | -20 °C or below | For lyophilized powder, long term |
| Common analytical method | Reverse-phase HPLC | Usually paired with mass spectrometry |
| Typical reported purity | At or above 95 percent by area | Research-grade material |
| Aqueous solubility | High | Solutions used in laboratory assays |
| Moisture sensitivity | Hydrolyzes in solution | Aseptic handling reduces degradation |
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
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.
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.
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.
== Further reading == (in French) Bernardi AC (1858). Monographie du genre Conus (in French). Berschauer D. (2010). Technology and the Fall of the Mono-Generic Family The Cone Collector 15: pp. 51–54 Bruguière JG (1792). "Histoire Naturelle des Vers". Encyclopédie Méthodique. Vol. 1. Paris: Panckoucke. pp. 345–757. Clench WJ (1942). "The Genus Conus in the Western Atlantic". Johnsonia. 1 (6): 1–40. Coltro Jr J (2004). "New species of Conidae from northeastern Brazil (Mollusca: Gastropoda)". Strombus. 11: 1–16. Flomenbaum NE, Goldfrank LR, Hoffman RS, Howland MA, Lewin NA, Nelson LS, eds. (28 March 2006). Goldfrank's Toxicologic Emergencies (8th ed.). New York: McGraw-Hill. ISBN 978-0-07-143763-9. Franklin JB, Subramanian KA, Fernando SA, Krishnan KS (2009). "Diversity and Distribution of Conidae from the Tamil Nadu Coast of India (Mollusca: Caenogastropoda: Conidae)". Zootaxa. 2250: 1–63. doi:10.11646/zootaxa.2250.1.1. Franklin JB, Fernando SA, Chalke BA, Krishnan KS (2007). "Radular morphology of Conus (Gastropoda: Caenogastropoda: Conidae) from India" (PDF). Molluscan Research. 27 (3): 111–122. doi:10.11646/mr.27.3.1. García EF (2006). "Conus sauros, a new Conus species (Gastropoda: Conidae) from the Gulf of Mexico". Novapex. 7: 71–76. Gmelin, J. F. 1791. Systema naturae per regna tria naturae. Editio decima tertia. Systema Naturae, 13th ed., vol. 1(6): 3021–3910. Lipsiae. Kiener LC (1845). "Genre Cone. (Conus, Lin.).". Spécies Général et Iconographie des Coquilles Vivantes. Vol. 2. pp. 1–111. Kohn A. A. (1992). "Chronological Taxonomy of Conus, 1758-1840".
The partisan section took care of the armed defense of the territory, women assisted men with provisions, and party cadres had to keep in touch with the party federation. The revolutionaries established a “People's Tribunal,” which was based in the town square and had the power to try “enemies of the people". An internment camp held many agrarians and notables. The revolutionary experience worried both conservatives and communist leaders, who pressed Cavallaro to calm tempers and end the revolution. The mayor became spokesman for the rebels and convinced most of them to return home and lay down their arms. Diehards refused and went into hiding. Finally, on March 9, the prefect of Reggio Calabria sent departments of carabinieri and police to Caulonia. They arrested 365 men, who were referred to the Locri court for constitution of an armed gang, murder, violence to private individuals and usurpation of public office. On April 15, Cavallaro resigned as mayor. British historian Jonathan Dunnage reported an "institutional continuity" of the civil servants who survived these regime changes Civil servants were not purged either after 1922 or 1943. The "institutional continuity" of the bureaucracy of Calabria were committed to preserving the social structure. On 2 June 1946 Calabria, like the rest of the Mezzogiorno, voted solidly to retain the monarchy. The traditional political system in Calabria continued after 1945. During the war, the already low living standards of Calabria declined further and the region was notorious as one of Italy's most violent areas.
In response, the Greenlandic prime minister Jens-Frederik Nielsen stated that Greenland had no wish to become part of the US. Trump proceeded to threaten him and denied he knew Nielsen. Trump officials again threatened that the American president could take action against Greenland within weeks.
Sources: en.wikipedia.org
=== Foreign political and diplomatic figures === Henry Cruger* (1758), member of the Parliament of Great Britain 1774–1790 and the New York State Senate Isaac Wilkins (1760), judge, member of the Nova Scotia House of Assembly Thomas Henry Barclay (1772), United Empire Loyalist; member of the 6th General Assembly of Nova Scotia Tang Shaoyi* (1882), first premier of the Republic of China William Sanford Evans (1895), Manitoba politician, mayor of Winnipeg 1909–1911 Pixley ka Isaka Seme (1906), founder and president of the African National Congress Wellington Koo (1909), president of the Republic of China and China's ambassador to the United States; Chinese delegate to the Paris Peace Conference, 1919 and the League of Nations; judge on the International Court of Justice 1957–1967 Jun Ke Choy (1915), former mayor of Hangzhou, chairman of China Merchants Group, and founder of the Chinese Culture Center Yu Tsune-chi (1922), Chinese ambassador to Italy and Spain, delegate to the San Francisco Conference, United Nations and the International Labour Organization Mario Laserna Pinzón (1948), Colombian diplomat and educator; founded the Universidad de Los Andes Colin Hughes (1949), first commissioner of the Australian Electoral Commission Uldis-Ivars Grava (1958), Latvian parliamentarian, former director of Latvijas Televīzija and chairman of American Latvian Association Johan Jorgen Holst (1960), Norwegian minister of Defence and Foreign Affairs; heavily involved with the Oslo Accords Yossi Alpher (1964), former Mossad officer and director of the Jaffee Center for Strategic Studies at Tel Aviv University Dore Gold (1975), Israeli political advisor and diplomat; former ambassador to the United States Toomas Hendrik Ilves (1975), president of Estonia Carson Wen (1975), three-time Hong Kong deputy to the National People's Congress and former vice chairman of the Democratic Alliance for the Betterment and Progress of Hong Kong Geoffrey Onyeama (1977), Nigerian minister of Foreign Affairs since 2015, son of Nigerian justice Charles Onyeama Michael Oren (1977), Israeli historian and former Israeli ambassador to the United States Miloon Kothari (1979), United Nations special rapporteur on adequate housing Kim Hyun-jong (1981), former South Korean minister of Trade and Special Advisor to President Moon Jae-in Ken Ofori-Atta (1984), Ghanaian economist and investment banker and current minister for Finance and Economic Planning, member of the Ofori-Atta family Akiva Tor (1985), Israeli ambassador to South Korea Abdullah bin Khalid bin Sultan Al Saud (2010), Saudi Arabia's permanent representative to the United Nations in Vienna, ambassador to Austria, Slovakia and Slovenia, great-grandson of Ibn Saud
=== Operation Expanded Testing === In October 2021, SHIELD and IDPH partnered with the United States Department of Health and Human Services' (HHS) Midwest COVID-19 Testing Coordination Center (MCC) to bring funding and resources from HHS "Operation Expanded Testing" to Illinois. This not only provided additional funding to Illinois but also provided testing to remote rural schools that previously were unable to manage the logistics of testing operations.
An enkephalin is a pentapeptide involved in regulating nociception (pain sensation) in the body. The enkephalins are termed endogenous ligands, as they are internally derived (and therefore endogenous) and bind as ligands to the body's opioid receptors. Discovered in 1975, two forms of enkephalin have been found, one containing leucine ("leu"), and the other containing methionine ("met"). Both are products of the proenkephalin gene:
Sources: en.wikipedia.org
The most common approach combines reverse-phase liquid chromatography with mass spectrometry. Chromatography separates the components while mass spectrometry confirms the molecular mass. Peptide sequencing or tandem mass analysis can further verify the amino acid order.
Lyophilized powder is usually kept frozen and protected from moisture. Solutions are less stable and are often used promptly or divided into aliquots to avoid repeated freeze-thaw cycles. Exact shelf-life values depend on purity and handling.
No. A purity figure derived from chromatographic area does not prove the amino acid sequence. Identity requires an orthogonal method such as mass spectrometry or sequencing. Truncated or isomerized peptides can co-elute with the target compound.
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.