This is a working overview of Pro-Gly-Pro, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-07-17. Anything still debated is marked as such rather than presented as settled.
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.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
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.
| 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 synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
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.
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.
== Honors and awards == EAS Award for Outstanding Achievements in the Fields of Analytical Chemistry (2023) Martin Medal (2019) Ralph N. Adams Award in Bioanalyical Chemistry (2016) ACS Award in Chromatography (2017) CASSS Award for Outstanding Achievements in Separation Science (2017) Marcel Golay Award for Lifetime Achievement in Capillary Chromatography (2012) Eastern Analytical Symposium Award for Separation Science (2012) McKnight Award for Technical Innovations in Neuroscience (2010) Rackham Distinguished Faculty Achievement Award (2009) American Microchemical Society's Benedetti-Pichler Memorial Award (2001)
== Cause == Sickle cell-Hb Lepore Boston syndrome is a type of sickle cell disease (HbS) that differs from homozygous sickle cell disease where both parents carry sickle hemoglobin. In this variant one parent has the sickle cell hemoglobin the second parent has Hb Lepore Boston, the only one of the three variants described in association with HbS.
CG Cosmogenic nuclide. DP Naturally occurring decay product (of thorium-232, uranium-238, or uranium-235), including products of neutron reactions other than fission. ESS Present in the early Solar System (first few million years), but extinct now as a primordial nuclide. Inherently overlaps with cosmogenic nuclides. FP Nuclear fission product , may occur naturally from spontaneous fission. IM Industry or medically used radionuclide.
=== Erections === Erections during sleep or when waking up are medically known as nocturnal penile tumescence and colloquially referred to as morning wood. The penis can regularly get erect during sleep and men or males often wake up with an erection. Once a male reaches his teenage years, erections occur much more frequently due to puberty. Erections can occur spontaneously at any time of day, and if clothed may cause a bulge or "hump". This can be disguised or hidden by wearing close-fitting underwear, a long shirt and baggier clothes. Erections are common for male prepubescent children and infants, and can even occur before birth. Spontaneous erections, also known as involuntary or unwanted erections, are normal. Such erections can be embarrassing if they happen in public, such as a classroom or living room.
Sources: en.wikipedia.org
=== Analytical reagent === Several chemical tests utilize copper sulfate. It is used in Fehling's solution and Benedict's solution to test for reducing sugars, which reduce the soluble blue copper(II) sulfate to insoluble red copper(I) oxide. Copper(II) sulfate is also used in the Biuret reagent to test for proteins. Copper sulfate is used to test blood for anemia. The blood is dropped into a solution of copper sulfate of known specific gravity—blood with sufficient hemoglobin sinks rapidly due to its density, whereas blood which sinks slowly or not at all has an insufficient amount of hemoglobin. Clinically relevant, however, modern laboratories utilize automated blood analyzers for accurate quantitative hemoglobin determinations, as opposed to older qualitative means. In a flame test, the copper ions of copper sulfate emit a deep green light, a much deeper green than the flame test for barium.
=== Factors affecting production === The effects of carbon, nitrogen sources, and amino acids on growth and tabtoxin production by pv. tabaci were examined by varying the components of a defined basal medium, which contained the following nutrients per liter: sucrose (10 g), KNO3 (5 g), MgSO4·7H2O (0.2 g), CaCl2·2H2O (0.11 g), FeSO4·7H2O (20 mg), NaH2PO4·2H2O (0.9 g) and H2PO4·3H2O (1 g). Both growth and quantity of tabtoxin synthesized were significantly affected by carbon source, nitrogen source, and amino acid supplements. Sorbitol, xylose, and sucrose proved to be the best carbon sources for tabtoxin production. Specific toxin production was very low using glucose as a single carbohydrate source, although bacterial growth was well supported by glucose. Amount and type of nitrogen sources (NH4Cl or KNO3) affected the growth of pv. tabaci and quantities of tabtoxin produced. Nitrate is the best of these two forms of nitrogen for production of tabtoxin. Some progress has been made on elucidating factors that regulate tabtoxin biosynthesis in P. syringae.
I am who I am, and what I believe in and what my spirituality is about is that we're all in this together. That I think it is not a good thing to believe as human beings we can turn our backs on the suffering of other people ... and this is not Judaism, this is what Pope Francis is talking about, that we can't just worship billionaires and the making of more and more money. Life is more than that. In 2016, he disclosed that he had "very strong religious and spiritual feelings", adding, "My spirituality is that we are all in this together and that when children go hungry, when veterans sleep out on the street, it impacts me." Sanders does not regularly attend synagogue, and he does not refrain from working on Rosh Hashanah, as observant Jews do. He has attended yahrzeit observances in memory of the deceased, for the father of a friend, and in 2015 attended a Tashlikh, an atonement ceremony, with the mayor of Lynchburg on the afternoon of Rosh Hashanah. According to Richard Sugarman, his Jewish identity is "certainly more ethnic and cultural than religious." His wife is Roman Catholic, and he has often expressed admiration for Pope Francis, saying that "the leader of the Catholic Church is raising profound issues. It is important that we listen to what he has said." He has said he feels very close to Francis's economic teachings, describing him as "incredibly smart and brave". In April 2016, he accepted an invitation from Marcelo Sánchez Sorondo, an aide close to Francis, to speak at a Vatican conference on economic and environmental issues.
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.
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.