If you have been reading about Pro-Gly-Pro 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 2026-02-24. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
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.
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.
==== William Henry Perkin’s mauveine ==== In 1856, 18 year old William Perkin accidentally discovered a dye he called mauve while trying to make quinine from the oxidation of allyl toluene in his home lab for his academic advisor and boss August Wilhelm von Hoffman. Hoffman reportedly referred to aniline, a major step in the synthesis, as his "first love," and was excited to have Perkin working with it. Perkin communicated with the textile industry, including Pullars of Perth, and John Hyde Christie, the chemist and general manager of John Orr Ewing and Co. about how to best market and produce his dye. He started production of aniline purple near London at the end of 1857 and remained the only producer for at least a few months. Perkin began making the intermediates for his dyes in-house, for example, nitro-benzene, expanding the scale of operations. By the summer of 1859, according to a satirical magazine Punch, London had fallen ill with 'the mauve measles'.
=== Diplomatic espionage === French diplomat Talleyrand served as a source of intelligence for the Coalition powers against Napoleon. At the Congress of Erfurt in September–October 1808, Talleyrand secretly counseled Tsar Alexander. Alexander's attitude towards Napoleon was one of apprehensive opposition. Talleyrand believed Napoleon would eventually destroy the empire he had worked to build across multiple rulers. After his resignation in 1807 from the ministry, Talleyrand began to accept bribes from hostile powers (mainly Austria, but also Russia), to betray Napoleon's secrets. Various agents of Napoleon were known such as Madame d'Oettlinger.
Cardiomyocites sheets have also been successfully implanted with an observed contractile function as a result of inter-cellular communication between the host and graft. However, from a practical point of view, such approach lacks of translational character as all studies share the lack of reproducibility, i.e. a construct of similar characteristics of the native tissue does not guarantee the same results. Another approach resides in the use of hydrogels. Natural hydrogels such as Matrigel, collagen and fibrin have been used as entrapment matrices, wherein the cells to be injected are embedded. However the associated high pressure of injection is associated with a high mortality rate for the cells thereby negatively impacting the benefit ratio of this approach. Furthermore, from a technical point of view, due to the polydispersity of these natural hydrogels, purification is a requisite but very difficult step. Synthetic hydrogels, such as polyethylene glycol, polylactic acid, polylactic acid-co-glycolic acid, polycaprolactone, polyacrylamide and polyurethane have been proposed. Metalloproteinase-sensitive polyethylene is of particular interest. Indeed, this polymer modulates its mechanical and biophysical properties accordingly to enzymatic activities associated with cardiomyogenic differentiation of implanted cells. To date, no hydrogel matrix is FDA-approved for stem cell therapy use despite a large number of biomaterials currently commercially available.
Sources: en.wikipedia.org
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Sources: en.wikipedia.org
==== Greek writers ==== It is assumed that the Hippocratic Corpus bears no direct mention of what we now know as diabetes. However, a number of indirect statements referring to excessive and "watery urine" suggest that Hippocratic writers may have been familiar with the condition. According to On Ancient Medicine, Hippocrates was under the impression that the slumbering and thirst which resulted from high blood sugar was due to the bowels struggling to digest too much food and the weaknesses resulting from low blood sugar were because the body lacked nourishment due to missing a meal.
The classic click reaction is the copper-catalyzed reaction of an azide with an alkyne to form a 5-membered C2N3 ring. This reaction is the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The first triazole synthesis, from diethyl acetylenedicarboxylate and phenyl azide, was reported by Arthur Michael in 1893. Later, in the middle of the twentieth century, this family of 1,3-dipolar cycloadditions took on Rolf Huisgen's name after his studies of their reaction kinetics and conditions.
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Sources: en.wikipedia.org
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.