Selank raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-06-17. Anything still debated is marked as such rather than presented as settled.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
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.
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 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.
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.
To ensure highly anisotropic, yet predictable solidification behavior within the SSZ, dynamic freezing patterns are preferred. Using dynamic freezing, the velocity of the solidification front, and, therefore, the ice crystal size, can be controlled with a changing temperature gradient. The increasing thermal gradient counters the effect of the growing thermal buffer imposed by the growing ice front. It has been shown that a linearly decreasing temperature on one side of a freeze-cast will result in near-constant solidification velocity, yielding ice crystals with an almost constant thickness along the SSZ of an entire sample. However, as pointed out by Waschkies et al. even with constant solidification velocity, the thickness of the ice crystals does increase slightly over the course of freezing. In contrast to that, Flauder et al. demonstrated that an exponential change of the temperature at the cooling plate leads to a constant ice crystal thickness within the complete SSZ, which was attributed to a measurably constant ice-front velocity in a distinct study. This approach enables a prediction of the ice-front velocity from the thermal parameters of the suspension. Consequently, if the exact relationship between the pore diameter and ice-front velocity is known, an exact control over the pore diameter can be achieved.
=== Quartz fiber filter === Quartz fiber filter paper has a high resistance to chemicals, does not absorb NOx and SOx dioxides, is unaffected by humidity and is easily sterilized. Thus, it is mostly used for air pollution analysis.
== People == Maxim (given name) Maxim (surname) Maxim (musician) Maxim., taxonomic author abbreviation of Karl Maximovich (1827–1891), Russian botanist Maksim, Metropolitan of all Rus, Metropolitan of Kiev (1283–1305) Maksim, Bulgarian Patriarch (1914–2012), Patriarch of the Bulgarian Orthodox Church Maksim, Serbian Patriarch (d. 1680), Patriarch of the Serbian Orthodox Church (1655-1674) Maksim Branković (d. 1516), Serbian Orthodox Metropolitan of Belgrade and Syrmia
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==== Axis patterning ==== In early embryo development, the formation of the primary body axes is a crucial step in establishing the organism's overall body plan. The axes include the anteroposterior axis, dorsoventral axis, and right-left axis. Wnt signaling is implicated in the formation of the anteroposterior and dorsoventral (DV) axes. Wnt signaling activity in anterior-posterior development can be seen in mammals, fish and frogs. In mammals, the primitive streak and other surrounding tissues produce the morphogenic compounds Wnts, BMPs, FGFs, Nodal and retinoic acid to establish the posterior region during late gastrula. These proteins form concentration gradients. Areas of highest concentration establish the posterior region while areas of lowest concentration indicate the anterior region. In fish and frogs, β-catenin produced by canonical Wnt signaling causes the formation of organizing centers, which, alongside BMPs, elicit posterior formation. Wnt involvement in DV axis formation can be seen in the activity of the formation of the Spemann organizer, which establishes the dorsal region. Canonical Wnt signaling β-catenin production induces the formation of this organizer via the activation of the genes twin and siamois. Similarly, in avian gastrulation, cells of the Koller's sickle express different mesodermal marker genes that allow for the differential movement of cells during the formation of the primitive streak. Wnt signaling activated by FGFs is responsible for this movement.
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Peripheral nerves frequently glide during movement of the extremities. For example, the brachial plexus can move up to 50mm with abduction and adduction of the shoulder. The median/ulnar nerves move 7.3mm and 9.8mm during elbow flexion and extension at the elbow. The median nerve moves 9.6mm with wrist flexion and extension. This nerve movement also applies to the spinal nerves, which can stretch and slacken with movement of the spine. This nerve gliding happens at intraneurial and extraneurial tissue planes. Outside the nerve, a thin layer of tissue similar to adventitia surrounds the nerve upon which the epineurial surface glides. Inside the nerve, fascicles can glide against each other. Inhibition of normal gliding at these tissue planes can lead to repetitive stretch injuries during movements. Studies on rabbit sciatic nerves have found that even a 6% acute stretch can lead to significant impairment with recovery and a 12% acute stretch can lead to complete impairment and no immediate recovery. A single adhesion tethers the nerve in two directions - between the spinal root to the adhesion and between the adhesion to the terminal branches. These injuries will lead to edema and fibrosis, not just in the nerve but also the surrounding tissues touching the nerve, which may further inhibit normal nerve gliding in a vicious cycle. The most commonly understood mechanism of impaired nerve gliding is through the formation of scar tissue that adheres separate tissue planes.
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Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
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.