This is a working overview of heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-09-02. Anything still debated is marked as such rather than presented as settled.
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.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
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.
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 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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
== Uses == PPG is used in many polyurethane formulations. Synthesis of waterborne polymers has been a feature with this substance. As the basic building block is propylene oxide, there are 3 carbons per oxygen on the backbone. This confers some degree of water miscibility though not as good as ethylene oxide-based molecules. It is used to synthesize the epoxy reactive diluent and flexibilizer, Poly(propylene glycol) diglycidyl ether. Another use of PPG is as a surfactant, wetting agent and dispersant in leather finishing. PPG is also employed as a reference and calibrant in mass spectrometry and HPLC. PPG and derivatives may be used as defoamers in drilling and other applications. It is also used as a primary ingredient in the making of paintballs. It has been evaluated as a corrosion inhibitor.
Plasmin is inactivated by proteins such as α2-macroglobulin and α2-antiplasmin. The primary protein responsible for plasmin inhibition is the α2-antiplasmin which is a serpin protein. The C-terminal of the α2-antiplasmin binds plasminogen Kringle domains via lysine residues allowing for the inhibition of plasmin. Another method of plasmin inactivation involves the cleavage of an α2-macroglobulin at the bait region (a segment of the aM that is particularly susceptible to proteolytic cleavage) by plasmin. This initiates a conformational change such that the α2-macroglobulin collapses about the plasmin. In the resulting α2-macroglobulin-plasmin complex, the active site of plasmin is sterically shielded, thus substantially decreasing the plasmin's access to protein substrates. Two additional events occur as a consequence of bait region cleavage, namely (i) a h-cysteinyl-g-glutamyl thiol ester of the α2-macroglobulin becomes highly reactive and (ii) a major conformational change exposes a conserved COOH-terminal receptor binding domain. The exposure of this receptor binding domain allows the α2-macroglobulin protease complex to bind to clearance receptors and be removed from circulation. Plasmin can also be inhibited by inhibiting its activators, inactivating PAI-1 and PAI-2 blocks the production of tPA and uPA which subsequently stop the conversion of plasminogen into plasmin. Defects in the SERPINE1 gene cause deficiencies in PA1-2. PAI-2 is only detectable during pregnancy and lacks a signal sequence it is not secreted by the cell.
is the observed value. An error of a measurement is an inverse measure of accurate measurement (i.e., smaller the error greater the accuracy of the measurement). Errors can be expressed relatively. Given the relative error (
Sources: en.wikipedia.org
from its lipids. By comparison with synthetically produced fatty acids, they were able to determine the position of the cyclopropane ring and proposed the name 11,12-methyleneoctadecanoic acid, without specifying the stereoisomerism of the structure. Viewed from the cyclopropane ring, different substituents are present on two carbon atoms, resulting in cis-trans-isomerism (see figure). The substituents can be on the same side (cis) or on different sides (trans) of the ring bond. Hofmann et al. were initially unable to clarify which structure was actually present at the time of discovery. However, in 1954 they hypothesized that the cis isomer was present. This was confirmed by a Canadian research group in 2005. A clear description of the spatial arrangement of the substituents is possible with the help of the Cahn-Ingold-Prelog priority rules, according to which the absolute configuration of the molecule is given as 11R,12S. The derived name (11R,12S)-methylenoctadecanoic acid is commonly used, even if it does not correspond to the recommendations of the IUPAC nomenclature. For the systematic naming of lactobacillic acid, the absolute configuration is given from the cyclopropane ring, with a C6 substituent (hexyl group) and a C10 substituent containing the carboxy group (decanoic acid), thus giving 10-[(1R,2S)-2-hexylcyclopropyl]decanoic acid
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Glycolipid transfer protein is a cytosolic protein that catalyses the transfer of glycolipids between different intracellular membranes. It was discovered by Raymond J. Metz and Norman S. Radin in 1980 and partially purified and characterized in 1982. Recent reviews on structure and possible function are available. This protein transports primarily different glycosphingolipids and glyceroglycolipids between intracellular membranes, but not phospholipids. It might be also involved in translocation of glucosylceramides. It was found in brain, kidney, spleen, lung, cerebellum, liver and heart.
=== Former === Jeff Jones – lead vocals, bass (1968) John Rutsey – drums, percussion, backing vocals (1968–1974; died 2008), lyrics (1968–1973) Joe Perna – bass, lead and backing vocals (1969) Lindy Young – keyboards, backing and lead vocals, guitars, percussion, harmonica (1969) Bob Vopni – guitars, backing vocals (1969) Mitch Bossi – guitars, backing vocals (1971–1972) Neil Peart – drums, percussion, lyrics (1974–2015; died 2020)
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.