If you have been reading about heptapeptide 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.
Last reviewed on 2025-10-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
| Property | Value | Notes |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected molecular mass |
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.
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.
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.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
== Biology == Unlike the other amino acids, no free pool of selenocysteine exists in the cell. Its high reactivity would cause damage to cells. Instead, cells store selenium in the less reactive oxidized form, selenocystine, or in methylated form, selenomethionine.
Short-term pair-bond: a transient mating or associations Long-term pair-bond: bonded for a significant portion of the life cycle of that pair Lifelong pair-bond: mated for life Social pair-bond: attachments for territorial or social reasons Clandestine pair-bond: quick extra-pair copulations Dynamic pair-bond: e.g. gibbon mating systems being analogous to "divorce"
Charged analytes have a more complex interaction in the capillary because they exhibit electrophoretic mobility, engage in electrostatic interactions with the micelle, and participate in hydrophobic partitioning. The fraction of the sample in the aqueous phase,
=== Reducing end === Disaccharides consist of two monosaccharides and may be either reducing or nonreducing. Even a reducing disaccharide will only have one reducing end, as disaccharides are held together by glycosidic bonds, which consist of at least one anomeric carbon. With one anomeric carbon unable to convert to the open-chain form, only the free anomeric carbon is available to reduce another compound, and it is called the reducing end of the disaccharide. A nonreducing disaccharide is that which has both anomeric carbons tied up in the glycosidic bond. Similarly, most polysaccharides have only one reducing end.
31 October The Independent Schools Council, which represents around 1,400 private schools in the UK, votes to take legal action against government plans to end their tax exemption status from January 2025. GB News is fined £100,000 by Ofcom for breaking impartiality rules with a programme featuring the former Prime Minister Rishi Sunak.
Sources: en.wikipedia.org
=== Skeletal system === Most of the readily visible signs are associated with the skeletal system. Many people with Marfan syndrome grow to above-average height, and some have disproportionately long, slender limbs with thin, weak wrists and long fingers and toes. The Steinberg sign, also known as the thumb sign, is one of the clinical examination tests for Marfan disease in the hands. It is a clinical test in which the tip of the thumb extends beyond the palm when the thumb is clasped in the clenched hand. Besides affecting height and limb proportions, people with Marfan syndrome may have abnormal lateral curvature of the spine scoliosis, thoracic lordosis, abnormal indentation (pectus excavatum) or protrusion (pectus carinatum) of the sternum, abnormal joint flexibility, a high-arched palate with crowded teeth and an overbite, flat feet, hammer toes, stooped shoulders, and unexplained stretch marks on the skin. It can also cause pain in the joints, bones, and muscles. Some people with Marfan have speech disorders resulting from symptomatic high palates and small jaws. Early osteoarthritis may occur. Other signs include limited range of motion in the hips due to the femoral head protruding into abnormally deep hip sockets.
Biochemistry is the study of the chemicals, chemical reactions and interactions that occur in living organisms. Biochemistry is highly interdisciplinary, covering medicinal chemistry, neurochemistry, molecular biology, forensics, plant science and genetics. Neurochemistry is the study of neurochemicals; including transmitters, peptides, proteins, lipids, sugars, and nucleic acids; their interactions, and the roles they play in forming, maintaining, and modifying the nervous system. Inorganic chemistry traditionally was the study of metals and minerals, but is mainly concerned with the structure and behavior of compounds derived from metals and main group elements. The distinction between organic and inorganic disciplines is not absolute and there is much overlap, most importantly in the sub-discipline of organometallic chemistry. Materials chemistry is the preparation, characterization, and understanding of solid state components or devices with a useful current or future function. The field is a new breadth of study in graduate programs, and it integrates elements from all classical areas of chemistry like organic chemistry, inorganic chemistry, and crystallography with a focus on fundamental issues that are unique to materials. Primary systems of study include the chemistry of condensed phases (solids, liquids, polymers) and interfaces between different phases. Organic chemistry is the study of the structure, properties, composition, mechanisms, and reactions of organic compounds. An organic compound is defined as any compound based on a carbon skeleton.
The samples were found to be "masses of virtually pure collagen" and not to have the "biochemical characteristics of invertebrate collagen, nor the collagen fiber arrangement of octopus mantle." The results suggest the samples are "the remains of the skin of an enormous warm-blooded vertebrate." The authors conclude that "there is no evidence to support the existence of Octopus giganteus" and concur with Verrill (1897) and Lucas (1897) that the St. Augustine carcass was "the remains of a whale, likely the entire skin [blubber layer] . . . nothing more or less."
== Production == Hexane is chiefly obtained by refining crude oil. The exact composition of the fraction depends largely on the source of the oil (crude or reformed) and the constraints of the refining. The industrial product (usually around 50% by weight of the straight-chain isomer) is the fraction boiling at 65–70 °C (149–158 °F).
== History == Thyroxine was first isolated in pure form in 1914 at the Mayo Clinic by Edward Calvin Kendall from extracts of hog thyroid glands. The hormone was synthesized in 1927 by British chemists Charles Robert Harington and George Barger.
Sources: en.wikipedia.org
Chloramphenicol binds to residues A2451 and A2452 in the 23S rRNA of the ribosome and inhibits peptide bond formation. Pleuromutilins also bind to the peptidyl transferase center. Macrolide antibiotics are thought to inhibit peptidyl transferase, in addition to inhibiting ribosomal translocation.
The postwar reconstruction administration was presided over by Lord Milner and his Oxford-educated Milner's Kindergarten. This group of civil servants had a profound effect on the region, eventually leading to the Union of South Africa:
Prescott DJ, Vagelos PR (1972). "Acyl carrier protein". Advances in Enzymology and Related Areas of Molecular Biology. Advances in Enzymology - and Related Areas of Molecular Biology. Vol. 36. pp. 269–311. doi:10.1002/9780470122815.ch8. ISBN 9780470122815. PMID 4561013. Vance DE, Mitsuhashi O, Bloch K (1973). "Purification and properties of the fatty acid synthetase from Mycobacterium phlei". J. Biol. Chem. 248 (7): 2303–9. doi:10.1016/S0021-9258(19)44110-0. PMID 4698221. Williamson IP, Wakil SJ (1966). "Studies on the mechanism of fatty acid synthesis. XVII. Preparation and general properties of acetyl coenzyme A and malonyl coenzyme A-acyl carrier protein transacylases". J. Biol. Chem. 241 (10): 2326–32. doi:10.1016/S0021-9258(18)96625-1. PMID 5330116. Lowe PN, Rhodes S (1988). "Purification and characterization of acyl-carrier-protein acetyltransferase from Escherichia coli". Biochem. J. 250 (3): 789–96. doi:10.1042/bj2500789. PMC 1148925. PMID 3291856. Tsay JT, Oh W, Larson TJ, Jackowski S, Rock CO (1992). "Isolation and characterization of the β-ketoacyl-acyl carrier protein synthase III gene (fabH) from Escherichia coli K-12". J. Biol. Chem. 267 (10): 6807–14. doi:10.1016/S0021-9258(19)50498-7. PMID 1551888. Rangan VS, Smith S (1997). "Alteration of the substrate specificity of the malonyl-CoA/acetyl-CoA:acyl carrier protein S-acyltransferase domain of the multifunctional fatty acid synthase by mutation of a single arginine residue". J. Biol. Chem. 272 (18): 11975–8. doi:10.1074/jbc.272.18.11975. PMID 9115261.
LCFAs are important to cells as they can act as stored sources of energy, signaling molecules, and as building blocks for cell membranes. Transporting these LCFAs through the cell so that they may serve these many roles is thus imperative for the cell to do. The carnitine shuttle evolved as a way for cells to be able transport LCFAs to the many places they are needed for these roles. The LCFA's are synthesized, or absorbed. Carnitine is similarly either synthesized, or absorbed. The acyl-CoA comes from Acyl-CoA synthetase. The shuttle's mechanism is as follows:
Sources: en.wikipedia.org
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.