heptapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-11-21 and is reviewed periodically as new material appears.
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.
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.
| 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 |
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.
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.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
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.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
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.
== Industrial use == Butane-1,4-diol is used industrially as a solvent and in the manufacture of some types of plastics, elastic fibers and polyurethanes. In organic chemistry, 1,4-butanediol is used for the synthesis of γ-butyrolactone (GBL). In the presence of phosphoric acid and high temperature, it dehydrates to the important solvent tetrahydrofuran. At about 200 °C in the presence of soluble ruthenium catalysts, the diol undergoes dehydrogenation to form butyrolactone. It is used to synthesize 1,4-butanediol diglycidyl ether which is then used as a reactive diluent for epoxy resins. 1,4-Butanediol is used in the production of polybutylene terephthalate (PBT) plastic. World production of butane-1,4-diol was claimed to be about one million metric tons per year and market price is about US$2,000 (€1,600) per ton in 2005. In 2013, worldwide production was claimed to be billions of pounds (consistent with approximately one million metric tons). Almost half of it is dehydrated to tetrahydrofuran to make fibers such as Spandex. The largest producer is BASF.
CT imaging uses X-rays in conjunction with computing algorithms to image the body. In CT, an X-ray tube opposite an X-ray detector (or detectors) in a ring-shaped apparatus rotates around a patient, producing a computer-generated cross-sectional image (tomogram). CT is acquired in the axial plane, with coronal and sagittal images produced by computer reconstruction. Radiocontrast agents are often used with CT for enhanced delineation of anatomy. Although radiographs provide higher spatial resolution, CT can detect more subtle variations in attenuation of X-rays (higher contrast resolution). CT exposes the patient to significantly more ionizing radiation than a radiograph.
2024 Conservative Party leadership election: Tom Tugendhat launches his leadership bid, and says he would take the UK out of the European Convention on Human Rights if he could not reform it. In a statement to the Scottish Parliament, Finance Secretary Shona Robison outlines £500m of spending cuts. She argues the cuts are needed because of an additional £800m in financial costs brought about by public sector pay deals, austerity from Westminster, inflation, the COVID-19 pandemic and the Russian invasion of Ukraine. 4 September – 2024 Conservative Party leadership election: Former Home Secretary Priti Patel is knocked out of the leadership content in the first round of voting by Conservative MPs. BBC News reports that the 2024 Conservative Party Conference will not have a leader's speech from Rishi Sunak, but will instead be dedicated to showcasing its leadership candidates. The Scottish Government abandons an unfulfilled commitment to expand free school meals to all primary school pupils. 5 September – The UK government sets out its plan to abolish hereditary peers in the House of Lords. The Northern Ireland Executive agrees a draft programme of government, seven months after the return of Stormont. 6 September – BBC News reports that Estonia's justice minister, Liisa Pakosta, discussed the possibility of housing foreign prisoners, including those from the UK, in one of its prisons with UK Justice Minister Shabana Mahmood at an AI summit in Vilnius the previous day.
The IAEA conservatively classifies plutonium of all isotopic vectors as "direct-use" material, that is, "nuclear material that can be used for the manufacture of nuclear explosives components without transmutation or further enrichment".
== Lifespan == Gastric pit cells are replaced every 2–4 days. This high rate of turnover is a protective mechanism designed to protect the epithelial lining of the stomach from both the proteolytic action of pepsin and the acid produced by parietal cells. Gastric chief cells are much longer lived and are believed to differentiate from stem cells located higher in the gastric unit in the isthmus. These stem cells differentiate into mucous neck cells in the isthmus and transition into chief cells as they migrate towards the base. Since the mucus neck cells do not divide as it becomes a chief cell this process is known as transdifferentiation. The gene Mist1 has been shown to regulate mucus neck cell to chief cell transdifferentiation and plays a role in the normal development of the chief cell organelles and structures.
Sources: en.wikipedia.org
Taihō had just launched 42 aircraft as a part of the second raid when Albacore fired the torpedo spread. Of the six torpedoes fired, four veered off-target. Japanese pilot Sakio Komatsu had recently launched and from his aircraft sighted one of the two torpedoes which were heading for Taihō. Komatsu dived into the path of the torpedo which then detonated. The sixth torpedo struck the carrier on her starboard side and ruptured two aviation fuel tanks. The carrier's escorting destroyers made depth charge attacks but caused only minor damage to Albacore. Initially, the damage to Taihō seemed minor; the flooding was quickly contained and the carrier's propulsion and navigation were unaffected. Taihō quickly resumed regular operations, but gasoline vapor from the ruptured fuel tanks began to fill the hangar decks, creating an increasingly dangerous situation on board.
Barry Halliwell, John MC Gutteridge. Free Radicals in Biology and Medicine (5th edn) (Oxford University Press, 2015) ISBN 0-19-871748-2 Barry Halliwell. Chloroplast Metabolism (2nd edn) (Oxford University Press, 1984) ISBN 0-19-854585-1 Reviews
== Occurrence and nomenclature == The term nucleic acid is the overall name for DNA and RNA, members of a family of biopolymers, and is a type of polynucleotide. Nucleic acids were named for their initial discovery within the nucleus, and for the presence of phosphate groups (related to phosphoric acid). Although first discovered within the nucleus of eukaryotic cells, nucleic acids are now known to be found in all life forms including within bacteria, archaea, mitochondria, chloroplasts, and viruses (There is debate as to whether viruses are living or non-living). All living cells contain both DNA and RNA (except some cells such as mature red blood cells), while viruses contain either DNA or RNA, but usually not both. The basic component of biological nucleic acids is the nucleotide, each of which contains a pentose sugar (ribose or deoxyribose), a phosphate group, and a nucleobase. Nucleic acids are also generated within the laboratory, through the use of enzymes (DNA and RNA polymerases) and by solid-phase chemical synthesis.
It got to a point where he'd kept himself so locked up, both physically and emotionally. I kept trying to make contact...Three times a week, like clockwork, I'd call him, but he'd never answer. Every time I was in the area, I was up in front of his place yelling for him ... Even if you could get in his building, he wasn't going to open the door. You'd phone and he wouldn't answer. You couldn't just kick the door in and grab him, though there were so many times I thought about doing that. But if someone won't help themselves, what, really, can anyone else do? Staley's physical appearance had become even worse than before: he had lost several teeth, his skin was sickly pale, and he was severely emaciated. Close friends such as Matt Fox said, "If no one heard from him for weeks, it wasn't unusual". Staley grew increasingly disconnected from his friends and bandmates who repeatedly tried to get him into rehab, but Staley refused. Staley's close friend Mark Lanegan said, "He didn't speak to anybody as of late... It's been a few months since I talked to him. But for us to not talk for a few months is par for the course."
Sources: en.wikipedia.org
=== 1918 influenza pandemic === The influenza pandemic of 1918 placed a sever strain on Oregon’s hospitals and public health infrastructure. At the time, the viral cause of influenza had not yet been identified, and many physicians believed that the high mortality rate resulted from secondary bacterial infections. In response, the Oregon State Board of Health supplied Lawrence’s laboratory with an infected tissue sample obtained from a navy yard in Bremerton, Washington. Lawrence isolated hemolytic streptococcus from patient samples and developed a vaccine targeting this bacterium, which was associated with secondary pneumonia in influenza patients. Although described at the time as an influenza vaccine, the preparation was designed to combat bacterial infections that frequently followed influenza rather than the virus itself. The vaccines produced in her laboratory were distributed to physicians throughout Oregon as part of broader public health efforts. Her work received national recognition, and she was later honored by President Woodrow Wilson for her contributions.
where, as indicated above, nA and nB represent the number of fish in the lake and the number of fish added to the lake, respectively; RA is the ratio of the native-to-marked fish in the lake prior to the addition of marked fish; RB is the ratio of the native-to-marked fish in the amount of marked fish added to the lake; finally, RAB is the ratio of the native-to-marked fish captured during the second visit.
== Regulation == Because governments regulate access to drugs, governments control drug distribution and the drug supply chain more than trade for other goods. Distribution begins with the pharmaceutical industry manufacturing drugs. From there, intermediaries in the public sector, private sector, and non-governmental organizations acquire drugs to provide them to other intermediaries. Eventually, the drugs reach different classes of consumers who use them. Good distribution practice (GDP) is an integrated system of procedures, standards and practices aimed at ensuring product quality at all stages of the supply chain, which includes requirements for purchase, receiving, storage, transportation and export of drugs intended for human consumption. It regulates the division and movement of pharmaceutical products from the premises of the manufacturer of medicinal products, or another central point, to the end user (usually defined as the medical facility or pharmacy that uses the product on or issues it to patients, or the retail outlet that sells to customers) thereof, or to an intermediate point by means of various transport methods, via various storage and/or health establishments.
=== Sex === This is especially concerning considering the epidemiology of opioid affliction among white women, who are at a greater risk because they receive more prescription medications than men. According to the NIH (2018), "The opioid epidemic is increasingly young, white, and female" with 1.2 million women being diagnosed with an opioid use disorder compared to 0.9 million men in 2015.
Magnetic resonance imaging (MRI) of the brain and spine may show areas of demyelination (lesions or plaques). Gadolinium can be administered intravenously as a contrast agent to highlight active plaques, and by elimination, demonstrate the existence of historical lesions not associated with symptoms at the moment of the evaluation. The central vein sign, which shows as a dark line in the MRI through the bright white lesion, can help verify that the lesions are due to MS. Active MS lesions can have an inactive centre surrounded by microglia which contain iron. In specific MRI scans, these can be visible as paramagnetic rim lesions, which are another way to show that the lesions are likely due to MS.
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.
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.