A practical reference on Pro-Gly-Pro: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-05-19. Anything still debated is marked as such rather than presented as settled.
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.
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 developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
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.
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.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
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.
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.
== Function and expression == Grb2 is widely expressed and is essential for multiple cellular functions. Inhibition of Grb2 function impairs developmental processes in various organisms and blocks transformation and proliferation of various cell types. It is thus not surprising that targeted gene disruption of Grb2 in mice is lethal at an early embryonic stage. Grb2 is best known for its ability to link the epidermal growth factor receptor tyrosine kinase to the activation of Ras and its downstream kinases, ERK1,2. Grb2 is composed of an SH2 domain flanked on each side by an SH3 domain. Grb2 has two closely related proteins with similar domain organizations, Gads and Grap. Gads and Grap are expressed specifically in hematopoietic cells and function in the coordination of tyrosine kinase mediated signal transduction.
Creating a genetically modified organism (GMO) is a multi-step process. Genetic engineers must isolate the gene they wish to insert into the host organism. This gene can be taken from a cell or artificially synthesized. If the chosen gene or the donor organism's genome has been well studied it may already be accessible from a genetic library. The gene is then combined with other genetic elements, including a promoter and terminator region and a selectable marker. A number of techniques are available for inserting the isolated gene into the host genome. Bacteria can be induced to take up foreign DNA, usually by exposed heat shock or electroporation. DNA is generally inserted into animal cells using microinjection, where it can be injected through the cell's nuclear envelope directly into the nucleus, or through the use of viral vectors. In plants the DNA is often inserted using Agrobacterium-mediated recombination, biolistics or electroporation. As only a single cell is transformed with genetic material, the organism must be regenerated from that single cell. In plants this is accomplished through tissue culture. In animals it is necessary to ensure that the inserted DNA is present in the embryonic stem cells. Further testing using PCR, Southern hybridization, and DNA sequencing is conducted to confirm that an organism contains the new gene. Traditionally the new genetic material was inserted randomly within the host genome.
== Overdose == Psilocybin has low toxicity, meaning that it has a low risk of inducing life-threatening events like breathing or heart problems. Research shows that health risks may develop with use of psilocybin. Nonetheless, hospitalizations from it are rare, and overdoses are generally mild and self-limiting. The lethal dose of psilocybin in humans is unknown, but has been estimated to be approximately 200 times a typical recreational dose. A review of the management of psychedelic overdoses suggested that psilocybin-related overdose management should prioritize managing the immediate adverse effects, such as anxiety and paranoia, rather than specific pharmacological interventions, as psilocybin's physiological toxicity tends to be rather limited. One analysis of people hospitalized for psilocybin poisoning found high urine concentrations of phenethylamine (PEA), suggesting that PEA might contribute to the effects of psilocybin poisoning. Despite acting as non-selective serotonin receptor agonists, psilocybin and other major serotonergic psychedelics like lysergic acid diethylamide (LSD) do not cause serotonin syndrome even in the context of extreme overdose. This is thought to be because they act as partial agonists of serotonin receptors like the serotonin 5-HT2A receptor, in contrast to serotonin itself, which is a full agonist. In rats, the median lethal dose (LD50) of psilocybin when administered orally is 280 mg/kg, approximately 1.5 times that of caffeine.
Sources: en.wikipedia.org
== Medical uses == Norgestrienone was used in hormonal contraception to prevent pregnancy. It has typically been used as an oral contraceptive at a dosage of 2 mg/day in combination with ethinylestradiol and 350 μ/day when used alone.
To ensure that soldiers and pack animals were properly fed, campaigns were timed for when grain was ripe and pastures were full. While on campaign, hoplites and other Greek soldiers would have foraged for food, hunted, purchased food from markets and traders, and pillaged towns and villages. Spartan soldiers are known to have brought bread, cheese, wine, and meat with them on campaigns. During wartime, Sparta's slave population, or helots, were promised their freedom if they brought enough supplies to the army, although historians are unsure if these promises would ultimately be honored. Sparta also offered military protection to villages which paid tribute, with villages failing to do so subject to plunder. Spartan soldiers were trained to carry and pilfer food during their childhood in the Agoge. Boys were taught to march long distances while carrying provisions for twenty days. They were also purposely underfed to encourage them to learn to steal food, but harshly punished if they were caught doing it so they would learn to do it stealthily. The Kingdom of Macedon, which conquered large swathes of territory, initially relied on oxen-drawn carts to carry the soldiers' burden, including food. During the reign of Philip II of Macedon, reforms were carried out under which soldiers would be expected to carry much of their own food rather than rely on oxen-drawn carts. This continued under the reign of his son Alexander the Great. During Alexander's conquests, Macedonian soldiers primarily lived off of grain rations.
=== Large-scale analysis === One example of this is a study by Washburn, Wolters, and Yates in which they used shotgun proteomics on the proteome of a Saccharomyces cerevisiae strain grown to mid-log phase. They were able to detect and identify 1,484 proteins as well as identify proteins rarely seen in proteome analysis, including low-abundance proteins like transcription factors and protein kinases. They were also able to identify 131 proteins with three or more predicted transmembrane domains.
== Similarities with TCA cycle == The glyoxylate cycle uses five of the eight enzymes associated with the tricarboxylic acid cycle: citrate synthase, aconitase, succinate dehydrogenase, fumarase, and malate dehydrogenase. The two cycles differ in that in the glyoxylate cycle, isocitrate is converted into glyoxylate and succinate by isocitrate lyase (ICL) instead of into α-ketoglutarate. This bypasses the decarboxylation steps that take place in the citric acid cycle (TCA cycle), allowing simple carbon compounds to be used in the later synthesis of macromolecules, including glucose. Glyoxylate is subsequently combined with acetyl-CoA to produce malate, catalyzed by malate synthase. Malate is also formed in parallel from succinate by the action of succinate dehydrogenase and fumarase. The difference between the two cycles can be seen through their net equations. In the citric acid cycle, two carbons that are part of the acetyl-CoA are lost as carbon dioxide, which results in net carbon loss. Unlike the citric acid cycle, the glyoxylate cycle bypasses the two decarboxylations. This allows the glyoxylate cycle the net synthesis of glucose from acetyl-CoA. The net equation of the glyoxylate cycle is: 2Acetyl-CoA + NAD+ + 2H2O → Succinate + 2CoA + NADH + H+.
Sources: en.wikipedia.org
=== Medical insurance coverage === Insurance companies in the United States typically require the physician to provide evidence that a woman's large breasts cause headaches or back and neck pain before they will pay for breast reduction. Insurance companies also mandate a woman who is overweight, which is often the case with gigantomastia, to first lose a certain amount of weight. They also commonly require the patient to try alternative treatments like physical therapy for a year or more.
While advertising of tobacco products is banned in most countries, television and radio e-cigarette advertising in several countries may be indirectly encouraging traditional cigarette use. E-cigarette advertisements are also in magazines, newspapers, online, and in retail stores. Between 2010 and 2014, e-cigarettes were second only to cigarettes as the top advertised product in magazines. As cigarette companies have acquired the largest e-cigarette brands, they currently benefit from a dual market of smokers and e-cigarette users while simultaneously presenting themselves as agents of harm reduction. This raises concerns about the appropriateness of endorsing a product that directly profits the tobacco industry. There is no evidence that the cigarette brands are selling e-cigarettes as part of a plan to phase out traditional cigarettes, despite some stating to want to cooperate in "harm reduction". E-cigarette advertising for using e-cigarettes as a quitting tool have been seen in the US, UK, and China, which have not been supported by regulatory bodies. In the US, six large e-cigarette businesses spent $59.3 million on promoting e-cigarettes in 2013. In the US and Canada, over $2 million is spent yearly on promoting e-cigarettes online. E-cigarette websites often made unscientific health statements in 2012. The ease to get past the age verification system at e-cigarette company websites allows underage individuals to access and be exposed to marketing.
On 28 February 2025, unidentified armed individuals fired upon a vehicle carrying Druze civilians traveling on a road leading to Damascus International Airport within Jaramana. Two elderly individuals suffered injuries in this attack, and were both hospitalized. In response to these incidents, the General Security Service initiated a comprehensive security operation throughout Jaramana beginning on 28 February. Security forces reinforced positions at city entry points and deployed substantial personnel numbers around Jaramana to pursue suspected individuals considered responsible for the violence. Reports indicated that security forces intended to storm into Jaramana.
A cytocentrifuge, sometimes referred to as a cytospin, is a specialized centrifuge used to concentrate cells in fluid specimens onto a microscope slide so that they can be stained and examined. Cytocentrifuges are used in various areas of the clinical laboratory, such as cytopathology, hematology and microbiology, as well as in biological research. The method can be used on many different types of specimens, including fine needle aspirates, cerebrospinal fluid, serous and synovial fluid, and urine.
A survey of patients using nonbenzodiazepine Z-drugs and benzodiazepine hypnotic users found that there was no difference in reports of adverse effects that were reported in over 41% of users and, in fact, Z-drug users were more likely to report that they had tried to quit their hypnotic drug and were more likely to want to stop taking Z-drugs than benzodiazepine users. Efficacy also did not differ between benzodiazepine and Z-drug users. A 2022 systematic review and network meta-analysis found that 40–50% of users have adverse effects from Z-drugs.
Sources: en.wikipedia.org
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.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.