Pro-Gly-Pro comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-07-11. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
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.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
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.
=== Discovery === In 1828, Morten Thrane Esmark found a black mineral on Løvøya island, Telemark county, Norway. He was a Norwegian priest and amateur mineralogist who studied the minerals in Telemark, where he served as vicar. He commonly sent the most interesting specimens, such as this one, to his father, Jens Esmark, a noted mineralogist and professor of mineralogy and geology at the Royal Frederick University in Christiania (today called Oslo). The elder Esmark determined that it was not a known mineral and sent a sample to Berzelius for examination. Berzelius determined that it contained a new element. He published his findings in 1829, having isolated an impure sample by reducing K[ThF5] (potassium pentafluorothorate(IV)) with potassium metal. Berzelius reused the name of the previous supposed element discovery and named the source mineral thorite.
== Approval == Pramlintide has been approved on 3/16/2005 by the FDA, for use by type 1 and type 2 diabetic patients who use insulin.(subscription required) Pramlintide allows patients to use less insulin, lowers average blood sugar levels, and substantially reduces what otherwise would be a large unhealthy rise in blood sugar that occurs in diabetics right after eating. Apart from insulin analogs, pramlintide is the only drug approved by the FDA to lower blood sugar in type 1 diabetics since insulin in the early 1920s.
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== Uses == Like G. lucidum, G. tsugae is non-poisonous but generally considered inedible, because of its solid woody nature; however, teas and extracts made from its fruiting bodies supposedly allow medicinal use of the compounds it contains, although this is controversial within the scientific community. A hot water extraction or tea can be very effective for extracting the polysaccharides; however, an alcohol or alcohol/glycerin extraction method is more effective for the triterpenoids. The fresh, soft growth of the "lip" of G. tsugae can be sautéed and prepared much like other edible mushrooms. While in this nascent stage it is not woody, it can still be tough and chewy.
Everything the intelligentsia had ever hoped for in terms of freedom of expression and publication was suddenly available. Thanks to glasnost, the Soviet press was full of informed, detailed criticisms of historical ‘mistakes’ such as collectivization, the Great Purges, bad decisions in World War II, wartime ethnic deportations and postwar anti-Semitism. Newspapers and thick journals competed with each other for exposés, publishing all the manuscripts in drawers that had hitherto been forbidden and pushing for rehabilitation of fallen revolutionary heroes. It was a wonderful time to be a Soviet writer of a certain age and type—a Khrushchevian truth-teller whose realist novels and plays unmasked social ills, historical cover-ups and political scandals. It was an equally exciting time to be a Soviet reader, except that there was too much to read, and what one read was likely to shake one's faith in the Soviet system. Gorbachev's assumption, like that of the old reform-minded thick journals, was that 'telling the truth' could not but be good, ultimately strengthening the Soviet system by purifying it. Unfortunately, the opposite proved to be the case. The effect of the crash course on the flaws of Soviet socialism was to undermine the public’s confidence rather than rally it for reform. Additionally, the internal political reforms associated with perestroika altered both the political consciousness of Soviet society and the strategic outlook of Soviet foreign policy.
Sources: en.wikipedia.org
=== Other countries === The flag was used in the Gaza war protests, such as in London in November 2023 and in Italy in September–October 2025. The flag was flown by some protesters during the Trillion Peso March which was against corruption and the "ghost projects" controversy in the Philippines, During another protest in the Philippines on 12 October, a motorcycle rider carrying the flag was confronted by other protestors who suspected him of being a provocateur, and he was escorted away by police. and by university students protesting lifetime pensions for parliament members in East Timor. During the French anti-government Bloquons tout protests in September 2025 after the fall of the Bayrou government, some protesters carried the flag. The flag was present during the 2025 Peruvian protests, where the flag was once again used by demonstrators protesting against pension reforms in Peru by the government of Dina Boluarte. Specifically, the flag was present again during the protest on 24 September in Plaza San Martín, Lima. Anti-government protesters in Asunción, Paraguay, in late September along with protesters at La Paz demanding an audit for the 2025 Bolivian general election in October also carried the flag. Gen Z protesters in Morocco used the flag. British magazine The Week noted the flag's presence in protests in New York, Rome, and Slovakia.
== Sources == Johnson, Daniel; Hashaikeh, Raed; Hilal, Nidal (2021). "Basic principles of osmosis and osmotic pressure". In Hilal, Nidal; Ismail, Ahmad Fauzi; Khayet, Mohamed; Johnson, Daniel (eds.). Osmosis Engineering. Elsevier. pp. 1–15. doi:10.1016/B978-0-12-821016-1.00011-5. ISBN 978-0-12-821016-1.
== American Society for Mass Spectrometry == The major awards from the American Society for Mass Spectrometry are John B. Fenn Award for a Distinguished Contribution in Mass Spectrometry, Biemann Medal, Fellows of ASMS, Research Award, Research at Primarily Undergraduate Institutions (PUIs) Award, Al Yergey Mass Spectrometry Scientist Award, Ron Hites Award, and Diversity, Equity, Inclusion, and Accessibility Mentorship Award. A number of notable women mass spectrometrists served as presidents of the American Society for Mass Spectrometry.
== Indication == Trimecaine has two main application fields. The first one is local anesthesia (topical, infiltrational, topical mucosal and inhalational, spinal and Bier's intravenous). It is used in concentrations 0.4 up to 4%, in some cases (e.g. in stomatology) in mixtures with adrenaline. The other field is prophylaxis and therapy of ventriculous arrhythmia on myocardial infarction and in cardiosurgery. It is used also for prophylaxis of sympathetic reaction during tracheal intubations.
Sources: en.wikipedia.org
Routine blood tests often discover anemia. A sufficiently low hemoglobin by definition makes the diagnosis of anemia, and a low hematocrit value is also characteristic of anemia. Further studies will be undertaken to determine the cause of anemia. If the anemia is due to iron deficiency, one of the first abnormal values to be noted on a complete blood count, as the body's iron stores begin to be depleted, will be a high red blood cell distribution width, reflecting an increased variability in the size of red blood cells. A low mean corpuscular volume also appears during the course of body iron depletion. It indicates a high number of abnormally small red blood cells. A low mean corpuscular volume, a low mean corpuscular hemoglobin or mean corpuscular hemoglobin concentration, and the corresponding appearance of red blood cells on visual examination of a peripheral blood smear narrows the problem to a microcytic anemia (literally, a small red blood cell anemia). The blood smear of a person with iron-deficiency anemia shows many hypochromic (pale, relatively colorless) and small red blood cells. It may also show poikilocytosis (variation in shape) and anisocytosis (variation in size). With more severe iron-deficiency anemia, the peripheral blood smear may show hypochromic, pencil-shaped cells and, occasionally, small numbers of nucleated red blood cells. The platelet count may be slightly above the high limit of normal in iron-deficiency anemia (termed a mild thrombocytosis), but severe cases can present with thrombocytopenia (low platelet count).
==== Behavioral consequences ==== The hyperactivity and difficulties in emotional regulation found in pediatric patients (children) are not reported in adults. OSA in adults is nevertheless associated with personality changes and automatic behavior. The biggest impact of OSA is the excessive daytime sleepiness (EDS), reported in approximately 30% of OSA patients. EDS can be caused by the disturbance of sleep quality, the insufficient sleep duration or the sleep fragmentation and it is responsible for further complications as it may lead to depressive symptoms, impairments of social life and decreased effectiveness at work. Studies have shown that those consequences of EDS can be improved following a CPAP treatment.
Certain lithium compounds, also known as lithium salts, are used as psychiatric medication, primarily for bipolar disorder and for major depressive disorder. Lithium is taken orally (by mouth). Common side effects include increased urination, shakiness of the hands, and increased thirst. Serious side effects include hypothyroidism, diabetes insipidus, and lithium toxicity. Blood level monitoring is recommended to decrease the risk of potential toxicity. If levels become too high, diarrhea, vomiting, poor coordination, sleepiness, and ringing in the ears may occur. Lithium is teratogenic and can cause birth defects at high doses, especially during the first trimester of pregnancy. The use of lithium while breastfeeding is controversial; many international health authorities advise against it, and the long-term outcomes of perinatal lithium exposure have not been studied. The American Academy of Pediatrics lists lithium as contraindicated for pregnancy and lactation. The United States Food and Drug Administration (FDA) categorizes lithium as having positive evidence of risk for pregnancy and possible hazardous risk for lactation. Lithium salts are classified as mood stabilizers. Lithium's mechanism of action is not known. In the nineteenth century, lithium was used in people who had gout, epilepsy, and cancer. Its use in the treatment of mental disorders began with Carl Lange in Denmark and William Alexander Hammond in New York City, who used lithium to treat mania from the 1870s onwards, based on now-discredited theories involving its effect on uric acid.
== Target == In research on Xenopus oocytes, it was found that kurtoxin affects low-threshold α1G and α1H calcium channels, but not the high-threshold α1A, α1B, α1C, and α1E Ca channels. Like other α-scorpion toxins, kurtoxin was also found to interact with voltage-gated sodium channels. In rat neurons, less selectivity for kurtoxin on calcium channels is found. Here, the toxin interacts with high affinity with T-type, L-type, N-type, and P-type channels.
Kozak consensus sequence Also simply Kozak sequence. A highly conserved nucleic acid sequence motif which functions as the recognition site for the initiation of translation in most eukaryotic messenger RNAs, generally a sequence of 10 bases immediately surrounding and inclusive of the start codon: GCCRCCAUGG. As the pre-initiation complex scans the transcript, recognition of this sequence (or a close variant) causes the complex to commit to full ribosome assembly and the start of translation. The Kozak sequence is distinct from other recognition sequences relevant to translation such as ribosome binding sites and internal ribosome entry sites.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.