This is a working overview of heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-05-04 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
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.
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.
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.
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.
==== Microspheres ==== Microspheres are microscopic spherical particles which can be used to encapsulate compounds. Estradiol is available in the form of an aqueous suspension of 1.0 mg estradiol in microspheres for use by intramuscular injection once a month under the brand name Juvenum E in Mexico. It achieves circulating estradiol levels of 163 pg/mL to 219 pg/mL in the first 3 to 12 hours following injection, which decrease to 42 to 66 pg/mL during the first 4 days post-injection and to 20 to 35 pg/mL after 8 days, with levels remaining in this range thereafter over 30 days. These estradiol levels are similar to the normal levels that occur during the early follicular phase of the menstrual cycle in premenopausal women (24 to 75 pg/mL). The elimination of the formulation follows three phases: a rapid phase in the first 2 days, a second phase during days 2 to 12 days with a biological half-life of 7 to 10 days, and a third phase in which estradiol levels remain elevated above baseline for up to 30 days.
We Spaniards have reached a point where we can no longer choose between staying as we are or making sacrifices. We do not have that freedom. Circumstances are not so generous. The only option that circumstances allow us is to either accept the sacrifices and give up something; or to reject the sacrifices and give up everything. Yet, on July 26, 2012, in the face of the danger of collapse of the entire Eurozone – Italy's risk premium had also skyrocketed, and Spain and Italy were 'too big to fail' — the president of the European Central Bank Mario Draghi intervened to assure that the ECB was going to do everything in its power to sustain the euro, behaving at last as a lender of last resort – Draghi's words were: "the ECB will do everything necessary to sustain the euro. And, believe me, that will be enough." Immediately, market pressure on debt eased and Spanish and Italian risk premiums began to fall, and the threat of a bailout receded.
=== Movement === In addition to the formation of lamellipodia and filopodia, intracellular concentration and cross-talk between different Rho proteins drives the extensions and contractions that cause cellular locomotion. Sakumura et al. proposed a model based on differential equations that helps explain the activity of Rho proteins and their relationship to motion. This model encompassed the three proteins Cdc42, RhoA, and Rac. Cdc42 was assumed to encourage filopodia elongation and block actin depolymerization. RhoA was considered to encourage actin retraction. Rac was treated to encourage lamellipodia extension but block actin depolymerization. These three proteins, although significantly simplified, covered the key steps in cellular locomotion. Through various mathematical techniques, solutions to the differential equations that described various regions of activity based on intracellular activity were found. The paper concludes by showing that the model predicts that there are a few threshold concentrations that cause interesting effects on the activity of the cell. Below a certain concentration, there is very little activity, causing no extension of the arms and feet of the cell. Above a certain concentration, the Rho protein causes a sinusoidal oscillation much like the extensions and contractions of the lamellipodia and filopodia. In essence, this model predicts that increasing the intracellular concentration of these three key active Rho proteins causes an out-of-phase activity of the cell, resulting in extensions and contractions that are also out of phase.
=== Fisher King's injury === The injury is a common theme in the telling of the Grail Quest. While the details and location of the injury vary, the injury ultimately represents the inability of the Fisher King to produce an heir. Although some iterations have two kings present, one or both are injured, most commonly in the thigh. The wound is sometimes presented as a punishment, usually for philandering. In Parzival, specifically, the king is injured by the bleeding lance as punishment for taking a wife, which was against the code of the "Grail Guardians". In some early storylines Percival asks the Fisher King the healing question, which cures the wound. The nature of the question differs between Perceval and Parzival, but the central theme is that the Fisher King can be healed only if Percival asks "the question". The location of the wound is significant to the legend. In most medieval stories, the mention of a wound in the groin or more commonly the "thigh" (such as the wounding of the ineffective suitor in Lanval from the Lais of Marie de France) is a euphemism for the physical loss of or grave injury to one's genitalia. In medieval times, acknowledging the actual type of wound was considered to rob a man of his dignity, thus the use of the substitute terms "groin" or "thigh", although any informed medieval listener or reader would have known exactly the real nature of the wound. Such a wound was considered worse than actual death because it signaled the end of a man's ability to function in his primary purpose: to propagate his line.
Osteolathyrism affects the bones and connecting tissues, instead of the nervous system. It is a skeletal disorder. It is caused by the toxin BAPN, which inhibits the copper-containing enzyme lysyl oxidase, responsible for cross-linking tropocollagen and proelastin. BAPN is also a metabolic product of a compound present in the sprouted seeds of grasspea, pea and lentil.
Sources: en.wikipedia.org
wrapped up the two-and-a-half-month Battle of Okinawa (which cost the lives of 260,000 people, including 150,000 civilians), it was faced with the prospect of invading the Japanese home islands in an operation codenamed Operation Downfall. Based on the U.S. casualties from the preceding island-hopping campaigns, American commanders estimated that between 50,000 and 500,000 U.S. troops would die and at least 600,000–1,000,000 others would be injured while invading the Japanese home islands. The U.S. manufacture of 500,000 Purple Hearts from the anticipated high level of casualties during the U.S. invasion of Japan gave a demonstration of how deadly and costly it would be. President Harry S. Truman realized he could not afford such a high casualty rate, especially since over 400,000 American combatants had already died fighting in both the European and the Pacific theaters of the war. On July 26, 1945, the United States, the United Kingdom, and the Republic of China issued a Potsdam Declaration that called for the unconditional surrender of Japan. It stated that if Japan did not surrender, it would face "prompt and utter destruction". The Japanese government ignored this ultimatum, sending a message that they were not going to surrender. In response to the rejection, President Truman authorized the dropping of the atomic bombs. At the time of its use, there were only two atomic bombs available, and despite the fact that more were in production back in mainland U.S., the third bomb wouldn't be available for combat until September.
=== Education === Kopeček graduated with his M.S. in macromolecular chemistry from the Institute of Chemical Technology in Prague, Czechoslovakia, in 1961. He then received his Ph.D. in macromolecular chemistry from the Institute of Macromolecular Chemistry at the Czechoslovak Academy of Sciences in Prague in 1965. In 1967, Kopeček pursued postdoctoral studies at the National Research Council of Canada in the Division of Applied Chemistry in Ottawa. In 1990 Kopeček received his D.Sc. in chemistry from the Czechoslovak Academy of Sciences. During his time in graduate school, he was mentored by professors Drahoslav Lim and Otto Wichterle, who invented hydrogels and created soft contact lenses. Kopeček received an honorary Ph.D. from the University of Helsinki in Finland in 2014.
==== Action and reference level ==== WHO presented in 2009 a recommended reference level (the national reference level), 100 Bq/m3, for radon in dwellings. The recommendation also says that where this is not possible, 300 Bq/m3 should be selected as the highest level. A national reference level should not be a limit, but should represent the maximum acceptable annual average radon concentration in a dwelling. The actionable concentration of radon in a home varies depending on the organization doing the recommendation, for example, the EPA encourages that action be taken at concentrations as low as 74 Bq/m3 (2 pCi/L), and the European Union recommends action be taken when concentrations reach 400 Bq/m3 (11 pCi/L) for old houses and 200 Bq/m3 (5 pCi/L) for new ones. On 8 July 2010, the UK's Health Protection Agency issued new advice setting a "Target Level" of 100 Bq/m3 whilst retaining an "Action Level" of 200 Bq/m3. Similar levels (as in the UK) are published by Norwegian Radiation and Nuclear Safety Authority (DSA) with the maximum limit for schools, kindergartens, and new dwellings set at 200 Bq/m3, where 100 Bq/m3 is set as the action level.
Archeological evidence from Peru shows that cocaine use dates back as far as 8000 B.C.E. Stimulants have been used to treat various conditions, such as narcolepsy, attention deficit hyperactivity disorder (ADHD), obesity, depression, and fatigue. They have also been used as recreational drugs, performance-enhancing substances, cognitive enhancers, and to promote aggression of combatants in wartime.
Isabel Kershner; British-born Israeli journalist and author, who began reporting from Jerusalem for The New York Times; has worked as senior Middle East editor for The Jerusalem Report magazine; also written for The New Republic and has provided commentary on Middle East affairs on BBC Radio; latest book is "The Land of Hope and Fear: Israel's Battle for its Inner Soul"; married to South African born Israeli author Hirsh Goodman, an employee of the Institute for National Security Studies, which is involved in promoting a positive image of Israel, and which Kershner often relies on as a source. Ian Katz (born 9 February 1968) of South African Jewish origin; journalist and broadcasting executive currently Chief Content Officer at Channel 4, overseeing all editorial decision making and commissioning across Channel 4's linear channels, streaming services and social media. Katz originally followed a career in print journalism, and was a deputy editor of The Guardian until 2013. He then became the editor of the Newsnight current affairs programme on BBC Two, a role which he left in late 2017 to join Channel 4. Mike Katz, chair of the Jewish Labour Movement; journalist for Jewish News, The Jewish Chronicle, Times of Israel, The Guardian, Forbes, Harvard Business Review, The Business Journals, HuffPost UK, New Statesman, LabourList, Camden New Journal, writing mainly on the theory of 'the new anti-Semitism' in Jeremy Corbyn's Labour Party and the demise of his leadership.
Sources: en.wikipedia.org
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.