A practical reference on heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-11. Anything still debated is marked as such rather than presented as settled.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | -20 °C or below | For lyophilized powder, long term |
| Common analytical method | Reverse-phase HPLC | Usually paired with mass spectrometry |
| Typical reported purity | At or above 95 percent by area | Research-grade material |
| Aqueous solubility | High | Solutions used in laboratory assays |
| Moisture sensitivity | Hydrolyzes in solution | Aseptic handling reduces degradation |
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
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.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
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 == Produced mainly in the liver, plasminogen is the inactive zymogen form of plasmin, and circulates in plasma in a closed conformation that cannot be activated. Binding clots or cell surfaces cause their conformation to change, allowing them to be activated by plasminogen activators. Plasminogen activators do so by cleaving the R561/V562 peptide bond, producing the active protein plasmin, which catalyzes the degradation of fibrin polymers that make up the structure of blood clots.
=== Extraterrestrial sulfuric acid === The permanent Venusian clouds are made of concentrated sulfuric acid, and produce a concentrated sulfuric acid rain, just as the clouds in the atmosphere of Earth are made of water and produce water rain. Sulfuric acid ice has been detected on Jupiter's moon Europa, where it forms when sulfur ions from Jupiter's magnetosphere implant into the icy surface.
Since the first formal cooperation treaties between Angola and the Soviet Union in 1976, the military sphere had constituted the pivot of Angolan-Soviet relations. The Soviet Navy benefited from its use of Angolan ports to stage exercises throughout the southern Atlantic and even negotiated with FAPLA for the construction of permanent bases. Luanda was named the regional headquarters for the 30th Operation Squadron of the Soviet Navy's Northern Fleet, which comprised eleven warships, three of which were in the port at any given time. From January 1976 onward, it also replaced Conakry as the primary base for Soviet Tupolev Tu-95 reconnaissance flights along Africa's western coast. Article 16 of the Angolan constitution banned the construction of foreign military bases, but exceptions could be made if base rights were considered essential to the country's national defence. The Soviet Union justified its continued air and naval presence as necessary measures to protect Angola from a South African invasion. One senior Soviet military official, General Valery Belyaev, remarked that the 30th Operational Squadron was, "by the very fact of its presence...restraining the South African aggression against Angola." In exchange for granting base rights, FAPLA became the beneficiary of more sophisticated Soviet arms. After Operation Sceptic, the Soviet Union transferred over 500 million dollars' worth of military equipment to FAPLA, the bulk of it apparently concentrated on air defence.
Moisture management and humidity control requires operating HVAC systems as designed. Moisture management and humidity control may conflict with efforts to conserve energy. For example, moisture management and humidity control requires systems to be set to supply make-up air at lower temperatures (design levels), instead of the higher temperatures sometimes used to conserve energy in cooling-dominated climate conditions. However, for most of the US and many parts of Europe and Japan, during the majority of hours of the year, outdoor air temperatures are cool enough that the air does not need further cooling to provide thermal comfort indoors. However, high humidity outdoors creates the need for careful attention to humidity levels indoors. High humidity give rise to mold growth and moisture indoors is associated with a higher prevalence of occupant respiratory problems. The "dew point temperature" is an absolute measure of the moisture in air. Some facilities are being designed with dew points in the lower 50s °F, and some in the upper and lower 40s °F. Some facilities are being designed using desiccant wheels with gas-fired heaters to dry out the wheel enough to get the required dew points. On those systems, after the moisture is removed from the make-up air, a cooling coil is used to lower the temperature to the desired level. Commercial buildings, and sometimes residential, are often kept under slightly positive air pressure relative to the outdoors to reduce infiltration. Limiting infiltration helps with moisture management and humidity control.
==== Stepped-up inspection program ==== According to a senior quality inspectorate official, the government aimed to establish nearly 400 product testing centres within the next two years, and 80 of these would be food testing centres. Working groups were established in nearly every single province in order to set up new food testing centres and replace outdated equipment. On 24 September 2008, China's newly appointed AQSIQ chief Wang Yong said that the government would "carry out 'forceful' measures to deal with the chemical contamination", and stated that inspectors had removed 7,000 tonnes of melamine-contaminated dairy products from shops all over China. On 4 October, the Ministry of Agriculture announced it had drawn up an emergency rescue plan with the Ministry of Finance to give special subsidies to dairy farmers seriously affected by the lack of demand following the contamination scandal; local governments had already drafted policies to stabilise the dairy industry; 150,000 officials had been sent to overhaul the entire supply chains from cattle feed to milk collection; 18,803 milk-collecting stations had been registered and checked by these officials. The ministry was reported to have investigated 98 dairy producers and farms, banned 151 illegal companies and indicted three manufacturers for feed containing melamine. During an investigation into melamine contamination at Yili and Mengniu in Hohhot, police arrested six more people for allegedly selling and mixing melamine into raw milk.
Sources: en.wikipedia.org
Helton enjoyed arguably his best season in 2000, leading the major leagues in batting average (.372), RBI (147), doubles (59), total bases (405), extra base hits (103), slugging percentage (.698) and OPS (1.162). He led the NL in hits (216) and on-base percentage (.463). Helton hit a league-leading home batting average of .391 and was third in the NL in road batting average (.353). Helton's MLB-leading 103 extra base hits tied for the fourth most in MLB history and the second most in NL history. His league-leading numbers in on-base percentage, slugging percentage and batting average gave him the "percentage triple crown." Helton became the second Rockies player, after Larry Walker in 1999, to accomplish that feat. Helton and Walker made the Rockies the first team in MLB history to record percentage triple crowns in consecutive seasons with different players. Helton became only the fourth player in NL history to lead the league in both batting average and RBI. He became the first player in NL history and the fifth player in MLB history (Babe Ruth, Lou Gehrig, Jimmie Foxx and Hank Greenberg are the others) to have at least 200 hits, 40 home runs, 100 RBI, 100 runs, 100 extra base hits, and 100 walks in one season. Helton was invited to his first career MLB All-Star Game in 2000. He also received NL Player of the Month honors for May and August. He finished fifth in voting for the MVP award. However, the Associated Press, Sporting News, USA Baseball Alumni, and Baseball Digest all named Helton the MLB Player of the Year.
The Centre Party (German: Zentrum, Z), officially the German Centre Party (German: Deutsche Zentrumspartei, DZP) and also known in English as the Catholic Centre Party, is a Christian democratic political party in Germany. It was most influential in the German Empire and Weimar Republic. Formed in 1870, it successfully battled the Kulturkampf waged by Chancellor Otto von Bismarck against the Catholic Church. It soon won a quarter of the seats in the Reichstag, and its middle position on most issues allowed it to play a decisive role in the formation of majorities. The party name Zentrum (Centre) originally came from the fact that Catholic representatives would take up the middle section of seats in parliament between the social democrats and the conservatives. For most of the Weimar Republic, the Centre Party was the third-largest party in the Reichstag and a bulwark of the Republic, participating in all governments until 1932. Following Adolf Hitler's rise to power in early 1933, the Centre Party was among the parties who voted for the Enabling Act, which granted legislative powers to Hitler's government. Nevertheless, the party was pressured into dissolving itself on 5 July, as the Nazi Party became the only legally permitted party in the country shortly thereafter. After World War II, the party was reconstituted, but could not rise again to its former importance, as most of its members joined the new interdenominational Christian Democratic Union (CDU) and, in Bavaria, the Christian Social Union (CSU).
=== Drug design === New design of anti-bacterial medications is of continuing importance in scientific research as bacterial antibiotic resistance to common antibiotics increases. A specific metabolic protein that uses FAD (Complex II) is vital for bacterial virulence, and so targeting FAD synthesis or creating FAD analogs could be a useful area of investigation. Already, scientists have determined the two structures FAD usually assumes once bound: either an extended or a butterfly conformation, in which the molecule essentially folds in half, resulting in the stacking of the adenine and isoalloxazine rings. FAD imitators that are able to bind in a similar manner but do not permit protein function could be useful mechanisms of inhibiting bacterial infection. Alternatively, drugs blocking FAD synthesis could achieve the same goal; this is especially intriguing because human and bacterial FAD synthesis relies on very different enzymes, meaning that a drug made to target bacterial FAD synthase would be unlikely to interfere with the human FAD synthase enzymes.
== Notes == "EMDB-1067: Ribosomal 80S-eEF2-sordarin complex from S. cerevisiae - EM Navigator". emnavi.protein.osaka-u.ac.jp. Retrieved 2009-08-06.{{cite web}}: CS1 maint: deprecated archival service (link) Giavalisco P, Wilson D, Kreitler T, et al. (March 2005). "High heterogeneity within the ribosomal proteins of the Arabidopsis thaliana 80S ribosome". Plant Mol. Biol. 57 (4): 577–591. Bibcode:2005PMolB..57..577G. doi:10.1007/s11103-005-0699-3. hdl:11858/00-001M-0000-0010-86C6-1. PMID 15821981. S2CID 14500573. "Ribosomes". www.cs.stedwards.edu. Archived from the original on 2009-03-20. Retrieved 2009-08-06.
== Localization of pyruvate decarboxylation == In eukaryotic cells the pyruvate decarboxylation occurs inside the mitochondrial matrix, after transport of the substrate, pyruvate, from the cytosol. The transport of pyruvate into the mitochondria is via the transport protein pyruvate translocase. Pyruvate translocase transports pyruvate in a symport fashion with a proton (across the inner mitochondrial membrane), which may be considered to be a form of secondary active transport, but further confirmation/support may be needed for the usage of "secondary active transport" descriptor here (Note: the pyruvate transportation method via the pyruvate translocase appears to be coupled to a proton gradient according to S. Papa et al., 1971, seemingly matching secondary active transport in definition). Alternative sources say "transport of pyruvate across the outer mitochondrial membrane appears to be easily accomplished via large non-selective channels such as voltage-dependent anion channels, which enable passive diffusion" and transport across inner mitochondrial membrane is mediated by mitochondrial pyruvate carrier 1 (MPC1) and mitochondrial pyruvate carrier 2 (MPC2). Upon entry into the mitochondrial matrix, the pyruvate is decarboxylated, producing acetyl-CoA (and carbon dioxide and NADH). This irreversible reaction traps the acetyl-CoA within the mitochondria (the acetyl-CoA can only be transported out of the mitochondrial matrix under conditions of high oxaloacetate via the citrate shuttle, a TCA intermediate that is normally sparse).
Sources: en.wikipedia.org
== Adverse effects == On May 12, 2016 the U.S. Food and Drug Administration advised that the serious, disabling and potentially permanent side effects associated with fluoroquinolone antibiotics (Cipro, Levaquin, Avelox, etc.) generally outweigh the benefits for patients with acute sinusitis, acute bronchitis, and uncomplicated urinary tract infections. These side effects can involve tendons, muscles, joints, nerves and the central nervous system as well as cardiac, dermatologic and worsening of myasthenia gravis conditions. With fluoroquinolones these effects are sometimes collectively called floxing.
=== Allegations of steroid use and National Baseball Hall of Fame === Bagwell was eligible for induction into the Baseball Hall of Fame for the first time in 2011. Speculation abounded that some baseball writers initially refrained from voting for Bagwell on the premise that he used performance-enhancing drugs, since most of his playing career took place during what is commonly referred to as "the steroid era." In spite of the speculation, as of 2016, no concrete evidence has surfaced linking him to the use of performance-enhancing drugs. However, one report indicates that he disclosed use of androstenedione to a Houston Chronicle reporter in 1998. At that time, neither the FDA nor MLB had banned its use. Bagwell has not been connected with any of the 104 positive samples in the 2003 survey tests that were leaked. Bagwell was not among the 89 players named in the Mitchell Report released in 2007. Longtime Atlanta Braves manager Bobby Cox said the following about Bagwell: "Jeff Bagwell was [in Houston] for so long and starred every year. For me a guy that dominated like that for one team, even in the league stats through the years. His are up there with anybody's. I would put him in right away. So he would get my vote on the first ballot." Still, in spite of the speculation that Bagwell used performance-enhancing drugs, San Francisco Chronicle sportswriter Bruce Jenkins wrote that Bagwell did not have the credentials to be in the Hall of Fame. In July 2015, he acknowledged "that many are suspicious of Bagwell—without proof, as you say.
== Vitamin B12 == Vitamin B12 plays an integral role in this reaction. Coenzyme B12 (adenosyl-cobalamin) is an organometallic form of vitamin B12 and serves as the cofactor of Methylmalonyl-CoA mutase, which is an essential enzyme in the human body. The transformation of Methylmalonyl-CoA to Succinyl-CoA by this enzyme is a radical reaction.
A biomaterial should perform its intended function within the living body without negatively affecting other bodily tissues and organs. In order to prevent unwanted organ and tissue interactions, biomaterials should be non-toxic. The toxicity of a biomaterial refers to the substances that are emitted from the biomaterial while in vivo. A biomaterial should not give off anything to its environment unless it is intended to do so. Nontoxicity means that biomaterial is: noncarcinogenic, nonpyrogenic, hypoallergenic, blood compatible, and noninflammatory. However, a biomaterial can be designed to include toxicity for an intended purpose. For example, application of toxic biomaterial is studied during in vivo and in vitro cancer immunotherapy testing. Toxic biomaterials offer an opportunity to manipulate and control cancer cells. One recent study states: "Advanced nanobiomaterials, including liposomes, polymers, and silica, play a vital role in the codelivery of drugs and immunomodulators. These nanobiomaterial-based delivery systems could effectively promote antitumor immune responses and simultaneously reduce toxic adverse effects." This is a prime example of how the biocompatibility of a biomaterial can be altered to produce any desired function.
Sources: en.wikipedia.org
The most common approach combines reverse-phase liquid chromatography with mass spectrometry. Chromatography separates the components while mass spectrometry confirms the molecular mass. Peptide sequencing or tandem mass analysis can further verify the amino acid order.
Lyophilized powder is usually kept frozen and protected from moisture. Solutions are less stable and are often used promptly or divided into aliquots to avoid repeated freeze-thaw cycles. Exact shelf-life values depend on purity and handling.
No. A purity figure derived from chromatographic area does not prove the amino acid sequence. Identity requires an orthogonal method such as mass spectrometry or sequencing. Truncated or isomerized peptides can co-elute with the target compound.
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.