If you have been reading about amino acid sequence and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-07-07. Numbers and descriptions here follow the published literature rather than marketing material.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
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 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.
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.
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=== Dental syringes === A dental syringe is used by dentists for the injection of an anesthetic. It consists of a breech-loading syringe fitted with a sealed cartridge containing an anesthetic solution. In 1928, Bayer Dental developed, coined and produced a sealed cartridge system under the registered trademark Carpule®. The current trademark owner is Kulzer Dental GmbH. The carpules have long been reserved for anesthetic products for dental use. It is practically a bottomless flask. The latter is replaced by an elastomer plug that can slide in the body of the cartridge. This plug will be pushed by the plunger of the syringe. The neck is closed with a rubber cap. The dentist places the cartridge directly into a stainless steel syringe, with a double-pointed (single-use) needle. The tip placed on the cartridge side punctures the capsule and the piston will push the product. There is therefore no contact between the product and the ambient air during use. The ancillary tool (generally part of a dental engine) used to supply water, compressed air or mist (formed by combination of water and compressed air) to the oral cavity for the purpose of irrigation (cleaning debris away from the area the dentist is working on), is also referred to as a dental syringe or a dental irrigation nozzle. A 3-way syringe/nozzle has separate internal channels supplying air, water or a mist created by combining the pressurized air with the waterflow. The syringe tip can be separated from the main body and replaced when necessary.
=== Rapid Gold BCA === This type of BCA assay seems to only be available from Thermo Fisher Scientific. Reportedly it uses "the same copper reduction method as the traditional BCA Protein Assay with a unique [proprietary] copper chelator.", that absorbs at 480 nm instead of 562 nm. This proprietor chelator and presumed optimized Biuret reaction formulation allows the assay to provide rapid (<5 min) results without the 37˚C+ incubation of the original BCA assay. However, the assay has a different interference profile from other non-protein components. The Pierce Quantitative Colorimetric Peptide Assay (now owned by and available from Thermo Fisher Scientific) appears to use a similar or identical 480 nm absorbing proprietary copper chelator.
In digital circuits and machine learning, a one-hot is a group of bits among which the legal combinations of values are only those with a single high (1) bit and all the others low (0). A similar implementation in which all bits are '1' except one '0' is sometimes called one-cold. In statistics, dummy variables represent a similar technique for representing categorical data.
== Life == Micah True was born Michael Randall Hickman in Oakland, California, the son of a Korean War Marine Corps Gunnery Sergeant and the second of four children. He grew up traveling the country as his family relocated to various nationally located Marine Corps bases. His family was conservative Roman Catholic, but True aligned himself with the counter-culture movement of the 1960s and 70s. True attended Humboldt State University, where he studied Eastern religions and Native American history. To earn money he began prizefighting in informal boxing bouts, using the name "Gypsy Cowboy," and perhaps taking the occasional dive for an easy payday. Between 1974 and 1982, Hickman was a professional middleweight boxer, fighting under the name Mike "True" Hickman. His career record was 9 wins (KO 2), 11 losses (KO 9), and 0 draws. At some point True spent 10 months living in a cave in Hawaii where he fell in love with a rich girl. It was when she left him, he said, that he took up long-distance running. He also changed his name from Michael Hickman to Micah True. (The name Micah comes from the Bible, while True came from the name of a beloved pet: True Dog.) By 1982, True had moved to Boulder, Colorado, where he began working as a self-employed furniture mover. By then he had become a "trailrunning bum" (like a "surfing bum or a climbing bum"). For almost 20 years, he spent winters running in Mexico, Guatemala, and Central America, averaging 170 miles (270 km) per week. He would return to Boulder during the summers to earn enough money to live on the rest of the year.
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== History == Cold hemagglutination was first reported by Landsteiner in 1903 and found to occur in human beings in 1918. The association of cold hemagglutination with hemolysis was described in 1937 by Rosenthal and Corten. During the 1960s, Dacie and Schubothe published systematic descriptions of 16 CAD patients each. The auto antibodies responsible for hemagglutination at low temperatures, cold agglutinins (CA), may be found in the sera of healthy subjects as well as in patients with AIHA of the cold reactive types. CA bind to erythrocyte surface antigens at a temperature optimum of 0–4 °C. In contrast to polyclonal CA in healthy individuals, monoclonal CA often have a high-thermal amplitude, which contributes to their pathogenicity at temperatures approaching 37 °C. Binding of CA causes agglutination of erythrocytes and the antigen–antibody complex induces complement (C) activation and hemolysis. Essential clinical manifestations of primary CAD are hemolytic anemia and cold-induced circulatory symptoms. Exact estimates of the severity of anemia and the frequency of cold-induced symptoms, however, have not been provided until recent years.
1985 Goldenes Ehrenzeichen, Republic of Austria 1994 Austrian Decoration for Science and Art, Republic of Austria 1997 Honorary Member, Slovak Chemical Society 2003 Cross of Merits, State of Tyrol 2004 Cross of Merits, Austria 2007 Cross of Honours in Science and Arts first class, Republic of Austria 2008 Jan-Weber-Medal of the Slovak Pharmaceutical Society 2010 Sitara-e-Qaid-i-Azam (Civil decoration of Pakistan) 2011 Knight Grand Cross (First Class of The Most Exalted Order of the White Elephant with Slash) According to the Theoretical Chemistry Genealogy Project, Bernd Michael Rode is the most successful doctoral thesis supervisor of German-speaking countries in the field of Theoretical Chemistry. Between 1976 and 2011 Prof. Rode has led not less than 70 students to their Ph.D. degree. Due to his close contacts to South-East-Asia many of them come from Asian countries.
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== Discovery == Flavoproteins were first mentioned in 1879, when they isolated as a bright-yellow pigment from cow's milk. They were initially termed lactochrome. By the early 1930s, this same pigment had been isolated from a range of sources, and recognised as a component of the vitamin B complex. Its structure was determined and reported in 1935 and given the name riboflavin, derived from the ribityl side chain and yellow colour of the conjugated ring system. The first evidence for the requirement of flavin as an enzyme cofactor came in 1935. Hugo Theorell and coworkers showed that a bright-yellow-coloured yeast protein, identified previously as essential for cellular respiration, could be separated into apoprotein and a bright-yellow pigment. Neither apoprotein nor pigment alone could catalyse the oxidation of NADH, but mixing of the two restored the enzyme activity. However, replacing the isolated pigment with riboflavin did not restore enzyme activity, despite being indistinguishable under spectroscopy. This led to the discovery that the protein studied required not riboflavin but flavin mononucleotide to be catalytically active. Similar experiments with D-amino acid oxidase led to the identification of flavin adenine dinucleotide (FAD) as a second form of flavin utilised by enzymes.
transactinides Also superheavy elements. In the periodic table, the set of chemical elements with an atomic number greater than 103, i.e. those heavier than the actinides. The transactinides are a subset of the transuranic elements.
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Sources: en.wikipedia.org
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
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.