This is a working overview of Selank, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-04-07. Anything still debated is marked as such rather than presented as settled.
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.
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.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
| Property | Value | Notes |
|---|---|---|
| Solubility | Freely soluble in water | Also in aqueous buffers |
| Typical purity (HPLC) | 95 percent or higher | Lot-dependent |
| Dry powder storage | Minus 20 degrees Celsius | Sealed, dry, protected from light |
| Solution storage | 2 to 8 degrees Celsius | Short-term use |
| Identity confirmation | Mass spectrometry | ESI or MALDI-TOF |
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
Considering all decay modes, various models indicate a shift of the center of the island (i.e., the longest-living nuclide) from 298Fl to a lower atomic number, and competition between alpha decay and spontaneous fission in these nuclides; these include 100-year half-lives for 291Cn and 293Cn, a 1000-year half-life for 296Cn, a 300-year half-life for 294Ds, and a 3500-year half-life for 293Ds, with 294Ds and 296Cn exactly at the N = 184 shell closure. It has also been posited that this region of enhanced stability for elements with 112 ≤ Z ≤ 118 may instead be a consequence of nuclear deformation, and that the true center of the island of stability for spherical superheavy nuclei lies around 306Ubb (Z = 122, N = 184). This model defines the island of stability as the region with the greatest resistance to fission rather than the longest total half-lives; the nuclide 306Ubb is still predicted to have a short half-life with respect to alpha decay. The island of stability for spherical nuclei may also be a "coral reef" (i.e., a broad region of increased stability without a clear "peak") around N = 184 and 114 ≤ Z ≤ 120, with half-lives rapidly decreasing at higher atomic number, due to combined effects from proton and neutron shell closures. Another potentially significant decay mode for the heaviest superheavy elements was proposed to be cluster decay by Romanian physicists Dorin N. Poenaru and Radu A. Gherghescu and German physicist Walter Greiner.
In 1386, Grand Duke Jogaila of Lithuania converted to Catholicism and married Queen Jadwiga of Poland. This act enabled him to become a king of Poland himself, and he ruled as Władysław II Jagiełło until his death in 1434. The marriage established a personal Polish–Lithuanian union ruled by the Jagiellonian dynasty. The first in a series of formal "unions" was the Union of Krewo of 1385, whereby arrangements were made for the marriage of Jogaila and Jadwiga. The Polish–Lithuanian partnership brought vast areas of Ruthenia controlled by the Grand Duchy of Lithuania into Poland's sphere of influence and proved beneficial for the nationals of both countries, who coexisted and cooperated in one of the largest political entities in Europe for the next four centuries. When Queen Jadwiga died in 1399, the Kingdom of Poland fell to her husband's sole possession. In the Baltic Sea region, Poland's struggle with the Teutonic Knights continued and culminated in the Battle of Grunwald (1410), a great victory that the Poles and Lithuanians were unable to follow up with a decisive strike against the main seat of the Teutonic Order at Malbork Castle. The Union of Horodło of 1413 further defined the evolving relationship between the Kingdom of Poland and the Grand Duchy of Lithuania. The privileges of the szlachta (nobility) kept expanding and in 1425 the rule of Neminem captivabimus, which protected the noblemen from arbitrary royal arrests, was formulated.
== Future == In May 2022, The Hollywood Reporter confirmed that Åkerlund would return to direct another film adaptation, The Black Kaiser, which its producers said would not be "a sequel or a prequel". Mikkelsen was set to reprise his role and co-write the screenplay with Jayson Rothwell, though it was later reported that only Rothwell was writing the film. One year later, Variety reported that Derrick Borte had replaced Åkerlund as director and that Hudgens would appear in the film. Filming was set to begin in the third quarter of 2023.
El Niño conditions are established when the Walker circulation weakens or reverses and the Hadley circulation strengthens, leading to the development of a band of warm ocean water in the central and east-central equatorial Pacific (approximately between the International Date Line and 120°W), including the area off the west coast of South America, as upwelling of cold water occurs less or not at all offshore. This warming causes a shift in the atmospheric circulation, leading to higher air pressure in the western Pacific and lower in the eastern Pacific, with rainfall reducing over Indonesia, India and northern Australia, while rainfall and tropical cyclone formation increases over the tropical Pacific Ocean. The low-level surface trade winds, which normally blow from east to west along the equator, either weaken or start blowing from the other direction. El Niño phases are known to happen at irregular intervals of two to seven years, and lasts nine months to two years. The average period length is five years. When this warming occurs for seven to nine months, it is classified as El Niño "conditions"; when its duration is longer, it is classified as an El Niño "episode".
A helix has an overall dipole moment due to the aggregate effect of the individual microdipoles from the carbonyl groups of the peptide bond pointing along the helix axis. The effects of this macrodipole are a matter of some controversy. α-helices often occur with the N-terminal end bound by a negatively charged group, sometimes an amino acid side chain such as glutamate or aspartate, or sometimes a phosphate ion. Some regard the helix macrodipole as interacting electrostatically with such groups. Others feel that this is misleading and it is more realistic to say that the hydrogen bond potential of the free NH groups at the N-terminus of an α-helix can be satisfied by hydrogen bonding; this can also be regarded as set of interactions between local microdipoles such as C=O···H−N.
Sources: en.wikipedia.org
and Using the author's own notation, if an enzyme has h {\displaystyle h} sites that can bind ligand, the form, in the general case, can be shown to be: v = V f σ ( 1 − ρ ) ( σ + π ) h − 1 1 + ( σ + π ) h {\displaystyle v={\frac {V_{f}\sigma (1-\rho )(\sigma +\pi )^{h-1}}{1+(\sigma +\pi )^{h}}}} The non-cooperative reversible Michaelis-Menten equation can be seen to emerge when we set the Hill coefficient to one. If the enzyme is irreversible the equation turns into the simple Michaelis-Menten equation that is irreversible. When setting the equilibrium constant to infinity, the equation can be seen to revert to the simpler case where the product inhibits the reverse step. A comparison has been made between the MWC and reversible Hill equation. A modification of the reversible Hill equation was published by Westermark et al where modifiers affected the catalytic properties instead. This variant was shown to provide a much better fit for describing the kinetics of muscle phosphofructokinase.
Bruce Glick grew up in Pittsburgh, Pennsylvania and was interested in birds as a child. His father, Peter Glick, was the Secretary of Labor for Pennsylvania. Glick served in World War II. He went to Rutgers University and studied birds majoring in poultry science, graduating in 1951. In 1950 he married Kay McCall. He received an M.S. degree from the University of Massachusetts in genetics in 1952 and attended Ohio State University as a Ph.D. student, graduating with a PhD in physiology in 1955. While there, he worked on determining the purpose of the Bursa of Fabricius, a gland that he was able to remove from a goose without any apparent effect. A fellow graduate student, Timothy Chang, worked with Glick's geese in a different study, and noticed that the birds without the Bursa of Fabricius did not produce expected antibodies. Glick and Chang wrote up the results of this study and were unable to get it published in Science, so it was published in Poultry Science in 1956. Their publication, considered a landmark paper, is one of the most cited works from Poultry Science.
There have been a few cases of exposure to americium, the worst case being that of Harold McCluskey, a chemical operations technician who at the age of 64 was exposed to 500 times the occupational standard for americium-241 as a result of an explosion in his lab. McCluskey died at the age of 75 of unrelated pre-existing disease.
== Medical use == It is used to treat both type 1 and type 2 diabetes. A recent Cochrane systematic review also compared the effects of insulin detemir to NPH insulin and other insulin analogues (insulin glargine, insulin degludec) in both children and adults with Type 1 diabetes. With respect to blood sugar management, it appears to work better than NPH insulin, however this finding was inconsistent across included and previous studies. In the same systematic review no other clinically significant differences were found between different insulin analogues in either adults nor children.
== History == The first definition of the term bioinformatics was coined by Paulien Hogeweg and Ben Hesper in 1970, to refer to the study of information processes in biotic systems. This definition placed bioinformatics as a field parallel to biochemistry (the study of chemical processes in biological systems). Bioinformatics and computational biology involved the analysis of biological data, particularly DNA, RNA, and protein sequences. The field of bioinformatics experienced explosive growth starting in the mid-1990s, driven largely by the Human Genome Project and by rapid advances in DNA sequencing technology. Analyzing biological data to produce meaningful information involves writing and running software programs that use algorithms from graph theory, artificial intelligence, soft computing, data mining, image processing, and computer simulation. The algorithms in turn depend on theoretical foundations such as discrete mathematics, control theory, system theory, information theory, and statistics.
Sources: en.wikipedia.org
In December 1959, the South African government announced that it would forcibly relocate all residents of Old Location, a black neighbourhood located near Windhoek's city center, in accordance with apartheid legislation. SWANU responded by organising mass demonstrations and a bus boycott on 10 December. In the ensuing confrontation South African police opened fire, killing eleven protestors. After the Old Location incident, the OPO split from SWANU, citing differences with the organisation's Herero leadership. Because the UN and potential foreign supporters reacted sensitively to any implications of tribalism and had favoured SWANU for its claim to represent the South West African people as a whole, the OPO renamed itself the South West African People's Organisation. It later opened its ranks to all South West Africans sympathetic to its aims.
multicellular Composed of more than one cell. The term is used especially to describe organisms or tissues consisting of many cells descendant from the same original parent cell which work together in an organized way, but may also describe groups of nominally single-celled organisms such as protists and bacteria which live symbiotically with each other in large colonies. Contrast unicellular.
=== Analogues === Retigabine is a bioisostere of flupirtine in which the pyridine ring has been replaced with a phenyl ring. Azetukalner (encukalner), pynegabine, and fluoxakalner are also analogues of flupirtine and retigabine.
== Connection to nitrogen storage in Cyanobacteria == Cyanophycin is highly resistant to degradation by all conventional proteases, and the only enzyme known to be capable of hydrolyzing it is cyanophycinase. Cyanophycin is a non-ribosomally synthesized peptidyl polymer that is used for nitrogen storage by cyanobacteria and other select eubacteria. Approximately 90% of cyanobacteria are diazotrophic, meaning that they can grow without an external source of fixed nitrogen. Diazotrophic growth was severely impaired in bacteria with a mutated cyanophycinase gene, indicating that the inability to degrade cyanophycin is detrimental for the diazotrophic growth of the cyanobacterium, due to an excess of nitrogen storage.
Sources: en.wikipedia.org
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.
Freeze-dried material is kept frozen, often at minus 20 degrees Celsius, and protected from light and moisture. Dissolved peptide is refrigerated for short-term use. Repeated freeze-thaw cycles are avoided.
A certificate of analysis typically lists purity by HPLC, the confirmed mass, appearance, and sometimes water or counter-ion content. It documents results for a specific batch. Details vary by supplier.
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.