Everything below concerns selank. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-03-14. Where a claim depends on a specific study, the study is described rather than over-claimed.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
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.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
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.
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.
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.
ΔG0 – empirically derived offset that in part corresponds to the overall loss of translational and rotational entropy of the ligand upon binding. ΔGhb – contribution from hydrogen bonding ΔGionic – contribution from ionic interactions ΔGlip – contribution from lipophilic interactions where |Alipo| is surface area of lipophilic contact between the ligand and receptor ΔGrot – entropy penalty due to freezing a rotatable in the ligand bond upon binding A more general thermodynamic "master" equation is as follows:
For instance, an arbitrarily chosen 50-nucleotide DNA fragment encoding for the Bos taurus (cattle) albumin mRNA was subjected to test-tube evolution to derive a catalytic DNA (a deoxyribozyme, also called a DNAzyme) with RNA-cleavage activity. After only a few weeks, a DNAzyme with significant catalytic activity had evolved. In general, DNA is much more chemically inert than RNA and hence much more resistant to obtaining catalytic properties. If in vitro evolution works for DNA it will happen much more easily with RNA. In 2022, Nick Lane and coauthors showed in a computational simulation that short RNA sequences could have been capable of catalyzing CO2 fixation which supported protocell replication and growth. Amino acid-RNA ligation The ability to conjugate an amino acid to the 3'-end of an RNA in order to use its chemical groups or provide a long-branched aliphatic sidechain. It has been suggested that amino acids may have initially been involved with RNA molecules as cofactors enhancing or diversifying their enzymatic capabilities, before evolving into more complex peptides. In today's world, this is most commonly seen in the form of aminoacyl-tRNA. Peptide bond formation The ability to catalyse the formation of peptide bonds between amino acids to produce short peptides or longer proteins. This is done in modern cells by ribosomes, a complex of several RNA molecules known as rRNA together with many proteins.
== Reactions == Menthol reacts in many ways like a normal secondary alcohol. It is oxidised to menthone by oxidising agents such as chromic acid, dichromate, or by calcium hypochlorite, in a green chemistry route. Under some conditions the oxidation using Cr(VI) compounds can go further and break open the ring. Menthol is easily dehydrated to give mainly 3-menthene, by the action of 2% sulfuric acid. Phosphorus pentachloride (PCl5) gives menthyl chloride.
(Silica aerogel is an especially good insulator because silica is also a poor conductor of heat; a metallic or carbon aerogel, on the other hand, would be less effective.) They are good convective inhibitors because air cannot circulate through the lattice. Aerogels are poor radiative insulators because infrared radiation (which transfers heat) passes through them. Owing to its hygroscopic nature, aerogel feels dry and acts as a strong desiccant. People handling aerogel for extended periods should wear gloves to prevent the appearance of dry brittle spots on their skin. The slight color it does have is due to Rayleigh scattering of the shorter wavelengths of visible light by the nano-sized dendritic structure. This causes it to appear smoky blue against dark backgrounds and yellowish against bright backgrounds. Aerogels by themselves are hydrophilic, and if they absorb moisture they usually suffer a structural change, such as contraction, and deteriorate, but degradation can be prevented by making them hydrophobic, via a chemical treatment. Aerogels with hydrophobic interiors are less susceptible to degradation than aerogels with only an outer hydrophobic layer, especially if a crack penetrates the surface.
Sources: en.wikipedia.org
=== Political grievances === Local authorities may also have become the focal point for more broad and abstract objections to the apartheid system. Boycott campaigns in 1983 and 1984 had sought to tie local grievances to the policies of the apartheid state, including the Koornhof reforms. On some accounts, attacks by protestors on the person and property of councillors and other state representatives was "a clear attack on apartheid symbols", while vigilantes' concern with rooting out collaborators reflected a similar concern with undermining the overall apartheid system. Some observers argued that, as the uprising continued, the strategies and aims of some participants changed, with many – particularly militant youth – setting their sights on the much larger goal of rendering the country "ungovernable" and, ultimately, that of dismantling apartheid through violence.
meiosis A specialized type of cell division that occurs exclusively in sexually reproducing eukaryotes, during which DNA replication is followed by two consecutive rounds of division to ultimately produce four genetically unique haploid daughter cells, each with half the number of chromosomes as the original diploid parent cell. Meiosis only occurs in cells of the sex organs, and serves the purpose of generating haploid gametes such as sperm, eggs, or spores, which are later fused during fertilization. The two meiotic divisions, known as Meiosis I and Meiosis II, may also include various genetic recombination events between homologous chromosomes.
Antineoplastic agents – Substances that inhibit or prevent the proliferation of neoplasms. Antisickling agents – Agents used to prevent or reverse the pathological events leading to sickling of erythrocytes in sickle cell conditions. Nucleic acid synthesis inhibitors – Compounds that inhibit cell production of DNA or RNA. Enzyme inhibitors – Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction. Cytochrome P-450 CYP2D6 inhibitors – Agents that inhibit one of the most important enzymes involved in the metabolism of xenobiotics in the body, CYP2D6, a member of the cytochrome P450 mixed oxidase system.
At least 19 people were killed and 54 others were injured in a Russian airstrike on a hypermarket and other locations in Kharkiv. Russia claimed to have taken the village of Arkhanhelske, north of Donetsk and near Ocheretyne. Ukrainian forces claimed to have shot down a Russian Su-25 jet over Donetsk Oblast using anti-aircraft guns. Russian officials claimed that four people were injured in Ukrainian air attacks in Belgorod Oblast. According to the regional governor, Vyacheslav Gladkov, four people, including a child, were killed in the villages of Dubovoye and Oktyabrsky by Ukrainian shelling and rockets. Several homes were damaged by shelling in Shebekino. Russian air defences also intercepted 29 drones over the oblast, plus another in Kursk Oblast.
=== By choosing the best age === Because of the intrinsic uncertainties within the three yield U-Pb ages (207Pb/235U, 206Pb/238U and 207Pb/206Pb), the age at ~1.4 Ga has the poorest resolution. An overall consensus for age with higher accuracy is to adopt:
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Several assumptions were made in the formulation of these equations: First, an individual in the population must be considered as having an equal probability as every other individual of contracting the disease with a rate of
=== September === 1 September: New government rules restricting the tethering of dogs, particularly puppies or pregnant dogs, come into force. Strong winds down trees and damage powerlines and property in Auckland, Waikato and the Bay of Plenty. MetService issues several weather watches including a strong wind warning for Stewart Island. Judge Brooke Gibson of the Auckland District Court imposes a record fine of NZ$2.25 million on Jetstar NZ for breaching the Fair Trading Act 1986 by misleading customers about compensation. Prime Minister Christopher Luxon confirms the Government will amend the Overseas Investment Amendment Act 2018 to allow investor visa holders to buy homes with a minimum value of NZ$5million. Regional Development Minister Shane Jones confirms that the Government will allocate NZ$30 million worth of loans to supporting regional airlines. 2 September: Nurses affiliated with the New Zealand Nurses Organisation launch rolling 48-hour strikes on 2 and 4 September to protest understaffing and government cost-cutting measures. Furniture and electronics retailer Smiths City goes into voluntary administration and temporarily closes all stores. Police extend Levin's "Gang Conflict Warrant" to cover the Manawatū District following two shooting incidents targeting Police in Palmerston North. 3 September – Disabilities Issues Minister Louise Upston announces that the Government will reform the disability support system, with changes being rolled out in 2026.
== Ion exchange SPE == Ion exchange sorbents separate analytes based on electrostatic interactions between the analyte of interest and the positively or negatively charged groups on the stationary phase. For ion exchange to occur, both the stationary phase and sample must be at a pH where both are charged.
5S rRNA is transcribed by RNA polymerase III. The 18S rRNA in most eukaryotes is in the small ribosomal subunit, and the large subunit contains three rRNA species (the 5S, 5.8S and 28S in mammals, 25S in plants, rRNAs). In flies, the large subunit contains four rRNA species instead of three with a split in the 5.8S rRNA that presents a shorter 5.8S subunit (123 nt) and a 30 nucleotide subunit named the 2S rRNA. Both fragments are separated by an internally transcribed spacer of 28 nucleotides. Since the 2S rRNA is small and highly abundant, its presence can interfere with construction of sRNA libraries and compromise the quantification of other sRNAs. The 2S subunit is retrieved in fruit fly and dark-winged fungus gnat species but absent from mosquitoes. The tertiary structure of the small subunit ribosomal RNA (SSU rRNA) has been resolved by X-ray crystallography. The secondary structure of SSU rRNA contains 4 distinct domains—the 5', central, 3' major and 3' minor domains. A model of the secondary structure for the 5' domain (500-800 nucleotides) is shown.
Richard Laurence Millington Synge (28 October 1914 – 18 August 1994) was an English biochemist, and shared the 1952 Nobel Prize in Chemistry for the invention of partition chromatography with Archer Martin.
Sources: en.wikipedia.org
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.