A practical reference on heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-07-10. Anything still debated is marked as such rather than presented as settled.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analog of the tetrapeptide tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Reported consistently across pharmacopoeial descriptions |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| Solubility | Freely soluble in water | Aqueous buffers; poor in nonpolar solvents |
| Typical storage temperature | -20 degrees Celsius | Lyophilized powder; protect from moisture |
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.
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.
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.
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== Bibliography == Touati, Sylvie (1976). Discrimination en France à l'égard des femmes dans l'emploi [Discrimination against women in employment in France] (in French). Mémoire DES. Boutillier, Sophie; Lestrade, Brigitte (2004). Le travail des femmes: axes d'émancipation [Women's work: paths to empowerment] (in French). Harmattan. Cova, A (1997). Maternité et droits des femmes en France, XIXe et XXe siècles [Motherhood and women's rights in France, 19th and 20th centuries] (in French). Paris: Anthropos. Milewski, Françoise; Périvier, Hélène (2011). Les discriminations entre les femmes et les hommes [Discrimination between women and men] (in French). Les Presses de Sciences Po. Fortino, Sabine (1999). "De la ségrégation sexuelle des postes à la mixité au travail : étude d'un processus" [From gender segregation in the workplace to gender diversity: a study of a process]. Sociologie du Travail (in French). 41 (4): 363–384. Maruani, Margaret (2011). Travail et emploi des femmes [Women's work and employment] (in French). La Découverte. Moreau, Marie-Pierre (2011). Les enseignants et le genre [Teachers and gender] (in French). Presses Universitaires de France.
=== Clinical attachment level === The clinical attachment level (CAL) combines the measurements of probing pocket depth and any gingival recession to give an overall indication of where the periodontal tissues attach to the root surface. It is measured from a constant reference point, usually the CEJ, to the base of the periodontal pocket. Due to the more stable and reproducible property, this is considered the best measure of changes in residual periodontal support over time.
To find the most effective pharmaceutical drug treatment, the dosages of medications must often be adjusted, different combinations of antidepressants tried, or antidepressants changed. Some of the medications have side effects that affect certain people in different ways. The combinations of medication can change these side effects, so it is essential to monitor the changes that occur once we begin medication.
Helium II is a superfluid, a quantum mechanical state of matter with strange properties. For example, when it flows through capillaries as thin as 10 to 100 nm it has no measurable viscosity. However, when measurements were done between two moving discs, a viscosity comparable to that of gaseous helium was observed. Existing theory explains this using the two-fluid model for helium II. In this model, liquid helium below the lambda point is viewed as containing a proportion of helium atoms in a ground state, which are superfluid and flow with exactly zero viscosity, and a proportion of helium atoms in an excited state, which behave more like an ordinary fluid. In the fountain effect, a chamber is constructed which is connected to a reservoir of helium II by a sintered disc through which superfluid helium leaks easily but through which non-superfluid helium cannot pass. If the interior of the container is heated, the superfluid helium changes to non-superfluid helium. In order to maintain the equilibrium fraction of superfluid helium, superfluid helium leaks through and increases the pressure, causing liquid to fountain out of the container. The thermal conductivity of helium II is greater than that of any other known substance, a million times that of helium I and several hundred times that of copper. This is because heat conduction occurs by an exceptional quantum mechanism. Most materials that conduct heat well have a valence band of free electrons which serve to transfer the heat. Helium II has no such valence band but nevertheless conducts heat well.
Sources: en.wikipedia.org
Graphite oxides absorb moisture in proportion to humidity and swell in liquid water. The amount of water absorbed by graphite oxides depends on the particular synthesis method and shows a strong temperature dependence. Brodie graphite oxide selectively absorbs methanol from water/methanol mixtures in a certain range of methanol concentrations. Membranes prepared from graphite oxides (recently more often called "graphene oxide" membranes) are vacuum tight and impermeable to nitrogen and oxygen, but are permeable to water vapors. The membranes are also impermeable to "substances of lower molecular weight". Permeation of graphite and graphene oxide membranes by polar solvents is possible due to swelling of the graphite oxide structure. The membranes in swelled state are also permeable by gases, e.g. helium. Graphene oxide sheets are chemically reactive in liquid water, leading them to acquire a small negative charge. The interlayer distance of dried graphite oxides was reported as ~6–7 Å but in liquid water it increases up to 11–13 Å at room temperature. The lattice expansion becomes stronger at lower temperatures. The inter-layer distance in diluted NaOH reached infinity, resulting in dispersion of graphite oxide into single-layered graphene oxide sheets in solution. Graphite oxide can be used as a cation exchange membrane for materials such as KCl, HCl, CaCl2, MgCl2, BaCl2 solutions. The membranes were permeable by large alkali ions as they are able to penetrate between graphene oxide layers.
Scottish Labour suspends Wilma Brown, its parliamentary candidate for Cowdenbeath and Kirkcaldy, following reports she liked racist and Islamophobic posts on social media. 11 April – The Department for Science, Innovation and Technology says that the legal fees for Michelle Donelan came to over £19,000. Sally Bunce, the Green Party candidate for Mayor of the Tees Valley in the May election, drops out of the contest saying she does not want to split the vote against the Conservative candidate. Reform UK apologise to the family of their dropped candidate for York Central Tommy Cawkwell for "inactivity" not knowing that he had died. Joe Haines and Lord Donoughue, who were two of Harold Wilson's advisers during his time as prime minister, tell The Times that Wilson had an affair with his deputy press secretary, Janet Hewlett-Davies, during the 1970s. Mid and East Antrim Borough Council is refused permission to rename its town hall complex after the late Queen Elizabeth II. 12 April – Greater Manchester Police launch an investigation into Labour's deputy leader, Angela Rayner, over the sale of her council house amid allegations she broke electoral law by giving false information about her place of residence. Rayner pledges to step down if she is found guilty of any crime. Keir Starmer says that if elected to government, Labour will raise defence spending to 2.5% of GDP. He also makes an "unshakable" commitment to nuclear weapons.
Furthermore, the rate of plutonium elimination in the excreta differed between species of animals by as much as a factor of five. Such variation made it extremely difficult to estimate what the rate would be for human beings.
1900 marked the so-called rediscovery of Mendel by Carl Correns, who arrived at Mendel's laws (which were not actually present in Mendel's work). Soon after, cytologists (cell biologists) proposed that chromosomes were the hereditary material. This was taken up by Carl Correns and others between 1910 and 1915 as the "Mendelian-chromosome theory" of heredity. Thomas Hunt Morgan and the "Drosophilists" in his fly lab applied this to a new model organism. They hypothesized crossing over to explain linkage and constructed genetic maps of the fruit fly Drosophila melanogaster, which became a widely used model organism. Hugo de Vries tried to link the new genetics with evolution; building on his work with heredity and hybridization, he proposed a theory of mutationism, which was widely accepted in the early 20th century. Lamarckism, or the theory of inheritance of acquired characteristics also had many adherents. Darwinism was seen as incompatible with the continuously variable traits studied by biometricians, which seemed only partially heritable. In the 1920s and 1930s—following the acceptance of the Mendelian-chromosome theory— the emergence of the discipline of population genetics, with the work of R.A. Fisher, J.B.S. Haldane and Sewall Wright, unified the idea of evolution by natural selection with Mendelian genetics, producing the modern synthesis. The inheritance of acquired characters was rejected, while mutationism gave way as genetic theories matured.
Sources: en.wikipedia.org
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.
The first four residues of Selank reproduce the tuftsin sequence Thr-Lys-Pro-Arg. A Pro-Gly-Pro extension at the C-terminus was added to slow enzymatic breakdown and extend residence time.
It holds marketing authorization in Russia, where nasal drop formulations are sold. No equivalent approval exists in the European Union, the United States, or most other countries.
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.