If you have been reading about Heptapeptide 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.
Last reviewed on 2026-05-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
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.
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.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
In the 337 participants with non-small cell lung cancer, the median age was 56 years (range: 26 to 83); 56% female; 76% Asian, 15% White, 0.6% Black or African American, 8% unknown or other races; and 1.8% were of Hispanic or Latino ethnicity. The number of participants representing efficacy findings differs from the number of participants representing safety findings due to different groups of study participants analyzed for efficacy and safety. The FDA granted the application for taletrectinib priority review, breakthrough therapy, and orphan drug designations.
Free movement of capital was traditionally seen as the fourth freedom, after goods, workers and persons, services and establishment. The original Treaty of Rome required that restrictions on free capital flows only be removed to the extent necessary for the common market. From the Treaty of Maastricht, now in TFEU article 63, "all restrictions on the movement of capital between Member States and between Member States and third countries shall be prohibited". This means capital controls of various kinds are prohibited, including limits on buying currency, limits on buying company shares or financial assets, or government approval requirements for foreign investment. By contrast, taxation of capital, including corporate tax, capital gains tax and Financial transaction tax are not affected so long as they do not discriminate by nationality. According to the Capital Movement Directive 1988, Annex I, 13 categories of capital which must move free are covered. In Baars v Inspecteur der Belastingen Particulieren the Court of Justice held that for investments in companies, the capital rules, rather than freedom of establishment rules, were engaged if an investment did not enable a "definite influence" through shareholder voting or other rights by the investor. That case held a Dutch Wealth Tax Act 1964 unjustifiably exempted Dutch investments, but not Mr Baars' investments in an Irish company, from the tax: the wealth tax, or exemptions, had to be applied equally.
In August, the Federal Police (PF) launched Operations Carbono Oculto, Quasar and Tank against a multibillion-real scheme of fraud in the fuel sector and money laundering, revealing that the First Capital Command (PCC) and companies in the financial market used fintechs and transactions via PIX to move and conceal large sums. According to the investigation, the absence of oversight, intensified by the disinformation that circulated on social media about the new Federal Revenue Service oversight rule that would be implemented at the beginning of the year but was revoked due to fake news, facilitated the criminal group's activity. Later, deputies requested the investigation of Nikolas over the video in which he criticized the new oversight of financial movements via Pix."These fake news were so strong that, despite all the effort of the Federal Revenue Service, we could not overcome these lies, because of the strength of those who boosted them. [...] And today's operations show who gained from these lies, from these fake news". — Robinson Barreirinhas, special secretary of the Federal Revenue Service.
The two substrates of this enzyme are 4-phospho-D-erythronic acid and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are (R)-3-hydroxy-2-oxo-4-phosphonooxybutanoic acid, reduced NADH, and a proton. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 4-phospho-D-erythronate:NAD+ 2-oxidoreductase. Other names in common use include PdxB, PdxB 4PE dehydrogenase, and 4-O-phosphoerythronate dehydrogenase. This enzyme participates in vitamin B6 metabolism.
Sources: en.wikipedia.org
== Separation of technetium-99 == Several methods have been proposed for technetium-99 separation, including crystallization, liquid-liquid extraction, molecular recognition methods, volatilization, and others. In 2012 the crystalline compound Notre Dame Thorium Borate-1 (NDTB-1) was presented by researchers at the University of Notre Dame. It can be tailored to safely absorb radioactive ions from nuclear waste streams. Once captured, the radioactive ions can then be exchanged for higher-charged species of a similar size, recycling the material for re-use. Lab results using the NDTB-1 crystals removed approximately 96 percent of technetium-99.
== Biochemistry == A1 receptors are implicated in sleep promotion by inhibiting wake-promoting cholinergic neurons in the basal forebrain. A1 receptors are also present in smooth muscle throughout the vascular system. In humans, the adenosine A1 receptor has been found to be most highly expressed in the brain, with lower expression in other tissues such as the testis, pancreas, and heart.
When Winston Churchill became Prime Minister in 1940, he bypassed the War Office altogether, and appointed himself Minister of Defence (though there was, curiously, no ministry of defence until 1947). Clement Attlee continued this arrangement when he came to power in 1945, but appointed a separate Minister of Defence for the first time in 1947. In 1964, the present form of the Ministry of Defence was established, unifying the War Office, Admiralty, and Air Ministry.
Sources: en.wikipedia.org
=== Protection === The lungs possess several characteristics which protect against infection. The respiratory tract is lined by respiratory epithelium or respiratory mucosa, with hair-like projections called cilia that beat rhythmically and carry mucus. This mucociliary clearance is an important defence system against air-borne infection. The dust particles and bacteria in the inhaled air are caught in the mucosal surface of the airways, and are moved up towards the pharynx by the rhythmic upward beating action of the cilia. The lining of the lung also secretes immunoglobulin A which protects against respiratory infections; goblet cells secrete mucus which also contains several antimicrobial compounds such as defensins, antiproteases, and antioxidants. The size of the respiratory tract and the flow of air also protect the lungs from larger particles. Smaller particles deposit in the mouth and behind the mouth in the oropharynx, and larger particles are trapped in nasal hair after inhalation.
== Signs and symptoms == Individuals with GAMT deficiency appear normal at birth with the current hypothesis of trans-placental creatine transport allowing in utero treatment. Shortly after birth, infants may start to show signs, as the consequences of decreased creatine levels in their body become more apparent. Symptoms generally begin during early infancy (3–6 months) to age two years. These clinical findings are relatively non-specific and do not immediately suggest a disorder of creatine metabolism. The most consistent clinical manifestation is developmental delay or intellectual disability, which is observed in all affected individuals, and can range from mild to severe. Most individuals have severe developmental delay or intellectual disability (50-75%). The next most consistent symptom is a behavior disorder, such as hyperactivity, autism, or self-injurious behavior, reported in 75% of GAMT deficient individuals. The third most consistent symptom is seizures, reported in more than 70% of affected individuals. Additional symptoms include movement disorders, such as chorea, athetosis, dystonia or ataxia, observed in about 30% of GAMT patients.
represent the country at home and abroad appoint and recall heads of diplomatic and consular missions receive letters of credence and recall from foreign diplomatic representatives confer medals and other decorations promulgate laws passed by the Parliament call for parliamentary elections In 2003, the powers of the president were extended to include the right to chair the Council of Ministers and propose the composition of the Council of Ministers to the parliament, effectively merging the powers of the head of government into the office. However, although the president became de jure both head of state and head of government, his role was largely limited because all the institutions were indirectly elected by confederal parliament, which was itself elected by parliaments of member states.
Sources: en.wikipedia.org
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.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.