Heptapeptide is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2025-08-26. Where a claim depends on a specific study, the study is described rather than over-claimed.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
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.
| Property | Value | Notes |
|---|---|---|
| Primary route studied | Intranasal | Also examined parenterally in animal work |
| Reported plasma half-life | Minutes to tens of minutes | Values vary widely between reports |
| Main model systems | Rodent behavioural and cell assays | Human trials are few and small |
| Principal proposed targets | GABA-A receptor, GABA transaminase | Monoamine and neurotrophic pathways also reported |
| Evidence grade | Preliminary | Limited independent replication |
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.
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.
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.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
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.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
== PAHs generation == Polycyclic aromatic hydrocarbons (PAHs) can be generated from the pyrolysis of different solid waste fractions, such as hemicellulose, cellulose, lignin, pectin, starch, polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). PS, PVC, and lignin generate significant amount of PAHs. Naphthalene is the most abundant PAH among all the polycyclic aromatic hydrocarbons. When the temperature is increased from 500 to 900 °C, most PAHs increase. With increasing temperature, the percentage of light PAHs decreases and the percentage of heavy PAHs increases.
=== Motivational disorders === Levodopa has been found to increase the willingness to exert effort for rewards in humans and hence appears to show pro-motivational effects. Other dopaminergic agents have also shown pro-motivational effects and may be useful in the treatment of motivational disorders.
Significant 6d involvement is expected in the Nh–Au bond, although it is expected to be more unstable than the Tl–Au bond and entirely due to magnetic interactions. This raises the possibility of some transition metal character for nihonium. On the basis of the small energy gap between the 6d and 7s electrons, the higher oxidation states +3 and +5 have been suggested for nihonium. Some simple compounds with nihonium in the +3 oxidation state would be the trihydride (NhH3), trifluoride (NhF3), and trichloride (NhCl3). These molecules are predicted to be T-shaped and not trigonal planar as their boron analogues are: this is due to the influence of the 6d5/2 electrons on the bonding. The heavier nihonium tribromide (NhBr3) and triiodide (NhI3) are trigonal planar due to the increased steric repulsion between the peripheral atoms; accordingly, they do not show significant 6d involvement in their bonding, though the large 7s–7p energy gap means that they show reduced sp2 hybridisation compared to their boron analogues. The bonding in the lighter NhX3 molecules can be considered as that of a linear NhX+2 species (similar to HgF2 or AuF−2) with an additional Nh–X bond involving the 7p orbital of nihonium perpendicular to the other two ligands. These compounds are all expected to be highly unstable towards the loss of an X2 molecule and reduction to nihonium(I):
=== Box office === In North America, Stone Cold opened on 1729 screens through TriStar Pictures on May 17, 1991. It debuted in fifth place, drawing $2.8 million in its first weekend, and quickly fell off the charts, ending its run with a disappointing $9.2 million at the domestic box office. In the U.K., the movie was also distributed by Columbia TriStar and opened on June 19, 1992, only reaching eighth place. It perhaps fared best in Germany, where it was a minor success for independent distributor Ascot Elite, drawing 781,000 admissions in a medium-wide release and spending four weeks in the nation's top ten.
Another class of common electrophiles are aryl and heterocyclic halides, especially bromides and iodides. Aryl triflates and sulfonates are also couple to a wide variety of organostannane reagents. Triflates tend to react comparably to bromides in the Stille reaction. Acyl chlorides are also used as coupling partners and can be used with a large range of organostannane, even alkyl-tin reagents, to produce ketones (see example below). However, it is sometimes difficult to introduce acyl chloride functional groups into large molecules with sensitive functional groups. An alternative developed to this process is the Stille-carbonylative cross-coupling reaction, which introduces the carbonyl group via carbon monoxide insertion.
Sources: en.wikipedia.org
Protein Data Bank (PDB) is a database of three dimensional structures of biological macromolecules, such as proteins and nucleic acids. The data are typically obtained by X-ray crystallography or nuclear magnetic resonance spectroscopy (NMR spectroscopy), and submitted manually by structural biologists worldwide through PDB member organizations – PDBe, RCSB, PDBj and BMRB. The database can be accessed through the webpages of its members, including PDBe (housed at the EMBL-EBI). As a member of the Worldwide Protein Data Bank (wwPDB) consortium, PDBe aids in the joint mission of archiving and maintenance of macromolecular structure data.
Fast parallel proteolysis (FASTpp) is a method to determine the thermostability of proteins by measuring which fraction of protein resists rapid proteolytic digestion. Proteolysis is widely used in biochemistry and cell biology to probe protein structure. In "limited trypsin proteolysis", low amounts of protease digest both folded and unfolded protein but at largely different rates: unstructured proteins are cut more rapidly, while structured proteins are cut at a slower rate (sometimes by orders of magnitude). Recently, several other assays of protein stability based on proteolysis have been proposed, exploiting other proteases with high specificity for cleaving unfolded proteins. These include Pulse Proteolysis, Proteolytic Scanning Calorimetry and FASTpp.
Brunton Medal 1979, Sir Francis Avery Jones research medal of the British Society of Gastroenterology, the highest research award that the national gastroenterology body confers on its researchers. Fellowships: Royal Colleges of Physicians of Glasgow (1975) London (1977) Edinburgh (1981) Royal College of Pathologists (1984) Fellow of the Royal Society of Edinburgh (1990) The Anne Ferguson building at the Western General Hospital, Edinburgh, is named after her. In 1966, she married John Ferguson, a sociology lecturer at the University of Strathclyde, and together they adopted two children, a girl and a boy. John Ferguson died of cancer in 1989. She married Professor Gerald Collee, emeritus Professor of Medical Microbiology at the University of Edinburgh in 1995. In her youth, Ferguson represented the University of Glasgow in athletics as a middle-distance runner. She was also on the Scottish women's basketball team. She enjoyed hill walking and mountaineering, and once visited the Himalayas with her first husband. Ferguson died of pancreatic cancer in Edinburgh on 21 December 1998.
=== Stable isotopes === Stable lutetium can be used as catalysts in petroleum cracking in refineries and can also be used in alkylation, hydrogenation, and polymerization applications. Lutetium aluminium garnet (Al5Lu3O12) has been proposed for use as a lens material in high refractive index immersion lithography. Additionally, a tiny amount of lutetium is added as a dopant to gadolinium gallium garnet, which was used in magnetic bubble memory devices. Cerium-doped lutetium oxyorthosilicate is currently the preferred compound for detectors in positron emission tomography (PET). Lutetium aluminium garnet (LuAG) is used as a phosphor in light-emitting diode light bulbs. Lutetium tantalate (LuTaO4) is the densest known stable white material (density 9.81 g/cm3) and therefore is an ideal host for X-ray phosphors. The only denser white material is thorium dioxide, with density of 10 g/cm3, but the thorium it contains is radioactive. Lutetium is also a compound of several scintillating materials, which convert X-rays to visible light. It is part of LYSO, LuAG and lutetium iodide scintillators. Research indicates that lutetium-ion atomic clocks could provide greater accuracy than any existing atomic clock.
Sulfonylureas were the first widely used oral anti-hyperglycemic medications. They are insulin secretagogues, triggering insulin release by inhibiting the KATP channel of the pancreatic beta cells. Eight types of these pills have been marketed in North America, but not all remain available. The "second-generation" sulfonylureas are now more commonly used. They are more effective than first-generation drugs and have fewer side-effects. All may cause weight gain. Current clinical practice guidelines from the AACE rate sulfonylureas (as well as glinides) below all other classes of antidiabetic drugs in terms of suggested use as first, second, or third line agents - this includes Bromocriptine, the bile acid sequestrant Colesevelam, α-glucosidase inhibitors, Thiazolidinediones (glitazones), and DPP-4 inhibitors (gliptins). The low cost of most sulfonylureas, however, especially when considering their significant efficacy in blood glucose reduction, tends to keep them as a more feasible option in many patients - neither SGLT2 inhibitors nor GLP-1 agonists, the classes most favored by the AACE guidelines after metformin, are currently available as generics. Sulfonylureas bind strongly to plasma proteins. Sulfonylureas are useful only in type 2 diabetes, as they work by stimulating endogenous release of insulin. They work best with patients over 40 years old who have had diabetes mellitus for under ten years. They cannot be used with type 1 diabetes, or diabetes of pregnancy. They can be safely used with metformin or glitazones.
Sources: en.wikipedia.org
Genus Aptenodytes (Great Penguins) Aptenodytes forsteri, Emperor penguin (2014) Aptenodytes patagonicus, King penguin (2019) Genus Eudyptes (Crested Penguins) Eudyptes chrysocome, Western rockhopper penguin (2019) Eudyptes chrysolophus chrysolophus, Macaroni penguin (2019) Eudyptes chrysolophus schlegeli, Royal penguin (2019) Eudyptes filholi, Eastern rockhopper penguin (2019) Eudyptes moseleyi, Northern rockhopper penguin (2019) Eudyptes pachyrhynchus, Fiordland penguin (2019) Eudyptes robustus, Snares penguin (2019) Eudyptes sclateri, Erect-crested penguin (2019) Genus Eudyptula (Little Penguins) Eudyptula minor albosignata, White-flippered penguin (2019) Eudyptula minor minor, Little blue penguin (2019) Eudyptula novaehollandiae, Fairy penguin (2019) Genus Megadyptes (Hoiho Penguins) Megadyptes antipodes antipodes, Yellow-eyed penguin (2019) Pygoscelis (Brush-tailed Penguins) Pygoscelis adeliae, Adélie penguin (2014) Pygoscelis antarctica, Chinstrap penguin (2019) Pygoscelis papua, Gentoo penguin (2019) Genus Spheniscus (Banded Penguins) Spheniscus demersus, African penguin (2019) Spheniscus humboldti, Humboldt penguin (2019) Spheniscus magellanicus, Magellanic penguin (2019) Spheniscus mendiculus, Galápagos penguin (2019)
==== Nucleic acid-based molecules ==== Nanogels are advantageous carriers of small, nucleic-acid based molecules that can be employed to treat a variety of diseases. Examples of three different types of molecules that fall into this category, oligonucleotides, miRNA, and nucleoside analogs, are discussed here. In one study, cationic synthetic nanogels modified with insulin and transferrin were synthesized to transport oligonucleotides, a possible therapeutic and diagnostic tool for neurodegenerative disorders, to the brain. These nanogels successfully localized through an in vitro model of the blood-brain barrier and accumulated in the brain in a mouse model. With the treatment of cardiovascular diseases in mind, polysaccharide-based nanogels have been functionalized with fucoidan to target overexpressed P-selectin receptors on platelets and endothelial cells. After loading with miRNA, these nanogels bound to platelets and became internalized by an endothelial cell line. Nanogels have also been used to encapsulate phosphorylated nucleoside analogs, or active forms of anticancer therapeutics. In one study, nanogels loaded with nucleoside 5'-triphosphates underwent surface modifications and successfully bound to overexpressed folate receptors on breast cancer cells. These nanogels were then internalized by the cells and produced a significant increase in cytotoxicity compared to control groups.
== End of the Cold War == After the end of the Revolutions of 1989, Gorbachev and President Bush Sr. met on the neutral island of Malta to discuss the events of the year, the withdrawal of the Soviet military from Eastern Europe, and the future course of their relationship. After their discussions, the two leaders publicly announced they would work together for German reunification, the normalization of relations, the resolution of Third World conflicts, and the promotion of peace and democracy (referred to by President Bush as a "New World Order"). Between the Malta Summit and the Dissolution of the Soviet Union, negotiations on several arms control pacts began, resulting in agreements such as START I and the Chemical Weapons Convention; the latter taking several years to fully implement. Additionally, the United States, still believing the Soviet Union would continue to exist in the long term, began to take steps to create a positive long-term relationship. This new relationship was demonstrated by the joint American-Soviet opposition to Iraq's invasion of Kuwait. The Soviet Union voted in the United Nations Security Council in favor of Resolution 678 authorizing the use of military force against its former Middle Eastern ally. During the late 1980s, several long-running conflicts in the developing world that had been sustained by Cold War rivalry began to wind down, including wars in Cambodia, Angola, and Nicaragua.
Atmosphere of the Sun: in detectable trace amounts Atmosphere of Mercury: 3.4%, and large amounts of water in Mercury's exosphere Atmosphere of Venus: 0.002% Earth's atmosphere: ≈0.40% over full atmosphere, typically 1–4% at surface Atmosphere of the Moon: in trace amounts Atmosphere of Mars: 0.03% Atmosphere of Ceres Atmosphere of Jupiter: 0.0004% – in ices only; and that of its moon Europa Atmosphere of Saturn – in ices only; Enceladus: 91% and Dione (subsurface ocean) Atmosphere of Uranus – in trace amounts below 50 bar Atmosphere of Neptune – found in the deeper layers Extrasolar planet atmospheres: including those of HD 189733 b and HD 209458 b, Tau Boötis b, HAT-P-11b, XO-1b, WASP-12b, WASP-17b, and WASP-19b. Stellar atmospheres: not limited to cooler stars and even detected in giant hot stars such as Betelgeuse, Mu Cephei, Antares and Arcturus. Circumstellar disks: including those of more than half of T Tauri stars such as AA Tauri as well as TW Hydrae, IRC +10216 and APM 08279+5255, VY Canis Majoris and S Persei.
Sources: en.wikipedia.org
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.
The peptide enters plasma rapidly and is broken down by ordinary proteases into amino acids and shorter fragments. Reported half-lives are short. Whether meaningful amounts of the intact molecule reach the brain is an open question.
Most clinical reports are small, published in Russian and not independently replicated. English-language reviews highlight the absence of large randomised trials. Conclusions about efficacy should be treated as provisional.
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.