This is a working overview of Heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-07-24. Anything still debated is marked as such rather than presented as settled.
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.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
=== Dextran microsphere applications === Dextran-based microspheres can encapsulate a variety of drugs and provide therapeutic delivery in the treatment of diseases such as cancer, colonic diseases, bone diseases, and cardiovascular diseases.
=== 1. Gingiva === The gingiva is the visible soft-tissue component of the periodontium and forms a biological seal around the cervical region of the teeth, protecting the underlying periodontal structures from mechanical trauma and microbial invasion.
Plasma as a blood product prepared from blood donations is used in blood transfusions, typically as fresh frozen plasma (FFP) or Plasma Frozen within 24 hours after phlebotomy (PF24). When donating whole blood or packed red blood cell (PRBC) transfusions, O- is the most desirable and is considered a "universal donor," since it has neither A nor B antigens and can be safely transfused to most recipients. Type AB+ is the "universal recipient" type for PRBC donations. However, for plasma the situation is somewhat reversed. Blood donation centers will sometimes collect only plasma from AB donors through apheresis, as their plasma does not contain the antibodies that may cross react with recipient antigens. As such, AB is often considered the "universal donor" for plasma. Special programs exist just to cater to the male AB plasma donor, because of concerns about transfusion related acute lung injury (TRALI) and female donors who may have higher leukocyte antibodies. However, some studies show an increased risk of TRALI despite increased leukocyte antibodies in women who have been pregnant.
=== Ceasefire attempts === Syrian minister of defense Murhaf Abu Qasra announced a ceasefire effective from 15 July 2025 after an agreement with the Druze leaders in Suwayda. The Syrian Ministry of Interior warned against any damage to private or public property in Suwayda. According to the ceasefire agreement, it was not a complete withdrawal of the administration, and it would be able to continue to maintain police forces in the district, which would operate together with local Druze, but it was required, as stated, to withdraw the military forces it had sent there in the battles in recent days. A mechanism was also agreed upon to regulate the issue of possession of heavy weapons in the area. The agreement also stipulates the establishment of an investigative committee that will examine atrocities committed by militants and regime members against the Druze, according to reports. Following the second ceasefire announced on 16 July 2025, Syrian president Ahmed al-Sharaa addressed the nation stating that the government's priority is to protect Druze citizens as Israel continues its assaults on Syria. He further said "we reject any attempt to drag you into hands of an external party. We are not among those who fear the war. We have spent our lives facing challenges and defending our people, but we have put the interests of the Syrians before chaos and destruction".
Sources: en.wikipedia.org
=== Next-generation matrix for compartmental models === In mathematical modelling of infectious disease, the dynamics of spreading is usually described through a set of non-linear ordinary differential equations (ODE). So there is always
=== Education === Humphreys graduated from Chickasha High School (Chickasha, Oklahoma) in 1948. He then attended Colorado College, graduating with his BA in 1952. He attended Seabury-Western Theological Seminary (in Evanston, Illinois), graduating with the MDiv degree in 1955. In 1965, he entered graduate school at Washington University to pursue a PhD in sociology. His dissertation adviser was Lee Rainwater. Humphreys obtained two pre-doctoral research fellowships from the National Institute of Mental Health to fund his dissertation research. He completed his dissertation in 1968, graduating with his PhD in that year. He published the dissertation as Tearoom Trade: Impersonal Sex in Public Places in 1970. His book won the C. Wright Mills Award from the Society for the Study of Social Problems in 1969. Due to the controversy around his research methods and the topic of his research, there was a failed attempt by the chancellor of Washington University to rescind his PhD.
A coup d'état ( ; French: [ku deta] ; lit. 'stroke of state'), or simply a coup, is typically an illegal and overt attempt by a military organization or other government elites to unseat an incumbent person or leadership. A self-coup is said to take place when a leader, having come to power through legal means, tries to stay in power through illegal means. By one estimate, there were 457 coup attempts from 1950 to 2010, half of which were successful. Most coup attempts occurred in the mid-1960s, but there were also large numbers of coup attempts in the mid-1970s and the early 1990s. Coups occurring in the post-Cold War period have been more likely to result in democratic systems than Cold War coups, though coups still mostly perpetuate authoritarianism. Many factors may lead to the occurrence of a coup, as well as determine the success or failure of a coup. Once a coup is underway, coup success is driven by coup-makers' ability to get others to believe that the coup attempt will be successful. The number of successful coups has decreased over time. Failed coups in authoritarian systems are likely to strengthen the power of the authoritarian ruler. The cumulative number of coups is a strong predictor of future coups, a phenomenon referred to as the "coup trap". In what is referred to as "coup-proofing", regimes create structures that make it hard for any small group to seize power. These coup-proofing strategies may include the strategic placing of family, ethnic, and religious groups in the military and the fragmenting of military and security agencies.
After Markov's death the wound on Kostov's back was examined and a ricin-laced pellet identical to the one used against Markov was removed. Several terrorist individuals and groups have experimented with ricin or planned to use it. There have been incidents of the poison being mailed to US politicians. For example, on 29 May 2013 two anonymous letters sent to New York City Mayor Michael Bloomberg contained traces of it. Another was sent to the offices of Mayors Against Illegal Guns in Washington, D.C. A letter containing ricin was also reported to have been sent to American President Barack Obama at the same time. Shannon Richardson, an actress, was later charged with the crime, and pleaded guilty that December; she was sentenced to 18 years in prison plus a restitution fine of US$367,000. On 2 October 2018, two letters suspected of containing ricin were sent to The Pentagon, one addressed to Secretary of Defense James Mattis, and the other to Chief of Naval Operations, Admiral John Richardson. A letter was received on 23 July 2019 at Pelican Bay State Prison in California which claimed to contain a suspicious substance. Authorities later confirmed it contained ricin; no detrimental exposures were identified. In 2020, some media in the Czech Republic reported, based on intelligence information, that a person carrying a Russian diplomatic passport and ricin had arrived in Prague with the intention of assassinating three politicians. Russian president Vladimir Putin denied the reports.
== History == The first compound of the homolog row of nitriles, the nitrile of formic acid, hydrogen cyanide was first synthesized by C. W. Scheele in 1782. In 1811 J. L. Gay-Lussac was able to prepare the very toxic and volatile pure acid. Around 1832 benzonitrile, the nitrile of benzoic acid, was prepared by Friedrich Wöhler and Justus von Liebig, but due to minimal yield of the synthesis neither physical nor chemical properties were determined nor a structure suggested. In 1834 Théophile-Jules Pelouze synthesized propionitrile, suggesting it to be an ether of propionic alcohol and hydrocyanic acid. The synthesis of benzonitrile by Hermann Fehling in 1844 by heating ammonium benzoate was the first method yielding enough of the substance for chemical research. Fehling determined the structure by comparing his results to the already known synthesis of hydrogen cyanide by heating ammonium formate. He coined the name "nitrile" for the newfound substance, which became the name for this group of compounds. In 1903, Arthur Lapworth investigated the formation of cyanohydrins by addition of hydrocyanic acid to aldehydes and ketones and discovered that the actual nucleophile is the cyanide ion, such that the addition of a base increases the reaction rate. This work represented one of the earliest investigations of an organic reaction mechanism. For a long time, nitriles were primarily of academic interest. Between the First and Second World War, however, research activity increased significantly.
Sources: en.wikipedia.org
If the mutation occurs in the region of the gene where transcriptional machinery binds to the protein, the mutation can affect the way in which transcription factors bind to the protein. The mechanisms of transcription bind to a protein through recognition of short nucleotide sequences. A mutation in this region may alter these sequences and, thus, change the way the transcription factors bind to the protein. Mutations in this region can affect the efficiency of gene transcription, which controls both the levels of mRNA and overall protein levels.
A five-door hatchback and four-door saloon, both featuring pillarless doors and distinct sheetmetal from other 323s, was sold in Japan as the Mazda Lantis, in Australia, New Zealand and South Africa as the Mazda 323 Astina, in Colombia as the Mazda Allegro and in Europe as the Mazda 323F. They were built on platforms distinct from the other 323s and actually appeared nearly a year before the new Familia, in September 1993. The bodyshape was designed by former Porsche designers. The Lantis was on the CB, a minor update of the CA that underpinned the luxury Mazda Xedos 6 and Eunos 500. The European 323F was designated BA, but was actually almost identical to the CB, and had little to do with other B platforms. These models were sold with the 1.5 L 1.6L and 1.8 L engines seen in the rest of the 323 range, as well as a 2.0 L (KF) V6 shared with the Eunos 500. The 2.0L V6 still remains one of the smallest V6 engines put into a production car.
=== Yeast === Eukaryotic cells can be used as an alternative to prokaryotic expression of proteins intended for therapeutic use. Yeast is a single cell fungus that uses high expression levels, fast growth, and inexpensive maintenance, similar to prokaryotic systems. Because yeast is a food organism, it is also favorable for the production of pharmaceutical products, as opposed to E. coli which may contain toxins. Yeast also has a relatively quick growth rate, with a doubling time of 90 minutes on simple media, and is easily manipulated. Similar to E.coli, yeast also has the complete genomic sequence available. The most commonly used yeast is S. cerevisiae, which can carry out post-translational modifications such as protein processing and protein folding. S. cerevisiae, P. pastoris are simple eukaryotic organisms that grow quickly and are highly adaptable. Eukaryotic systems have human applications and successfully made vaccines for hepatitis B and Hantavirus. There is a progressive increase in the use of mammalian cells for recombinant technology and synthesis of complete biological activity. This system secretes and glycosylates proteins, while introducing proper protein folding and post-translational modifications. However, when increased glycosylation abilities are employed, hyper-mannosylation, or the addition of a large number of mannose, is often observed. This hinders proper protein folding. Overall, yeast is a compromise between bacterial and mammalian cells, and remains a popular host system.
== Chromatography == Along with its medical applications, hydroxyapatite is also used in downstream applications under mixed-mode chromatography in polishing step. The ions present on the surface of hydroxyapatite make it an ideal candidate with unique selectivity, separation and purification of biomolecule mixtures. In mixed-mode chromatography, hydroxyapatite is used as the stationary phase in chromatography columns. The combined presence of calcium ions (C- sites) and phosphate sites (P-sites) provide metal affinity and ion exchange properties respectively. The C-sites on the surface of the resin undergo metal affinity interactions with phosphate or carboxyl groups present on the biomolecules. Concurrently, these positively charged C-sites tend to repel positively charged functional groups (e.g., amino groups) on biomolecules. P-sites undergo cationic exchange with positively charged functional groups on biomolecules. They exhibit electrostatic repulsion with negatively charged functional groups on biomolecules. For the elution of molecules buffer with high concentration of phosphate and sodium chloride is used. The nature of different charged ions on the surface of hydroxyapatite provides the framework for unique selectivity and binding of biomolecules, facilitating robust separation of biomolecules. Hydroxyapatite is available in different forms and in different sizes for the purpose of protein purification. The advantages of hydroxyapatite media are its high product stability and uniformity in various lots during its production.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.