Pro-Gly-Pro comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-09-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
| Property | Value | Notes |
|---|---|---|
| Solubility | Freely soluble in water | Also in aqueous buffers |
| Typical purity (HPLC) | 95 percent or higher | Lot-dependent |
| Dry powder storage | Minus 20 degrees Celsius | Sealed, dry, protected from light |
| Solution storage | 2 to 8 degrees Celsius | Short-term use |
| Identity confirmation | Mass spectrometry | ESI or MALDI-TOF |
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.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
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.
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.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Those with mass 5 decay to helium-4 and a proton or a neutron, and those with mass 8 decay to two helium-4 nuclei; their half-lives (helium-5, lithium-5, and beryllium-8) are very short, unlike the half-lives for all other such nuclides with A ≤ 209, which are very long. (Such nuclides with A ≤ 209 are primordial nuclides except 146Sm.) Working out the details of the theory leads to an equation relating the half-life of a radioisotope to the decay energy of its alpha particles, a theoretical derivation of the empirical Geiger–Nuttall law.
This imbalance, he argued, made it difficult for indigenous East German parties and civic movements to compete on equal terms. This large-scale West German involvement was not limited to campaign workers and funding. West German media, political advertisements and party materials flooded East German spaces in the run-up to the election, promoting a vision of rapid reunification under Western terms. While many East Germans were eager for economic stability and political freedom, critics argue that this form of campaigning blurred the lines between support and manipulation. The West German framing of the vote as a de facto referendum on reunification placed enormous pressure on the East German electorate and marginalised alternative visions for East Germany's future. Although the election was formally free, the conditions surrounding it raise ongoing debate over whether it represented a fully sovereign exercise in democracy or a lopsided contest shaped by the overwhelming influence of West Germany.
Throughout human history, intentional application of poison has been used as a method of murder, pest-control, suicide, and execution. As a method of execution, poison has been ingested, as the ancient Athenians did (see Socrates), inhaled, as with carbon monoxide or hydrogen cyanide (see gas chamber), injected (see lethal injection), or even as an enema. Poison's lethal effect can be combined with its allegedly magical powers; an example is the Chinese gu poison. Poison was also employed in gunpowder warfare. For example, the 14th-century Chinese text of the Huolongjing written by Jiao Yu outlined the use of a poisonous gunpowder mixture to fill cast iron grenade bombs. While arsenic is a naturally occurring environmental poison, its artificial concentrate was once nicknamed inheritance powder. In Medieval Europe, it was common for monarchs to employ personal food tasters to thwart royal assassination, in the dawning age of the Apothecary.
Consultancy firm Cornwall Insight forecasts that energy bills will fall by 16% in April, saving the average household around £300 a year. The UK and US launch fresh air strikes against Houthi targets in Yemen. The UK's Charity Commission launches an investigation into antisemitic speeches given by members of the Iranian Revolutionary Guard to students at a UK-based Islamic charity, which included chants of "death to Israel". 23 January Data from the Office for National Statistics indicates government borrowing in December was at £7.8bn, a fall from £16.2bn in December 2022, and the lowest since 2019. Sunak tells Parliament the UK will not hesitate to launch further air strikes against Houthi rebels if they continue to attack shipping targets in the Red Sea, but does not seek confrontation with the group. Most of the UK is placed under a Met Office yellow weather warning for high winds as Storm Jocelyn arrives. 2023 Nottingham attacks: Valdo Calocane admits three counts of manslaughter and three of attempted murder. 24 January Sir Patrick Sanders, the Chief of the General Staff, warns that the UK should train a "citizen army" ready to fight a war on land in the future, highlighting Russia as a potential threat and the steps being taken by other European countries to put their populations on a "war footing". Ofcom publish plans to reform Royal Mail with the options of reducing postal deliveries from six to five or three days a week, or delaying the time the service takes to fulfil its deliveries.
=== Fish === Lungs are found in three groups of fish; the coelacanths, the bichirs and the lungfish. Like in tetrapods, but unlike fish with swim bladder, the opening is at the ventral side of the oesophagus. The coelacanth has a nonfunctional and unpaired vestigial lung surrounded by a fatty organ. Bichirs, the only group of ray-finned fish with lungs, have a pair which are hollow unchambered sacs, where the gas-exchange occurs on very flat folds that increase their inner surface area. The lungs of lungfish show more resemblance to tetrapod lungs. There is an elaborate network of parenchymal septa, dividing them into numerous respiration chambers. In the Australian lungfish, there is only a single lung, albeit divided into two lobes. Other lungfish, however, have traditionally been considered having two lungs, but newer research defines paired lungs as bilateral lung buds that arise simultaneously and are both connected directly to the foregut, which is only seen in tetrapods. In all lungfish, including the Australian, the lungs are located in the upper dorsal part of the body, with the connecting duct curving around and above the oesophagus. The blood supply also twists around the oesophagus, suggesting that the lungs originally evolved in the ventral part of the body, as in other vertebrates.
Sources: en.wikipedia.org
The current model of atomic structure is the quantum mechanical model. Traditional chemistry starts with the study of elementary particles, atoms, molecules, substances, metals, crystals and other aggregates of matter. Matter can be studied in solid, liquid, gas and plasma states, in isolation or in combination. The interactions, reactions and transformations that are studied in chemistry are usually the result of interactions between atoms, leading to rearrangements of the chemical bonds which hold atoms together. Such behaviors are studied in a chemistry laboratory. The chemistry laboratory stereotypically uses various forms of laboratory glassware. However glassware is not central to chemistry, and a great deal of experimental (as well as applied/industrial) chemistry is done without it.
While this has been well known since the 19th century, an insistence on only monophyletic taxa has resulted in vertebrate classification being in a state of flux. The majority of animals more complex than jellyfish and other cnidarians are split into two groups, the protostomes and deuterostomes, the latter of which contains chordates. It seems very likely the 555 million-year-old Kimberella was a member of the protostomes. If so, this means the protostome and deuterostome lineages must have split some time before Kimberella appeared—at least 558 million years ago, and hence well before the start of the Cambrian 538.8 million years ago. Three enigmatic species that are possible very early tunicates, and therefore deuterostomes, were also found from the Ediacaran period – Ausia fenestrata from the Nama Group of Namibia, the sac-like Yarnemia ascidiformis, and one from a second new Ausia-like genus from the Onega Peninsula of northern Russia, Burykhia hunti. Results of a new study have shown possible affinity of these Ediacaran organisms to the ascidians. Ausia and Burykhia lived in shallow coastal waters slightly more than 555 to 548 million years ago, and are believed to be the oldest evidence of the chordate lineage of metazoans. The Russian Precambrian fossil Yarnemia is identified as a tunicate only tentatively, because its fossils are nowhere near as well-preserved as those of Ausia and Burykhia, so this identification has been questioned.
== Contraband detection == In 1984, a joint venture was formed between MDS SCIEX and British Aerospace to develop a tandem mass spectrometer system for contraband detection. Based on the TAGA platform, the AROMIC was a triple quadrupole instrument that was part of the CONDOR, an integrated contraband detection system for screening shipping containers for the presence of drugs and explosives. The CONDOR system consisted of a large X-Ray facility for imaging whole shipping containers, combined with the AROMIC mass spectrometer system to sample container air space for the presence of vapours and particulates indicative of the presence of drugs, alcohol or explosives. Designed for rapid screening of containers at border crossings, systems were sold and installed in two countries in the Middle and Far East.
Lebanese Christians and Druze became a genetic isolate in the predominantly Islamic world. The Druzite and Maronite community in Lebanon played an important role in the formation of the modern state of Lebanon. Contact between Christians (members of the Maronite, Eastern Orthodox, Melkite, and other churches) and the Unitarian Druze led to the presence of mixed villages and towns in Mount Lebanon (Aley District, Baabda District, and Chouf District), Rashaya District, Hasbaya, Matn District, and Marjeyoun District. The relationship between the Druze and Christians in Lebanon has been characterized by harmony and coexistence, and they lived in the Shuf Mountains in the past in complete harmony. Historian Ray Jabre Mouawad observes that there was religious symbiosis between the Druze and Christians in Mount Lebanon during the Ottoman period. Numerous cultural interactions took place in Mount Lebanon, resulting overlapped symbolism, veneration of common saints, and the use of common terminology to refer to God. Traces of these interactions can be found in the palaces and mausoleums of Druze lords, as well as in Maronite and Greek Orthodox churches. Druze and Christians in Lebanon engage in mutual celebrations, including births, weddings, funerals, and religious festivities such as Christmas, Maundy Thursday and Easter. These traditions of sharing and celebration persisted both before and after Lebanese Civil War.
Food Administration International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) African Union: African Medicines Agency Australia: Therapeutic Goods Administration Brazil: National Health Surveillance Agency Canada: Marketed Health Products Directorate Canada: Health Canada Denmark: Danish Medicines Agency European Union: European Food Safety Authority and European Medicines Agency Germany: Federal Institute for Drugs and Medical Devices India: Food Safety and Standards Authority of India and Central Drugs Standard Control Organization Japan: Ministry of Health, Labour and Welfare (MHLW) Japan: Pharmaceuticals and Medical Devices Agency Mexico: Federal Commission for the Protection against Sanitary Risk Philippines: Food and Drug Administration (FDA) Singapore: Health Sciences Authority United Kingdom: Food Standards Agency and Medicines and Healthcare products Regulatory Agency
Sources: en.wikipedia.org
Each carbon of the backbone has tetrahedral geometry, and those carbons that have a phenyl group (benzene ring) attached are stereogenic. If the backbone were to be laid as a flat elongated zig-zag chain, each phenyl group would be tilted forward or backward compared to the plane of the chain. The relative stereochemical relationship of consecutive phenyl groups determines the tacticity, which affects various physical properties of the material.
== Treatment == Emerging therapies for genetic skeletal dysplasias include enzyme replacement therapy, small molecule therapy, hematopoietic stem cell transplantation and gene therapy. These therapies aim at preventing disease progression and thus improving quality of life. Enzyme replacement therapies are some of the mucopolysaccharidoses and Gaucher disease. Results have shown effectivity of enzyme replacement therapy. Hematopoietic stem cell transplantation can be lifesaving for some disorders, such as with malignant infantile osteopetrosis. Even with treatments such as enzyme replacement therapy and stem cell transplantation, people with skeletal dysplasia often require orthopedic surgery and other disease management interventions. There is a lack of information available to support these patients as most physicians may only see one or two skeletal dysplasia patients in their lifetime. Guidelines are available to support best practices for managing several areas of skeletal dysplasia, such as the craniofacial aspects of skeletal dysplasia, spinal disorders, diagnosis and management of type II collagen disorders, pregnancy of people with skeletal dysplasia, peri-operative management, and foramen magnum stenosis in achondroplasia. Written and video resources for patients with skeletal dysplasia and caregivers are also available.
== Pathophysiology == As of 2016, the pathophysiology of tendinopathy was poorly understood. While inflammation plays a role, the relationships among changes to the structure of tissue, the function of tendons, and pain are not understood. Several models are proposed, none of which have been fully validated or falsified. Molecular mechanisms involved in inflammation include release of inflammatory cytokines such as IL-1β which reduce the expression of type I collagen mRNA in human tenocytes and cause extracellular matrix degradation in the tendon. A 2020 review noted that while various inflammatory markers were present in two thirds of the reviewed articles, data heterogeneity and lack of comparable studies prevented any conclusion about a common pathophysiology. Multifactorial theories include tensile overload, tenocyte-related collagen synthesis disruption, load-induced ischemia, neural sprouting, thermal damage, and adaptive compressive responses. The intratendinous sliding motion of fascicles and shear force at interfaces of fascicles could predispose tendons to rupture. The most commonly accepted cause is an overuse syndrome in combination with factors leading to what may be seen as a progressive interference or the failing of the innate healing response. Tendinopathy involves apoptosis, matrix disorganization and neovascularization. Classic characteristics include degenerative changes in the collagenous matrix, hypercellularity, hypervascularity, and a lack of inflammatory cells, which has challenged the misnomer "tendinitis".
== Toxicity == S2F10 was considered a potential chemical warfare pulmonary agent in World War II because it does not produce lacrimation or skin irritation, thus providing little warning of exposure. Disulfur decafluoride is a colorless gas or liquid with a sulfur dioxide (SO2)-like odor. Its toxicity is thought to be caused by its disproportionation in the lungs into SF6, which is inert, and SF4, which reacts with moisture to form sulfurous acid and hydrofluoric acid.
Sources: en.wikipedia.org
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.
Freeze-dried material is kept frozen, often at minus 20 degrees Celsius, and protected from light and moisture. Dissolved peptide is refrigerated for short-term use. Repeated freeze-thaw cycles are avoided.
A certificate of analysis typically lists purity by HPLC, the confirmed mass, appearance, and sometimes water or counter-ion content. It documents results for a specific batch. Details vary by supplier.
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.