A practical reference on Pro-Gly-Pro: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-01-31. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| 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 |
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.
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.
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.
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.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
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.
=== Biosecurity and bioterrorism === Some ethical issues relate to biosecurity, where biosynthetic technologies could be deliberately used to cause harm to society and/or the environment. Since synthetic biology raises ethical issues and biosecurity issues, humanity must consider and plan on how to deal with potentially harmful creations, and what kinds of ethical measures could possibly be employed to deter nefarious biosynthetic technologies. With the exception of regulating synthetic biology and biotechnology companies, however, the issues are not seen as new because they were raised during the earlier recombinant DNA and genetically modified organism (GMO) debates, and extensive regulations of genetic engineering and pathogen research are already in place in many jurisdictions. Additionally, the development of synthetic biology tools has made it easier for individuals with less education, training, and access to equipment to modify and use pathogenic organisms as bioweapons. This increases the threat of bioterrorism, especially as terrorist groups become aware of the significant social, economic, and political disruption caused by pandemics like COVID-19. As new techniques are developed in the field of synthetic biology, the risk of bioterrorism is likely to continue to grow.
A cell-free system is an in vitro tool widely used to study biological reactions that happen within cells apart from a full cell system, thus reducing the complex interactions typically found when working in a whole cell. Subcellular fractions can be isolated by ultracentrifugation to provide molecular machinery that can be used in reactions in the absence of many of the other cellular components. Eukaryotic and prokaryotic cell internals have been used for creation of these simplified environments. These systems have enabled cell-free synthetic biology to emerge, providing control over what reaction is being examined, as well as its yield, and lessening the considerations otherwise invoked when working with more sensitive live cells.
The act was revised in 1801 and 1805, and in 1823–24 an elaborate inquiry was followed by an act making quarantine only at the discretion of the Privy Council, which recognised yellow fever or other highly infectious diseases as calling for quarantine, along with plague. The threat of cholera in 1831 was the last occasion in England when quarantine restrictions were used. Cholera affected every country in Europe despite all efforts to keep it out. When cholera returned to England in 1849, 1853, and 1865–66, no attempt was made to seal the ports. In 1847 the privy council ordered all arrivals with a clean bill of health from the Black Sea and the Levant to be admitted, provided there had been no case of plague during the voyage and afterwards, the practice of quarantine was discontinued. In modern maritime law, biosecurity measures for arriving vessels centre on 'pratique', a licence issued by border control officials permitting a ship to enter port, on the assurance of the captain that the vessel is free from contagious disease. The clearance granted is commonly referred to as 'free pratique'. A ship can signal a request for 'pratique' by flying a solid yellow square-shaped flag. This yellow flag is the Q flag in the set of international maritime signal flags. In the event that 'free pratique' is not granted, a vessel will be held in quarantine according to biosecurity rules prevailing at the port of entry until a border control officer inspects the vessel. During the COVID-19 pandemic, a controversy arose as to who granted pratique to the Ruby Princess.
nucleotide Also nucleoside monophosphate (NMP). An organic molecule that serves as the fundamental monomer or subunit of nucleic acid polymers, including RNA and DNA. Each nucleotide is composed of three connected functional groups: a nitrogenous base, a five-carbon sugar (either ribose or deoxyribose), and a single phosphate group. Though technically distinct, the term "nucleotide" is often used interchangeably with nitrogenous base, nucleobase, and base pair when referring to the sequences that make up nucleic acids. Compare nucleoside.
Sources: en.wikipedia.org
On 20 December 1989, the "All-American", as part of the United States invasion of Panama, conducted their first combat jump since World War II onto Torrijos International Airport, Panama. The goal of the 1st Brigade task force, which was made up of the 1–504th and 2–504th INF as well as 4–325th INF and Company A, 3–505th INF, and 3–319th FAR, was to oust Manuel Noriega from power. They were joined on the ground by 3–504th INF, which was already in Panama. The invasion was initiated with a night combat jump and airfield seizures. The 82nd conducted follow-on combat air assault missions in Panama City and the surrounding areas of the Gatun Locks. The operation continued with an assault of multiple strategic installations, such as the Punta Paitilla Airport in Panama City and a Panamanian Defense Forces (PDF) garrison and airfield at Rio Hato, where Noriega also maintained a residence. The attack on La Comandancia (PDF HQ) touched off several fires, one of which destroyed most of the adjoining and heavily populated El Chorrillo neighborhood in downtown Panama City. The 82nd Airborne Division secured several other key objectives such as Madden Dam, El Ranacer Prison, Gatun Locks, Gamboa and Fort Cimarron. Overall, the operation involved 27,684 US troops and over 300 aircraft, including C-130 Hercules, AC-130 Spectre gunship, OA-37B Dragonfly observation, and attack aircraft, C-141 and C-5 strategic transports, F-117A Nighthawk stealth aircraft and AH-64 Apache attack helicopters. The invasion of Panama was the first combat deployment for the AH-64, the HMMWV, and the F-117A.
Santa Cruz) outlines the financially driven undertones of the company's actions. UCC had participated in decades of previous instances of "environmental negligence in every part of the world", directing its "responsibility… to its shareholders", and numerous dealings with local and international political and economic powers. The company's response to the Bhopal accident was what Rajan describes as a "campaign of erasure", meaning the transfer of liability and responsibility of the cause of the gas leak, the event itself, and the aftermath. Rajan then argues that this type of response is to be expected "according to [the] established cultural practice" within large corporations such as UCC. Since UCC absolved itself from the situation, the Indian government was the next institution that was looked to by the people of Bhopal, but they had also not prepared for such an event. The government's attempts at short and long-term plans failed in successfully aiding victims and instead "created an ecology of opportunity… built largely at the expense of the victims."
THC and its 11-OH-THC and THC-COOH metabolites can be detected and quantified in blood, urine, hair, oral fluid or sweat using a combination of immunoassay and chromatographic techniques as part of a drug use testing program or in a forensic investigation. There is ongoing research to create devices capable of detecting THC in breath.
The Incas herded vicuñas by the tens of thousands into pens, sheared the wool for the exclusive use of high nobles, and then released the animals. In the 20th century, vicuñas were hunted for their fur, so that the population declined to about 8,000 animals and was put under wild life protection. Vicuñas were listed in CITES appendix I until 1994, when conservation efforts had led to a partial restoration of the population and vicuñas were listed in appendix II. Nowadays vicuñas are a protected species. In Peru, Chile, Bolivia and Argentina, they are kept free-ranging in national parks for commercial use, and more rarely in extensive enclosures (especially in Argentina). In Peru, three companies were licensed in 1994 to harvest vicuña wool legally: Loro Piana, Agnona, and Incalpaca TPX. In 2009, 5,500 to 6,000 kilograms of vicuña wool were harvested worldwide. The hair of the vicuña is used to make a variety of products. The hair of the vicuña is sheared in pens after a traditional roundup ("chaccu"). A wool with an average fiber length of 2–4 cm (0.8–2 in) is obtained every other year. The weight of shorn wool hairs per animal is about 250 g (8.8 oz) every two years to 450 g (16 oz), after removal of unwanted guard hairs from the down hair. Before processing, the down hair is separated from the guard hair by sorting. After sorting the wool, the down hairs are spun into yarn and woven or knitted into textiles. The surface of woven fabrics is often roughened with a raising card to create a softer feel, higher volume and greater thermal insulation.
=== Generic names === Elagolix is the generic name of the drug and its INNTooltip International Nonproprietary Name and USANTooltip United States Adopted Name. It is also known by its former developmental code names NBI-56418 and ABT-620.
Sources: en.wikipedia.org
The defeat of the Russian armies forced Vladimir Lenin and the Soviet leadership to postpone their strategic objective of linking up with the German and other European revolutionary leftist collaborators to spread communist revolution. Lenin also hoped for generating support for the Red Army in Poland, which failed to materialize. Piłsudski's seizure of Vilnius in October 1920 (known as Żeligowski's Mutiny) was a nail in the coffin of the already poor Lithuania–Poland relations that had been strained by the Polish–Lithuanian War of 1919–1920; both states would remain hostile to one another for the remainder of the interwar period. Piłsudski's concept of Intermarium (an East European federation of states inspired by the tradition of the multiethnic Polish–Lithuanian Commonwealth that would include a hypothetical multinational successor state to the Grand Duchy of Lithuania) had the fatal flaw of being incompatible with his assumption of Polish domination, which would amount to an encroachment on the neighboring peoples' lands and aspirations. At the time of rising national movements, the plan thus ceased being a feature of Poland's politics.[a] A larger federated structure was also opposed by Dmowski's National Democrats. Their representative at the Peace of Riga talks, Stanisław Grabski, opted for leaving Minsk, Berdychiv, Kamianets-Podilskyi and the surrounding areas on the Soviet side of the border.
Since 1978, Lagin's primary life and creativity has been in photography and art. Lagin began photography in 1953, at the age of five, starting with a Baby Brownie camera. With that camera he made his first photographs at the Bronx Zoo of animals sadly in bare cages, photographs which his mother had developed and printed, and he then put together in his first "book". From childhood, and continuing through to the beginning of college, photography, "picture-making", and "picturing" was part of being an amateur naturalist and scientist and grew from his love and fascination with nature, with natural history drawings, maps, and electronic and scientific drawings and schematics. Growing up near New York City in the 1950's and 1960's, Lagin spent a great amount of time looking at dioramas, pictures, exhibits, displays, reconstructions, models, and galleries at the American Museum of Natural History, the Metropolitan Museum of Art, the Museum of Modern Art, and other museums and art galleries. The wide range of photography and art influences and inspirations for Lagin include Ansel Adams, Elliot Porter, Walker Evans, Edward Weston, the natural history books by Rachel Carson, Life magazine and The World We Live In, and National Geographic. as well as by the 20th century artists Juan Miro, Paul Klee and others, and the intent (but not the style) of 19th Century American landscape painters who portrayed nature as "a revelation of spiritual meaning" placing small figures (animals, humans) "in large transcendental landscapes”.
=== Nationalization === After the U.S. entered World War I, due to its German connections, Merck & Co. was the subject of expropriation under the Trading with the Enemy Act of 1917. The government seized 80 percent of the shares owned by the German parent company and sold it. In 1919, George F. Merck (head of the American branch of the Merck family), in partnership with Goldman Sachs and Lehman Brothers, bought the company back at a U.S. government auction for $3.5 million, but Merck & Co. remained a separate company from its former German parent. Merck & Co. holds the trademark rights to the "Merck" name in the United States and Canada, while its former parent company retains the rights in the rest of the world; the right to use the Merck name was the subject of litigation between the two companies in 2016. In 1925, George W. Merck succeeded his father George F. Merck as president. In 1927, the corporation merged with the Powers-Weightman-Rosengarten Company, a Philadelphia quinine manufacturer. George Merck remained president and Frederic Rosengarten became chairman of the board. In 1929, H. K. Mulford Company merged with Sharp and Dohme, Inc. and brought vaccine technology, including immunization of cavalry horses in World War I and delivery of a diphtheria antitoxin to Merck & Co. In 1943, streptomycin was discovered during a Merck-funded research program in Selman Waksman's laboratory at Rutgers University. It became the first effective treatment for tuberculosis.
=== Triggers apoptosis === Cardiolipin distribution to the outer mitochondrial membrane would lead to apoptosis of the cells, as evidenced by cytochrome c (cyt c) release, Caspase-8 activation, MOMP induction and NLRP3 inflammasome activation. During apoptosis, cyt c is released from the intermembrane spaces of mitochondria into the cytosol. Cyt c can then bind to the IP3 receptor on endoplasmic reticulum, stimulating calcium release, which then reacts back to cause the release of cyt c. When the calcium concentration reaches a toxic level, this causes cell death. Cytochrome c is thought to play a role in apoptosis via the release of apoptotic factors from the mitochondria. A cardiolipin-specific oxygenase produces CL hydroperoxides which can result in the conformation change of the lipid. The oxidized CL transfers from the inner membrane to the outer membrane, and then helps to form a permeable pore which releases cyt c.
The UNESCO International Bioethics Committee recommended a precautionary global moratorium on the creation of mirror-image organisms, and the UK Government Office for Science held an expert roundtable that recommended "prevent[ing] the development of replicating mirror organisms." Several philanthropic funders have also stated that they will not fund research with the goal of creating mirror-image organisms, including Renaissance Philanthropy. In 2026, the UN Scientific Advisory Board called for "proactive multilateral action, such as a dedicated global forum, to define clear 'red lines', strengthen safety and monitoring practices, and establish responsible policy well before mirror life becomes feasible", and Chinese and US policy research organizations issued a joint statement calling for "national and international frameworks to guard against the risks posed by mirror life, reaffirming the shared view that such organisms should never be created." Some scientists and scholars have argued that concerns about mirror-image life are theoretical and/or that bans on research and funding bans are premature. Others have argued that the immune system might be able to recognize mirror versions of a certain type of biomolecule. Some scientists have proposed developing guidelines for synthetic biological entities regardless of their chirality.
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.
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.