If you have been reading about Enkephalinase and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-05-15. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
| 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 |
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.
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.
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.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
The IDF is an integrated military force, without a separate ground arm from 1948 to 1998, when the Ground Forces were formally brought under a single command now known as GOC Army Headquarters (Hebrew: מפקדת זרוע היבשה, Mifkedet Zro'a HaYabasha, abbreviated Mazi). The Ground Forces are not yet a formal arm of the IDF, in the same way that the Israeli Air Force and Israeli Navy are.
Acrolein (systematic name: propenal) is the simplest unsaturated aldehyde. It is a colorless liquid with a foul and acrid aroma. The smell of burnt fat (as when cooking oil is heated to its smoke point) is caused by glycerol in the burning fat breaking down into acrolein. It is produced industrially from propylene and mainly used as a biocide and a building block to other chemical compounds, such as the amino acid methionine.
Gonadotropic cells (also known as gonadotropes, gonadotrophs, delta cells, or delta basophils) are endocrine cells in the anterior pituitary that produce gonadotropins. More specifically, gonadotrophs produce and secrete glycoprotein polypeptide hormones, such as the follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which are released due to the positive input of gonadotropin-releasing hormone (GnRH). These gonadotropins are essential in the development and maintenance of reproductive function in mammals. This control of the reproductive system is coordinated by the electrical activity and signaling pathways of gonadotrophs as well as the tight regulation of gonadotropic cells by both sex steroids and paracrine factors.
Sources: en.wikipedia.org
Peter Giles later called it one of Fripp's "cute political moves". According to Michael Giles, his brother had become disillusioned with the band's lack of success and departed before Fripp ever made this suggestion.
The ascent led through forests of chestnut, laurels, and heaths, and onto higher, barren volcanic plains such as Llano del Retama, where vegetation diminished and only shrubs and wildlife remained. At Estancia de los Ingleses, a traditional rest point at about 8,000 feet (2,400 m), the group endured a cold, windy night before continuing the climb at 3 a.m. on 22 June 1799. They crossed the Malpays, an area of broken lava and little vegetation, and reached the summit at 8 a.m. At the peak, the party observed the structure of the volcano, measured ground temperatures, and collected air samples. The elliptical crater showed no recent eruptions inside, but the volcano remained active, with recent lava flows and geothermal activity. The summit provided panoramic views of the surrounding islands and the diverse ecological zones descending from the peak, which Humboldt recorded in a sketch. He noted five distinct vegetation zones, from grasses at the summit to cultivated tropical and temperate plants near the coast. The descent took the party back through the varying ecological regions. Humboldt made broader geological observations, considering questions about the structure and origins of volcanoes and the laws governing geological phenomena. The round trip from La Orotava to the summit and back lasted twenty-one hours. The Pizarro’s departure was delayed until 24 or 25 June 1799 due to the presence of an English squadron, allowing Humboldt and Bonpland additional time to explore the island’s surroundings.
=== Houston Astros === Bagwell spent his entire major-league career with the Houston Astros. Alongside teammate Craig Biggio, he was associated with the group of Astros players known as the “Killer B’s” during the 1990s and 2000s. From 1994 to 2003, Bagwell and Biggio combined for nine All-Star selections, five Gold Glove Awards, five top-five finishes in Most Valuable Player voting, 689 home runs, 2,485 runs batted in and 3,083 runs scored. During this period, the Astros reached the postseason six times. With an exaggerated and unusual batting style, Bagwell waited for each pitch in a low crouch, with legs wide open and knees bent nearly 90 degrees, appearing as if he was sitting on an invisible bench. He stepped back with his front foot as he began his swing. Next, he would rise from his stance and rotate his hands with the bat forward into his powerful, uppercut swing. "That wide stance keeps him from over striding", Joe Torre observed, "which can be your biggest problem when you're trying to hit for power." The low crouch also shrunk his strike zone, allowing him to walk more often. Standing 6 feet tall (72 inches (180 cm)) and weighing 195 pounds (88 kg), he did not present the image of an imposing, home run-hitting giant that would cause pitchers to be very careful when he batted after he began his major league career.
Sangeeta N. Bhatia (born June 24, 1968) is an American inventor, professor, and entrepreneur who holds both medical and engineering training. She holds multiple appointments and directs substantial research programs at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts She is reported to be the first woman physician-scientist to be elected to all five of the United States' National Academies.
Sources: en.wikipedia.org
=== New ownership === In December 2017, Patrick Cryne and his family sold an 80% stake in the club to NewCity Capital's Chien Lee and Pacific Media Group's Paul Conway. They were joined by Indian investor Neerav Parekh and Billy Beane, minority owner of and advisor for the Athletics, who was widely known for the Moneyball film portrayal, as part of an international investor consortium. Barnsley were relegated to the third tier in 2017–18. Following this, the new owners adopted a data-driven approach to identify talents, focusing on young players and team rebuilding. The club appointed Daniel Stendel as head coach, who introduced a high-pressing style of play. Barnsley were promoted back to the Championship the following season. In the 2019–20 season, under new coach Gerhard Struber, Barnsley avoided relegation from the Championship. In 2020–21, under the management of Valérien Ismaël, Barnsley finished fifth place and reached the EFL Championship Play-offs for the first time in 24 years, doing so with the youngest squad and one of the smallest budgets in the division. The Wall Street Journal called Barnsley a "Moneyball experiment". Prior to the 2021–22 season, Markus Schopp was appointed as the new head coach. In November 2021, he was dismissed after seven consecutive defeats. Three weeks later Poya Asbaghi was appointed as his successor. Fortunes improved little as Barnsley were relegated from the 2021–22 EFL Championship following a 2–1 defeat against Huddersfield Town. Asbaghi left the club by mutual consent shortly afterwards.
In 1870, German physicians Gustav Fritsch and Eduard Hitzig reported the modulation of brain activity in dogs by electrical stimulation of the motor cortex. In 1887, Spanish neuroanatomist professor Santiago Ramón y Cajal improved the Golgi's method of visualizing nervous tissue under light microscopy by using a technique he termed "double impregnation". He discovered a number of facts about the organization of the nervous system: the nerve cell as an independent cell, insights into degeneration and regeneration, and ideas on brain plasticity.
Soon after the Normans began to enter Italy, they entered the Byzantine Empire and then Armenia, fighting against the Pechenegs, the Bulgarians, and especially the Seljuk Turks. Norman mercenaries were first encouraged to come to the south by the Lombards to act against the Byzantines, but they soon fought in Byzantine service in Sicily. They were prominent alongside Varangian and Lombard contingents in the Sicilian campaign of George Maniaces in 1038–40. There is debate whether the Normans in Greek service actually were from Norman Italy, and it now seems likely only a few came from there. It is also unknown how many of the "Franks", as the Byzantines called them, were Normans and not other Frenchmen.
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.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.