A practical reference on Enkephalinase: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-11-30 and is reviewed periodically as new material appears.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
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.
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.
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.
=== Chemical synthesis === Digital Microfluidics (DMF) allows for precise manipulation and coordination in small-scale chemical synthesis reactions due to its ability to control micro scale volumes of liquid reagents, allowing for overall less reagent use and waste. This technology can be used in the synthesis compounds such as peptidomimetics and PET tracers. PET tracers require nanogram quantities and as such, DMF allows for automated and rapid synthesis of tracers with 90-95% efficiency compared to conventional macro-scale techniques. Organic reagents are not commonly used in DMF because they tend to wet the DMF device and cause flooding; however synthesis of organic reagents can be achieved through DMF techniques by carrying the organic reagents through an ionic liquid droplet, thus preventing the organic reagent from flooding the DMF device. Droplets are combined together by inducing opposite charges thus attracting them to each other. This allows for automated mixing of droplets. Mixing of droplets are also used to deposit MOF crystals for printing by delivering reagents into wells and evaporating the solutions for crystal deposition. This method of MOF crystal deposition is relatively cheap and does not require extensive robotic equipment. Chemical synthesis using digital microfluidics (DMF) has been applied to many noteworthy biological reactions. These include polymerase chain reaction (PCR), as well as the formation of DNA and peptides.
BRD-6929, also widely known as "compound 60" (Cpd-60 or Cmpd60), is a histone deacetylase (HDAC) inhibitor which is used in scientific research. It has been described in the past as the prototypical selective HDAC1 and HDAC2 inhibitor. However, subsequent findings suggest that BRD-6929 may not actually be selective for HDAC1 and HDAC2 over HDAC3.
Valerie Horsley is an American cell and developmental biologist. She currently works as an associate professor at Yale University, where she has extensively researched the growth, restoration, and maintenance of skin cells. She is a currently a member of the Yale Cancer Center and Yale Stem Cell Center. She received a Presidential Early Career Award for Scientists and Engineers in 2012 and in 2013 she was the recipient of the Rosalind Franklin Young Investigator Award.
The Coffee Bean & Tea Leaf (sometimes shortened to simply "Coffee Bean" or "The Coffee Bean") is an American coffee chain founded in 1963. It was previously owned and operated by International Coffee & Tea, LLC based in Los Angeles, California, before it was acquired in 2019 by Jollibee Group, a multinational company based in the Philippines, for $350 million. As of 2024, the chain has 1,232 stores spread across 24 countries.
Sources: en.wikipedia.org
At the regulatory site, the binding of a ligand may elicit amplified or inhibited protein function. The binding of a ligand to an allosteric site of a multimeric enzyme often induces positive cooperativity, that is the binding of one substrate induces a favorable conformation change and increases the enzyme's likelihood to bind to a second substrate. Regulatory site ligands can involve homotropic and heterotropic ligands, in which single or multiple types of molecule affects enzyme activity respectively. Enzymes that are highly regulated are often essential in metabolic pathways. For example, phosphofructokinase (PFK), which phosphorylates fructose in glycolysis, is largely regulated by ATP. Its regulation in glycolysis is imperative because it is the committing and rate limiting step of the pathway. PFK also controls the amount of glucose designated to form ATP through the catabolic pathway. Therefore, at sufficient levels of ATP, PFK is allosterically inhibited by ATP. This regulation efficiently conserves glucose reserves, which may be needed for other pathways. Citrate, an intermediate of the citric acid cycle, also works as an allosteric regulator of PFK.
=== Audio === Todd played the title character in Bleak December Inc.'s 2016 audio drama adaptation of Bram Stoker's Dracula. Todd was the narrator of the spoken word version of Ice Nine Kills' album The Silver Scream, released on June 29, 2023.
IATA estimates that over a billion lithium metal and lithium-ion cells are flown each year. Some kinds of lithium batteries may be prohibited aboard aircraft because of the fire hazard. Some postal administrations restrict air shipping (including EMS) of lithium and lithium-ion batteries, either separately or installed in equipment.
=== Franchises in Israeli settlements === Further controversies have occurred during the company's expansion in the Middle East. The opening of a Burger King location in Ma'aleh Adumim, an Israeli settlement in the Israeli-occupied Palestinian territories, led to a breach of contract dispute between Burger King and its Israeli franchise due to the hotly contested international dispute over the legality of Israeli settlements in the Palestinian territories in accordance to international law. The controversy eventually erupted into a geopolitical dispute involving Muslim and Jewish groups on multiple continents over the application of, and adherence to, international law. The case eventually elicited reactions from the members of the 22-nation Arab League. The Islamic countries within the League made a joint threat to the company of legal sanctions, including the revocation of Burger King's business licenses within the member states' territories.
=== Mental tools === FM can cause negative mental effects. German guidance encourages FM patients to focus on coping with symptoms (instead of fighting the syndrome), on aspects of life which are important to them, on ceasing perfectionism, and on establishing and respecting their limits. In a 2020 Cochrane review, cognitive behavioral therapy (CBT) was found to have a small but beneficial effect for reducing pain and distress, but adverse events were not well evaluated. CBT and related psychological and behavioral therapies have a small to moderate effect in reducing symptoms of fibromyalgia. Effect sizes tend to be small when psychological therapies are used as treatment for patients with fibromyalgia, and are comparable to the effect sizes seen with other drug and pain treatments. Multicomponent treatment appears to have greater efficacy than any individual treatment. Several reviews have found that CBT has no significant effect in pain reduction, although it does improve sleep quality. There is also limited evidence that acceptance and commitment therapy improves outcomes such as health-related quality of life and pain acceptance. Patient education is recommended by the European League Against Rheumatism (EULAR) as an important treatment component. As of 2022, there is only low-quality evidence showing that patient education can decrease pain and fibromyalgia impact. Sleep hygiene interventions show low effectiveness in improving insomnia in people with chronic pain.
Sources: en.wikipedia.org
Some literature even describes unique cases where muscle pain, cramping, and elevated creatine kinase levels are the only presenting symptoms instead of the classic presentation of muscle weakness.Becker muscular dystrophy occurs in approximately 1.5 to 6 in 100,000 male births, making it much less common than Duchenne muscular dystrophy. Symptoms usually appear in men at about ages 8–25, but may sometimes begin later. Genetic counseling may be advisable when potential carriers or patients want to have children. Sons of a man with Becker muscular dystrophy do not develop the disorder, but daughters will be carriers (and some carriers can experience some symptoms of muscular dystrophy), so the daughters' sons may develop the disorder.
The controversy over the demolition of such a well-known landmark, and its deplored replacement, is often cited as a catalyst for the architectural preservation movement in the United States. Within the decade, Grand Central Terminal was protected under the city's new landmarks preservation act, a protection upheld by the courts in 1978 after a challenge by Grand Central's owner, Penn Central (the corporate successor of the PRR, following its merger with the rival New York Central Railroad).
The cones are less abundant than rods and come in three types, each contains its own type of iodopsin, the opsins of the cones. The cones mediate color vision, and vision in bright light (day vision).
Following the accession of Franz Joseph to the throne in 1848, the political representatives of the Kingdom of Bohemia hoped and insisted that account should be taken of their historical state rights in the upcoming constitution. They felt the position of Bohemia within the Habsburg monarchy should have been highlighted by a coronation of the new ruler to the king of Bohemia in Prague (the last coronation took place in 1836). However, before the 19th century the Habsburgs had ruled Bohemia by hereditary right and a separate coronation was not deemed necessary. His new government installed the system of neoabsolutism in Austrian internal affairs to make the Austrian Empire a unitary, centralised and bureaucratically administered state. When Franz Joseph returned to constitutional rule after the debacles in Italy at Magenta and Solferino and summoned the diets of his lands, the question of his coronation as king of Bohemia again returned to the agenda, as it had not since 1848. On 14 April 1861, Emperor Franz Joseph received a delegation from the Bohemian Diet with his words (in Czech):
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
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.