Enkephalinase raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-11-09. Anything still debated is marked as such rather than presented as settled.
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.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
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.
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.
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.
Sorenson, MD, from the Mayo Clinic in Rochester, Minnesota "While this is very disappointing, at least it was definitive and gives, I think, a pretty definitive answer, at least for this strategy for this drug," Dr. Sorenson said. However, he added, "there is still a great deal of evidence that the IGF-1 pathway can be beneficial to people who have ALS, but just not the way we administered it." Novel methods of delivering IGF-1 in a more selected fashion are now under way, including the use of viral mediators or stem cells. Two previous phase 3 trials of IGF-1 in ALS showed inconsistent results: 1 trial, carried out in North America, did find a benefit, whereas the other, a European trial, did not confirm the earlier findings. "The results of our study most resemble those of the previous European study, with no benefit in either survival or functional scales", De Sorenson concludes. "It is disappointing that we were unable to confirm the benefit that was noted in the previous North American study." Conclusive evidence points, what Iplex (and any form of IGF-1) can't slow progression in human ALS. Lot of sites that have published articles about the link between Lyme disease and ALS are sponsored by clinics specializing in the treatment of chronic Lyme disease, or by the sellers of products for treating this, or both.
A new King Crimson formation was announced in 2007: Fripp, Belew, Levin, Mastelotto, and a new second drummer, Gavin Harrison of Porcupine Tree. In August 2008, after a period of rehearsals, the five completed the band's 40th Anniversary Tour. The setlists featured no new material, drawing instead from the existing Larks' Tongues-era/Discipline-era/Double Trio/Double Duo repertoire. Additional shows were planned for 2009, but were cancelled due to scheduling clashes with Belew. King Crimson began another hiatus after the 40th Anniversary Tour. Belew continued to lobby for reviving the band, and discussed it with Fripp several times in 2009 and 2010. Among Belew's suggestions was a temporary reunion of the 1980s line-up for a thirtieth anniversary tour: an idea declined by both Fripp and Bruford, the latter commenting "I would be highly unlikely to try to recreate the same thing, a mission I fear destined to failure." In December 2010, Fripp wrote that the King Crimson "switch" had been set to "off" since October 2008, citing several reasons for this decision. In August 2012, Fripp announced his planned retirement from the music industry, leaving the future of King Crimson uncertain.
July 12: Law concerning freedom of higher education (for boys). July 24: "Women of ill repute" are kept away from the gendarmerie. 1879 August 9: Law establishing primary teacher training colleges: each department is required to have one, with a version for training male teachers and another for training female teachers—destined for communal schools. December 5: Decree organizing the General Inspectorate of Administrative Services of the Ministry of the Interior; among the planned measures is the creation of a post for a female general inspector—her salary is lower than that of her male counterparts; this general inspector is particularly in charge of inspecting girls' penal institutions and women's establishments. 1880
==== Taxation of e-commerce ==== In early 2023 the government announced plans to remove tax exemptions for international purchases up to US$50 between individuals. After negative reactions the government maintained the rule, but later introduced the “Remessa Conforme” program in August 2023.
He also helped fund much research, through the iron foundry which he owned and directed. His statue is prominently placed in front of the Gallery of Evolution. Following the French Revolution the MNHN was reorganised, with twelve professorships of equal rank. Some of its early professors included eminent comparative anatomist Georges Cuvier and the pioneers of the theory of evolution, Jean-Baptiste de Lamarck and Étienne Geoffroy Saint-Hilaire. The museum's aims were to instruct the public, put together collections and conduct scientific research. The naturalist Louis Jean Marie Daubenton wrote extensively about biology for the pioneer French Encyclopédie, and gave his name to several newly discovered species. The museum sent its trained botanists on scientific expeditions around the world. Major figures in the MNHN included Déodat de Dolomieu, who gave his name to the mineral dolomite and to a volcano on Réunion island, and the botanist Rene Desfontaines, who spent two years collecting plants for study Tunisia and Algeria, and whose book "Flora Atlantica" (1798–1799, 2 vols), added three hundred genera new to science. When Napoleon Bonaparte launched his military campaign to conquer Egypt in 1798, his army was accompanied by more than 154 scientists, including botanists, chemists, mineralogists, including Étienne Geoffroy Saint-Hilaire, Vivant Denon, Joseph Fourier, and Claude Louis Berthollet, who together took back a large quantity of specimens and illustrations to enrich the collections of the museum.
Sources: en.wikipedia.org
Amino acids have been considered as components of biodegradable polymers, which have applications as environmentally friendly packaging and in medicine in drug delivery and the construction of prosthetic implants. An interesting example of such materials is polyaspartate, a water-soluble biodegradable polymer that may have applications in disposable diapers and agriculture. Due to its solubility and ability to chelate metal ions, polyaspartate is also being used as a biodegradable antiscaling agent and a corrosion inhibitor. The commercial production of amino acids usually relies on mutant bacteria that overproduce individual amino acids using glucose as a carbon source. Some amino acids are produced by enzymatic conversions of synthetic intermediates. 2-Aminothiazoline-4-carboxylic acid is an intermediate in one industrial synthesis of L-cysteine for example. Aspartic acid is produced by the addition of ammonia to fumarate using a lyase.
These weight reduction treatments include the injection of HCG, a drug which has not been approved by the Food and Drug Administration as safe and effective in the treatment of obesity or weight control. There is no substantial evidence that HCG increases weight loss beyond that resulting from caloric restriction, that it causes a more attractive or "normal" distribution of fat, or that it decreases the hunger and discomfort associated with calorie-restrictive diets. There was a resurgence of interest in the "HCG diet" following promotion by Kevin Trudeau, who was banned from making HCG diet weight-loss claims by the U.S. Federal Trade Commission in 2008, and eventually jailed over such claims. A 1976 study in the American Journal of Clinical Nutrition concluded that HCG is not more effective as a weight-loss aid than dietary restriction alone. A 1995 meta analysis found that studies supporting HCG for weight loss were of poor methodological quality and concluded that "there is no scientific evidence that HCG is effective in the treatment of obesity; it does not bring about weight-loss or fat-redistribution, nor does it reduce hunger or induce a feeling of well-being". On November 15, 2016, the American Medical Association (AMA) passed policy that "The use of human chorionic gonadotropin (HCG) for weight loss is inappropriate."
== Health concerns == For introduction of radionuclides into an organism, ingestion is the most important route. Insoluble compounds are not absorbed from the gut and cause only local irradiation before they are excreted. Soluble forms however show wide range of absorption percentages.
This allows the creation of a novel formulation that retains the smooth control of a long-acting basal with rapid-acting mealtime control from insulin aspart. This 2-component insulin retains the ultralow risk characteristics of degludec with simultaneous mealtime coverage.
The stable isotope composition of amino acids refers to the abundance of heavy and light non-radioactive isotopes of carbon (13C and 12C), nitrogen (15N and 14N), and other elements within these molecules. Amino acids are the building blocks of proteins. They are synthesized from alpha-keto acid precursors that are in turn intermediates of several different pathways in central metabolism. Carbon skeletons from these diverse sources are further modified before transamination, the addition of an amino group that completes amino acid biosynthesis. Bonds to heavy isotopes are stronger than bonds to light isotopes, making reactions involving heavier isotopes proceed slightly slower in most cases. This phenomenon, known as a kinetic isotope effect, gives rise to isotopic differences between reactants and products that can be detected using isotope ratio mass spectrometry. Amino acids are synthesized via a variety of pathways with reactions containing different, unknown isotope effects. Because of this, the 13C content of amino acid carbon skeletons varies considerably between the amino acids. There is also an isotope effect associated with transamination, which is apparent from the abundance of 15N in some amino acids. Because of these properties, amino acid isotopes record useful information about the organisms that produce them. Variations in metabolism between different taxonomical groups give rise to characteristic patterns of 13C enrichment in their amino acids. This allows the sources of carbon in food webs to be identified.
Sources: en.wikipedia.org
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.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.