A practical reference on Enkephalinase: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-06-07. Anything still debated is marked as such rather than presented as settled.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
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.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
=== Management of acute flare === During moderate or severe symptomatic attacks, a short course (usually 3–5 days) of high doses of corticosteriods is the usual approach. Initially, oral corticosteroids are used; if that is ineffective, an intravenous course can be tried. Milder attacks may not need treatment. Although targeted at acute attacks, they might also have a small longer-term benefit. Severe attacks that do not respond to corticosteroids might be treatable by plasma exchange.
Fatty acids are made by fatty acid synthases that polymerize and then reduce acetyl-CoA units. The acyl chains in the fatty acids are extended by a cycle of reactions that add the acyl group, reduce it to an alcohol, dehydrate it to an alkene group and then reduce it again to an alkane group. The enzymes of fatty acid biosynthesis are divided into two groups: in animals and fungi, all these fatty acid synthase reactions are carried out by a single multifunctional type I protein, while in plant plastids and bacteria separate type II enzymes perform each step in the pathway. Terpenes and isoprenoids are a large class of lipids that include the carotenoids and form the largest class of plant natural products. These compounds are made by the assembly and modification of isoprene units donated from the reactive precursors isopentenyl pyrophosphate and dimethylallyl pyrophosphate. These precursors can be made in different ways. In animals and archaea, the mevalonate pathway produces these compounds from acetyl-CoA, while in plants and bacteria the non-mevalonate pathway uses pyruvate and glyceraldehyde 3-phosphate as substrates. One important reaction that uses these activated isoprene donors is sterol biosynthesis. Here, the isoprene units are joined to make squalene and then folded up and formed into a set of rings to make lanosterol. Lanosterol can then be converted into other sterols such as cholesterol and ergosterol.
== History == Multiple epiphyseal dysplasia was described separately by Seved Ribbing and Harold Arthur Thomas Fairbank in the 1930s. In 1994, Ralph Oehlmann's group mapped MED to the peri-centromeric region of chromosome 19, using genetic linkage analysis. Michael Briggs' group mapped PSACH to the same area. COMP gene was firstly linked to MED and PSACH in 1995. In 1995, the group led by Knowlton did a "high-resolution genetic and physical mapping of multiple epiphyseal dysplasia and pseudoachondroplasia mutations at chromosome 19p13.1-p12." Research on COMP led to mouse models of the pathology of MED. In 2002, Svensson's group generated a COMP-null mouse to study the COMP protein in vivo. These mice showed no anatomical, histological, or even ultrastructural abnormalities and none of the clinical signs of PSACH or MED. Lack of COMP was not compensated for by any other protein in the thrombospondin family. This study confirmed that the disease is not caused by reduced expression of COMP. In 2007, Piròg-Garcia's group generated another mouse model carrying a mutation previously found in a human patient. With this new model, they were able to demonstrate that reduced cell proliferation and increased apoptosis are significant pathological mechanisms involved in MED and PSACH. In 2010, this mouse model allowed a new insight into myopathy and tendinopathy, which are often associated with PSACH and MED. These patients show increased skeletal muscle stress, as indicated by the increase in myofibers with central nuclei.
In the classical era, Aristotle divided animals, based on his own observations, into those with blood (roughly, the vertebrates) and those without. The animals were then arranged on a scale from man (with blood, two legs, rational soul) down through the live-bearing tetrapods (with blood, four legs, sensitive soul) and other groups such as crustaceans (no blood, many legs, sensitive soul) down to spontaneously generating creatures like sponges (no blood, no legs, vegetable soul). Aristotle was uncertain whether sponges were animals, which in his system ought to have sensation, appetite, and locomotion, or plants, which did not: he knew that sponges could sense touch and would contract if about to be pulled off their rocks, but that they were rooted like plants and never moved about. In 1758, Carl Linnaeus created the first hierarchical classification in his Systema Naturae. In his original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then, the last four have all been subsumed into a single phylum, the Chordata, while his Insecta (which included the crustaceans and arachnids) and Vermes have been renamed or broken up. The process was begun in 1793 by Jean-Baptiste de Lamarck, who called the Vermes une espèce de chaos ('a chaotic mess') and split the group into three new phyla: worms, echinoderms, and polyps (which contained corals and jellyfish).
Sources: en.wikipedia.org
In some cases, even marine taxa that had acquired spongy bone can revert to thicker, compact bones if they become adapted to live in shallow water, or in hypersaline (denser) water. Many animals, particularly herbivores, practice osteophagy—the eating of bones. This is presumably carried out in order to replenish lacking phosphate. Many bone diseases that affect humans also affect other vertebrates—an example of one disorder is skeletal fluorosis.
Analysis of the debris at the test site of the United States' first thermonuclear weapon, Ivy Mike (1 November 1952, Enewetak Atoll), besides einsteinium, fermium, plutonium and americium also revealed isotopes of berkelium, californium and curium, in particular 245Cm, 246Cm and smaller quantities of 247Cm, 248Cm and 249Cm. Atmospheric curium compounds are poorly soluble in common solvents and mostly adhere to soil particles. Soil analysis revealed about 4,000 times higher concentration of curium at the sandy soil particles than in water present in the soil pores. An even higher ratio of about 18,000 was measured in loam soils. The transuranic elements up to fermium, including curium, should have been present in the natural nuclear fission reactor at Oklo, but any quantities produced then would have long since decayed away.
Members of some Christian sects in the Southern United States are regularly bitten while participating in "snake handling" rituals. Snake handling is when people hold venomous snakes, unprotected, as part of a religious service inspired by a literal interpretation of the Bible verses Mark 16:17–18, which reads, "In my name ... They shall take up serpents ...."
an α-amino acid + an alcohol This enzyme belongs to the family of hydrolases, specifically those acting on carboxylic ester bonds. The systematic name is α-amino-acid-ester aminoacylhydrolase. This enzyme is also called α-amino acid ester hydrolase.
== Political impact == In Britain the Liberal Party objected to, and later opposed, the Boer War. Later, Jameson became Prime Minister of the Cape Colony (1904–08) and one of the founders of the Union of South Africa. He was made a baronet in 1911 and returned to England in 1912. On his death in 1917, he was buried next to Cecil Rhodes and the 34 BSAC soldiers of the Shangani Patrol (killed in 1893 in the First Matabele War) in the Matobos Hills, near Bulawayo.
Sources: en.wikipedia.org
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
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.