This is a working overview of proteolysis, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-01. Anything still debated is marked as such rather than presented as settled.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
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.
| Property | Value | Notes |
|---|---|---|
| Primary route studied | Intranasal | Also examined parenterally in animal work |
| Reported plasma half-life | Minutes to tens of minutes | Values vary widely between reports |
| Main model systems | Rodent behavioural and cell assays | Human trials are few and small |
| Principal proposed targets | GABA-A receptor, GABA transaminase | Monoamine and neurotrophic pathways also reported |
| Evidence grade | Preliminary | Limited independent replication |
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.
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.
=== Insecticidal properties === Capsaicin deters insects in multiple ways. The first is by deterring insects from laying their eggs on the pepper due to the effects capsaicin has on these insects. Capsaicin can cause intestinal dysplasia upon ingestion, disrupting insect metabolism and causing damage to cell membranes within the insect. This in turn disrupts the standard feeding response of insects.
Martin Keown felt the manager harmed their chances by boasting they could go the season unbeaten. "Look, I said that because I think you can do it. But you must really want it," was Wenger's reply, as he believed the squad had the right mixture of technique, intelligence and physique. Arsenal did little transfer business given the financial demands that came with their new stadium project; their only major signing was Jens Lehmann, who replaced David Seaman as goalkeeper. Wenger retained his best players, despite interest shown by Chelsea's new owner Roman Abramovich. Six games into the league season, Arsenal were involved in a brawl against Manchester United; the ill-feeling stemmed from Vieira's dismissal late on. Several players were charged and fined accordingly by the FA and Wenger apologised for his team's over-reaction. The team restored their image with an entertaining performance against Newcastle; Henry Winter in his match report wrote: "Henry's opening goal encapsulated all that is good about Arsenal, the slick passing and intelligent movement." Wenger led his side to league triumph without a single defeat – an accomplishment last achieved by Preston North End 115 years before, in the Football League. "Somebody threw me a T-shirt after the trophy was presented which read 'Comical Wenger says we can go the whole season unbeaten.' I was just a season too early!," he remarked during the club's victory parade. Arsenal's run of 49 league games unbeaten came to an end with a 2–0 defeat at Manchester United on 24 October 2004.
The first national team was in the kingdom that existed between the two world wars. The Football Federation of what was then the Kingdom of Serbs, Croats and Slovenes was founded in Zagreb in 1919 under the name Jugoslavenski nogometni savez (and admitted into FIFA), and the national team played its first international game at the Summer Olympics in Antwerp in 1920. The opponent was Czechoslovakia, and the historic starting eleven that represented Kingdom of SCS on its debut were: Dragutin Vrđuka, Vjekoslav Župančić, Jaroslav Šifer, Stanko Tavčar, Slavin Cindrić, Rudolf Rupec, Dragutin Vragović, Artur Dubravčić, Emil Perška, Ivan Granec, and Jovan Ružić. They lost by a huge margin 0–7, but nonetheless got their names in the history books.
=== Synthetic ionophores === Many synthetic ionophores are based on crown ethers, cryptands, and calixarenes. Pyrazole-pyridine and bis-pyrazole derivatives have also been synthesized. These synthetic species are often macrocyclic. Some synthetic agents are not macrocyclic, e.g. carbonyl cyanide-p-trifluoromethoxyphenylhydrazone. Even simple organic compounds, such as phenols, exhibit ionophoric properties. The majority of synthetic receptors used in the carrier-based anion-selective electrodes employ transition elements or metalloids as anion carriers, although simple organic urea- and thiourea-based receptors are known.
Sources: en.wikipedia.org
== mRNA == The mRNA sequence of EPCIP in humans has one known isoform. This isoform is called uncharacterized protein C21orf62 isoform X1. This isoform is 458 base pairs, or 104 amino acids, in length, and it is significantly shorter than the most observed sequence of EPCIP in humans. In addition to having an isoform, EPCIP also has splice variants. All splice variants encode the same gene, but the differences in splice variant sequences occur in the 5' untranslated region of the mRNA sequence.
In February 2025, US president Trump imposed a 10% tariff on Chinese imports, claiming the move as a way "to pressure China into taking action on fentanyl" but experts have expressed concern that these tariffs could reverse the progress made under the Biden administration and weaken the international cooperation necessary to combat global drug trafficking. India has also emerged as a source of fentanyl and fentanyl precursors, where Mexican cartels have already developed networks for the import of synthetic drugs. It is possible that fentanyl and precursor production may disperse to other countries, such as Nigeria, South Africa, Indonesia, Myanmar, and the Netherlands. In 2020, the Myanmar military and police confiscated 990 gallons of "methyl fentanyl" [sic], as well as precursors for the illicit synthesis of the drug. According to the United Nations Office on Drugs and Crime, the Shan State of Myanmar has been identified as a major source for fentanyl derivatives. In 2021, the agency reported a further drop in opium poppy cultivation in Burma, as the region's synthetic drug market continues to expand and diversify. According to the national archives and the Drug Enforcement Administration (DEA), direct fentanyl shipments from China have stopped since 2022. The majority of illicit fentanyl and analogues now entering the U.S. from Mexico are final products in the form of "tablets", and adulterated heroin from previously synthesized fentanyl.
==== Histone O-GlcNAcylation ==== Histone proteins, the primary protein component of chromatin, have been reported to be modified by O-GlcNAc, though other studies have not been able to detect histone O-GlcNAc. The presence of O-GlcNAc on histones has been suggested to affect gene transcription as well as other histone marks such as acetylation and monoubiquitination. TET2 has been reported to interact with the TPR domain of OGT and facilitate recruitment of OGT to histones. Phosphorylation of OGT T444 via AMPK has been found to inhibit OGT-chromatin association and downregulate H2B S112 O-GlcNAc.
Etonitazene, also known as EA-4941 or CS-4640, is a benzimidazole opioid, first reported in 1957, that has been shown to have approximately 1,000 to 1,500 times the potency of morphine in animals. Because it is characterized by a strong dependency potential and a tendency to produce profound respiratory depression, it is not used in humans. It is, however, useful in animal models for addiction studies, particularly those requiring the animals to drink or ingest the agent, because it is not as bitter as opiate salts like morphine sulfate.
At first Coleridge welcomed the relief from pain provided by Kendal Black Drop, but was later to say that his "eyes had been opened to the true nature of the habit into which I had been ignorantly deluded by the seeming magic effects of opium".
Sources: en.wikipedia.org
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.
The peptide enters plasma rapidly and is broken down by ordinary proteases into amino acids and shorter fragments. Reported half-lives are short. Whether meaningful amounts of the intact molecule reach the brain is an open question.
Most clinical reports are small, published in Russian and not independently replicated. English-language reviews highlight the absence of large randomised trials. Conclusions about efficacy should be treated as provisional.
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.