Enkephalinase comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
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.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
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.
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.
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.
==== 1998 congressional campaign ==== In 1998, Yates opted to forgo reelection, and Pritzker ran in the Democratic primary to succeed him, reconstituting his campaign committee in April 1997. Also running in the primary were state representative Jan Schakowsky and state senator Howard W. Carroll. The district covered the northern lakefront of Chicago, as well as the suburbs of Evanston and Skokie. It had a large Jewish electorate and had long been regarded as the "Jewish seat" in Illinois's congressional delegation. Yates was Jewish, as were all three Democratic contenders to succeed him. The district had been described as being among the most liberal in the country. Journalist James Ylisela Jr. observed that Pritzker, Schakowsky, and Carroll largely all ran on platforms aligned with the "liberal Democratic Party agenda" that Yates had championed. But the Chicago Tribune wrote that Pritzker and Carroll ran on more moderate platforms than Schakowsky, and therefore potentially wound up competing with each other for many of the same voters. At the time, the election was one of the most expensive congressional primaries in U.S. history, and Pritzker spent nearly $1 million of his own money on his campaign. This included $500,000 on television ads in the Chicago market. He finished third among five candidates in the Democratic primary, with 20.5% of the vote to Schakowsky's 45.1% and Carroll's 34.4%. Schakowsky went on to represent the district for 28 years, retiring after the 2026 election.
The first aircraft carrying troopers from the 2–325th touched down at Point Salines 17 hours after H-Hour notification. In March 1988, a brigade task force made up of two battalions from the 504th Infantry and 3d Battalion (Airborne), 505th Infantry, conducted a parachute insertion and air/land operation into Honduras as part of Operation Golden Pheasant. The deployment was billed as a joint training exercise, but the paratroopers were ready to fight. The deployment caused the Sandinistas to withdraw to Nicaragua. Operation Golden Pheasant prepared the paratroopers for future combat in an increasingly unstable world.
=== Linker === Between the reactive group and the tag, ABPs often include a linker / spacer / biorecognition element, which can tune probe solubility, steric accessibility, and substrate mimicry. Simple linkers may consist of alkyl chains or polyethylene glycol (PEG) spacers which adjust hydrophobicity and improve labeling across diverse proteomes. More complex designs incorporate biorecognition elements which can impart enzyme family or subfamily selectivity. For example, substrate-mimetic phosphonates have been used to target specific serine proteases and optimized peptide sequences can discriminate caspase isoforms. Binding or targeting motifs within the linker can further enhance interactions with enzymes whose active sites impose structural constraints, thereby improving probe specificity. In addition, linker length and composition can modulate probe permeability and distribution in cellular or in vivo contexts. This component allows probe designers to balance breadth (profiling an entire enzyme class) versus specificity (targeting individual members).
==== Sniper killings ==== In February 2024, an American doctor returning from the Gaza Strip wrote an op-ed in the Los Angeles Times stating that she had witnessed children being deliberately targeted by Israeli snipers, writing, "On one occasion, a handful of children, all about ages 5 to 8, were carried to the emergency room by their parents. All had single sniper shots to the head... None of these children survived." A Canadian doctor returning from a week in Gaza stated she had seen crimes against humanity, including small children "dying of hunger, bombs, sniper shots." Israeli drone footage released in March 2024 showed Israeli snipers killing an unarmed boy in Jabalia. In April 2024, doctors said they were seeing "a steady stream of children, elderly people and others who were clearly not combatants with single bullet wounds to the head or chest." Dr. Mark Perlmutter, an American doctor working in Gaza, stated Israeli snipers were targeting children, stating, "No toddler gets shot twice by mistake by the 'world's best sniper.' And they're dead-center shots." In August 2024, an American doctor returning from Gaza stated, "We had kids shot in the chest and shot in the head – in other words, clearly deliberate, clearly targeted". In October 2024, The New York Times reported compiled testimony from 44 doctors, nurses, and paramedics who treated multiple cases of preteen children with gunshot wounds to the head or chest in Gaza.
=== Hybrid === When the parent anticyclone is weaker or not ideally located, the diabatic process must start to contribute in order to develop CAD. In scenarios where there is an equal contribution from dry synoptic forcing and diabatic processes, it is considered a hybrid damming event. The 250-mb jet is weaker and slightly farther south relative to a classical composite 24 hours prior to CAD onset. With the surface parent high farther west, it builds in eastward into the northern Great Plains and western Great Lakes region, located beneath a region of confluent flow from the 250-mb jet.
Sources: en.wikipedia.org
=== Murine === Initial therapeutic antibodies were murine analogues (suffix -omab). These antibodies have: a short half-life in vivo (due to immune complex formation), limited penetration into tumour sites and inadequately recruit host effector functions. Chimeric and humanized antibodies have generally replaced them in therapeutic antibody applications. Understanding of proteomics has proven essential in identifying novel tumour targets. Initially, murine antibodies were obtained by hybridoma technology, for which Jerne, Köhler and Milstein received a Nobel prize. However the dissimilarity between murine and human immune systems led to the clinical failure of these antibodies, except in some specific circumstances. Major problems associated with murine antibodies included reduced stimulation of cytotoxicity and the formation of complexes after repeated administration, which resulted in mild allergic reactions and sometimes anaphylactic shock. Hybridoma technology has been replaced by recombinant DNA technology, transgenic mice and phage display.
Hydrogen cyanide is a bulk chemical; global production in 2001 was approximately 2.6 million tons. Key derivatives produced from it include adiponitrile, acetone cyanohydrin, sodium cyanide, and cyanuric chloride. Chelating agents are also synthesized from hydrogen cyanide, for example ethylenediaminetetraacetic acid from formaldehyde, ethylenediamine, hydrogen cyanide, and sodium hydroxide. An important industrial route to amino acids is the Strecker synthesis, in which hydrogen cyanide serves as a starting material. A quantitatively important amino acid is methionine, which is produced from acrolein, hydrogen cyanide, and hydrogen sulphide and is used primarily in animal feed.
=== Transdermal patch === Transdermal patches can be a very precise time released method of delivering a drug. Cutting a patch in half might affect the dose delivered. The release of the active component from a transdermal delivery system (patch) may be controlled by diffusion through the adhesive which covers the whole patch, by diffusion through a membrane which may only have adhesive on the patch rim or drug release may be controlled by release from a polymer matrix. Cutting a patch might cause rapid dehydration of the base of the medicine and affect the rate of diffusion.
Clot-dissolving agents (tissue plasminogen activator) Maggot larval debridement Correction of the underlying plasma calcium and phosphorus abnormalities (lowering the Ca x P product below 55 mg2/dL2) Avoiding further local tissue trauma (including avoiding all subcutaneous injections, and all not-absolutely-necessary infusions and transfusions) Patients who have received kidney transplants also receive immunosuppression. Considering lowering the dose of or discontinuing the use of immunosuppressive drugs in people who have received kidney transplants and continue to have persistent or progressive calciphylactic skin lesions can contribute to an acceptable treatment of calciphylaxis. A group in 2013 reported plasma exchange effective and proposed a serum marker and perhaps a mechanistic mediator (calciprotein)
Claremont and Miller's Wolverine (1982) introduces the motif that Wolverine emulates samurai ethics and practices to control and humanize his violent impulses and abilities. While he is able to master samurai fighting styles and some norms of behavior, he is not able to fully integrate himself into Japanese society. Comics scholar Jim Davis points out that Claremont took his knowledge of samurai culture from James Clavell's novel Shogun (1975), which takes place in the 16th century; Claremont has confirmed he was inspired by the 1980 TV adaptation. Davis believes that Claremont's depiction of Japanese society seems fixed in the feudal era, which he indicates is problematic. Academic Eric Sobel argues that Wolverine's samurai proficiency is an example of cultural appropriation and that his Japanese supporting characters are highly stereotyped. However, fellow academic Andrew Deman contests Sobel's argument, particularly his omission of Yukio, who is a complex Japanese character and counterpart to Wolverine. Larry Hama, whose Wolverine stories returned the title character to Japan and acted as a sequel to the Claremont–Miller miniseries, credited the influence of Yakuza films and Ridley Scott's Black Rain (1989) as inspiration. Being a Japanese American, Hama believed that his depiction of Japan was more authentic than previous American superhero stories set in the country. Tsutomu Nihei, a Japanese manga artist, created his own interpretation of Wolverine in the miniseries Wolverine: Snikt! (2003).
Sources: en.wikipedia.org
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.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
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.