The short version of Enkephalinase fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-02-17 and is reviewed periodically as new material appears.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
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.
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.
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.
| 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 |
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.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
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.
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.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
== Design == Brentuximab vedotin consists of the chimeric monoclonal antibody brentuximab (cAC10, which targets the cell-membrane protein CD30) linked with maleimide attachment groups, cathepsin-cleavable linkers (valine-citrulline), and para-aminobenzylcarbamate spacers to three to five units of the antimitotic agent monomethyl auristatin E (MMAE, reflected by the 'vedotin' in the drug's name). The peptide-based linker bonds the antibody to the cytotoxic compound in a stable manner so the drug is not easily released from the antibody under physiologic conditions to help prevent toxicity to healthy cells and ensure dosage efficiency. The peptide antibody-drug bond facilitates rapid and efficient drug cleavage inside target tumor cell. The antibody cAC10 part of the drug binds to CD30 which often occurs on diseased cells but rarely on normal tissues. The antibody portion of the drug attaches to CD30 on the surface of malignant cells, delivering MMAE which is responsible for the anti-tumour activity. Once bound, brentuximab vedotin is internalised by endocytosis and thus selectively taken up by targeted cells. The vesicle containing the drug is fused with lysosomes and lysosomal cysteine proteases, particularly cathepsin B, start to break down valine-citrulline linker and MMAE is no longer bound to the antibody and is released directly into the tumor environment.
=== The nucleic acid template hypotheses === Alexander Dounce, of the University of Rochester Medical Center in New York, came close to the correct interpretation of protein synthesis from RNA. In 1952, he proposed the first notion, naming it the "nucleic acid template hypotheses," that proteins were made from RNA, rather than from DNA. However, since the exact chemical structure of DNA or RNA was not known at the time, he suggested erroneously that proteins and RNA have complimentary sequences, as he described in Enzymologia: "the specific arrangement of amino acid residues in a given peptide chain is derived from the specific arrangement of nucleotide residues in a corresponding specific nucleic acid molecule." It was met with criticism in Nature the next year, to which Dounce defended his hypothesis:In the hypothesis proposed by me, ribonucleic acid was deliberately chosen as the template, since it seems probable from a number of considerations and experimental investigations that protein syn- thesis may occur in cytoplasm as well as in nuclei. There can be no objection at the present time to assuming that the genes are templates, but it is not necessary to assume that the genes act directly as templates for protein synthesis.
In modern everyday life there are many observations that can be successfully explained by application of Bernoulli's principle, even though no real fluid is entirely inviscid, and a small viscosity often has a large effect on the flow.
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==== Support for Bashar al-Assad ==== Galloway supported the Syrian occupation of Lebanon, telling the Lebanese Daily Star in August 2008: "Syrian troops in Lebanon maintain stability and protect the country from Israel". In the same article he expressed his opposition to United Nations Security Council Resolution 1559, which urged the Lebanese Government to establish control over all its territory. When Syria did withdraw from Lebanon, Galloway objected and said the occupation had been entirely "legal"; Christopher Hitchens, citing the Taif Accords of 1989, disputed his comment. Referring to Syrian president Bashar al-Assad, Galloway said during a visit to the University of Damascus in November 2005: "For me he is the last Arab ruler, and Syria is the last Arab country. It is the fortress of the remaining dignity of the Arabs". He also called Assad a "breath of fresh air". Galloway again praised the government of Assad in a leaked 2010 email to Assad's advisor Bouthaina Shaaban when asking for help in a Viva Palestina convoy, and reminded her of previous help from the Syrian government for the campaign. In the correspondence, leaked by the Anonymous hacking group, she responded: "God bless your amazing efforts and I will be honoured to be part and parcel of it". "I knew that I could rely on you and the last Arab country in this historic endeavour", Galloway wrote in response. Galloway said in a July 2011 interview on Hezbollah's Al-Manar station: "Bashar Assad wants reform and change, to realise the aspirations of his people".
Bisulfite treated DNA is then PCR amplified, resulting in cytosine residues at originally methylated positions, and thymine residues at originally unmethylated position (that were converted to uracil). Primers used during this step do not contain CpG sites (the common target of cytosine methylation), so the amplification process does not discriminate between templates based on methylation status. PCR products are purified to ensure complete digestion in the following step.
antibody Any of a diverse family of glycoproteins known as immunoglobulins capable of binding specifically but reversibly via non-covalent interactions to a particular antigen or immunogen. Antibodies are generated as part of an organism's immune response to the introduction of a specific antigen into a host organism, and their binding of the antigen frequently (though not always) counteracts or inhibits any biological activity the antigen may have. Antibodies have a characteristic Y-shaped structure consisting of a heavy chain and light chain held together by disulfide bonds.
In February 1917, revolution broke out in Russia in which workers, soldiers and peasants established soviets, the monarchy was forced into exile fell and a provisional government was formed until the election of a constituent assembly. Alexander Kerensky, a Russian lawyer and revolutionary, became a key political figure in the Russian Revolution of 1917. After the February Revolution, Kerensky joined the newly formed Russian Provisional Government, first as Minister of Justice, then as Minister of War and after July as the government's second Minister-Chairman. A leader of the moderate socialist Trudovik faction of the Socialist Revolutionary Party known as the Labour Group, Kerensky was also the vice-chairman of the powerful Petrograd Soviet. After failing to sign a peace treaty with the German Empire to exit from World War I which led to massive popular unrest against the government cabinet, Kerensky's government was overthrown on 7 November by the Bolsheviks led by Vladimir Lenin in the October Revolution. Soon after the October Revolution, the Russian Constituent Assembly elected Socialist-Revolutionary leader Victor Chernov as President of a Russian Republic, but it rejected the Bolshevik proposal that endorsed the Soviet decrees on land, peace and workers' control and acknowledged the power of the Soviets of Workers', Soldiers' and Peasants' Deputies.
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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.
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.