A practical reference on amino acid sequence: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-16. Anything still debated is marked as such rather than presented as settled.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
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.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
| Property | Value | Notes |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected molecular mass |
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.
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.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
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.
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.
=== Family === In 1987, while in high school, Morgan married his girlfriend Sabina. The pair have three sons together. Morgan filed for divorce in August 2009, after having been separated for approximately eight years. Morgan credits one of his sons with having saved him from his alcoholism. Of his extended family, Morgan said in 2009, "I'm estranged from my own mother and most of my family, and I'm not sure that's going to change much". Morgan then dated Tanisha Hall. She donated one of her kidneys to Morgan in December 2010. In September 2011, on the red carpet at the Emmy Awards, Morgan announced he and model Megan Wollover had become engaged six months earlier in San Francisco. Their first child, a daughter, was born in New York City on July 2, 2013. Morgan and Wollover married on August 23, 2015. Morgan filed for divorce July 2020. In 2023, on an episode of Finding Your Roots, Morgan discovered he is third cousins with American rapper Nas. Morgan joked that working with Daniel Radcliffe on The Fall and Rise of Reggie Dinkins made him "a cool Dad".
== Synthesis == Fumaric acid is produced based on catalytic isomerisation of maleic acid in aqueous solutions at low pH. It precipitates from the reaction solution. Maleic acid is accessible in large volumes as a hydrolysis product of maleic anhydride, produced by catalytic oxidation of benzene or butane.
==== Sublingual ==== Sublingual administration is fulfilled by placing the drug between the tongue and the lower surface of the mouth. The sublingual mucosa is highly permeable and thereby provides access to the underlying expansive network composed of capillaries, leading to rapid drug absorption.
== Mechanism of self-resistance == Lariocidin-producing Paenibacillus sp. M2 encodes a GCN5-related N-acetyltransferase LrcE. Its gene is a part of the lariocidin biosynthetic gene cluster. LrcE specifically acetylates the side chain of LAR's Lys16, which reduces compound's affinity to the binding site on the ribosome. Similarly acting acetyltransferases confer resistance to LAR-like lasso peptides triculamin (TriT) and gelatinamin (GelT).
A major target of poaching is the totoaba in the Gulf of California, due to its perceived similarity to the traditional high-grade swim bladder of Bahaba taipingensis. The totoaba, a critically endangered species, is protected by CITES. Poachers use gillnets to capture the totoaba, and often remove the valuable bladder and toss the dead fish into the sea to minimize evidence. Poaching operations were backed by a transnational organized crime ring known by the moniker 'the Dragon Cartel' (Spanish: Cártel del Dragón): a cooperation between Chinese organized crime and Mexican cartels, particularly the Sinaloa cartel, operating in Mexicali, Baja California. Mexican cartels poached totoaba maw (Spanish: buches) and smuggled them through local restaurateurs to international ports like Vancouver, and traded them with Chinese criminals for the chemical precursors to fentanyl. As of 2021, a single totoaba maw sold for US$3-5,000 equivalent in Mexico, US$10-15,000 in the US, and US$60,000 in China. For its high price and involvement with drug trafficking, totoaba maw has been given the media moniker "cocaine of the sea". In 2019, internal documents of the Secretariat of Environment and Natural Resources (SEMARNAT) of Mexico claimed that the government has minimally investigated cartel activity. SEMARNAT's prosecution branch PROFEPA opened 42 investigations into totoaba poaching between 2012 and 2021, resulting in two arrests.
Sources: en.wikipedia.org
== Veterinary uses == Veterinary overdose in dogs is very well treated by cyproheptadine HCl. Venlafaxine is highly toxic to Bacillariophyta and Chlorophyta phytoplankton. Cats are drawn to the smell of venlafaxine and tend to ingest the pills, which are highly toxic to them.
== Mechanism of action == Tedizolid phosphate (TR-701) is a prodrug activated by plasma or intestinal phosphatases to tedizolid (TR-700) following administration of the drug either orally or intravenously. Once activated, tedizolid exerts its bacteriostatic microbial activity through inhibition of protein synthesis by binding to the 50S ribosomal subunit (on the acceptor site) of the bacteria.
=== Common biochemistry === All known forms of life are based on the same fundamental biochemical organization: genetic information encoded in DNA, transcribed into RNA, through the effect of protein- and RNA-enzymes, then translated into proteins by (highly similar) ribosomes, with ATP, NADPH and others as energy sources. Analysis of small sequence differences in widely shared substances such as cytochrome c further supports universal common descent. Some 23 proteins are found in all organisms, serving as enzymes carrying out core functions like DNA replication. The fact that only one such set of enzymes exists is convincing evidence of a single ancestry. 6,331 genes common to all living animals have been identified; these may have arisen from a single common ancestor that lived 650 million years ago in the Precambrian.
q = 1/2ρv2 is dynamic pressure, h = z + p/ρg is the piezometric head or hydraulic head (the sum of the elevation z and the pressure head) and p0 = p + q is the stagnation pressure (the sum of the static pressure p and dynamic pressure q). The constant in the Bernoulli equation can be normalized. A common approach is in terms of total head or energy head H:
Sources: en.wikipedia.org
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.