Tuftsin analogue 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.
Last reviewed on 2026-06-19. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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 |
|---|---|---|
| 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 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.
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.
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.
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.
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Dominated by revolutionary zealots, mostly youths, the Revolutionary Committees were based in Tripoli and met with Gaddafi annually. Membership was drawn from within the BPCs. The revolutionary committee system became "a key—if not the main—mechanism through which [Gaddafi] exercises political control in Libya". Publishing a weekly magazine, The Green March, starting October 1980 they took control of the press. Responsible for perpetuating the revolution, they performed ideological surveillance, adopting a significant security role, making arrests and putting people on trial according to the "law of the revolution". With no legal or safeguards, the administration of revolutionary justice was largely arbitrary and resulted in widespread abuse and the suppression of civil liberties: the "Green Terror". In 1979, the committees began the redistribution of land in the Jefara plain, continuing through 1981. In May 1980, measures to redistribute and equalize wealth were implemented; anyone with over 1000 dinar in their bank account saw that extra money expropriated. The next year, the GPC announced that the government would take control of all import, export and distribution functions, with state supermarkets replacing privately owned businesses; this led to a decline in the availability of consumer goods and the development of a thriving black market. Gaddafi was frustrated by the slow pace of social reform on women's issues, and in 1979 launched a Revolutionary Women's Formation, to replace the more gradualist Libyan General Women's Federation.
=== In vitro drug development === Heterologous expression systems can be clinically incorporated to evaluate enzyme activity under highly reproducible conditions for in vitro drug development. This works to minimize patient risk by serving as an alternative to highly invasive procedures, or potential for the development adverse drug reactions. Enzyme activity analysis requires various expression systems to classify enzyme variants. As opposed to other animals, the expression of functional recombinant proteins is a costly process for mammalian cells specifically, due to low expression levels of enzymes contributing to drug metabolism. As a result, post-translational modification processes differ between species and limit accurate comparisons. The first heterologous protein product released to the market was human insulin, most commonly known as Humulin. This product was made with a strain of E. coli. Most bacteria, including E. coli, are unable to successfully secrete such proteins, requiring added cell harvesting, cell disruption, and product isolation steps before protein purification. Like Humulin, there have been many successes using heterologous expression for drug development. Heterologous expression via cloning of genes producing natural bioactive products of interest also can be expressed in host systems and scaled up for drug production. For example, several clinically relevant natural products in fungi are difficult to culture in laboratory settings.
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== History == The discovery and characterization of aminopeptidases date back to the early 20th century. The term "aminopeptidase" was first introduced in 1929 by Linderstrøm-Lang and Sato in order to describe enzymes that cleave amino acids from the N-terminus of peptides. In the 1950s and 1960s, the discovery of leucine aminopeptidase (LAP) and aminopeptidase N (APN) marked important milestones in the field. LAP was found to be crucial for protein digestion, while APN was recognized for its role in the regulation of peptide-mediated effects. These discoveries were pivotal in understanding the physiological functions of aminopeptidases and their involvement in health and disease. The subsequent decades saw extensive research into the structure, function, and mechanisms of action of various aminopeptidases. For example, the M1 family of aminopeptidases, which includes puromycin-sensitive aminopeptidase (PSA), was characterized by conserved zinc-dependent sites and exopeptidase motifs. The study of PSA in different model organisms revealed its essential roles in growth and behavior. Mutations in orthologs of PSA in different species were linked to errors in meiosis and reduced viability of embryos. Aminopeptidase N, also known as AP-N or CD13, was extensively characterized for its broad substrate specificity (ability to bind to its targets) and its presence in various tissues such as the brush border membranes of the kidney, small intestine, and placenta.
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=== Cor–Cz === Robert Corey (1897–1971). American protein chemist at Caltech, known for work with Linus Pauling on the α-helix and β-sheet. Member Natl. Acad. Sci. USA. Carl Ferdinand Cori (1896–1984). American biochemist at Washington University and Albert Einstein College of Medicine, who worked on glycogen. Nobel Prize in Physiology or Medicine (1947). Member Natl. Acad. Sci. USA. Gerty Cori (1896–1957). Czech-American biochemist at Washington University, known for glycogen research. Nobel Prize in Physiology or Medicine (1947). Athel Cornish-Bowden (b. 1943). British enzymologist at the CNRS, Marseille. He has contributed to the development of metabolic control analysis, and is the author of Fundamentals of Enzyme Kinetics. Suzanne Cory (b. 1942). Australian molecular biologist known fotr work on the genetics of the immune system, at the Walter and Eliza Hall Institute of Medical Research, Melbourne. Peter Coveney (b. 1958). British Computational molecular biology specialist at University College London, University of Amsterdam and Yale. Nicholas R. Cozzarelli (1938–2006). American biochemist at UC Berkeley, and former editor-in-chief of the Proceedings of the National Academy of Sciences. Member Natl. Acad. Sci. USA. Gerald Crabtree (b. 1946). American biochemist at Stanford, known for defining the Ca2+-calcineurin-NFAT signalling pathway, pioneering the development of synthetic ligands for regulation of biological processes. Robert K. Crane (1919–2010).
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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.
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.