If you have been reading about heptapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-03-11. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
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 developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
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.
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.
== Clinical significance == Patients with chronic diarrhea due to bile acid malabsorption have been shown to have reduced fasting FGF19. Surgical resection of the ileum (as often occurs in Crohn's disease) will reduce bile acid absorption and remove the stimulus for FGF19 production. In primary bile acid diarrhea, absorption of bile acids is usually normal, but defective FGF19 production can produce excessive bile acid synthesis, as shown by increased levels of 7α-hydroxy-4-cholesten-3-one, and excessive bile acid fecal loss, indicated by reduced SeHCAT retention. This was confirmed in a prospective study of patients with chronic diarrhea, where the predictive value for FGF19 in diagnosis of primary bile acid diarrhea and response to bile acid sequestrants was demonstrated. FGF19 is also found in the liver of patients with cholestasis. It can be synthesised in the gall-bladder and secreted into bile. FGF19 is expressed in around half of hepatocellular carcinomas and was associated with larger size, early recurrence and poor prognosis. Patients with the metabolic syndrome, non-alcoholic fatty liver disease and insulin resistance have reduced levels of FGF19. FGF19 increases to normal values in obese patients who undergo Roux-en-Y gastric bypass and other types of bariatric surgery.
Roberts with a £300 MRC grant in July 1935, and for the next two years Roberts worked with Florey and Maegraith on Florey's lysozyme project. Still, Florey wanted a biochemist on his own staff. He tried to get Hugh Macdonald Sinclair, but Sinclair declined the offer. Norman Pirie asked Florey if he could assume the role, but when Florey approached Sir Frederick Gowland Hopkins, Pirie's boss, Hopkins refused to release Pirie. He tempered this refusal by recommending Ernst Boris Chain, one of many Jewish refugees from Nazi Germany who had found sanctuary in the UK. Chain had recently completed his PhD thesis under Hopkins's supervision. He gratefully accepted Florey's offer of an appointment although it was initially for one year only, and with an annual salary of £200 (equivalent to £12,000 in 2025). In turn, Chain felt that he needed a collaborator, and he had one in mind: Norman Heatley, who was finishing his PhD in Hopkins's department. Heatley was happy to come, and Florey was able to arrange for the MRC to fund the position.
Electron capture: the decay energy is 0.93 MeV and the decay product is uranium-236. This usually decays (with a half-life of 23 million years) to thorium-232. Beta emission: the decay energy is 0.48 MeV and the decay product is plutonium-236. This usually decays (half-life 2.8 years) to uranium-232, which usually decays (half-life 69 years) to thorium-228, which decays in a few years to lead-208. Alpha emission: the decay energy is 5.007 MeV and the decay product is protactinium-232. This decays with a half-life of 1.3 days to uranium-232. Neptunium-236 is a fissile material; it has an estimated critical mass of 6.79 kg (15.0 lb), though precise experimental data is not available (as sufficient material for criticality is not). 236Np is produced in small quantities via the (n,2n) and (γ,n) capture reactions of 237Np, however, it is nearly impossible to separate in any significant quantities from its parent 237Np. It is for this reason that despite its low critical mass and high neutron cross section, it has not been researched extensively as a nuclear fuel in weapons or reactors. Nevertheless, 236Np has been considered for use in mass spectrometry and as a radioactive tracer, because it decays predominantly by beta emission with a long half-life. Several alternative production routes for this isotope have been investigated, namely those that reduce isotopic separation from 237Np or the isomer 236mNp. The most favorable reactions to accumulate 236Np were shown to be proton and deuteron irradiation of uranium-238.
Sources: en.wikipedia.org
== Background == In Canada, clinical chemists work as members of the medical laboratory management team, which consists of pathologists, laboratory managers, and senior technologists. They are primarily responsible for setting the standards of performance for the clinical biochemistry laboratory. The knowledge they acquired from post doctoral training programs is applied to maintain efficiency in the lab.
The enzyme naringenin 8-dimethylallyltransferase uses dimethylallyl diphosphate and (2S)-naringenin to produce diphosphate and 8-prenylnaringenin. Cunninghamella elegans, a fungal model organism of the mammalian metabolism, can be used to study the naringenin sulfation. In plants, the biosynthetic pathway to anthocyanins continues when the enzyme flavanone 3-dioxygenase inserts a hydroxyl group into the dihydropyran ring:
== Cytokine therapy == Cytokines are proteins produced by many types of cells present within a tumor. They can modulate immune responses. The tumor often employs them to allow it to grow and reduce the immune response. These immune-modulating effects allow them to be used as drugs to provoke an immune response. Two commonly used cytokines are interferons and interleukins. Interleukin-2 and interferon-α are cytokines, proteins that regulate and coordinate the behavior of the immune system. They have the ability to enhance anti-tumor activity and thus can be used as passive cancer treatments. Interferon-α is used in the treatment of hairy-cell leukaemia, AIDS-related Kaposi's sarcoma, follicular lymphoma, chronic myeloid leukaemia and melanoma. Interleukin-2 is used in the treatment of melanoma and renal cell carcinoma.
This lowers the temperature of the liquid nitrogen below its boiling point, so that when the specimen is plunged into it, it envelops the specimen closely for a brief period of time and extracts heat from it more efficiently. Even faster cooling can be obtained by plunging specimens into liquid propane or ethane (ethane has been found to be more efficient) cooled very close to their melting points using liquid nitrogen or by slamming the specimen against highly polished liquid nitrogen-cooled metal surfaces made of copper or silver. Secondly, two properties of water itself prevent rapid cryofixation in large specimens. The thermal conductivity of ice is very low compared with that of metals, and water releases of latent heat of fusion as it freezes, defeating rapid cooldown in specimens more than a few micrometres thick.
Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.