A practical reference on Heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-05-29 and is reviewed periodically as new material appears.
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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
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.
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.
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.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
. It is used as a measure of affinity, with higher values indicating a lower affinity. For the given equation (E = enzyme, S = substrate, P = product), E + S ⟺ k − 1 k 1 E S ⟺ k 2 E + P {\displaystyle E+S{\overset {k_{1}}{\underset {k_{-}{1}}{\Longleftrightarrow }}}ES{\overset {k_{2}}{\Longleftrightarrow }}E+P} k d {\displaystyle k_{d}} would be equivalent to k − 1 / k 1 {\displaystyle k_{-1}/k_{1}} , where k 1 {\displaystyle k_{1}} and k − 1 {\displaystyle k_{-1}} are the rates of the forward and backward reaction, respectively in the conversion of individual E and S to the enzyme substrate complex. Information theory allows for a more quantitative definition of specificity by calculating the entropy in the binding spectrum. The chemical specificity of an enzyme for a particular substrate can be found using two variables that are derived from the Michaelis-Menten equation. k m {\displaystyle k_{m}} approximates the dissociation constant of enzyme-substrate complexes. k c a t {\displaystyle k_{cat}}
The European Bioinformatics Institute (EMBL-EBI) is an intergovernmental organization (IGO) which, as part of the European Molecular Biology Laboratory (EMBL) family, focuses on research and services in bioinformatics. It is located on the Wellcome Genome Campus in Hinxton near Cambridge, and employs over 600 full-time equivalent (FTE) staff. Further, the EMBL-EBI hosts training programs that teach scientists the fundamentals of the work with biological data and promote the plethora of bioinformatic tools available for their research, both EMBL-EBI-based and not so. One of the roles of the EMBL-EBI is to index and maintain biological data in a set of databases, including Ensembl (housing whole genome sequence data), UniProt (protein sequence and annotation database) and Protein Data Bank (protein and nucleic acid tertiary structure database). A variety of online services and tools is provided, such as Basic Local Alignment Search Tool (BLAST) or Clustal Omega sequence alignment tool, enabling further data analysis.
VIP is highly localised in lungs (70%) and binds with alveolar type II (AT II) cells via VPAC1. The biological (vasodilator) activity of vasoactive intestinal peptide (VIP) was discovered in the lungs before the peptide was isolated and chemical identity characterized from intestine. VIP levels are also considerably high in the brain and the gut. It is localized in key sites in the lung, has potent activities on its major functions, and appears to play an important role in pulmonary physiology and disease. The principal localization of VIP-containing neurons in the tracheobronchial tree is in the smooth muscle layer, around submucosal mucous glands and in the walls of pulmonary and bronchial arteries. Immunoreactive VIP is also present in neuronal cell bodies forming microglia that provide a source of intrinsic innervation of pulmonary structures.
CPC Scientific’s manufacturing processes primarily use solid-phase peptide synthesis (SPPS), first described by Robert Bruce Merrifield in 1963. SPPS allows peptides to be assembled stepwise on a solid support, enabling the preparation of long and complex sequences for use as active pharmaceutical ingredients (APIs), investigational drugs, and research materials. Researchers associated with the company have published studies involving peptide synthesis methodologies, including work related to hydrocarbon stapling. Products manufactured by the company have been used and cited in various scientific studies. Official website
Sources: en.wikipedia.org
It is believed that the tyrosine amino acid found along the amino acid sequence of alpha-sarcin allows for the specificity when alpha-sarcin binds to the rRNA. It is the alcohol group found on the tyrosine amino acid that allows for this binding. This was determined in tests that removed the alcohol group, replacing tyrosine with phenylalanine, and the binding affinity was greatly reduced. The region of the DNA that makes alpha-sarcin is highly conserved, along with the corresponding sequence on the targeted ribosome. The corresponding sequence on the targeted ribosome is a centered around a guanine nucleotide located on what is called the "bulged-G motif".
2-Arachidonoylglycerol (2-AG) is an endocannabinoid, an endogenous agonist of the CB1 receptor and the primary endogenous ligand for the CB2 receptor. It is an ester formed from the omega-6 fatty acid arachidonic acid and glycerol. It is present at relatively high levels in the central nervous system, with cannabinoid neuromodulatory effects. It has been found in bovine and human milk. The chemical was first described in 1994–1995, although it had been discovered some time before that. The activities of phospholipase C (PLC) and diacylglycerol lipase (DAGL) mediate its formation. 2-AG is synthesized from arachidonic acid-containing diacylglycerol (DAG). 2-AG, unlike anandamide (another endocannabinoid), is present at relatively high levels in the central nervous system; it is the most abundant molecular species of monoacylglycerol found in mouse and rat brain (~5–10 nmol/g tissue). Detection of 2-AG in brain tissue is complicated by the relative ease of its isomerization to 1-AG during standard lipid extraction conditions. It has been found in bovine as well as human milk.
The charged aerosol detector (CAD) is a detector used in conjunction with high-performance liquid chromatography (HPLC) and ultra high-performance liquid chromatography (UHPLC) to measure the amount of chemicals in a sample by creating charged aerosol particles which are detected using an electrometer. It is commonly used for the analysis of compounds that cannot be detected using traditional UV/Vis approaches due to their lack of a chromophore. The CAD can measure all non-volatile and many semi-volatile analytes including, but not limited to, antibiotics, excipients, ions, lipids, natural products, biofuels, sugars and surfactants. The CAD, like other aerosol detectors (e.g., evaporative light scattering detectors (ELSD) and condensation nucleation light scattering detectors (CNLSD)), falls under the category of destructive general-purpose detectors (see Chromatography detectors).
Knowledge base annotation is done based on the information of gene attribute, protein function and its metabolism. In this type of annotation more emphasis is given to genetic variation that disrupts the protein function domain, protein-protein interaction and biological pathway. The non-coding region of genome contain many important regulatory elements including promoter, enhancer and insulator, any kind of change in this regulatory region can change the functionality of that protein. The mutation in DNA can change the RNA sequence and then influence the RNA secondary structure, RNA binding protein recognition and miRNA binding activity. This method mainly identifies variant function based on the information whether the variant loci are in the known functional region that harbor genomic or epigenomic signals. The function of non-coding variants are extensive in terms of the affected genomic region and they involve in almost all processes of gene regulation from transcriptional to post translational level
The tumor-suppressor protein p53 accumulates when DNA is damaged due to a chain of biochemical factors. Part of this pathway includes alpha-interferon and beta-interferon, which induce transcription of the p53 gene, resulting in the increase of p53 protein level and enhancement of cancer cell-apoptosis. p53 prevents the cell from replicating by stopping the cell cycle at G1, or interphase, to give the cell time to repair; however, it will induce apoptosis if damage is extensive and repair efforts fail. Any disruption to the regulation of the p53 or interferon genes will result in impaired apoptosis and the possible formation of tumors.
Sources: en.wikipedia.org
The binding of S-arrestin to rhodopsin is specific and involves changes that occur in rhodopsin after activation. Important serine (Ser) and threonine (Thr) residues in rhodopsin's tail, particularly Thr-340 and Ser-343, are phosphorylated by enzymes called GRKs. These phosphorylated residues strongly attract S-arrestin, helping it bind tightly and effectively shut down rhodopsin's signaling. Additionally, studies of the protein structure have shown that during activation, rhodopsin's transmembrane helix 7 (TM7) and helix 8 change shape. These changes expose a binding site that interacts with a specific part of arrestin called the "finger loop." This interaction, clearly seen in the crystal structure (PDB ID: 4ZWJ), shows how arrestin fits precisely onto activated and phosphorylated rhodopsin, efficiently stopping the visual signal. Arrestin at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
Competitive antagonists are usually structurally similar to the active compound since they are structural analogues that have to bind to the same pocket. Examples of reversible competitive antagonists like antihistamines (Figure 1) compete with histamine (Figure 2) to bind to histamine receptors, blocking the allergic response by histamine. They are used in treating histamine-mediated allergies and allergic rhinitis. Irreversible competitive antagonists like phenoxybenzamine do not dissociate from alpha-adrenergic receptors. It is used to block the activity of alpha receptors in sympathetic pathway and is used in the treatment of paroxysmal hypertension and sweating resulting from pheochromocytoma and benign prostate hyperplasia.
Immobilized metal ion affinity chromatography (IMAC) is based on the specific coordinate covalent bond of amino acids, particularly histidine, to metals. This technique works by allowing proteins with an affinity for metal ions to be retained in a column containing immobilized metal ions, such as cobalt, nickel, or copper for the purification of histidine-containing proteins or peptides, iron, zinc or gallium for the purification of phosphorylated proteins or peptides. Many naturally occurring proteins do not have an affinity for metal ions, therefore recombinant DNA technology can be used to introduce such a protein tag into the relevant gene. Methods used to elute the protein of interest include changing the pH, or adding a competitive molecule, such as imidazole.
Because protein chains are open, AlphaKnot uses closure procedures before applying knot invariants. Its probabilistic method repeatedly closes the chain using randomly selected points on a large surrounding sphere and assigns the dominant topology obtained from the ensemble of closures. Deterministic alternatives connect the chain termini using prescribed geometries, including a direct closure and a closure constructed using the centre of mass. Knot identification uses the HOMFLY polynomial to distinguish knot types. AlphaKnot recognizes knots with minimal representations containing up to 12 crossings. In large-scale database calculations, structures that exhibit evidence of a nontrivial knot are subsequently analysed to determine the corresponding knot core, the smallest portion of the protein chain required to retain the detected topology. The database primarily reports the topology of the complete protein chain. More detailed information about subchain topologies can be obtained by calculating a knot map, which records the topology of different portions of the sequence. Because producing full knot maps for hundreds of thousands of structures would require substantial computational resources, these calculations are performed on demand rather than precomputed for the entire AlphaFold DB v4 dataset.
Many drugs are metabolised by a set of liver enzymes called CYP450s. The activity of these enzymes would determine the rate of pro-drug activation and the rate of inactivation of active drugs. For example, warfarin, a commonly used anticoagulant drug in atrial fibrillation, is metabolised by an enzyme called CYP2C9. Phenytoin, a CYP2C9 inducer, would increase its activity and the rate of warfarin breakdown, thereby reducing its efficacy. Patients should avoid the co-administration of warfarin and phenytoin. In cases where both drugs must be used together, warfarin dosing may be titrated up to cope with the reduced efficacy. The kidney excretes most drugs through urine. Since urine is weakly alkaline in nature, weakly acid drugs would ionise in urine, making it difficult for them to be reabsorbed. Therefore, in cases of aspirin (weak acid) toxicity, injecting intravenous sodium bicarbonate could increase urine pH, thereby increasing the excretion of aspirin through urine. A similar approach can be used in other weakly acidic drug toxicity.
Sources: en.wikipedia.org
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.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.