A practical reference on heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-08-13. Anything still debated is marked as such rather than presented as settled.
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.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
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.
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.
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.
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.
== Etymology == The term tempe is thought to be derived from the Old Javanese tumpi, a whitish food made of fried batter made from sago or rice flour which resembles rempeyek. The historian Denys Lombard also suggests that it could be linked to a later term tape or tapai which means 'fermentation'. In the western world, tempeh rather than tempe is the most common spelling, to emphasise that the final "e" is pronounced. The first known usage of this spelling is in an 1896 German article. Other spellings, such as témpé, were also used, but tempeh has become the standard spelling in English since the 1960s.
As part of the planning, a force had been placed at Pitsane, on the border of the Transvaal, by the order of Rhodes so as to be able to quickly offer support to the Uitlanders in the uprising. The force was placed under the control of Leander Starr Jameson, the administrator general of the chartered company (of which Cecil Rhodes was the chairman) for Matabeleland. Among the other commanders was Raleigh Grey. The force was around 600 men, about 400 from the Matabeleland Mounted Police and the remainder other volunteers. It was equipped with rifles, somewhere between eight and sixteen Maxim machine guns, and between three and eleven light artillery pieces.
pleomorphism 1. Variability in the size, shape, or staining of cells and/or their nuclei, particularly as observed in histology and cytopathology, where morphological variation is frequently an indicator of a cellular abnormality such as disease or tumor formation. 2. In microbiology, the ability of some microorganisms such as certain bacteria and viruses to alter their morphology, metabolism, or mode of reproduction in response to changes in their environment.
Sources: en.wikipedia.org
==== False information and fines ==== During the elections, Jornal da Band released false polling that showed Melo in the lead against d'Ávila. Melo's campaign would later post their findings onto his Instagram account. Jornal da Band would later correct the polling data and Melo's campaign removed the post from social media. He was later condemned by electoral courts under the Brazilian Election Justice and was made to pay 106,000 reais for spreading false information. The judge that made the decision made the call to forward the case to the Federal Police for a criminal investigation. Melo and Gomes were fined again through the Election Justice for 41,900 reais for a series of irregularities in the campaign's finances, including the use of provisions to print religiously styled pamphlets that displayed him appearing alongside city council candidates from the PTB, a party that had not formally become a member of his coalition. Allies of Melo also went around the city to spread rumors that if d'Ávila was elected, that she would close the city's churches and force people to eat dog meat.
=== Komagataella as an experimental model organism === As an experimental model organism, Komagataella was mainly used as the host system for transformation. Due to its abilities of recombination with foreign DNA and processing large proteins, much research has been carried out to investigate the possibility of producing new proteins and the function of artificially designed proteins, using Komagataella as a transformation host. In the last decade, Komagataella was engineered to build expression system platforms, which is a typical application for a standard experimental model organism, as described below.
== Checkups == Although the symptoms of diabetes mellitus such as frequent urination, thirstiness, greater appetites and inactiveness are easily visible, frequent checking of the dog for the disease is required. The dog's body weight should be determined and calculated once every two weeks using weight scale. The daily caloric requirement by the dog's body and BCS should also be determined using a scale as part of dietary management in maintaining average body weight. The protein intake by the dog should also be considered and checked twice a month. Blood pressure of the dog should also be constantly and daily checked in order to predict any future occurrence. The blood sugar level may also be checked using glucometer to check the glucose level in the body of the dog.
== Genome and genetics == H. influenzae was the first free-living organism to have its entire genome sequenced. The sequencing was completed in 1995 by Craig Venter and his team at the Institute for Genomic Research, now part of the J. Craig Venter Institute. Haemophilus was chosen because one of the project leaders, Nobel laureate Hamilton Smith, had been working on it for decades and was able to provide high-quality DNA libraries. The sequencing method used was whole-genome shotgun, which was completed and published in Science in 1995. The genome of strain Rd KW20 consists of 1,830,138 base pairs of DNA in a single circular chromosome that contains 1604 protein-coding genes, 117 pseudogenes, 57 tRNA genes, and 23 other RNA genes. About 90% of the genes have homologs in E. coli, another gamma-proteobacterium. In fact, the similarity between genes of the two species ranges from 18% to 98% protein sequence identity, with the majority sharing 40–80% of their amino acids (with an average of 59%). Conjugative plasmids (DNA molecules that are capable of horizontal transfer between different species of bacteria) can frequently be found in H. influenzae. It is common that the F+ plasmid of a competent Escherichia coli bacterium conjugates into the H. influenzae bacterium, which then allows the plasmid to transfer among H. influenzae strands via conjugation.
Sources: en.wikipedia.org
== Chemistry == Kurtoxin is a protein containing 63 amino acid residues with a mass of 7386.1 daltons. Its formula is C324H478N94O90S8. It can be isolated from the venom of Parabuthus transvaalicus by high-performance liquid chromatography (HPLC). Kurtoxin is closely related to α-scorpion toxins, a family of toxins that slow inactivation of voltage-gated sodium channels. The complete primary amino-acid sequence of kurtoxin is: KIDGYPVDYW NCKRICWYNN KYCNDLCKGL KADSGYCWGW TLSCYCQGLP DNARIKRSGR CRA.
ionophore Any chemical compound or macromolecule that facilitates the movement of ions across biological membranes, or more specifically, any chemical species that reversibly binds electrically charged atoms or molecules. Many ionophores are lipid-soluble proteins that catalyze the transport of monovalent and divalent cations across the hydrophobic lipid bilayers surrounding cells and vesicles.
troops back in could have saved South Vietnam. On 17 April 1975, the Lon Nol regime collapsed, and the Khmer Rouge took Phnom Penh. On 20 April, Kissinger instructed Graham Martin, U.S. ambassador in Saigon, to start preparing to evacuate all Americans from the country. Kissinger further instructed Martin that no South Vietnamese were to be included in the pull out. Martin complained to Kissinger that the "only ass which isn't covered is mine", Kissinger assured him: "When this thing is finally over, I'll be hanging several yards higher than you". On 29 April, Option IV, the largest helicopter evacuation in history, began as 70 Marine helicopters flew 8,000 people from the American embassy to the fleet offshore. Later in the day, Kissinger ordered Martin to blow up the satellite terminal at the embassy, saying, "I want you heroes home". At 7:53 am, the last Marine helicopter departed from the embassy in Saigon, marking the end of the American presence in Vietnam. On 30 April 1975, Saigon fell to the PAVN, and the war in Vietnam finally ended.
In 1998, the European Union's Directive 98/44/ECclarified that patents on DNA sequences were allowable. In 2010 in the US, AMP sued Myriad Genetics to challenge the latter's patents regarding two genes, BRCA1, BRCA2, which are associated with breast cancer. In 2013, the U.S. Supreme Court partially agreed, ruling that a naturally occurring gene sequence could not be patented.
Overlapping peptide libraries - in which the entirety of a larger protein is used to produce a library of 8-20 amino acid peptides which overlap; these libraries can be used to identify the specific regions of a larger protein which participate in a given interaction or to provide pre-digested versions of a larger protein for binding. Truncation peptide libraries - in which a given peptide is produced with various or all N or C terminal truncations, these smaller fragments can be used to identify the minimal required region of a peptide for a given interaction being studied. Random libraries - randomly generated peptides of a set length, or range of lengths, can be used to identify novel binding partners of a target of interest. Alanine scanning libraries - in which each amino acid of a given protein or peptide is replaced with an alanine sequentially such that each peptide contains only one alanine mutations but all possible mutations to alanine are present; this can be used to identify critical residues for binding Positional or scrambled peptide libraries - in which specific positions in the peptide are substituted for many or all other amino acids such that the effect of each amino acid at that position in the peptide on the binding or other activity of the peptide can be tested. Scrambled libraries are often random peptides and used as negative controls. Solid phase peptide synthesis is limited to a peptide chain length of approximately 70 amino acids and is generally unsuitable for the study of larger proteins.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.