Selank Background And Chemical Identity — Practical Notes

By Editorial Desk · published 2026-06-05 · last reviewed 2026-06-27 · Guide

This is a working overview of heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.

Reviewed 2026-06-27. Anything still debated is marked as such rather than presented as settled.

Selank Background And Chemical Identity

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.

Peptide Identity and Structure

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.

Selank at a glance

Background and Peptide Identity

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.

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Background and Molecular Identity

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.

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.

Analytical Methods And Storage Stability

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.

Further detail

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These molecules activate both CD8+ T cells as well as natural killer cells and attract them to the tumor. It has been shown that in cancer cell lines, UV-inactivated SeV triggers the production of an which is a macrophage-1 antigen (Mac-1) and Mac-1 and LFA-1 are receptors found on leukocytes. This induced production happens through the activation of nuclear factor-κB downstream of the mitochondrial antiviral signaling pathway and the retinoic acid-inducible gene I. The increased concentration of ICAM-1 on the surface of cancer cells, which is triggered by SeV, increases the vulnerability of these cells to natural killer cells.

== Normal amount == In a urinalysis, the normal amount of urinary calcium can be measured in amount per time (commonly per 24 hours). It can also be measured in amount per mass of creatinine, which avails for estimating the urinary calcium excretion in a spot urine sample, because urinary creatinine clearance is relatively unaffected by differences in free water clearance which occurs, for example, in dehydration and which would distort the interpretation of the urinary calcium in a spot urine sample. Normally, in an average adult, the amount of calcium excreted in the urine is 100–250 mg over a 24-hour period. For those on low-calcium diets, there is normally 50–150 mg/24 hours, while those on a calcium-free diet will have 5–40 mg/24 hours. The following reference ranges are for persons with average calcium intake (600–800 mg/day for adults):

=== Techniques === There are four major methods used to quantify the metabolome of single cells; they are: fluorescence–based detection, fluorescence biosensors, FRET biosensors, and mass spectroscopy. The first three methods listed use fluorescence microscopy to detect molecules in a cell. Usually these assays use small fluorescent tags attached to molecules of interest, however this has been shown be too invasive for single cell metabolomics, and alters the activity of the metabolites. The current solution to this problem is to use fluorescent proteins which will act as metabolite detectors, fluorescing whenever they bind to a metabolite of interest. Mass spectroscopy is becoming the most frequently used method for single cell metabolomics. Its advantages are that there is no need to develop fluorescent proteins for all molecules of interest, and is capable of detecting metabolites in the femtomole range. Similar to the methods discussed in proteomics, there has also been success in combining mass spectroscopy with separation techniques such as capillary electrophoresis to quantify metabolites. This method is also capable of detecting metabolites present in femtomole concentrations. Another method utilizing capillary microsampling combined with mass spectrometry with ion mobility separation has been demonstrated to enhance the molecular coverage and ion separation for single cell metabolomics. Furthermore, direct infusion mass spectrometry, so call-ed live-single cell mass spectrometry, has also been successfully performed on human cells.

== History == SDMA was first mentioned in the scientific literature by 2013, but was only conceptually described at this time. Subsequently, its synthesis and preclinical pharmacology were described by Nina Kastner and colleagues including Matthias Grill at MiHKAL in 2025. In addition, SDMA was patented by Mydecine as a shorter-acting MDMA alternative in 2023. Prodrugs of SDMA and/or related compounds have also been described. The drug is of interest for potential therapeutic use, for instance treatment of post-traumatic stress disorder (PTSD).

Sources: en.wikipedia.org

Supporting material

The structure of hemoglobins varies across species. Hemoglobin occurs in all kingdoms of organisms, but not in all organisms. Primitive species such as bacteria, protozoa, algae, and plants often have single-globin hemoglobins. Many nematode worms, molluscs, and crustaceans contain very large multisubunit molecules, much larger than those in vertebrates. In particular, chimeric hemoglobins found in fungi and giant annelids may contain both globin and other types of proteins. One of the most striking occurrences and uses of hemoglobin in organisms is in the giant tube worm (Riftia pachyptila, also called Vestimentifera), which can reach 2.4 meters length and populates ocean volcanic vents. Instead of a digestive tract, these worms contain a population of bacteria constituting half the organism's weight. The bacteria oxidize H2S from the vent with O2 from the water to produce energy to make food from H2O and CO2. The worms' upper end is a deep-red fan-like structure ("plume"), which extends into the water and absorbs H2S and O2 for the bacteria, and CO2 for use as synthetic raw material similar to photosynthetic plants. The structures are bright red due to their content of several extraordinarily complex hemoglobins that have up to 144 globin chains, each including associated heme structures. These hemoglobins are remarkable for being able to carry oxygen in the presence of sulfide, and even to carry sulfide, without being completely "poisoned" or inhibited by it as hemoglobins in most other species are.

Sanders' Original Recipe of "11 herbs and spices" is one of the best known trade secrets in the catering industry. The recipe is not patented, because patent law requires public disclosure of an invention and provides protection only for a strictly limited term, whereas trade secrets can remain the intellectual property of their holders in perpetuity. A copy of the recipe, signed by Sanders, is held inside a safe inside a vault in KFC's Louisville headquarters, along with 11 vials containing the herbs and spices. To maintain the secrecy of the recipe, half of it is produced by Griffith Laboratories before it is given to McCormick, who add the second half. In 1999, a couple who bought the house formerly occupied by Colonel Sanders found scribbled notes purported to be the secret recipe. Initially, KFC wanted to file a lawsuit against the couple to stop an auction of the notes but, by early 2001, it dropped the lawsuit, claiming the scribbled notes are "nowhere close" to the original recipe. Joe Ledington of Kentucky, a nephew by marriage of Colonel Sanders, claimed to have found a copy of the original KFC fried chicken recipe on a handwritten piece of paper in an envelope in a scrapbook. In August 2016, Chicago Tribune staffers conducted a cooking test of this recipe and claimed after a few attempts that, with the addition of the MSG flavor-enhancer Ac'cent, they produced fried chicken which tasted "indistinguishable" from the chicken they purchased at KFC.

== Stigmata and gender == In the late nineteenth century, a French physician named Dr. Antoine Imbert-Goubeyre began compiling a census of known stigmatics from the thirteenth century to his own time. This census includes 280 female and 41 male stigmatics, meaning women comprise a little over 87% of the list. Additionally, the University of Antwerp released a database of information on 244 stigmatics in April 2019. 92% of the stigmatics in the database are female. In some cases, convent sisters have attempted to shield stigmatic women from public scrutiny, often out of fear of how their condition would affect the convent's reputation. So, the number of women stigmatics may be even higher than historical record shows. Despite the high number of women stigmatics throughout history, the best-known and least contested stigmatics, such as Francis of Assisi and Padre Pio, have been men.

A more commonly used parameter is the half-life T1/2. Given a sample of a particular radionuclide, the half-life is the time taken for half the radionuclide's atoms to decay. For the case of one-decay nuclear reactions:

Pressure-driven operations microfiltration ultrafiltration nanofiltration reverse osmosis gas separation Concentration driven operations dialysis pervaporation forward osmosis artificial lung Operations in an electric potential gradient electrodialysis membrane electrolysis e.g. chloralkaline process electrode ionization electro filtration fuel cell Operations in a temperature gradient membrane distillation

Sources: en.wikipedia.org

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