Everything below concerns Tuftsin analogue. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-11-22. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Solubility | Freely soluble in water | Also in aqueous buffers |
| Typical purity (HPLC) | 95 percent or higher | Lot-dependent |
| Dry powder storage | Minus 20 degrees Celsius | Sealed, dry, protected from light |
| Solution storage | 2 to 8 degrees Celsius | Short-term use |
| Identity confirmation | Mass spectrometry | ESI or MALDI-TOF |
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.
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 developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
== Chemistry == The separation of the stereoisomers is one of the easier in organic chemistry and is described in the original patent. It involves "treatment of racemic methadone base with d-(+)-tartaric acid in an acetone/water mixture [which] precipitates almost solely the dextro-methadone levo-tartrate, and the more potent Levomethadone can easily be retrieved from the mother liquor in a high state of optical purity." There is now an asymmetric synthesis available to prepare both levomethadone (R-(−)-methadone) and dextromethadone (S-(+)-methadone).
Benzhydrocodone (INN; contracted from benzoate-hydrocodone) is an opioid prodrug of the morphinan class. Its chemical structure consists of hydrocodone coupled with benzoic acid. Benzhydrocodone itself is inactive and acts as a prodrug to hydrocodone upon cleavage of the benzoate portion of the molecule. It is designed to be an opioid analgesic with a low chance of recreational use. Created by Kempharm, Inc., a biopharmaceutical company in Coralville, Iowa, President and CEO, Travis Mickle, believes the molecular-based approach to abuse deterrent may be more effective than many formulation-based approaches. When approved, Apadaz received a labeling that highlighted all relevant aspects of the drug, including the lower abuse profile compared to traditional hydrocodone-acetaminophen. The labeling showed several items supporting a lower abuse profile than traditional hydrocodone-acetaminophen; namely, a lower Drug Liking in the first two hours after intranasal abuse (snorting), and the conversion of benzhydrocodone to hydrocodone in vitro being a "difficult process" — with benzhydrocodone being a more difficult drug to abuse according to FDA advisory committee documents.
RGD was identified as the minimal recognition sequence within fibronectin required for cell attachment by Ruoslahti and Pierschbacher in the early 1980s. To do this, the authors synthesized various peptides based on the hypothesized cell attachment site of fibronectin. They then coupled those peptides to protein-coated plastic and tested each for cell attachment-promoting activity. Only those that contained the RGD sequence were found to enhance cell attachment. Further, they showed that peptides containing RGD were able to inhibit cell attachment to fibronectin-coated substrates, whereas peptides not containing RGD did not. These foundational studies also identified the cellular receptors that recognize the sequence. These studies utilized a synthetic RGD-containing peptide to isolate the putative receptors, and then demonstrated that liposomes containing the isolated proteins could bind to fibronectin, in much the same way as cells with surface receptors. The discovered receptors were later named integrins. The RGD motif is presented in slightly different ways in different proteins, making it possible for the many RGD-binding integrins to selectively distinguish individual adhesion proteins.
Sources: en.wikipedia.org
Southern Rhodesia was represented in the Dodecanese Campaign of September–November 1943 by the Long Range Desert Group, which was withdrawn from the North African front in March 1943. After retraining for mountain operations in Lebanon, the LRDG moved in late September to the Dodecanese island of Kalymnos, north-west of Kos and south-east of Leros, off the coast of south-west Turkey. In the fall-out from the Armistice of Cassibile between Italy and the Allies, which had been concluded in the first week of September, the Allies were attempting to capture the Dodecanese so the islands could be used as bases against the German-occupied Balkans. Most of the Italian forces had changed sides; the LRDG found itself in an infantry role, acting as a mobile reserve for Italian troops. The Germans swiftly mobilised to expel the Allied forces and launched heavy air assaults on Kos and Leros. Without fighter support, the islands' defence was soon precarious; the LRDG and the rest of the troops on Kalymnos were withdrawn to Leros on 4 October after the Germans won the Battle of Kos. German air assaults on Leros intensified during late October, and at dawn on 12 November 1943 the Germans attacked Leros by sea and air. During the ensuing Battle of Leros, the LRDG Rhodesians at Point 320, commanded by Rhodesian Captain J R Olivey, spiked their position's guns and withdrew before counter-attacking and retaking the point the next day. They held that position for three more days, during which they learned that the Germans were winning the battle.
Adult rats of various strains became obese when they were fed a highly palatable diet for several months. Analysis of their adipose tissue morphology revealed increases in both adipocyte size and number in most depots. Reintroduction of an ordinary chow diet to such animals precipitated a period of weight loss during which only mean adipocyte size returned to normal. Adipocyte number remained at the elevated level achieved during the period of weight gain.
Countercurrent exchange is used extensively in biological systems for a wide variety of purposes. For example, fish use it in their gills to transfer oxygen from the surrounding water into their blood, and birds use a countercurrent heat exchanger between blood vessels in their legs to keep heat concentrated within their bodies. In vertebrates, this type of organ is referred to as a rete mirabile (originally the name of the organ in the fish gills). Mammalian kidneys use countercurrent exchange to remove water from urine so the body can retain water used to move the nitrogenous waste products (see countercurrent multiplier).
Sources: en.wikipedia.org
=== Safety issues for certain target groups === Like all protein-rich foods, spirulina contains the essential amino acid phenylalanine (2.6–4.1 g/100 g), which should be avoided by people who have phenylketonuria, a rare genetic disorder that prevents the body from metabolizing phenylalanine. Microcystins have various potential toxicity, especially to children and pregnant women, including liver damage, shock, and death. In 2024, a literature review on the allergic properties of spirulina was published. It was noted that to date (by July 2023), there have been 5 cases of allergy to spirulina, with 4 out of 5 cases resulting in anaphylaxis according to the classification from the World Allergy Organization's Anaphylaxis Guidance of 2020. Based on their research findings, instances of spirulina allergy are infrequently reported or identified.
=== Protein === Due to alternative splicing, insulin-degrading enzyme has two isoforms. Isoform1 is ~118 kDa in size and composed of 1019 amino acids while the isoform 2 is ~54.2 kDa size and composed of 464 amino acids (missing 1-555 amino acids). The calculated theoretical pI of this protein isoform is 6.26. Structural studies of IDE by Shen et al. have provided insight into the functional mechanisms of the protease. Reminiscent of the previously determined structure of the bacterial protease pitrilysin, the IDE crystal structure reveals defined N and C terminal units that form a proteolytic chamber containing the zinc-binding active site. In addition, it appears that IDE can exist in two conformations: an open conformation, in which substrates can access the active site, and a closed state, in which the active site is contained within the chamber formed by the two concave domains. Targeted mutations that favor the open conformation result in a 40-fold increase in catalytic activity. Based upon this observation, it has been proposed that a possible therapeutic approach to Alzheimer's might involve shifting the conformational preference of IDE to the open state, and thus increasing Aβ degradation, preventing aggregation, and, ideally, preventing the neuronal loss that leads to disease symptoms.
Periodic actin rings – A periodic structure constructed of evenly spaced actin rings is found in axons. In this structure, the actin rings, together with spectrin tetramers that link the neighboring actin rings, form a cohesive cytoskeleton that supports the axon membrane. The structure periodicity may also regulate the sodium ion channels in axons.
Sources: en.wikipedia.org
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.
Freeze-dried material is kept frozen, often at minus 20 degrees Celsius, and protected from light and moisture. Dissolved peptide is refrigerated for short-term use. Repeated freeze-thaw cycles are avoided.
A certificate of analysis typically lists purity by HPLC, the confirmed mass, appearance, and sometimes water or counter-ion content. It documents results for a specific batch. Details vary by supplier.
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.