Everything below concerns freeze-thaw. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-03-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Modeled on tuftsin |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues |
| Approximate molecular mass | Around 750 Da | Depends on counter-ion and hydration |
| Common forms | Lyophilized powder | Also described as aqueous solution |
| Primary origin of research | Russian laboratories | Mid-1990s onward |
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
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.
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, 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.
=== Cultured method === The cultured method relies on natural bacterial fermentation to coagulate milk proteins and develop flavour. It is the dominant methodology used across the United Kingdom and continental Europe, where commercial dairy producers (such as Arla Foods) align with consumer preferences for clean-label, minimally processed foods that avoid direct chemical additives.
== Metalloenzymes == Metalloenzymes all have one feature in common, namely that the metal ion is bound to the protein with one labile coordination site. As with all enzymes, the shape of the active site is crucial. The metal ion is usually located in a pocket whose shape fits the substrate. The metal ion catalyzes reactions that are difficult to achieve in organic chemistry. These metalloenzymes acts in accordance to radical chemistry as these metalloenzymes use various techniques to create, stabilize, and use highly reactive radical intermediates.
Finally, a civilization known as "Type III" reaches the milepost set in 5,800 years when humanity's rate of energy consumption is predicted by the author to match the power emitted by the approximated 1011 stars in the Milky Way galaxy, which involves harnessing power of up to an estimated 4×1037 W. Assuming the development of radio, Kardashev predicted that in the following two decades (i.e. in the 1980s) it would be possible to build antennas of 100,000 m2 capable of detecting Type II and III civilizations. A Type I civilization like that of Earth would be able to receive the extraordinary energetic emissions of the other types of civilizations, which would supposedly be able to emit continuously. Kardashev then examined the characteristics of a transmission from an artificial source. He mentioned the two cosmic radio sources discovered in 1963 by the California Institute of Technology, CTA-21 and CTA-102 in particular, which would have characteristics close to those of a presumed artificial source. The most suitable region of the galaxy for observing Type II and III civilizations would then be the Galactic Center, due to the high density of the stellar population it harbors. He then recommended that the search programs for such artificial sources should focus on other nearby galaxies, such as the Andromeda Galaxy, the Magellanic Clouds, M87, or Centaurus A. Kardashev concluded his paper by noting that the possible discovery of even the simplest organisms on Mars would increase the likelihood that Type II civilizations exist in the galaxy.
Ayyadurai garnered 3.39% of the vote as an independent candidate in the 2018 U.S. Senate election in Massachusetts, and ran for the Republican Party nomination in the 2020 U.S. Senate election in Massachusetts but lost to Kevin O'Connor in the primary. After the election, he promoted false claims of election fraud. In 2024, Ayyadurai launched a campaign to be the president of the United States. However, because he is not a natural-born American citizen, he is ineligible to serve as president.
Sources: en.wikipedia.org
== Future research == The pathophysiology of IIMs is not well understood. Muscle weakness can be caused by a single or combined effect on muscle tissue by inflammation, inflammatory infiltrates, muscle atrophy, metabolic abnormalities that indicate disordered energy metabolism, and possibly neuropathy, among others. Therefore, physical exercise has the potential to cause harm. However, the results of these exercise studies, at minimum, show that exercise can attenuate muscle damage due to disease, inactivity and steroid use. They reflect the benefit of exercise through the strengthening of complement (non-diseased) muscles, and should encourage further studies to confirm whether diseased muscle may experience regeneration. The definition of improvement must be established, and reproducible longitudinal studies must be conducted to determine the efficacy of exercise as therapy for IIM.
=== Domestic === Afghanistan: Afghanistan's Ministry of Defence condemned the airstrikes, claiming that Pakistan had "hit a religious school and residential homes". Foreign Minister Amir Khan Muttaqi said Afghanistan was "facing an imposed war" from Pakistan. Taliban spokesman, Zabihullah Mujahid, said Afghanistan had not initiated the conflict with Pakistan and that its forces were acting only in self-defence. He also stated that Taliban forces were not violating Pakistani territory and were responding only to protect the population. Afghanistan Freedom Front: The Afghan Freedom Front said the Taliban had moved Pakistani Taliban militants into government buildings and crowded civilian areas, accusing them of using civilians as human shields. The Front also criticized the Taliban for secrecy and propaganda amid Pakistani attacks, condemned civilian killings, called for an independent international investigation, and urged Afghans not to be misled by Taliban messaging. National Resistance Front: Ahmad Massoud said Pakistan's strikes were a consequence of Taliban policies, accusing the group of sheltering the Pakistani Taliban, Al-Qaeda, and other militant organisations and turning Afghanistan into a centre of regional insecurity. At the same time, he rejected foreign military attacks and political deals with the Taliban, arguing that Afghanistan's freedom and any lasting solution must come from the Afghan people themselves through a coordinated and legitimate national effort. Fazel Ahmed Manawi, a senior NRF leader praised Pakistan for its air operations and voiced support.
While in Constantine's treatise Liber de Coitu, the clitoris is referred to a few times, Magnus gave an equal amount of attention to male and female organs. Like Avicenna, Magnus also used the word virga for the clitoris, but employed it for the male and female genitals; despite his efforts to give equal ground to the clitoris, the cycle of suppression and rediscovery of the organ continued, and a 16th-century justification for clitoridectomy appears to have been confused with intersex conditions and the imprecision created by the word nymphae substituted for the word clitoris. Nymphotomy was a medical operation to excise an unusually large clitoris, but what was considered "unusually large" was often a matter of perception. The procedure was routinely performed on Egyptian women, due to physicians such as Jacques Daléchamps who believed that this version of the clitoris was "an unusual feature that occurred in almost all Egyptian women [and] some of ours, so that when they find themselves in the company of other women, or their clothes rub them while they walk or their husbands wish to approach them, it erects like a male penis and indeed they use it to play with other women, as their husbands would do ... Thus the parts are cut".
==== Extraterrestrial ==== PAHs are prevalent in the interstellar medium (ISM) of galaxies in both the nearby and distant Universe and make up a dominant emission mechanism in the mid-infrared wavelength range, containing as much as 10% of the total integrated infrared luminosity of galaxies. PAHs generally trace regions of cold molecular gas, which are optimum environments for the formation of stars. NASA's Spitzer Space Telescope and James Webb Space Telescope include instruments for obtaining both images and spectra of light emitted by PAHs associated with star formation. These images can trace the surface of star-forming clouds in our own galaxy or identify star forming galaxies in the distant universe. In June 2013, PAHs were detected in the upper atmosphere of Titan, the largest moon of the planet Saturn.
A video report by the BBC titled More than 350 people killed in Syria clashes showed widespread violence in affected areas. Drone footage showed damaged neighborhoods in Sweida following the fighting. CCTV footage from Sweida hospital circulated online, reportedly showing armed men killing a person inside the hospital while medical staff were forced to the ground. A video report from The Guardian titled Killed for what, religion? featured testimonies describing summary executions and retaliatory violence during the sectarian escalation. Human Rights Watch reported that the conflict was accompanied by "serious abuses," including summary executions, arson attacks on homes, looting of property, and the forced displacement of civilians.
Sources: en.wikipedia.org
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.
It originates from research in Russia, associated with the Institute of Molecular Genetics of the Russian Academy of Sciences. The first descriptions date to the mid-1990s. Most published studies come from Russian laboratories.
No, Selank itself does not occur naturally. Its backbone is based on tuftsin, which is produced in the body, but the seven-residue version is a synthetic construct. It is supplied as a manufactured peptide.
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.