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 2026-07-12 and is reviewed periodically as new material appears.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
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.
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.
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.
Lenton Parr AM, founding dean, 1972–1975 William Kelly, 1975–1982 John Walker, 1982–1985 Gareth Sansom, 1986–1991 Norman Baggaley, 1991–1997 Mostyn Bramley-Moore, 1997–1999 Su Baker, 2000–2010 Barry Conyngham, 2010–2021 Marie Sierra, 2021–present
== Films == Out in the Silence (Dir Joe Wilson, Dean Hamer, 2009). WPSU website Kumu Hina" (Dir. Dean Hamer, Joe Wilson, 2014). PBS website Leitis in Waiting (Dir Dean Hamer, Joe Wilson, Prod Hinaleimoana Wong-Kalu, 2018). PBS website Kapaemahu (Dir Hinaleimoana Wong-Kalu, Dean Hamer, Joe Wilson, 2020). Kanak Pakipika website
=== Infectious diseases === Imaging infections with molecular imaging technologies can improve diagnosis and treatment follow-up. Clinically, PET has been widely used to image bacterial infections using FDG to identify the infection-associated inflammatory response. Three different PET contrast agents have been developed to image bacterial infections in vivo are [18F]maltose, [18F]maltohexaose, and [18F]2-fluorodeoxysorbitol (FDS). FDS has the added benefit of being able to target only Enterobacteriaceae.
Courtaulds purchased the patents for this process in 1904, leading to significant growth of viscose fiber production. By 1931, expiration of patents for the viscose process led to its adoption worldwide. Global production of regenerated cellulose fiber peaked in 1973 at 3,856,000 tons. Regenerated cellulose can be used to manufacture a wide variety of products. While the first application of regenerated cellulose was as a clothing textile, this class of materials is also used in the production of disposable medical devices as well as fabrication of artificial membranes.
Sources: en.wikipedia.org
=== Alkaline corneal burns === Hitoshi et al. showed that trimebutine can inhibit inflammation in corneal burns caused by alkali. This protective activity is thought to be mediated by high-mobility group box 1-receptor inhibitor, which causes decreased macrophage and neutrophil infiltration.
The degree of tissue disruption caused by a projectile is related to the cavitation the projectile creates as it passes through tissue. A bullet with sufficient energy will have a cavitation effect in addition to the penetrating track injury. As the bullet passes through the tissue, initially crushing then lacerating, the space left forms a cavity; this is called the permanent cavity. Higher-velocity bullets create a pressure wave that forces the tissues away, creating not only a permanent cavity the size of the caliber of the bullet but a temporary cavity or secondary cavity, which is often many times larger than the bullet itself. The temporary cavity is the radial stretching of tissue around the bullet's wound track, which momentarily leaves an empty space caused by high pressures surrounding the projectile that accelerate material away from its path. The extent of cavitation, in turn, is related to the following characteristics of the projectile:
== Prevention == A primary means of limiting risk from aflatoxins in the food supply is food hygiene in the commercial commodity supply chain, such as rejecting moldy grain for use in food processing plants and testing of batches of ingredients for aflatoxin levels before adding them to the mix. Regulatory agencies such as the FDA set limits on acceptable levels. Grain drying itself, which is necessary for viable combine harvesting in many regions, assists in this effort by preventing stored grain from being too damp in the first place. The use of nixtamalization, the processing of maize or other grains by soaking and cooking in alkali solution, greatly reduces aflatoxin concentrations. There is very limited evidence to show that agricultural and nutritional education can reduce exposure to aflatoxin in low to middle-income countries.
== Diuretics and masking agents == Diuretics, sometimes known as ‘water pills,’ are drugs that alter the body's fluid and salt balance, increasing urine production. They are used for the swelling and bloating of premenstrual syndrome, for treating high blood pressure, and in older people for heart failure caused by weakening of the heart's pumping mechanism. Diuretics can be used to pass a drug test because they increase the amount of urine produced by the body, thereby it dilutes any drugs in the urine which makes it harder to identify them. Examples of diuretics and masking agents are bumetanide, chlorothiazide, furosemide, hydrochlorothiazide, probenecid, spironolactone (canrenone), triameterene, and trichlormethiazide. Finasteride is not banned.
When the United States Navy ended Japan's Sakoku policy, and thus its isolation, the latter found itself defenseless against military pressures and economic exploitation by the Western powers. For Japan to emerge from the feudal period, it had to avoid the colonial fate of other Asian countries by establishing genuine national independence and equality. Following the María Luz Incident, Japan released the Chinese coolies from a western ship in 1872, after which the Qing imperial government of China gave thanks to Japan. However, tension soon rose between Qing China and Meiji Japan as a result of geopolitical tug-of-war for control and influence over the strategically vital Korean Peninsula. In 1884, pro-Japanese reformers in Korea, whom admired the successes of the Meiji Restoration and wanted to get rid of Korea's traditional subservience to an already weakened China after the Opium Wars, staged a brief coup d'état which triggered a clash with Qing troops stationed in Seoul who intervened to rescue the Korean king. In 1885, both nations signed an agreement to withdraw their troops from Korea and agreed to notify one another before sending military forces to the peninsula in the future. Tensions flared further in 1894 when Kim Ok-kyun, the pro-Japanese leader of the 1884 coup, was lured to Shanghai and assassinated, allegedly by Qing agents. The Japanese public was outraged, viewing this as a direct affront. At the same time, a massive peasant uprising broke out in Korea and the Korean king requested military aid from the Qing government to disperse the rebels.
Sources: en.wikipedia.org
=== Brust-Schiffrin method === This method was discovered by Brust and Schiffrin in the early 1990s, and can be used to produce gold nanoparticles in organic liquids that are normally not miscible with water (like toluene). It involves the reaction of a chlorauric acid solution with tetraoctylammonium bromide (TOAB) solution in toluene and sodium borohydride as an anti-coagulant and a reducing agent, respectively. Here, the gold nanoparticles will be around 5–6 nm. NaBH4 is the reducing agent, and TOAB is both the phase transfer catalyst and the stabilizing agent. TOAB does not bind to the gold nanoparticles particularly strongly, so the solution will aggregate gradually over the course of approximately two weeks. To prevent this, one can add a stronger binding agent, like a thiol (in particular, alkanethiols), which will bind to gold, producing a near-permanent solution. Alkanethiol protected gold nanoparticles can be precipitated and then redissolved. Thiols are better binding agents because there is a strong affinity for the gold-sulfur bonds that form when the two substances react with each other. Tetra-dodecanthiol is a commonly used strong binding agent to synthesize smaller particles. Some of the phase transfer agent may remain bound to the purified nanoparticles, this may affect physical properties such as solubility. In order to remove as much of this agent as possible, the nanoparticles must be further purified by soxhlet extraction.
=== Instability === A 2021 Federal Reserve review of the bank found several deficiencies in its risk management procedures. The bank failed to fix six citations issued by the Fed and was placed under a full supervisory review in July 2022. In the autumn, San Francisco Fed officials met with SVB senior leaders to discuss the bank's ability to raise cash in a crisis and possible exposure to losses as interest rates rose. Fed officials determined the bank was using flawed models that led SVB officers to incorrectly believe rising interest rates would increase the bank's interest revenue to substantially stabilize its financial condition. By early 2023, the Fed placed SVB in a "horizontal review" of its risk management procedures. In the week before the collapse, Moody's Investors Service reportedly informed SVB Financial, the bank's holding company, that it was facing a potential double-downgrade of its credit rating because of its unrealized losses. On March 8, 2023, SVB announced it had sold over $21 billion worth of its investments, borrowed $15 billion, and would hold an emergency sale of its stock to raise $2.25 billion, including $500 million to General Atlantic. JPMorgan Chase and Bank of America turned down opportunities to acquire the bank. Despite the steps taken by the bank, Moody's downgraded SVB on March 8.
== Description and conceptual basis == Writing for Science-Based Medicine, Harriet Hall described myofascial release as an umbrella term for several types of physical manipulation, which might more simply be described as a kind of massage based on vaguely defined scientific notions.
==== 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.
Steiner (1945), scholar of social policy and fourth president of the Brookings Institution Richard Heffner (1946), professor and host of The Open Mind Fritz Stern (1946), Seth Low Professor of History Emeritus; pre-eminent in German studies George Herbert Borts (1947), economist at Brown University and managing editor of The American Economic Review 1969–1980 William Bell Dinsmoor Jr. (1947), Classical archaeologist and architectural historian John Michael Montias (1947), economist and art historian at Yale University Harold E. Pagliaro (1947), professor of English literature at Swarthmore College Howard Stein (1947), philosopher at the University of Chicago Lambros Comitas (1948), anthropologist Elihu Katz (1948), sociologist and communication scholar, known for developing the two-step flow of communication theory Norman Kelvin (1948), literary scholar, professor at City College of New York and Graduate Center, CUNY Victorino Tejera (1948), professor of philosophy and comparative literature at Stony Brook University Uriel Weinreich (1948), linguist and professor at Columbia University Albert Elsen (1949), professor at Stanford University and Auguste Rodin expert Donald M. Friedman (1949), professor of Renaissance literature at University of California, Berkeley Marvin Harris (1949), anthropologist famous for developing cultural materialism Anthony Leeds (1949), anthropologist, professor at Boston University Robert F.
Sources: en.wikipedia.org
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.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
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.