heptapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-12-20. 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.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
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 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.
| 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 |
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.
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.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
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.
Until the late 1950s, the Precambrian was not believed to have hosted multicellular organisms. However, with radiometric dating techniques, it has been found that fossils initially found in the Ediacara Hills in Southern Australia date back to the late Precambrian. These fossils are body impressions of organisms shaped like disks, fronds and some with ribbon patterns that were most likely tentacles. These are the earliest multicellular organisms in Earth's history, despite the fact that unicellularity had been around for a long time before that. The requirements for multicellularity were embedded in the genes of some of these cells, specifically choanoflagellates. These are thought to be the precursors for all animals. They are highly related to sponges (Porifera), which are the simplest multicellular animals. In order to understand the transition to multicellularity during the Precambrian, it is important to look at the requirements for multicellularity—both biological and environmental.
Many street-level harm-reduction strategies have succeeded in reducing HIV transmission in people who inject substances and sex-workers. HIV education, HIV testing, condom use, and safer-sex negotiation greatly decreases the risk of acquiring and transmitting HIV.
== Enzyme structure == Cystathionine γ-lyase is a member of the Cys/Met metabolism PLP-dependent enzymes family. Other members include cystathionine γ synthase, cystathionine β lyase, and methionine γ lyase. It is also a member of the broader aspartate aminotransferase family. Like many other PLP-dependent enzymes, cystathionine γ-lyase is a tetramer with D2 symmetry. Pyridoxal phosphate is bound in the active site by Lys212.
Day of Defeat's initial retail offering included fifteen maps, each depicting different scenarios with variation in size and thematic locations. These often drew inspiration from historical World War II battles, such as the battle at Omaha Beach and street-fighting in the Italian city of Salerno during Operation Avalanche. The game also features a Glider mission wherein the American 101st Airborne lands in a WACO Glider and destroys such objectives as a radio antenna and Flak 88 mm gun anti-aircraft gun. Weapons in the game are also of historical significance, with much of the weaponry being accurate representations of those used in World War II. The weapon selection is also realistic in its usage, with recoil and accuracy representative of the gun's real-life counterparts.
Sources: en.wikipedia.org
Following the initial line (used for a unique description of the sequence) was the actual sequence itself in the standard one-letter character string. Anything other than a valid character would be ignored (including spaces, tabulators, asterisks, etc...). It was also common to end the sequence with an "*" (asterisk) character (in analogy with use in PIR formatted sequences) and, for the same reason, to leave a blank line between the description and the sequence. Below are a few sample sequences:
The HEVC encoder has 17 3G-SDI inputs and uses 17 boards for parallel processing with each board encoding a row of 7680 × 256 pixels to allow for real time video encoding. The HEVC encoder is compliant with draft 4 of the HEVC standard and has a maximum bit rate of 340 Mbit/s. The HEVC encoder was shown at the NHK Science & Technology Research Laboratories Open House 2013 that took place from May 30 to June 2. At the NHK Open House 2013 the HEVC encoder used a bit rate of 85 Mbit/s, which gives a compression ratio of 350∶1. On May 21, 2013, Microsoft announced the Xbox One, which supports 4K resolution (3840 × 2160) video output and 7.1 surround sound. Yusuf Mehdi, corporate vice president of marketing and strategy for Microsoft, has stated that there is no hardware restriction that would prevent Xbox One games from running at 4K resolution. On May 30, 2013, Eye IO announced that their encoding technology was licensed by Sony Pictures Entertainment to deliver 4K Ultra HD video. Eye IO encodes their video assets at 3840 × 2160 and includes support for the xvYCC color space. In mid-2013, a Chinese television manufacturer produced the first 50-inch UHD television set costing less than $1,000. On June 11, 2013, Comcast announced that they had demonstrated the first public U.S.-based delivery of 4K Ultra HD video at the 2013 NCTA show. The demonstration included segments from Oblivion, Defiance, and nature content sent over a DOCSIS 3.0 network.
=== Insomnia === Ramelteon is approved for the treatment of insomnia characterized by difficulty with sleep onset in adults. In regulatory clinical trials, it was found to significantly reduce latency to persistent sleep (LPS). A 2009 pooled analysis of four clinical trials found that ramelteon at a dose of 8 mg reduced sleep onset by 13 minutes (30% decrease) relative to placebo on the first and second nights of use. Subsequent meta-analyses of longer-duration use have found that ramelteon decreases subjective sleep latency by about 4 to 7 minutes. Meta-analyses are mixed on whether ramelteon increases total sleep time. Ramelteon also improves sleep quality (SMDTooltip standardized mean difference –0.074, 95% CITooltip confidence interval –0.13 to –0.02) and sleep efficiency. The clinical improvement in insomnia with ramelteon is small and of questionable benefit. Ramelteon is approved in the United States but was not approved in the European Union owing to concerns that it lacked effectiveness. The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) noted that ramelteon had only been found to improve sleep onset and not other sleep outcomes, only one of three clinical trials actually found that it improved sleep onset, and that the improvement in sleep onset was too small to be clinically meaningful. The CHMP also noted that the long-term effectiveness of ramelteon had not been demonstrated.
The blackcurrant (Ribes nigrum), black currant or cassis is a deciduous shrub in the family Grossulariaceae grown for its edible berries. It is native to temperate parts of central and northern Europe and northern Asia, where it prefers damp fertile soils. It is widely cultivated both commercially and domestically. It is winter hardy, but cold weather at flowering time during the spring may reduce the size of the crop. Bunches of small, glossy black fruit develop along the stems in the summer and can be harvested by hand or by machine. The raw fruit is particularly rich in vitamin C and polyphenols. Blackcurrants can be eaten raw but are usually cooked in various dishes. They are used to make jams, preserves, and syrups and are grown commercially for the juice market. The fruit is also used to make alcoholic beverages and dyes.
=== Metabolism, recycling and excretion === Cholesterol is susceptible to oxidation and easily forms oxygenated derivatives called oxysterols. These can be formed by three different mechanisms: autoxidation, secondary oxidation to lipid peroxidation, and cholesterol-metabolizing enzyme oxidation. A great interest in oxysterols arose when they were shown to exert inhibitory actions on cholesterol biosynthesis. This finding became known as the "oxysterol hypothesis". Additional roles for oxysterols in human physiology include their participation in bile acid biosynthesis, function as transport forms of cholesterol, and regulation of gene transcription. In biochemical experiments, radiolabelled forms of cholesterol, such as tritiated-cholesterol, are used. These derivatives undergo degradation upon storage, and it is essential to purify cholesterol prior to use. Cholesterol can be purified using small Sephadex LH-20 columns. Cholesterol is oxidized by the liver into a variety of bile acids. These, in turn, are conjugated with glycine, taurine, glucuronic acid, or sulfate. A mixture of conjugated and nonconjugated bile acids, along with cholesterol itself, is excreted from the liver into the bile. Approximately 95% of the bile acids are reabsorbed from the intestines, and the remainder are lost in the feces. The excretion and reabsorption of bile acids forms the basis of the enterohepatic circulation, which is essential for the digestion and absorption of dietary fats.
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.
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.