Peptide mapping 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.
Updated 2025-08-07. Numbers and descriptions here follow the published literature rather than marketing material.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
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.
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.
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.
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.
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.
During the 1970s, the expansion of Arby's took place at a rate of 50 stores per year. During this time it created several menu items, including the Beef 'n Cheddar, Jamocha Shakes, chicken sandwiches, curly fries, and two signature sauces: Arby's Sauce and Horsey Sauce. Baked potatoes were added to the menu in 1985. Curly fries were initially introduced as Curly-Q Fries in 1988. It became the first restaurant in the fast food industry to offer a complete "lite" menu in 1991 with several sandwiches and salads under 300 calories and 94 percent fat-free. The family-owned business tried converting into a public company in 1970 by offering the sale of stock, but the IPO never went through when the stock market subsequently fell. Arby's filed for reorganization with the United States bankruptcy court in February 1971, owing to a large number of debts accrued in expansion, as well as a nationwide recession and relatively high price point compared to other fast-food chains of the time. In 1976, the family sold the company to RC Cola for $18 million and Leroy Raffel remained as CEO until his retirement three years later. In 1984, Victor Posner obtained Arby's via a hostile takeover of its then parent Royal Crown through his DWG Corporation. Nine years later, with a new owner of DWG Corporation and a new name, Triarc Companies, Inc., a former PepsiCo executive, Don Pierce, was brought in to "resurrect" Arby's. With $100 million additional funding, Pierce moved to a new "Roast Town" concept, similar in format to Boston Market, in 1996.
A myxoma (New Latin from Greek muxa 'mucus') is a myxoid tumor of primitive connective tissue. It is most commonly found in the heart (and is the most common primary tumor of the heart in adults) but can also occur in other locations.
A carboxylic acid has the general formula R-C(O)OH, where R is an organic radical. The carboxyl group -C(O)OH contains a carbonyl group, C=O, and a hydroxyl group, O-H. Acetic acid (CH3COOH) Citric acid (C6H8O7) Formic acid (HCOOH) Gluconic acid HOCH2-(CHOH)4-COOH Lactic acid (CH3-CHOH-COOH) Oxalic acid (HOOC-COOH) Tartaric acid (HOOC-CHOH-CHOH-COOH) Halogenation at alpha position increases acid strength, so that the following acids are all stronger than acetic acid. Fluoroacetic acid Trifluoroacetic acid Chloroacetic acid Dichloroacetic acid Trichloroacetic acid Normal carboxylic acids are the direct union of a carbonyl group and a hydroxyl group. In vinylogous carboxylic acids, a carbon-carbon double bond separates the carbonyl and hydroxyl groups. Ascorbic acid Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) Listing of strengths of common acids and bases Zumdahl, Steven S. (1997). Chemistry (4th ed.). Boston: Houghton Mifflin. ISBN 9780669417944. Pavia, D. L.; Lampman, G. M.; Kriz, G. S. (2004). Organic Chemistry Volume I. Mason, OH: Cengage Learning. ISBN 0759347271.
If the predicted half-life falls into an experimentally accessible range, such isotopes have a chance to move from the list of stable nuclides to the radioactive category, once their activity is observed. For example, 209Bi and 180W were formerly classed as stable, but were found to be alpha-active in 2003. However, such nuclides do not change their status as primordial when they are found to be radioactive. Most stable isotopes on Earth are believed to have been formed in processes of nucleosynthesis, either in the Big Bang, or in generations of stars that preceded the formation of the Solar System. However, some stable isotopes also show abundance variations in the earth as a result of decay from long-lived radioactive nuclides. These decay-products are termed radiogenic isotopes, in order to distinguish them from the much larger group of 'non-radiogenic' isotopes.
=== Dietary avoidance === The primary way of managing the symptoms of lactose intolerance is to limit the intake of lactose to a level that can be tolerated. Lactase deficient individuals vary in the amount of lactose they can tolerate, and some report that their tolerance varies over time, depending on health status and pregnancy. However, as a rule of thumb, people with primary lactase deficiency and no small intestine injury are usually able to consume at least 12 grams of lactose per sitting without symptoms, or with only mild symptoms, with greater amounts tolerated if consumed with a meal or throughout the day.
Sources: en.wikipedia.org
=== Since 1994 === A new interim constitution, introduced in 1994 after four years of negotiation, finally introduced all-race democracy and enfranchised men and women of all races on equal terms, the minimum age remaining 18 years. Parliament was reconstituted to consist of a Senate and a National Assembly.
Progesterone is a naturally occurring pregnane steroid and is also known as pregn-4-ene-3,20-dione. It has a double bond (4-ene) between the C4 and C5 positions and two ketone groups (3,20-dione), one at the C3 position and the other at the C20 position. Due to its pregnane core and C4(5) double bond, progesterone is often abbreviated as P4. It is contrasted with pregnenolone, which has a C5(6) double bond and is often abbreviated as P5.
1st Special Air Service 2nd Special Air Service 3rd Special Air Service – 3e Régiment de Chasseurs Parachutistes 4th Special Air Service – 2e Régiment de Chasseurs Parachutistes 5th Special Air Service – lineage continued by Belgian Special Forces Group F Squadron – responsible for signals and communications It was tasked with parachute operations behind the German lines in France and carried out operations supporting the Allied advance through France (Operations Houndsworth, Bulbasket, Loyton, Kipling and Wallace-Hardy), Belgium, the Netherlands (Operation Pegasus), and eventually into Germany (Operation Archway and Operation Howard). As a result of Hitler's issuing of the Commando Order on 18 October 1942, the members of the unit faced the additional danger that they would be summarily executed if captured by the Germans. In July 1944, following Operation Bulbasket, 34 captured SAS commandos were indeed summarily executed by the Germans; in October 1944, in the aftermath of Operation Loyton, another 31 captured SAS commandos were summarily executed by the Germans. The last original member of the Special Air Service and the last survivor of the Long Range Desert Group, Mike Sadler, died on 4 January 2024, at the age of 103.
=== Anti-inflammatory and analgesic agents === Glucocorticoids can be used in the short term and at the lowest dose possible for flare-ups and while waiting for slow-onset drugs to take effect. Combination of glucocorticoids and conventional therapy has shown a decrease in rate of erosion of bones. Steroids may be injected into affected joints during the initial period of RA, before the use of DMARDs or oral steroids. Non-NSAID drugs to relieve pain, like paracetamol may be used to help alleviate the pain symptoms; they do not change the underlying disease. The use of paracetamol may be associated with the risk of developing ulcers. NSAIDs reduce both pain and stiffness in those with RA but do not affect the underlying disease and appear to have no effect on people's long term disease course and thus are no longer first line agents. NSAIDs should be used with caution in those with gastrointestinal, cardiovascular, or kidney problems. Rofecoxib was withdrawn from the global market as its long-term use was associated to an increased risk of heart attacks and strokes. Use of methotrexate together with NSAIDs is safe, if adequate monitoring is done. COX-2 inhibitors, such as celecoxib, and NSAIDs are equally effective. A 2004 Cochrane review found that people preferred NSAIDs over paracetamol. However, it is yet to be clinically determined whether NSAIDs are more effective than paracetamol. The neuromodulator agents, topical capsaicin, may be reasonable to use in an attempt to reduce pain.
Snake toxins vary greatly in their functions. The two broad classes of toxins found in snake venoms are neurotoxins (mostly found in elapids) and hemotoxins (mostly found in viperids). However, exceptions occur – the venom of the black-necked spitting cobra (Naja nigricollis), an elapid, consists mainly of cytotoxins, while that of the Mojave rattlesnake (Crotalus scutulatus), a viperid, is primarily neurotoxic. Both elapids and viperids may carry numerous other types of toxins.
Sources: en.wikipedia.org
=== Iron compounds === Iron(III) oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding large iron parts (like rails) and purifying ores. Iron(III) oxide and oxyhydroxide are used as reddish and ocher pigments. Iron(III) chloride finds use in water purification and sewage treatment, in the dyeing of cloth, as a coloring agent in paints, as an additive in animal feed, and as an etchant for copper in the manufacture of printed circuit boards. It can also be dissolved in alcohol to form tincture of iron, which is used as a medicine to stop bleeding in canaries. Iron(II) sulfate is used as a precursor to other iron compounds. It is also used to reduce chromate in cement. It is used to fortify foods and treat iron deficiency anemia. Iron(III) sulfate is used in settling minute sewage particles in tank water. Iron(II) chloride is used as a reducing flocculating agent, in the formation of iron complexes and magnetic iron oxides, and as a reducing agent in organic synthesis. Sodium nitroprusside is a drug used as a vasodilator. It is on the World Health Organization's List of Essential Medicines.
=== Classical PKU === Classical PKU, and its less severe forms "mild PKU" and "mild hyperphenylalaninemia" are caused by a mutated gene for the enzyme phenylalanine hydroxylase (PAH), which converts phenylalanine to tyrosine, which is a conditionally essential amino acid for PKU patients, because without the enzyme PAH, tyrosine cannot be produced in the body through oxidation of Phe. PAH deficiency causes a spectrum of disorders, including classic phenylketonuria (PKU) and mild hyperphenylalaninemia (also known as "hyperPhe" or "mild HPA"), a less severe accumulation of phenylalanine. Compared to classic PKU patients, patients with "hyperPhe" have greater PAH enzyme activity and are able to tolerate larger amounts of phenylalanine in their diets. Without dietary intervention, mild HPA patients have blood Phe levels higher than those people with normal PAH activity. Currently, no international consensus exists on the definition of mild HPA, but it is most frequently diagnosed at blood Phe levels between 2 and 6 mg/dL. Phenylalanine is a large, neutral (hydrophobic) amino acid (LNAA). LNAAs compete for transport across the blood–brain barrier (BBB) via the large neutral amino acid transporter (LNAAT). If phenylalanine is in excess in the blood, it saturates the transporter. Excessive phenylalanine levels tend to decrease the levels of other LNAAs in the brain. As these amino acids are necessary for protein and neurotransmitter synthesis, Phe buildup disrupts the development of the brain, causing intellectual disability.
== Legal status == There was a proposal being discussed by the UN Commission on Narcotic Drugs (CND) to include butyrfentanyl in Schedule 1 of the 1961 Single Convention on Narcotic Drugs which was passed 16 March 2017.
==== Pulmonary tissues ==== Lung tissue engineering focuses on developing functional respiratory structures to treat end-stage pulmonary diseases, such as chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, and acute respiratory distress syndrome (ARDS). Due to the complex, highly vascularized three-dimensional architecture of the lung, which comprises over forty distinct cell types and a delicate alveolar-capillary basement membrane, whole-organ biofabrication typically relies on decellularized donor lung scaffolds. This process strips away immunogenic cellular material while preserving the native extracellular matrix geometry and mechanical compliance required for ventilation. Research strategies prioritize the multi-lineage recellularization of these scaffolds using patient-specific induced pluripotent stem cells (iPSCs) differentiated into alveolar epithelial cells (type I and II) and microvascular endothelial cells. Additionally, biomimetic microfluidic platforms, or "lung-on-a-chip" models, are utilized to study cellular shear stress and gas-exchange dynamics, serving as precursors to transplantable bioartificial lung devices.
Uranium-235 fissions with low-energy thermal neutrons because the binding energy resulting from the absorption of a neutron is greater than the threshold required for fission; therefore uranium-235 is fissile. By contrast, the binding energy released by uranium-238 absorbing a thermal neutron is less than the critical energy, so the neutron must possess additional energy for fission to be possible. Consequently, uranium-238 is fissionable but not fissile. An alternative definition defines fissile nuclides as those nuclides that can be made to undergo nuclear fission (i.e., are fissionable) and also produce neutrons from such fission that can sustain a nuclear chain reaction in the correct setting. Under this definition, the only nuclides that are fissionable but not fissile are those nuclides that can be made to undergo nuclear fission but produce insufficient neutrons, in either energy or number, to sustain a nuclear chain reaction. As such, while all fissile isotopes are fissionable, not all fissionable isotopes are fissile. In the arms control context, particularly in proposals for a Fissile Material Cutoff Treaty, the term fissile is often used to describe materials that can be used in the fission primary of a nuclear weapon. These are materials that sustain an explosive fast neutron nuclear fission chain reaction. Under all definitions above, uranium-238 (238U) is fissionable, but not fissile.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
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.