Everything below concerns Tuftsin analogue. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-10-30. Numbers and descriptions here follow the published literature rather than marketing material.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
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 |
|---|---|---|
| Typical storage temperature | -20 °C or below | For lyophilized powder, long term |
| Common analytical method | Reverse-phase HPLC | Usually paired with mass spectrometry |
| Typical reported purity | At or above 95 percent by area | Research-grade material |
| Aqueous solubility | High | Solutions used in laboratory assays |
| Moisture sensitivity | Hydrolyzes in solution | Aseptic handling reduces degradation |
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.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
The 1–508 PIR served in Regional Command-South. Working mostly out of Kandahar province as the theater tactical force, they mentored the Afghan National Security Force (ANSF), conducting combined operations with both ANSF and NATO partners in the Helmand Province. Supporting the division were the 36th Engineer Brigade, and the 43d Area Support Group.
By early December 1984, most of the plant's MIC related safety systems were malfunctioning and many valves and lines were in poor condition. In addition, several vent gas scrubbers had been out of service, as well as the steam boiler intended to clean the pipes. During the late evening hours of 2 December 1984, water was believed to have entered tank E610 via a side pipe during attempts to unclog it. The tank still contained the 42 tons of MIC that had been there since late October. The introduction of water into the tank resulted in a runaway exothermic reaction, which was accelerated by contaminants, high ambient temperatures, and various other factors such as the presence of iron from corroding non-stainless steel pipelines. The pressure in tank E610, although initially nominal at 14 kilopascals (2 psi) at 10:30 p.m., reached 70 kilopascals (10 psi) as of 11 p.m. Two different senior refinery employees assumed the reading was instrumentation malfunction. By 11:30 p.m., workers in the MIC area were feeling the effects of minor exposure to MIC gas and began to look for a leak. One was found by 11:45 p.m. and reported to the MIC supervisor on duty at the time. The decision was made to address the problem after a 12:15 a.m. tea break, and in the meantime, employees were instructed to continue looking for leaks. The problem was discussed by MIC area employees during the break. When the tea break concluded at 12:40 a.m., the reaction in tank E610 escalated to a critical state at a rapid speed within five minutes.
Activation energies consistent with proline isomerization, which typically has an activation of about 20 kcal/mol. Two-state folding kinetics indicative of both fast-folding and slow-folding populations in the unfolded or denatured state. "Double-jump" assays in which proline-containing proteins are unfolded and refolded, and the population of non-native proline conformations are studied as a function of the extent of folding. Acceleration of the in vitro folding rate by the addition of a prolyl isomerase. Acceleration of the in vitro folding rate in mutant protein variants with one or more proline residues replaced by another amino acid. Not every proline peptide bond is critical to the structure or function of a protein, and not every such bond has a significant influence on folding kinetics, especially trans bonds. Furthermore, some prolyl isomerases have a degree of sequence specificity and therefore may not catalyze the isomerization of prolines in certain sequence contexts.
=== Water vascular system === The water vascular system of the starfish is a hydraulic system made up of a network of fluid-filled canals and is concerned with locomotion, adhesion, food manipulation and gas exchange. Water enters the system through the madreporite, a porous, often conspicuous, sieve-like ossicle on the aboral surface. It is linked through a calcareous-lined canal called the stone canal, to a ring canal around the mouth opening. A set of radial canals branch off from the ring canal; one radial canal runs along the ambulacral groove in each arm. There are short lateral canals branching off alternately to either side of the radial canal, each ending in an ampulla. These bulb-shaped organs are joined to tube feet (podia) on the exterior of the animal by short linking canals that pass through ossicles in the ambulacral groove. There are usually two rows of tube feet but in some species, the lateral canals are alternately long and short and there appear to be four rows. The interior of the whole canal system is lined with cilia. Water is pushed into the tube face when longitudinal muscles in the ampullae contract, and shut the valves in the lateral canals. This causes the tube feet to stretch and touch the substrate. Although the tube feet resemble suction cups in appearance, the gripping action is a function of adhesive chemicals rather than suction. Other chemicals and relaxation of the ampullae allow for release from the substrate. The tube feet latch on to surfaces and move in a wave, with one arm section attaching to the surface as another releases.
Democratic Left was a post-communist political organisation that operated in the United Kingdom from 1991 to 1998. It emerged from the Eurocommunist faction within the Communist Party of Great Britain (CPGB) and was closely associated with the magazine Marxism Today, which ceased publication around the same period. The organisation was founded on 11 November 1991 following the CPGB's decision to dissolve and reconstitute itself as a left-wing reformist think tank and grassroots campaign group. This transformation was guided by the party's Manifesto for New Times, which outlined a vision for post-communist politics in Britain. Nina Temple, who had served as the final general secretary of the CPGB, became the organisation's secretary. Temple, who had been Press and Publicity Officer of the CPGB from 1983 to 1989 before becoming general secretary in 1990 at age 33, was one of the leading proponents of the CPGB's dissolution. The CPGB's transformation into Democratic Left proved controversial within the party. Many members rejected this reformist direction and instead affiliated with the Communist Party of Britain, which had split from the CPGB in 1988, while others in Scotland established the Communist Party of Scotland.
Sources: en.wikipedia.org
Indigo dye is a dark blue crystalline powder that sublimes at 390–392 °C (734–738 °F). It is insoluble in water, alcohol, or ether, but soluble in DMSO, chloroform, nitrobenzene, and concentrated sulfuric acid. The chemical formula of indigo is C16H10N2O2. The molecule absorbs light in the orange part of the spectrum (λmax=613 nm). The compound owes its deep color to the conjugation of the double bonds, i.e. the double bonds within the molecule are adjacent and the molecule is planar. In indigo white, the conjugation is interrupted because the molecule is non-planar.
The hydrogenation process was widely adopted by the food industry in the early 1900s; first for the production of margarine, a replacement for butter and shortening, and eventually for various other fats used in snack food, packaged baked goods, and deep fried products. Hydrogenation makes the fat more saturated, which has desirable properties:
The U.S. and Canadian Dietary Reference Intake review for protein concluded that there was not sufficient evidence to establish a Tolerable upper intake level, i.e., an upper limit for how much protein can be safely consumed. When amino acids are in excess of needs, the liver takes up the amino acids and deaminates them, a process converting the nitrogen from the amino acids into ammonia, further processed in the liver into urea via the urea cycle. Excretion of urea occurs via the kidneys. Other parts of the amino acid molecules can be converted into glucose and used for fuel. When food protein intake is periodically high or low, the body tries to keep protein levels at an equilibrium by using the "labile protein reserve" to compensate for daily variations in protein intake. However, unlike body fat as a reserve for future caloric needs, there is no protein storage for future needs. Excessive protein intake may increase calcium excretion in urine, occurring to compensate for the pH imbalance from oxidation of sulfur amino acids. This may lead to a higher risk of kidney stone formation from calcium in the renal circulatory system. One meta-analysis reported no adverse effects of higher protein intakes on bone density. Another meta-analysis reported a small decrease in systolic and diastolic blood pressure with diets higher in protein, with no differences between animal and plant protein. High protein diets have been shown to lead to an additional 1.21 kg of weight loss over a period of 3 months versus a baseline protein diet in a meta-analysis.
The Journal of Chromatographic Science (JCS) is a peer reviewed academic journal of chromatography. It is published by Oxford University Press. The Journal focuses on research papers describing practical and preparative applications and analytical methods relevant to a broad range of laboratory work. The editors-in-chief are Huba Kalász and Neil Danielson. According to the Journal Citation Reports, the journal has a 2020 impact factor of 1.618.
The Swiss Federal Tribunal (SFT) has decided not to entertain the appeal filed by the players against the CAS award of 11 January 2016, imposing a 2-year ban on each player following an anti-doping rule violation. The SFT determined that since the players did not formally challenge the jurisdiction of CAS during the arbitration procedure and accepted the application of the CAS Rules (including the rule providing for a de novo hearing, i.e. for a procedure allowing the CAS to conduct a full review of the case), they had lost their right to challenge the CAS jurisdiction in appeal. The SFT added that, even if the players had properly challenged the jurisdiction of CAS, CAS jurisdiction in this matter would have been confirmed, and the appeal would have been dismissed. The players did not seek an injunction against their suspensions when appealing with the Federal Supreme Court, meaning that they would have served their 2016 suspensions even if the guilty verdicts had been cleared. This was to eliminate any risk that a new, two-year period of suspension could be ordered to be served in full if the appeal were unsuccessful.
Sources: en.wikipedia.org
The most common approach combines reverse-phase liquid chromatography with mass spectrometry. Chromatography separates the components while mass spectrometry confirms the molecular mass. Peptide sequencing or tandem mass analysis can further verify the amino acid order.
Lyophilized powder is usually kept frozen and protected from moisture. Solutions are less stable and are often used promptly or divided into aliquots to avoid repeated freeze-thaw cycles. Exact shelf-life values depend on purity and handling.
No. A purity figure derived from chromatographic area does not prove the amino acid sequence. Identity requires an orthogonal method such as mass spectrometry or sequencing. Truncated or isomerized peptides can co-elute with the target compound.
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.