Everything below concerns tuftsin. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-07-10. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
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.
=== Criminal justice === As attorney general, Schmitt supported an effort in the Missouri legislature to increase the number of police officers in St. Louis City by lifting the residency requirement for police officers.
The Watson and Crick discovery of the DNA double helix structure was made possible by their willingness to combine theory, modelling and experimental results (albeit mostly done by others) to achieve their goal. The DNA double helix structure proposed by Watson and Crick was based upon "Watson-Crick" bonds between the four bases most frequently found in DNA (A, C, T, G) and RNA (A, C, U, G). However, later research showed that triple-stranded, quadruple-stranded and other more complex DNA molecular structures required Hoogsteen base pairing. In the field of synthetic biology, bases other than A, C, T and G are used in a synthetic DNA. In addition to synthetic DNA there are also attempts to construct synthetic codons, synthetic endonucleases, synthetic proteins and synthetic zinc fingers. Using synthetic DNA, instead of there being 43 codons, if there are n new bases there could be as many as n3 codons. Research is currently being done to see if codons can be expanded to more than 3 bases. These new codons can code for new amino acids. These synthetic molecules can be used not only in medicine, but in creation of new materials. The discovery was made on 28 February 1953; the first Watson/Crick paper appeared in Nature on 25 April 1953. Sir Lawrence Bragg, the director of the Cavendish Laboratory, where Watson and Crick worked, gave a talk at Guy's Hospital Medical School in London on Thursday 14 May 1953 which resulted in an article by Ritchie Calder in the News Chronicle of London, on Friday 15 May 1953, entitled "Why You Are You.
=== Anti-competitive practices === In February 2017, the European Commission began investigating Valve and five other publishers—Bandai Namco Entertainment, Capcom, Focus Home Interactive, Koch Media and ZeniMax Media—for anti-competitive practices, specifically the use of geo-blocking through the Steam storefront and Steam product keys to prevent access to software to citizens of certain countries. Such practices would be against the Digital Single Market initiative by the European Union. While the other five companies named are in stages of settling with the EU as of August 2019, Valve has stated it plans to fight the charges, asserting that geo-blocking affects less than 3% of its games, and that it had turned off such geo-blocking within the EU in 2015. In January 2021, five gamers filed a proposed class-action antitrust lawsuit in California against Valve, alleging that the company "abuses the Steam platform's market power" by requiring game developers and publishers to enter into a "most favored nation" agreement with Valve, restricting their ability to sell games for less on other platforms and thereby preventing price competition. This suit was later consolidated with the Wolfire Games lawsuit.
The spot indole test is used to determine if a microbe can deaminate tryptophan to produce indole. This test is performed by saturating a piece of filter paper with Indole Kovacs Reagent and scraping a portion of microbe onto the paper. A color to a pink-red color indicates a positive result while no color change indicates the lack of tryptophanase.
=== Product production === Fermentation plays a significant role in producing precursor polymers to products and food additives such as amino acids, organic acids, triglycerides and fatty acids. Amino acids are industrially produced through fermentation by microorganisms such as Corynebacterium glutamicum and Escherichia coli. The global market application for amino acids is primarily food and feed additive. L-glutamic acid and L-lysine are the most commonly found amino acids in this market with L-glutamic acid being mainly used as a food flavoring in the form of monosodium glutamate (MSG) and L-lysine being mainly used as an animal feed supplement. Other amino acids like L-threonine and L-phenylalanine are also produced on large scales for different applications. Organic acids such as citric acid, lactic acid, and acetic acid are procured by microbial fermentation. Citric acid finds widespread use in the food industry as a preservative and flavoring agent. Lactic acid is used in food preservation and as a precursor for biodegradable plastics. Acetic acid is used in food as vinegar and as a chemical reagent in industries. These organic acids are produced using microorganisms like Aspergillus niger and Lactobacillus species under controlled fermentation conditions. Fatty acids and triglycerides are produced by fermentation on oleaginous microorganisms such as Yarrowia lipolytica and certain fungi. These microorganisms can accumulate lipids under specific culture conditions and therefore are suitable for industrial-scale production of lipids.
Sources: en.wikipedia.org
Typhoid epidemics also broke out in the resettlement camps, which were often isolated, located far from urban areas, and lacked health facilities, sanitation, and schools. The forced relocations of blacks to the Ciskei resulted in high population densities in the homeland, a situation that persists to the present day. On several occasions, the Ciskei government imposed collective punishment on communities that opposed its rule, and people fled the Bantustan back into South Africa proper, because of the harassment and denial of government services to dissenters. In common with other Bantustans, its independence was not recognised by the international community. Sebe once claimed that the State of Israel had granted official recognition to Ciskei, but the Israeli Foreign Ministry denied this.
Further investigations by Sir Edward Abraham and Guy Newton were made in England and isolation of culture fluids from the Sardinian fungus yielded cephalosporin P, N and C. These natural compounds were not found to be potent enough to use as antimicrobial agents but with chemical methods and removal of the natural side chain it was possible to produce 7-aminocephalosporanic acid (7-ACA) which could be further fit with unnatural side chains. 7-ACA is analogous to 6-aminopenicillanic acid (6-APA), a starting block for making several derivatives of penicillins. In 1959 Abraham reported that his N-phenylacetyl derivative of cephalosporin C was much more potent against Staphylococcus aureus strains than the parent compound. This derivative was later named Cephaloram, a cephalosporin analogue of benzylpenicillin. Eli Lilly developed a method for producing 7-ACA based on cleaving the α-aminoadipoyl side chain of cephalosporin C. Further work by Robert Morin led to semisynthesis of 3-deacetoxy-7-ACA (7-ADCA) from penicillins which is convenient because penicillins can be fermented with more ease than cephalosporins. For example, 7-ADCA can be semisynthesized in seven chemical reaction steps from phenoxymethylpenicillin.
=== Calciseptine as an L-type calcium channel blocker === Calciseptine resembles the abovementioned 1,4-dihydropyridines in its biological action, as it has the same ability to bind and block the L-type calcium channels in smooth and cardiac muscle. The amino acids responsible for binding and blocking the L-type calcium channels are probably located in the third ‘finger’ of the calciseptine structure, somewhere between amino acids 40 and 50. Although peptides from the three-fingered family are alike in structure, only some of them are able to bind and block calcium channels. Multiple sequence alignment studies yielded 12 amino acid residues that were unique to the toxins with channel-blocking activities. These residues are located at the tips of loops II and III in the three-fingered structure. A model has been proposed in which the amino acids 45 to 48, MWPY, of the FS2 toxin are considered to bind the calcium channels. This model is based on a prediction of the interactions of these amino acids with the calcium channel. These interactions resemble the hydrophobic and hydrogen bonding properties of nifedipine, a known 1,4-dihydropyridine blocker. Because of the similarities between calciseptine and FS2, this model could account for the interactions of calciseptine with the L-type calcium channels as well. Another model is based on a larger segment of the same loop, containing amino acids 42 to 47, PTAMWP.
=== RsfS === RsfS (Ribosome silencing factor S) inhibits translation by preventing the 30S and 50S subunits of the ribosome from binding to each other again after they split during ribosome recycling. It has also been suggested to be a ribosome biogenesis factor rather than a hibernation factor.
Sources: en.wikipedia.org
=== Bee–Ber === Lorena S. Beese(20th–21st century). Biochemist at Duke University, known for structural biochemistry of DNA replication and protein prenylation enzymes. Member Natl. Acad. Sci. USA. Helmut Beinert (1913–2007). German born-American biochemist at the University of Wisconsin–Madison, a pioneer of and advocate for the use of electron paramagnetic resonance in biological systems. Member Natl. Acad. Sci. USA. Marlene Belfort (b. 1945). American biochemist at the New York State Department of Health involved in the discovery of self-splicing introns in bacteriophage. Member Natl. Acad. Sci. USA. Boris Pavlovich Belousov (1893–1970). Chemist and biophysicist in the Ministry of Health of the USSR who discovered the Belousov–Zhabotinsky reaction. Awarded the Lenin Prize (1980). Myron L. Bender (1924–1988). American biochemist at Northwestern University, who pioneered mechanistic studies of enzymes, especially chymotrypsin and other proteases. Member Natl. Acad. Sci. USA. Stephen J. Benkovic (b. 1938). American bioorganic chemist at Pennsylvania State University. Member Natl. Acad. Sci. USA. Steven A. Benner (b. 1954). American chemist at the University of Florida known for establishing synthetic biology and paleogenetics, aas wll as contributing to understanding of the origin of life; Paul Berg FRS (foreign member) (1926–2023). American biochemist at Stanford, known for pioneering work involving gene splicing of recombinant DNA. He was awarded the Nobel Prize in Chemistry in 1980. Helen M. Berman (b. 1943).
When the duty cycle is increased to d = 0.60 the range of completely stable q values decreases (see Fig 3 (b)) as indicated by the reduction of green that the horizontal line intersects. In this representation the total range of stable q values along the x-axis, that is defined by the intersection of the line through the blue and green regions, is greater than the total range of stable q values along the y-axis that is defined by the intersection of the line through the yellow and green regions. In Fig 3 (b) the overall stability of the linear DIT in the y direction is smaller than in the x direction. If the frequency of the linear DIT is decreased to cause a particular ion to have a q value that corresponds to right hand side boundary of the completely stable green region, then it will excite and ultimately eject in the y direction. This is the fundamental mechanism that allows control over the direction of ion excitation in a linear DIT without resonant excitation.
=== Combat === Every weapon is used one-handed, as Valve wanted players to have a hand free to interact with the world at all times. The crowbar, a weapon from previous Half-Life games, was omitted as Valve could not make melee combat work in VR, and because players would accidentally catch it on objects in the game world as they moved, creating confusion. Additionally, players associated the crowbar with Gordon Freeman, the protagonist of previous games. Valve wanted to create a different identity for Alyx, portraying her as a "hacker and tinkerer". Other discarded weapon concepts include a trip mine, slingshot, shield and rocket launcher. As players move at more realistic speeds in VR compared to typical FPS games, Valve had to adjust enemies to make combat fair and fun. Antlions, returning enemies from Half-Life 2, would quickly overwhelm players with their speed. The team slowed the antlions' movement and added the ability to shoot their legs off to slow them down. Fast zombies and fast headcrabs, also introduced in Half-Life 2, were cut as they were too frightening for some players in VR. According to the designer Dario Casali, "The shock of having [them] come around the corner and latch onto you before you'd even know what was going on was just too much."
==== Measures of fractionation ==== The study of HIBGC relies on the fact that various physicochemical processes preferentially enrich or deplete 2H relative to 1H (see kinetic isotope effect [KIE], etc.). Various measures have been developed to describe the fractionation in an isotope between two pools, often the product and reactant of a physiochemical process. α notation describes the difference between two hydrogen pools A and B with the equation:
Simultaneously, the government tried a direct negotiation with the ETA leadership but the "Algiers talks" did not lead to any result; on the contrary, the group perpetrated some of the bloodiest attacks in its history: the Hipercor bombing, in Barcelona, and the Zaragoza barracks bombing. The government then sought to reach a great "anti-terrorist" pact that would also include democratic Basque nationalism, which was finally achieved with the signing of the Ajuria Enea Pact in January 1988. A few months later, two policemen, José Amedo and Michel Domínguez were arrested, accused of being involved in the kidnapping of Segundo Marey among other crimes committed by the GAL, and with the aggravating circumstance that they had counted on the reserved funds of the Ministry of the Interior to carry out the attacks. The knowledge of this fact forced the Minister of the Interior José Barrionuevo to resign and he was replaced by José Luis Corcuera. The consolidation of the democratic system included the development of the rights and freedoms recognized in the Constitution of 1978.
Sources: en.wikipedia.org
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
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.