Tuftsin analogue 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 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
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.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
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.
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.
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.
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.
=== Pharmacokinetics === The percentage of ribociclib absorbed in the gut has not been determined. Highest blood plasma levels are reached after one to four hours; and after repeated dosage, steady state concentrations are reached after about eight days. Food intake has no effect on absorption rates. When in the bloodstream, about 70% of ribociclib is bound to plasma proteins. The substance is mainly metabolized by CYP3A4 and subsequently by various phase II enzymes, resulting in a large number of metabolites. Those with highest blood plasma concentrations in humans are called CCI284 (an unspecified N-hydroxylation product), LEQ803 (the N-demethylation product) and M1 (a glucuronide). All metabolites have negligible clinical activity. Ribociclib has a slight tendency to accumulate in the body. It is eliminated with an average biological half-life of 32 hours, mostly (69%) via the feces, but also (23%) via the urine. The unchanged drug accounts for 17% of the substance in the feces and 12% of the substance in the urine, the rest being metabolites.
Some sources say that the El Niños of 2006-07 and 2014-16 were also Central Pacific El Niños. Recent years when La Niña Modoki events occurred include 1973–1974, 1975–1976, 1983–1984, 1988–1989, 1998–1999, 2000–2001, 2008–2009, 2010–2011, and 2016–2017. The recent discovery of ENSO Modoki has some scientists believing it to be linked to global warming. However, comprehensive satellite data go back only to 1979. More research must be done to find the correlation and study past El Niño episodes. More generally, there is no scientific consensus on how/if climate change might affect ENSO. There is also a scientific debate on the very existence of this "new" ENSO. A number of studies dispute the reality of this statistical distinction or its increasing occurrence, or both, either arguing the reliable record is too short to detect such a distinction, finding no distinction or trend using other statistical approaches, or that other types should be distinguished, such as standard and extreme ENSO. Likewise, following the asymmetric nature of the warm and cold phases of ENSO, some studies could not identify similar variations for La Niña, both in observations and in the climate models, but some sources could identify variations on La Niña with cooler waters on central Pacific and average or warmer water temperatures on both eastern and western Pacific, also showing eastern Pacific Ocean currents going to the opposite direction compared to the currents in traditional La Niñas.
This involves electron capture or positron decay of potassium-40 to argon-40. Potassium-40 has a half-life of 1.3 billion years, so this method is applicable to the oldest rocks. Radioactive potassium-40 is common in micas, feldspars, and hornblendes, though the closure temperature is fairly low in these materials, about 350 °C (mica) to 500 °C (hornblende).
=== Extraction === Bovine lactoferrin can be isolated from raw milk, colostrum, or whey using methods such as salt extraction, chromatography, and membrane filtration. Lactoferrin from a variety of species, including humans, can also be produced using transgenic organisms as a recombinant protein.
== Definition == A variety of definitions have been proposed throughout the years, but the simplest and most recent definition of fermentation proposed is "catabolism where organic compounds are both the electron donor and acceptor." This definition distinguishes fermentation from aerobic respiration (when oxygen is the acceptor) and types of anaerobic respiration (when an inorganic species is the acceptor). However, this definition does not encompass all forms of fermentation. For example, propionate fermentation which uses H2 as an electron donor, or the second step of butyrate fermentation where CO2 can act as an electron acceptor. Thus, it is simplest to use this definition while acknowledging that protons can also be used as electron donors and CO2 as acceptors. In 1876, before the discovery of anaerobic respiration, Louis Pasteur described it as "la vie sans air" (life without air). It was also common for fermentation to be defined based on how fermentation forms ATP which was catabolism that forms ATP through only substrate-level phosphorylation. Industrial fermentation is another type of fermentation that is defined loosely as a large-scale biological manufacturing process; however, this definition focuses on the process of manufacturing rather than metabolic details.
Sources: en.wikipedia.org
=== 2012 === On February 23, 2012, NHK announced that with Shizuoka University they had developed an 8K sensor that can shoot video at 120 fps. In April 2012, Panasonic, in collaboration with NHK announced a 145 inches (370 cm) display (7680 × 4320 at 60 fps), which has 33.2 million 0.417 mm square pixels. In April 2012, the four major South Korean terrestrial broadcasters (KBS, MBC, SBS, and EBS) announced that in the future, they would begin test broadcasts of UHDTV on channel 66 in Seoul. At the time of the announcement, the UHDTV technical details had not yet been decided. LG Electronics and Samsung are also involved in UHDTV test broadcasts. In May 2012, NHK showed the world's first ultra-high-definition shoulder-mount camera. By reducing the size and weight of the camera, the portability had been improved, making it more maneuverable than previous prototypes, so it could be used in a wide variety of shooting situations. The single-chip sensor uses a Bayer color-filter array, where only one color component is acquired per pixel. Researchers at NHK also developed a high-quality up-converter, which estimates the other two color components to convert the output into full resolution video. Also in May 2012, NHK showed the ultra-high-definition imaging system it has developed in conjunction with Shizuoka University, which outputs 33.2-megapixel video at 120 fps with a color depth of 12 bits per component.
== Science and technology == Process capability index (Cpk), a measure of process capability CPK coloring, a way to color atoms when visualizing molecular models Creatine phosphokinase, an enzyme found in humans, or alternatively a blood test for it
==== Protection from UV radiation ==== Ultraviolet UV-A and UV-B radiation is harmful to living systems. An important tool used to deal with UV exposure is the biosynthesis of small-molecule sunscreens. MAAs have been implicated in UV radiation protection. The genetic basis for this implication comes from the observed induction of MAA synthesis when organisms are exposed to UV radiation. This has been observed in aquatic yeasts, cyanobacteria, marine dinoflagellates and some Antarctic diatoms. MAAs have also been identified in 572 species of other algae : 45 species in Chlorophyta, 41 species in Phaeophyta, 486 species in Rhodophyta which also present anti-aging, anti-inflammatory, antioxidative and wound healing properties. When MAAs absorb UV light the energy is dissipated as heat. UV-B photoreceptors have been identified in cyanobacteria as the molecules responsible for the UV light induced responses, including synthesis of MAAs. Helioguard™365 containing Porphyra-334 and shinorine derived from Porphyra umbilicalis is already a creme on the market were developed by Mibelle AG biochemistry and shows preventive effects against UVA. An MAA known as palythine, derived from seaweed, has been found to protect human skin cells from UV radiation even in low concentrations. "MAAs, in addition to their environmental benefits, appear to be multifunctional photoprotective compounds," says Dr. Karl Lawrence, lead author of a paper on the research. "They work through the direct absorption of UVR [ultraviolet radiation] photons, much like the synthetic filters.
To overcome this effect, a new index was created, named the Equatorial Southern Oscillation Index (EQSOI). To generate this index, two new regions, centered on the Equator, were defined. The western region is located over Indonesia and the eastern one over the equatorial Pacific, close to the South American coast. However, data on EQSOI goes back only to 1949. Sea surface height (SSH) changes up or down by several centimeters in Pacific equatorial region with the ENSO: El Niño causes a positive SSH anomaly (raised sea level) because of thermal expansion while La Niña causes a negative SSH anomaly (lowered sea level) via contraction.
Ansuvimab is a monoclonal antibody therapy that is infused intravenously into people with Ebola virus disease. Ansuvimab is a neutralizing antibody, meaning it binds to a protein on the surface of Ebola virus that is required to infect cells. Specifically, ansuvimab neutralizes infection by binding to a region of the Ebola virus envelope glycoprotein that, in the absence of ansuvimab, would interact with virus's cell receptor protein, Niemann-Pick C1 (NPC1). This "competition" by ansuvimab prevents Ebola virus from binding to NPC1 and "neutralizes" the virus's ability to infect the targeted cell.
Sources: en.wikipedia.org
Methods have been developed to purify DNA from organisms, such as phenol-chloroform extraction, and to manipulate it in the laboratory, such as restriction digests and the polymerase chain reaction. Modern biology and biochemistry make intensive use of these techniques in recombinant DNA technology. Recombinant DNA is a man-made DNA sequence that has been assembled from other DNA sequences. They can be transformed into organisms in the form of plasmids or in the appropriate format, by using a viral vector. The genetically modified organisms produced can be used to produce products such as recombinant proteins, used in medical research, or be grown in agriculture.
Serum, suspected to contain IgE antibodies, is drawn from the allergic (atopic) patient. This serum is injected intradermally into a non-allergic person. The suspected antigens are then intradermally injected into the non-allergic person 24–48 hours later. If the person being tested for an allergy has made antibodies for the antigen, this will cause a local reaction in the non-allergic person when the antibodies mix with the antigen. This demonstrates a type I hypersensitivity reaction, and the allergic reaction to the injected antigen is confirmed for the patient being tested. A positive PK test usually appears as a wheal and flare. The test was developed by Otto Prausnitz and Heinz Küstner. The first PK test occurred in 1921 when Prausnitz injected Küstner's serum into his abdominal skin. Küstner had previously noted that he developed allergic symptoms after eating fish. After eating some fish, Prausnitz's skin became hot, red, and swollen at the site of the serum injection, confirming their hypothesis that Küstner was allergic to fish.
== Boron-8 == Boron-8 is an isotope of boron that undergoes β+ decay to beryllium-8 with a half-life of 771.9(9) ms. It is the strongest candidate for a halo nucleus with a loosely-bound proton, in contrast to neutron halo nuclei such as lithium-11. Although boron-8 beta decay neutrinos from the Sun make up only about 80 ppm of the total solar neutrino flux, they have a higher energy centered around 10 MeV, and are an important background to dark matter direct detection experiments. They are the first component of the neutrino floor that dark matter direct detection experiments are expected to eventually encounter.
== Comparison == The following table compares some common anti-diabetic agents, generalizing classes, although there may be substantial variation in individual drugs of each class. When the table makes a comparison such as "lower risk" or "more convenient" the comparison is with the other drugs on the table.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
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.