The short version of Tuftsin fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-05-25. Anything still debated is marked as such rather than presented as settled.
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.
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 |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
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.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
== Absorption, metabolism and excretion == When found in foods, most pantothenic acid is in the form of CoA or bound to acyl carrier protein (ACP). For the intestinal cells to absorb this vitamin, it must be converted into free pantothenic acid. Within the lumen of the intestine, CoA and ACP are hydrolyzed into 4'-phosphopantetheine. The 4'-phosphopantetheine is then dephosphorylated into pantetheine. Pantetheinase, an intestinal enzyme, then hydrolyzes pantetheine into free pantothenic acid. Free pantothenic acid is absorbed into intestinal cells via a saturable, sodium-dependent active transport system. At high levels of intake, when this mechanism is saturated, some pantothenic acid may also be additionally absorbed via passive diffusion. As a whole, when intake increases 10-fold, absorption rate decreases to 10%. Pantothenic acid is excreted in urine. This occurs after its release from CoA. Urinary amounts are on the order of 2.6 mg/day, but decreased to negligible amounts when subjects in multi-week experimental situations were fed diets devoid of the vitamin. Mutation of pantothenate kinase (the first enzyme in the pathway converting pantothenic acid to CoA) is the cause of pantothenate kinase associated neurodegeneration (PKAN), a rare neurodegenerative disease.
In plants, light-dependent reactions occur in the thylakoid membranes of the chloroplasts where they drive the synthesis of ATP and NADPH. The light-dependent reactions are of two forms: cyclic and non-cyclic. In the non-cyclic reaction, the photons are captured in the light-harvesting antenna complexes of photosystem II by chlorophyll and other accessory pigments (see diagram "Z-scheme"). The absorption of a photon by the antenna complex loosens an electron by a process called photoinduced charge separation. The antenna system is at the core of the chlorophyll molecule of the photosystem II reaction center. That loosened electron is taken up by the primary electron-acceptor molecule, pheophytin. As the electrons are shuttled through an electron transport chain (the so-called Z-scheme shown in the diagram), a chemiosmotic potential is generated by pumping proton cations (H+) across the membrane and into the thylakoid space. An ATP synthase enzyme uses that chemiosmotic potential to make ATP during photophosphorylation, whereas NADPH is a product of the terminal redox reaction in the Z-scheme. The electron enters a chlorophyll molecule in Photosystem I. There it is further excited by the light absorbed by that photosystem. The electron is then passed along a chain of electron acceptors to which it transfers some of its energy. The energy delivered to the electron acceptors is used to move hydrogen ions across the thylakoid membrane into the lumen.
== Research == Paul Kaesberg's research had major impacts on the fields of biochemistry and virology. Some of his most influential research involved bacteriophage morphology, mosaic viruses, and X-ray scattering.
Sources: en.wikipedia.org
Ion exchangers can have binding preferences for certain ions or classes of ions, depending on the physical properties and chemical structure of both the ion exchanger and ion. This can be dependent on the size, charge, or structure of the ions. Common examples of ions that can bind to ion exchangers are:
cyclin family proteins: Cyclin D, Cyclin E transcriptional regulators: Myc, E2f1, p130 cyclin-dependent kinase inhibitors (CKIs): p27Kip1, p21, Wee1 centriole proteins: Cep250, Ninein There are approximately seventy human FBPs, several of which are involved in cell cycle control as a component of SCF complexes. Skp2 is an FBP that binds CKIs such as p27Kip1 and p21. Skp2 binds p27Kip1 only when two conditions are met: p27Kip1 is phosphorylated by E/A/CKD2 and bound to Cks1. As a consequence of binding Skp2, p27Kip1 is ubiquitinated and targeted for degradation in late G1 and early S. SCF-Skp2 also targets p130 for degradation in a phosphorylation dependent manner. Beta-transducin repeat-containing protein (βTRCP) is an FBP that targets emi1—an APC/C-Cdh1 inhibitor—and wee1 for degradation during early mitosis. βTRCP recognizes these substrates after they are phosphorylated by Polo-like kinase 1 or Cyclin B-CDK1. Fbw7, which is the human homolog of cdc4 in yeast, is an FBP that targets Cyclin E, Myc, Notch and c-Jun for degradation. Fbw7 is stable throughout the cell cycle and is localized to the nucleus due to the presence of a nuclear localization sequence (NLS). SCF-Fbw7 targets Sic1—when at least six out of nine possible sites are phosphorylated—and Swi5 for degradation. Since Sic1 normally prevents premature entry into S-phase by inhibiting Cyclin B-CDK1, targeting Sic1 for degradation promotes S-phase entry.
Starting the next row, for potassium and calcium the 4s subshell is the lowest in energy, and therefore it fills next. Potassium adds one electron to the 4s shell ([Ar] 4s1), and calcium then completes it ([Ar] 4s2). However, starting from scandium ([Ar] 3d1 4s2) the 3d subshell becomes the next highest in energy. The 4s and 3d subshells have approximately the same energy and they compete for filling the electrons, and so the occupation is not quite consistently filling the 3d orbitals one at a time. The precise energy ordering of 3d and 4s changes along the row, and also changes depending on how many electrons are removed from the atom. For example, due to the repulsion between the 3d electrons and the 4s ones, at chromium the 4s energy level becomes slightly higher than 3d, and so it becomes more profitable for a chromium atom to have a [Ar] 3d5 4s1 configuration than an [Ar] 3d4 4s2 one. A similar anomaly occurs at copper, whose atom has a [Ar] 3d10 4s1 configuration rather than the expected [Ar] 3d9 4s2. These are violations of the Madelung rule. Such anomalies, however, do not have any chemical significance: most chemistry is not about isolated gaseous atoms, and the various configurations are so close in energy to each other that the presence of a nearby atom can shift the balance. Therefore, the periodic table ignores them and considers only idealized configurations. At zinc ([Ar] 3d10 4s2), the 3d orbitals are completely filled with a total of ten electrons.
In more recent years, CT scanning has become an invaluable tool in the study of mummification by allowing researchers to digitally "unwrap" mummies without risking damage to the body. The level of detail in such scans is so intricate that small linens used in tiny areas such as the nostrils can be digitally reconstructed in 3-D. Such modelling has been utilized to perform digital autopsies on mummies to determine the cause of death and lifestyle, such as in the case of Tutankhamun.
Sources: en.wikipedia.org
=== PIP1 and PIP2 === The 3-D structures of the open and closed forms of plant aquaporins, PIP1 and PIP2, have been solved (PDB: 4JC6). In the closed conformation, loop D caps the channel from the cytoplasm and thereby occludes the pore. In the open conformation, loop D is displaced up to 16 Å, and this movement opens a hydrophobic gate blocking the channel entrance from the cytoplasm. These results reveal a molecular gating mechanism which appears conserved throughout all plant plasma membrane aquaporins. In plants it regulates water intake/export in response to water availability and cytoplasmic pH during anoxia.
=== Switching political parties === In the 2004 election, Kennedy endorsed Democratic presidential nominee John Kerry over George W. Bush. After being courted by the Republican Party for months, Kennedy declared in a letter to his constituents that he was leaving the Democratic Party and joining the Republicans, effective August 27, 2007. In his letter, he stated that he would run again for state treasurer later that year.
=== General and cited references === Chinn, George M., ed. (1987). The Machine Gun: History, Evolution, and Development of Manual, Automatic, and Airborne Repeating Weapons (PDF). Vol. V. Ann Arbor, Michigan: Edward Brothers Publishing Co. Retrieved 28 April 2019.
=== Portal hypertension === The portal vein also known as the hepatic portal vein carries blood drained from most of the gastrointestinal tract to the liver. Portal hypertension is mainly caused by cirrhosis of the liver. Other causes can include an obstructing clot in a hepatic vein (Budd Chiari syndrome) or compression from tumors or tuberculosis lesions. When the pressure increases in the portal vein, a collateral circulation develops, causing visible veins such as esophageal varices.
Resveratrol and related polyphenols (usually as "grape seed extract") are often included. Yohimbine has also been used as an ingredient (often as Pausinystalia johimbe extract), as a supposed testosterone booster and fat-loss agent, but it has been associated with dangerous side effects, and is also a prescription medicine in many countries. Phenylpiracetam is also sometimes used as an ingredient for its nootropic and stimulant effects. Capsaicin is sometimes used as an ingredient in gelcap pre-workout formulations, both as a supoosed weight loss aid and for improvement of endurance. Plant extracts, such as Ginkgo biloba, Panax ginseng, Rhodiola rosea and Huperzine A (from Huperzia serrata), are sometimes included for their supposed ability to improve endurance and mental clarity, despite limited evidence for efficacy. Ecdysteroids, such as ecdysterone and turkesterone, and other plant derived steroid like compounds such as 5α-Hydroxylaxogenin are sometimes used as ingredients, despite inconclusive results as to their supposed anabolic effects. Prohormones such as DHEA, CDMA, 1-androstenediol and 7α-methyl-19-norandrostenedione were widely used in pre-workout formulations prior to 2014 when they were formally banned. These compounds are not anabolic agents in their own right, but are metabolised into anabolic steroids of a type which at the time were not restricted.
Sources: en.wikipedia.org
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.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
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.