The short version of tuftsin fits in a sentence. The long version — which is the one that helps — is below.
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Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
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.
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.
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.
CP, Crude protein; NRC MR, National Research Council Minimal Requirement; NR, not required (taurine not an essential amino acid in the dog); NA, not adequate sample for analysis Amino acids measured on a mg/g DM basis The results demonstrated that all evaluated insects met the canine and feline MR for growth of the NRC for EAA and CP with exception to the black soldier fly in regards to taurine, where composition was lower than recommended.
=== Histology === Histological structure of type 1 consists of tight tissue fibers and loose connective tissues. The surrounding loose fibers are rich in blood vessels with pathways for nerves. Tendinous fibers are rarely found and are in single direction. Type 2 juncturae tendinum is also composed of single direction fibers like type 1, but with thicker bundles. Histological structure of the type 3 juncturae is denser and thicker than type 2 juncturae and tendinous fibers are arranged in two layers. Tendinous fibers of the type 3 show crosswise direction with single direction and oblique bundles. No muscular tissue is observed in any type of the juncturae tendinum.
=== Water vapor capture and dehumidification === Some MOFs can capture water vapor from ambient air. In 2021 under humid conditions, a polymer-MOF lab prototype yielded 17 liters (4.5 gal) of water per kg per day without added energy. MOFs can be used to increase energy efficiency in room temperature space cooling applications.
== Background == The PDCAAS value is different from measuring the quality of protein from the protein efficiency ratio (PER) and the biological value (BV) methods. The PER was based upon the amino acid requirements of growing rats, which differ significantly from those of humans. The PDCAAS allows evaluation of food protein quality based on the needs of humans as it measures the quality of a protein based on the amino acid requirements (adjusted for digestibility) of a 2- to 5-year-old child (considered the most nutritionally demanding age group). The BV method uses nitrogen absorption as a basis. However, it does not take into account certain factors influencing the digestion of the protein and is of limited use for application to human protein requirements because what is measured is maximal potential of quality and not a true estimate of quality at requirement level. Nevertheless, BV can be used to assess requirements of protein derived from foods with known quality differences and measure the proportion of absorbed nitrogen which is retained and presumably used for protein synthesis as an accurate indicator for protein measurement. The FDA gave two reasons for adopting the PDCAAS in 1993: 1) PDCAAS is based on human amino acid requirements, which makes it more appropriate for humans than a method based on the amino acid needs of animals. 2) The Food and Agricultural Organization/World Health Organization (FAO/WHO) had previously recommended PDCAAS for regulatory purposes.
Sources: en.wikipedia.org
=== Distribution === Ibutilide has a relatively large volume of distribution among individual subjects, which is about 11L/kg. Approximately 40% of the drug is bound with plasma albumin of healthy volunteers in a trial. This is also approximately close to patients with atrial fibrillation and flutter.
The 1st Special Forces Group is responsible for operations in the Pacific. Currently, the First Battalion is stationed at Okinawa while the 2nd, 3rd, 4th, and Group Support Battalions are stationed at Joint Base Lewis-McChord, Washington. 1st Special Forces Group's history began at Fort Bragg, NC, in 1955. Four Special Forces Operational Detachments - the 12th, 13th, 14th, and 16th - were selected from the 77th Special Forces Group and transferred to the Pacific theater over the next year. 1st Special Forces Group was officially activated at Fort Buckner, Okinawa, on 24 June 1957, with LTC A. Scott Madding as commander and MSG Robert L. Voss as the sergeant major. The 1st Special Forces Group holds the distinction of having the first and last Special Forces soldiers killed in Vietnam: Captain Harry Cramer killed 21 October 1957, and Captain Richard M. Rees killed 15 December 1973. Decades later, another 1st Special Forces Group soldier became the first American to die by hostile fire in Afghanistan: Sergeant First Class Nathan Chapman killed 2 January 2002. The 1st Special Forces Group on Okinawa was one of two Special Action Forces/Security Assistance Forces (SAF) built around Special Forces Groups. The other was built around the 8th Special Forces Group in Panama. SAF Asia was flexible and 1st Group could task organize a detachment for any time of mission in the Pacific rim. During the Vietnam War, it sent teams to Vietnam for six-month temporary duty.
=== Harm assessment === Professor David Nutt, former chair of the Advisory Council on the Misuse of Drugs (ACMD) in the UK has said in 2009, "people are better off taking ecstasy or amphetamines than those [drugs] we know nothing about" and "Who knows what's in [mephedrone] when you buy it? We don't have a testing system. It could be very dangerous[;] we just don't know. These chemicals have never been put into animals, let alone humans." Les King, a former member of the ACMD, has stated mephedrone appears to be less potent than amphetamine and ecstasy, but that any benefit associated with this could be negated by users taking larger amounts. He also told the BBC, "all we can say is [mephedrone] is probably as harmful as ecstasy and amphetamines and wait until we have some better scientific evidence to support that."
=== Chemical === Darmstadtium is the eighth member of the 6d series of transition metals, and should be much like the platinum group metals. Calculations on its ionization potentials and atomic and ionic radii are similar to that of its lighter homologue platinum, thus implying that darmstadtium's basic properties will resemble those of the other group 10 elements, nickel, palladium, and platinum. Prediction of the probable chemical properties of darmstadtium has not received much attention recently. Darmstadtium should be a very noble metal. The predicted standard reduction potential for the Ds2+/Ds couple is 1.7 V. Based on the most stable oxidation states of the lighter group 10 elements, the most stable oxidation states of darmstadtium are predicted to be the +6, +4, and +2 states; however, the neutral state is predicted to be the most stable in aqueous solutions. In comparison, only platinum is known to show the maximum oxidation state in the group, +6, while the most stable state is +2 for both nickel and palladium. It is further expected that the maximum oxidation states of elements from bohrium (element 107) to darmstadtium (element 110) may be stable in the gas phase but not in aqueous solution. Darmstadtium hexafluoride (DsF6) is predicted to have very similar properties to its lighter homologue platinum hexafluoride (PtF6), having very similar electronic structures and ionization potentials. It is also expected to have the same octahedral molecular geometry as PtF6.
Proprotein convertases (PPCs) are a family of proteins that activate other proteins. Many proteins are inactive when they are first synthesized, because they contain chains of amino acids that block their activity. Proprotein convertases remove those chains and activate the protein. The prototypical proprotein convertase is furin. Proprotein convertases have medical significance, because they are involved in many important biological processes, such as cholesterol synthesis. Compounds called proprotein convertase inhibitors can block their action, and block the target proteins from becoming active. Many proprotein convertases, especially furin and PACE4, are involved in pathological processes such as viral infection, inflammation, hypercholesterolemia, and cancer, and have been postulated as therapeutic targets for some of these diseases.
Sources: en.wikipedia.org
== Release details == 1907, France, L'illustration, Pub September–November 1907, magazine serial (in French) 1908, France, Editions Jacques Lafitte (ISBN NA), (First edition) (in French) 1934, UK, Oxford University Press ISBN 0-19-832345-X, (in French) 1977, UK, Dover Publications ISBN 0-486-23460-6 1978, UK, Remploy ISBN 0-7066-0759-7 1996, US, Books on Tape ISBN 5-557-12771-2 1996, US, Buccaneer Books ISBN 0-89966-141-6 1997, UK, Dedalus Ltd ISBN 1-873982-38-0 2002, US, Indypublish.com ISBN 1-4043-2003-2 2002, US, Indypublish.com ISBN 1-4043-2002-4 2004, UK, Thorndike Press ISBN 0-7862-6991-X 2005, US, Kessinger Publishing ISBN 0-7661-9366-7 2006, UK, Blackstone Audiobooks ISBN 0-7861-7523-0, audio book (MP3 CD) 2006, UK, Dover Publications ISBN 0-486-44928-9 2009, US, Black Coat Press ISBN 1-934543-60-8
2,4-Dinitrochlorobenzene (DNCB) is an organic compound with the chemical formula (O2N)2C6H3Cl. It is a yellow solid that is soluble in organic solvents. It is an intermediate for the industrial production of other compounds.
Hydroxyl radicals are highly reactive and undergo chemical reactions that make them short-lived. When biological systems are exposed to hydroxyl radicals, they can cause damage to cells, including those in humans, where they can react with DNA, lipids, and proteins.
Initially, pyruvate and thiamine pyrophosphate (TPP or vitamin B1) are bound by pyruvate dehydrogenase subunits. The thiazolium ring of TPP is in a zwitterionic form, and the anionic C2 carbon performs a nucleophilic attack on the C2 (ketone) carbonyl of pyruvate. The resulting intermediate undergoes decarboxylation to produce an acyl anion equivalent (see cyanohydrin or aldehyde-dithiane umpolung chemistry, as well as benzoin condensation). This anion attacks S1 of an oxidized lipoate species that is attached to a lysine residue. In a ring-opening SN2-like mechanism, S2 is displaced as a sulfide or sulfhydryl moiety. Subsequent collapse of the tetrahedral intermediate ejects thiazole, releasing the TPP cofactor and generating a thioacetate on S1 of lipoate. The E1-catalyzed process is the rate-limiting step of the whole pyruvate dehydrogenase complex.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
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.