This is a working overview of mass spectrometry, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
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.
| Property | Value | Notes |
|---|---|---|
| Solubility | Freely soluble in water | Also in aqueous buffers |
| Typical purity (HPLC) | 95 percent or higher | Lot-dependent |
| Dry powder storage | Minus 20 degrees Celsius | Sealed, dry, protected from light |
| Solution storage | 2 to 8 degrees Celsius | Short-term use |
| Identity confirmation | Mass spectrometry | ESI or MALDI-TOF |
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.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
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.
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.
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.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Edgar Degas's 1876 painting The Absinthe Drinker or Glass of Absinthe (L'Absinthe) can be seen at the Musée d'Orsay epitomising the popular view of absinthe addicts as sodden and benumbed, and Émile Zola described its effects in his novel L'Assommoir. In 1905, Swiss farmer Jean Lanfray murdered his wife and two children and then attempted to kill himself after drinking absinthe. Lanfray had drunk a lot of wine and brandy before the killings, but that was overlooked or ignored, and blame for the murders was placed solely on his consumption of two glasses of absinthe. The Lanfray murders were the tipping point in this hotly debated topic, and a subsequent petition collected more than 82,000 signatures to ban it in Switzerland. A referendum was held on 5 July 1908. It was approved by voters, and the prohibition of absinthe was written into the Swiss constitution. In 1906, Belgium and Brazil banned the sale and distribution of absinthe although these were not the first countries to take such action. It had been banned as early as 1898 in the colony of the Congo Free State. The Netherlands banned it in 1909, Switzerland in 1910, the United States in 1912, and France in 1914. The prohibition of absinthe in France eventually led to the popularity of pastis, and to a lesser extent, ouzo, and other anise-flavoured spirits that do not contain wormwood.
The alpha and beta subunits share approximately 25% sequence similarity, whereas the similarity between beta subunits is approximately 65%. In mammals, four beta subunits have been described, called activin βA, activin βB, activin βC and activin βE. Activin βA and βB are identical to the two beta subunits of inhibin. A fifth subunit, activin βD, has been described in Xenopus laevis. Two activin βA subunits give rise to activin A, one βA, and one βB subunit gives rise to activin AB, and so on. Various, but not all theoretically possible, heterodimers have been described. The subunits are linked by a single covalent disulfide bond. The βC subunit is able to form activin heterodimers with βA or βB subunits but is unable to dimerize with inhibin α.
== Conformational change and inhibitory mechanism == Inhibitory serpins do not inhibit their target proteases by the typical competitive (lock-and-key) mechanism used by most small protease inhibitors (e.g. Kunitz-type inhibitors). Instead, serpins use an unusual conformational change, which disrupts the structure of the protease and prevents it from completing catalysis. The conformational change involves the RCL moving to the opposite end of the protein and inserting into β-sheet A, forming an extra antiparallel β-strand. This converts the serpin from a stressed state, to a lower-energy relaxed state (S to R transition). Serine and cysteine proteases catalyse peptide bond cleavage by a two-step process. Initially, the catalytic residue of the active site triad performs a nucleophilic attack on the peptide bond of the substrate. This releases the new N-terminus and forms a covalent ester-bond between the enzyme and the substrate. This covalent complex between enzyme and substrate is called an acyl-enzyme intermediate. For standard substrates, the ester bond is hydrolysed and the new C-terminus is released to complete catalysis. However, when a serpin is cleaved by a protease, it rapidly undergoes the S to R transition before the acyl-enzyme intermediate is hydrolysed. The efficiency of inhibition depends on fact that the relative kinetic rate of the conformational change is several orders of magnitude faster than hydrolysis by the protease.
Militias from the Cao Đài sect, which had initially joined the Viet Minh in their struggle against the return of the French, made a truce with France when their leader was captured on 6 June 1946. The Viet Minh later attacked the Cao Đài after open conflict had erupted with France, which led them to join the French side. The Viet Minh assassinated the Hòa Hảo leader Huỳnh Phú Sổ in April 1947. Vietnamese society also polarized along ethnic lines: the Nùng and Chinese Nùng minority assisted the French, while the Tày assisted the Việt Minh. The Khmer Krom also sided with France. Surviving Vietnamese nationalist partisans and politico-religious groups rallied behind the exiled Bảo Đại to reopen negotiations with France in opposition to communist domination. The State of Vietnam (SVN), with Bảo Đại as Chief of State, was established and positioned within the anticommunist Western Bloc. With the recognition of the DRV by China and the Soviet Union, and the recognition of the SVN by the United States in 1950, the civil war and the colonial war in Vietnam became internationalized and intertwined with the global Cold War.
Sources: en.wikipedia.org
=== Pharmacodynamics === Sarcosine acts as a competitive inhibitor of GlyT1, a glycine transporter that is predominantly expressed on glial cells and is responsible for the reuptake of glycine from the synaptic cleft in the central nervous system. By blocking GlyT1, sarcosine elevates the extracellular concentration of glycine in the vicinity of NMDA receptors, thereby augmenting NMDA receptor-mediated neurotransmission. In addition to its indirect enhancement of NMDA receptor function via GlyT1 blockade, sarcosine directly acts as a co-agonist at the glycine binding site (also termed the GluN1 site) of the NMDA receptor. It increases NMDA-mediated currents in a dose-dependent manner. Sarcosine differs from glycine as a co-agonist in that it produces markedly less NMDA receptor desensitization at subsaturating concentrations. At equivalent receptor occupancy (EC20 to EC50), sarcosine significantly slowed the rate of glycine-dependent desensitisation compared with glycine itself, whereas the rate of glycine-independent desensitisation was similar for both ligands. At concentrations higher than those required for GlyT1 inhibition or NMDA receptor co-agonism, sarcosine additionally activates strychnine-sensitive glycine receptors (GlyRs). It evokes a chloride current that is dose-dependent, inhibited by strychnine, and shows a lack of additivity with glycine. Sarcosine is less potent and efficacious than glycine at GlyRs, potentially due to steric constraints imposed by the N-methyl group within the glycine binding site on the receptor.
=== United States === One entrepreneur who was quick to spot the advantages of machine-made cigarettes was James Buchanan Duke. Previously a producer of smoking tobacco only, his firm, W. Duke & Sons & Co., entered the cigarette industry in the early 1880s. After installing two Bonsack machines, Duke spent heavily on advertising and sales promotion, and by 1889 his was the largest cigarette manufacturer in the country. The new Bonsack machines were of decisive importance in the rapid, cheap manufacture of all tobacco products but one. Cigars needed slow, laborious hand rolling and were produced in hundreds of small workshops, especially in New York City. In 1890 Duke and the other four major cigarette companies combined to form the American Tobacco Company, a firm that dominated the market and used aggressive tactics on hundreds of small competitors until they sold out to the firm. It was also called the "Tobacco Trust". The trust soon expanded its operations to include cigars, smoking, chewing tobacco and snuff. Among the companies drawn into this organization were the plug manufacturers Liggett & Myers and R. J. Reynolds Tobacco Company, which at the time produced twist and flat plug, and P. Lorillard, an old-line manufacturer of snuff. By 1910 the trust produced 86% of all cigarettes produced in the United States, and 75% to 95% of other forms, but only 14% of cigars produced in the country. At the start of the 20th century, the per capita annual consumption in the U.S.
=== Colorimetric biosensors === Biosensors are attached to a substance of interest. Normally, this substance would not be able to absorb light, but with the attached biosensor, light can be absorbed and emitted on a spectrophotometer. Additionally, biosensors that are fluorescent can be viewed with the naked eye. Some fluorescent biosensors also have the ability to change color in changing environments (ex: from blue to red). A researcher would be able to inspect and get data about the surrounding environment based on what color he or she could see visibly from the biosensor-molecule hybrid species. Colorimetric assays are normally used to determine how much concentration of one species there is relative to another.
Sources: en.wikipedia.org
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.
Freeze-dried material is kept frozen, often at minus 20 degrees Celsius, and protected from light and moisture. Dissolved peptide is refrigerated for short-term use. Repeated freeze-thaw cycles are avoided.
A certificate of analysis typically lists purity by HPLC, the confirmed mass, appearance, and sometimes water or counter-ion content. It documents results for a specific batch. Details vary by supplier.
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.