mass spectrometry raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-07-24 and is reviewed periodically as new material appears.
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.
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.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
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.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
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 sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
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.
==== Mechanism of action ==== Cannabinoid inhibits the activity of both cannabinoid receptor 1 (CBR1) and cannabinoid receptor 2 (CBR2), with a stronger inhibitory effect observed in the former. Cannabidiol also interacts with non-cannabinoid receptors, including serotonin 1A receptors. Yet, the mechanism of cannabinoid in controlling seizures is not clearly established.
The UGR comes in two menu variations: breakfast and lunch/dinner. Menus are intended to be cycled through regularly. They include both standard American cuisine and diverse cuisines. The UGR-E also has a unique holiday menu variant. UGR modules come with mandatory and optional meal supplements—namely UHT milk, cereal, bread, fruits, vegetables, salads, drink mixes, and condiments—as well as eating utensils, kitchen utensils, disposable mess trays, cups, napkins, and trash bags.
Microcapsules that respond to magnetic and photo stimuli, such as these constructed of graphene oxide, are useful for biomedical applications that require in vivo, contact-free manipulation of cellular structures such as stem cells.
Light Source Spectra at the Wayback Machine (archived 2025-05-28) 60 W–100 W Incandescent light bulb spectra, from Cornell University Program of Computer Graphics Slow-motion video of an incandescent lightbulb filament Ribbon machine in operation at Osram-Sylvania in 2016
Sources: en.wikipedia.org
costs in 2016 were substantially higher than other OECD countries, at 17.2% GDP versus 12.4% GDP for the next most expensive country (Switzerland). For scale, a 5% GDP difference represents about $1 trillion or $3,000 per person. Some of the many reasons cited for the cost differential with other countries include: Higher administrative costs of a private system with multiple payment processes; higher costs for the same products and services; more expensive volume/mix of services with higher usage of more expensive specialists; aggressive treatment of very sick elderly versus palliative care; less use of government intervention in pricing; and higher income levels driving greater demand for healthcare. Healthcare costs are a fundamental driver of health insurance costs, which leads to coverage affordability challenges for millions of families. There is ongoing debate whether the current law (ACA/Obamacare) and the Republican alternatives (AHCA and BCRA) do enough to address the cost challenge.
== See also == 25-NB, BOx, HOT-x, scaline, 3C, DOx, 4C, Ψ-PEA, FLY, TWEETIO List of miscellaneous serotonin 5-HT2A receptor agonists The Shulgin Index Substituted amphetamines Substituted methoxyphenethylamine Substituted methylenedioxyphenethylamines Substituted phenethylamines Substituted tryptamines
The Infantry Regiment Großdeutschland was activated on 14 June 1939 and was still in training when World War II in Europe began with the German invasion of Poland on 1 September. The regiment first saw action in the May-June 1940 Battle of France, and took part in the invasion of Yugoslavia in April 1941. It was attached to Panzer Group 2 in the opening phases of Operation Barbarossa – the invasion of the Soviet Union – and was nearly destroyed in the Battle of Moscow in late 1941. On the last day of February 1942, the remnants of the regiment absorbed two battalions of reinforcements that arrived from Neuruppin and the regiment was reconstituted. It later moved to Orel (now Oryol), and on 1 April 1942 the former Infantry Regiment Großdeutschland was reinforced and expanded into the Infanterie-Division Großdeutschland (mot.) (motorized Infantry Division Grossdeutschland) using newly arrived troops from Germany.
Sources: en.wikipedia.org
=== General Features === Recently emerged de novo genes differ from established genes in a number of ways. Across a broad range of species, young and/or taxonomically restricted genes have been reported to be shorter in length than established genes, more positively charged, faster evolving, and to be less expressed. Although these trends could be a result of homology detection bias, a reanalysis of several studies that accounted for this bias found that the qualitative conclusions reached were unaffected. Another feature includes the tendency for young genes to have their hydrophobic amino acids more clustered near one another along the primary sequence. The expression of young genes has also been found to be more tissue- or condition-specific than that of established genes. In particular, relatively high expression of de novo genes was observed in male reproductive tissues in Drosophila, stickleback, mice, and humans, and, in the human brain. In animals with adaptive immune systems, higher expression in the brain and testes may be a function of the immune-privileged nature of these tissues. An analysis in mice found specific expression of intergenic transcripts in the thymus and spleen (in addition to the brain and testes). It has been proposed that in vertebrates de novo transcripts must first be expressed in tissues lacking immune cells before they can be expressed in tissues that have immune surveillance.
It is revealed at the 1991 Thanksgiving dinner episode that the absent Al has had a mistress for over 20 years, for which Bev eventually divorces him. Around this time Roseanne Barr was in a public battle with her real-life parents, claiming that both had physically and sexually abused her. Barr insisted that parental abuse be incorporated into the series storyline, so it is revealed that her father was physically abusive to both her and Jackie, who lived in fear of him for most of their childhood. Upon his death, Roseanne meets with his mistress, Joan, who is unaware of Al's abusive behavior, as he had led her to believe that Roseanne and Jackie were ungrateful daughters despite his doing so much for them. At Al's funeral, after privately reading him a list of the things she hates him doing to her and Jackie, Roseanne thanks her father for giving her his humorous nature.
These non-peptide inhibitors can be more stable than inhibitors containing peptide bonds, because they will not be substrates for peptidases and are less likely to be degraded. In drug design it is important to consider the concentrations of substrates to which the target enzymes are exposed. For example, some protein kinase inhibitors have chemical structures that are similar to ATP, one of the substrates of these enzymes. However, drugs that are simple competitive inhibitors will have to compete with the high concentrations of ATP in the cell. Protein kinases can also be inhibited by competition at the binding sites where the kinases interact with their substrate proteins, and most proteins are present inside cells at concentrations much lower than the concentration of ATP. As a consequence, if two protein kinase inhibitors both bind in the active site with similar affinity, but only one has to compete with ATP, then the competitive inhibitor at the protein-binding site will inhibit the enzyme more effectively.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.