If you have been reading about mass spectrometry and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-05-31. Where a claim depends on a specific study, the study is described rather than over-claimed.
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 |
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.
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.
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.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
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.
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.
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.
The company laid off an unspecified number of staffers in March 2005, although Kudirka denied rumors that the company was closing. He soon dissolved 2015 and moved to Florida, returning to Tulsa when he realized he wanted to continue working on video games. Konami Digital Entertainment released Time Ace, developed under the Trainwreck Studios name, in June 2007. On September 24, 2008, Kudirka announced that 2015 had received "several million dollars" in funding from private investors, with which it opened another division, Tornado Studios. The new studio started out with two people, including Kudirka, and sought to make casual games, including for the Wii. At the same time, 2015 was to continue making action games. By March 2009, Tornado Studios had 15 employees and was nearing the release of its first game, Powerbike, through Majesco. The game was released in April under the Trainwreck Studios name. Its first game was Project Runway, initially called World of Fashion until Atari signed to publish it and licensed the series's name. It was released in March 2010. In November, Tornado Studios released Fun with Death for iOS devices. Kudirka said that the rise of digital distribution allowed Tornado Studios to self-publish its games, aiming to release as many games as possible. A third game, Anomaly for personal computers and for the PlayStation 3 via PlayStation Network, was two-thirds-complete by this time and scheduled to be released by April 1, 2011. Tornado Studios had 25 employees, including contractors, at this time.
The Trump administration took the unusual step of subjecting approximately 50 members of the US military's Joint Chiefs of Staff to polygraph tests over leaks to journalists, including information about how the war has resulted in a shortage of critical munitions. Early attacks on US bases caused logistics issues in US aircraft carrier USS Abraham Lincoln. The Pentagon has transferred weapons stored in Asia and Europe to replenish stockpiles in the Middle East. Still, missile interceptors shortage reportedly persuaded Trump to call off a planned major attack on Iran. The Trump administration blames the shortage on Joe Biden giving too many weapons to Ukraine. On 17 September, Lockheed Martin received the first batch of Patriot interceptor parts from General Motors less than a month after the two companies signed a manufacturing agreement, in a success for the Pentagon's push for faster weapon production, particularly the Patriot missile defense system, as it remained one of the world's most sought-after weapons for the war and Russia's war in Ukraine.
=== Water footprint === One ton of hide or skin generally produces 20 to 80 m3 of waste water, including chromium levels of 100–400 mg/L, sulfide levels of 200–800 mg/L, high levels of fat and other solid wastes, and notable pathogen contamination. Producers often add pesticides to protect hides during transport. With solid wastes representing up to 70% of the wet weight of the original hides, the tanning process represents a considerable strain on water treatment installations.
In situations where the partial pressure of oxygen in the water is low, diffusion of oxygen into the blood is reduced, Henry's law can explain this phenomenon. The law states that at equilibrium, the partial pressure of oxygen in water will be equal to that in air; but the concentrations will differ due to the differing solubility. This law explains why O. vulgaris has to alter the amount of water cycled through its mantle cavity as the oxygen concentration in water changes. The gills are in direct contact with water – carrying more oxygen than the blood – that has been brought into the mantle cavity of the octopus. Gill capillaries are quite small and abundant, which creates an increased surface area that water can come into contact with, thus resulting in enhanced diffusion of oxygen into the blood. Some evidence indicates that lamellae and vessels within the lamellae on the gills contract to aid in propelling blood through the capillaries.
Sources: en.wikipedia.org
== History == As part of their adaptation from marine life, terrestrial plants began producing non-marine antioxidants such as ascorbic acid (vitamin C), polyphenols, and tocopherols. The evolution of angiosperm plants between 50 and 200 million years ago resulted in the development of many antioxidant pigments – particularly during the Jurassic period – as chemical defences against reactive oxygen species (ROS) that are byproducts of photosynthesis. Originally, the term antioxidant specifically referred to a chemical that prevented the consumption of oxygen. In the late 19th and early 20th centuries, extensive study concentrated on the use of antioxidants in important industrial processes, such as the prevention of metal corrosion, the vulcanization of rubber, and the polymerization of fuels in the fouling of internal combustion engines. Early research on the role of antioxidants in biology focused on their use in preventing the oxidation of unsaturated fats, which is the cause of rancidity. Antioxidant activity could be measured simply by placing the fat in a closed container with oxygen and measuring the rate of oxygen consumption. However, it was the identification of vitamins C and E as antioxidants that revolutionized the field and led to the realization of the importance of antioxidants in the biochemistry of living organisms. The possible mechanisms of action of antioxidants were first explored when it was recognized that a substance with anti-oxidative activity is likely to be one that is itself readily oxidized.
=== Enlarged prostate === Physicians sometimes prescribe finasteride for the treatment of benign prostatic hyperplasia, informally known as an enlarged prostate. Finasteride may improve the symptoms associated with BPH such as difficulty urinating, getting up during the night to urinate, hesitation at the start and end of urination, and decreased urinary flow. The use of the drug showed significant sexual adverse effects such as erectile dysfunction and less sexual desire, in particular when obstructive symptoms due to an enlarged prostate were present.
=== Mutation === IDH1 mutations are heterozygous, typically involving an amino acid substitution in the active site of the enzyme in codon 132. These mutations are somatic, meaning they primarily occur in cells that can become cancerous, such as those in brain and bone tumors. The mutation results in a loss of normal enzymatic function and the abnormal production of 2-hydroxyglutarate (2-HG). It has been considered to take place due to a change in the binding site of the enzyme. 2-HG has been found to inhibit enzymatic function of many alpha-ketoglutarate dependent dioxygenases, including histone and DNA demethylases, causing widespread changes in histone and DNA methylation and potentially promoting tumorigenesis.
Total land sales amounted to around half the area of the state of Saxony-Anhalt. At the end of 2007, it still owned over 500,000 hectares (1,200,000 acres) of agricultural land and just under 100,000 hectares (250,000 acres) of forest land.
Buckwheat pancakes were a common food in American pioneer days. Buckwheat blinis form gluten-free Russian-style pancakes. Buckwheat is a permitted sustenance during fasting in several traditions. In India, on Hindu fasting days (Navaratri, Ekadashi, Janmashtami, Maha Shivaratri, etc.), fasting people in northern states of India eat foods made of buckwheat flour. Eating cereals such as wheat or rice is prohibited during such fasting days. While strict Hindus do not even drink water during their fast, others give up cereals and salt and instead eat non-cereal foods such as buckwheat (kuttu). In the Russian Orthodox tradition, it is eaten on the St. Philip fast. Buckwheat honey is dark, strong and aromatic. It is normally produced as a monofloral honey.
Sources: en.wikipedia.org
=== Chemical bonds === A fatty acid is characterized as either saturated or unsaturated based on the respective absence or presence of C=C double bonds in its backbone. If the molecule contains no double C=C bonds, it is said to be saturated; otherwise, it is unsaturated to some degree. The C=C double bond is rotationally rigid. If the hydrogen atoms bonded to each of the carbons in this double bond are on the same side, this is called cis, and leads to a bent molecular chain. If the two hydrogens are on opposite sides, this is called trans, and leads to a straight chain.
=== Acid-base reactions === Carboxylic acids react with bases to form carboxylate salts, in which the hydrogen of the hydroxyl (–OH) group is replaced with a metal cation. For example, acetic acid found in vinegar reacts with sodium bicarbonate (baking soda) to form sodium acetate, carbon dioxide, and water:
Since the war, the US has had a continued presence of 5,000 troops stationed in Saudi Arabia – a figure that rose to 10,000 during the 2003 conflict in Iraq. Operation Southern Watch enforced the no-fly zones over southern Iraq set up after 1991; oil exports through the Persian Gulf's shipping lanes were protected by the Bahrain-based US Fifth Fleet. Since Saudi Arabia houses Mecca and Medina, Islam's holiest sites, many Muslims were upset at the permanent military presence. The continued presence of U.S. troops in Saudi Arabia after the war was one of the stated motivations behind the 11 September terrorist attacks, the Khobar Towers bombing, and the date chosen for the 1998 US embassy bombings (7 August), which was eight years to the day that US troops were sent to Saudi Arabia. Osama bin Laden interpreted the Islamic prophet Muhammad as banning the "permanent presence of infidels in Arabia". In 1996, bin Laden issued a fatwa, calling for US troops to leave Saudi Arabia. In a December 1999 interview with Rahimullah Yusufzai, bin Laden said he felt that Americans were "too near to Mecca" and considered this a provocation to the entire Islamic world.
=== Crystallization === The structure of β-Amanitin was determined using X-ray crystallography. The crystallization and analysis were performed by Edward C. Kostansek and William H. Lipscomb in 1978. They crystallized β-Amanitin by dissolving a purified sample in almost pure ethanol in a round bottom flask. The flask was left open overnight and crystals formed as the ethanol evaporated. This is considered to be an incredibly easy crystallization to perform.
=== Reactions === Crisis services for the LGBTQ+ community saw a sharp increase in usage during the election week. The Trevor Project's crisis lines saw a 125% increase since around midnight on election night according to a statement by CEO Jaymes Black on November 6, and followed an about 200% increase in election related conversations that had been seen November 3–4. By November 8, it was reported that the organization saw an overall increase by 700%. The Crisis Text Line also reported that 56% of their users reported as LGBTQ+ on election day. A company that assists wealthy Americans in securing foreign citizenship saw a 200× jump in inquiries following the election.
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.