The short version of amino acid sequence fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-05-22 and is reviewed periodically as new material appears.
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.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
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.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
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.
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.
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.
Thus, the molar mass of a substance X can be calculated as M(X) = Ar(X) ⋅ Mu, with the molar mass constant Mu equal to exactly 1 Da/ent, which (for all practical purposes) is equal to 1 g/mol, as the mole was historically defined such that the Avogadro number (the number of atomic-scale entities comprising one mole) was exactly equal to the number of daltons in a gram (g/Da). This means that (for all practical purposes): 1 mol = (g/Da) ent. The relationship between the molar mass of carbon-12, M(12C) = 12 g/mol, and its atomic mass, ma(12C) = 12 Da, can be expressed as M(12C) = ma(12C) · NA. Rearranging and substituting the given values into the equation yields the following expression for the Avogadro constant: NA = (g/Da) mol−1, making the Avogadro number equal to the number of daltons in a gram, and equivalently the number of atoms in 12 grams of carbon-12 (as in the 1971 definition of the mole). The mole was defined in such a way that the numerical value of the molar mass of a substance in g/mol, i.e. M(X)/(g/mol), was equal to the numerical value of the average mass of one entity (atom, molecule, formula unit) in Da, i.e. ma(X)/Da = Ar(X), so that M(X) = Ar(X) g/mol. The equivalence was exact before the redefinition of the mole in 2019, and is now only approximate, but equality may still be assumed with high accuracy. Thus, for example, the average mass of a molecule of water is about 18.0153 Da, and the molar mass of water is about 18.0153 g/mol.
Lipoate–protein ligase (EC 2.7.7.63, LplA, lipoate protein ligase, lipoate–protein ligase A, LPL, LPL-B) is an enzyme with systematic name ATP:lipoate adenylyltransferase. This enzyme catalyses the following chemical reaction
=== Special Counsel to Buddy Roemer === In 1988, Kennedy became special counsel to Governor Buddy Roemer. In 1991, he was also appointed secretary to the governor's cabinet and served in both posts until 1992. Roemer tasked Kennedy with helping him pass two key priorities: tort and campaign finance reforms. Roemer instructed Kennedy to draft the Louisiana Products Liability Act, a bill that aimed to set forth four clear legal theories by which manufacturers could be held liable for damage their products caused. The new code also clarified what counted as "unreasonably dangerous" to help make potential sources of liability more predictable to both businesses and buyers with claims. Roemer then tasked Kennedy with building support for passing the legislation. As part of his advocacy, Kennedy published a law review article titled "A Primer on the Louisiana Products Liability Act". He argued that the Products Liability Act would "bring added clarity, precision and certainty to Louisiana's products liability doctrine" and "strike an equitable balance between the right of a claimant who is injured in a product-related accident to just compensation and the right of the product's manufacturer to be judged fairly." Kennedy also delivered public testimony before the Louisiana House Committee on Civil Law and Procedure in support of the bill, saying that the bill "provides for a state-of-the-art defense for manufacturers." The Louisiana legislature enacted the Louisiana Products Liability Act in 1988.
=== Disorders of mineral metabolism === 275 Disorders of mineral metabolism 275.0 Disorders of iron metabolism Aceruloplasminemia Hemochromatosis 275.1 Disorders of copper metabolism Wilson's disease 275.2 Disorders of magnesium metabolism Hypermagnesemia Hypomagnesemia 275.3 Disorders of phosphorus metabolism Familial hypophosphatemia Hypophosphatasia 275.4 Disorders of calcium metabolism 275.41 Hypocalcemia 275.42 Hypercalcemia 275.49 Pseudohypoparathyroidism
During the mid-19th century, one of the most remarkable painters was Ramón Torres Méndez, who produced a series of good quality paintings depicting the people and their customs of different Colombian regions. Also noteworthy in the 19th century were Andrés de Santa María, Pedro José Figueroa, Epifanio Garay, Mercedes Delgado Mallarino, José María Espinosa, Ricardo Acevedo Bernal, between many others. More recently, Colombian artists Pedro Nel Gómez and Santiago Martínez Delgado started the Colombian Murial Movement in the 1940s, featuring the neoclassical features of Art Deco. Since the 1950s, the Colombian art started to have a distinctive point of view, reinventing traditional elements under the concepts of the 20th century. Examples of this are the Greiff portraits by Ignacio Gómez Jaramillo, showing what the Colombian art could do with the new techniques applied to typical Colombian themes. Carlos Correa, with his paradigmatic "Naturaleza muerta en silencio" (silent dead nature), combines geometrical abstraction and cubism. Alejandro Obregón is often considered as the father of modern Colombian painting, and one of the most influential artist in this period, due to his originality, the painting of Colombian landscapes with symbolic and expressionist use of animals, (specially the Andean condor). Fernando Botero, Omar Rayo, Enrique Grau, Édgar Negret, David Manzur, Rodrigo Arenas Betancourt, Oscar Murillo, Doris Salcedo and Oscar Muñoz are some of the Colombian artists featured at the international level.
Sources: en.wikipedia.org
== Production == Kana Akatsuki reported that Agents of the Four Seasons was born while she was in charge of the scenario for the Sword Art Online: Alicization Lycoris DLC. Initially intended to be a self-contained volume, due to the large number of scenes to be represented, at the publisher's suggestion, it was intended to be released in two volumes, however this led the author to integrate many battle developments with frequent scene changes, which brought the work to its current state. Akatsuki had always found some phenomena mysterious, leading her to ask "Why does the moon chase me?" and "Why do the seasons change?", but instead of seeking a scientific basis, she took pleasure in imagining them in a fantasy world. The work was created using the sensitivity of her childhood.
Rönnberg also filmed himself firing various guns at a shooting range to make the gun animations more authentic. Throughout the mod's development, Team Psykskallar released "videocasts" on the Mod DB page for Cry of Fear, which were medium-length videos that documented the team's development on the mod, as well as showcased new and improved features. The videos consisted of various team members, but most notably Rönnberg, Marchant, and Sydtangen.
Pliny the Elder, in his Natural History, assembled a similarly encyclopaedic account of things in nature, including accounts of many plants and animals. Aristotle, and nearly all Western scholars after him until the 18th century, believed that creatures were arranged in a graded scale of perfection rising from plants on up to humans: the scala naturae or Great Chain of Being. A few scholars in the Hellenistic period under the Ptolemies—particularly Herophilus of Chalcedon and Erasistratus of Chios—amended Aristotle's physiological work, even performing dissections and vivisections. Claudius Galen became the most important authority on medicine and anatomy. Though a few ancient atomists such as Lucretius challenged the teleological Aristotelian viewpoint that all aspects of life are the result of design or purpose, teleology (and after the rise of Christianity, natural theology) would remain central to biological thought essentially until the 18th and 19th centuries. Ernst W. Mayr argued that "Nothing of any real consequence happened in biology after Lucretius and Galen until the Renaissance." The ideas of the Greek traditions of natural history and medicine survived, but they were generally taken unquestioningly in medieval Europe.
In humans (as well as in rodents), five subtypes have been identified and named EAAT1-5 (SLC1A3, SLC1A2, SLC1A1, SLC1A6, SLC1A7). Subtypes EAAT1-2 are found in membranes of glial cells (astrocytes, microglia, and oligodendrocytes). However, low levels of EAAT2 are also found in the axon-terminals of hippocampal CA3 pyramidal cells. EAAT2 is responsible for over 90% of glutamate reuptake within the central nervous system (CNS). The EAAT3-4 subtypes are exclusively neuronal, and are expressed in axon terminals, cell bodies, and dendrites. Finally, EAAT5 is only found in the retina where it is principally localized to photoreceptors and bipolar neurons in the retina. When glutamate is taken up into glial cells by the EAATs, it is converted to glutamine and subsequently transported back into the presynaptic neuron, converted back into glutamate, and taken up into synaptic vesicles by action of the VGLUTs. This process is named the glutamate–glutamine cycle.
Traditionally the inherited metabolic diseases were classified as disorders of carbohydrate metabolism, amino acid metabolism, organic acid metabolism, or lysosomal storage diseases. In recent decades, hundreds of new inherited disorders of metabolism have been discovered and the categories have proliferated. Following are some of the major classes of congenital metabolic diseases, with prominent examples of each class.
Sources: en.wikipedia.org
==== Regulation of release ==== Regulation of TRH release is regulated principally by a negative feedback loop by thyroid hormone, and a neuronal open loop by hypothalamic factors. TRH release is additionally regulated by other circulating hormones (including glucocorticoids, and oestrogens), and inhibited by cytokines. The tanycytes of the median eminence also exert a regulatory effect on TRH release.
During this period, state and local governments initiated controversial drug policies that demonstrated racial biases, such as the stop-and-frisk police practice in New York City, and state-level "three strikes" felony laws, which began with California in 1994. During the 1990s, opioid use in the US dramatically rose, leading to the ongoing situation commonly called the opioid epidemic. A loose consensus of observers describe three main phases to date: overprescription of legal opioids beginning in the early to mid-1990s; a rise in heroin use in the later 2000s as prescription opioids became more difficult to obtain; and the rise of more powerful fentanyl and other synthetic opioids around the mid-2010s. Prior to 1990s, the use of opioids to treat chronic pain in the US was limited; some scholars suggest there was hesitation to prescribe opioids due to historical problems with addiction dating back to the 1800s. A critical point in the development of the epidemic is often seen as the release in 1996 of OxyContin (oxicodone) by Purdue Pharma, and the subsequent aggressive and deceptive opioid marketing efforts by Purdue and other pharma companies, conducted without sufficient official oversight. Thus the problem emerged from within the healthcare system: the DEA initially targeted doctors, pharmacists, pill mills, and pharmaceutical companies. As law enforcement cracked down on the pharmaceutical supply, illicit drug trafficking in opioids grew to meet demand. The George W. Bush (2001–2009) administration maintained the hard line approach.
Food and Drug Administration showed that targeting the GLP-1 receptor was a viable strategy and inspired other pharmaceutical companies to focus on that receptor. In 2011, Lilly and Amylin dissolved their partnership, with Amylin keeping the rights to exenatide. Lilly continued to develop drugs of the same class. The 2024 American Diabetes Association conference included presentations on at least 27 GLP-1 receptor agonists then in development. By July 2024, Novo Nordisk's semaglutide and Eli Lilly's tirzepatide were ranked among the world's most popular and lucrative drugs. Novo Nordisk's rollout of semaglutide turned it into the most valuable company in Europe in 2024. Its market capitalization of $570 billion was larger than the entire economy of its home country of Denmark; its $2.3 billion income tax bill for 2023 made it the country's largest taxpayer; and its rapid growth represented nearly all of Denmark's economic growth. By October 2024, tirzepatide had turned Eli Lilly into the world's most valuable drug company.
==== Conditional requirements ==== In addition, cysteine, tyrosine, and arginine are considered semiessential amino acids, and taurine a semi-essential aminosulfonic acid in children. Some amino acids are conditionally essential for certain ages or medical conditions. Essential amino acids may also vary from species to species. The metabolic pathways that synthesize these monomers are not fully developed.
Sources: en.wikipedia.org
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.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.