Everything below concerns RP-HPLC purity. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-09-20. Where a claim depends on a specific study, the study is described rather than over-claimed.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
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.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Empagliflozin/linagliptin/metformin, sold under the brand name Trijardy XR, is a fixed-dose combination medication used for the treatment of type 2 diabetes. It is a combination of empagliflozin, linagliptin, and metformin. Empagliflozin/linagliptin/metformin was approved for use in the United States in January 2020.
== External links == Large+Neutral+Amino+Acid-Transporter+1 at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Amino+Acid+Transport+System+L at the U.S. National Library of Medicine Medical Subject Headings (MeSH) This article incorporates text from the United States National Library of Medicine, which is in the public domain.
Allied technological cooperation during World War II List of aircraft of the United Kingdom in World War II List of aircraft of World War II List of fighter aircraft List of military aircraft of the United States
=== Binding stoichiometry === Growth hormone binds to GHBP and GHR via an interactive region of helices 1 and 4 of GH. Two receptor molecules are pre-dimerized upon GH binding, so it always binds in a 1:2 ratio. Assays estimate that growth hormone and growth hormone binding protein form a natural complex at a 1:1 ratio for transport and preservation of the ligand through the bloodstream. However, some sources have shown that high physiological concentration of GHBP will result in a 1:2 ratio. When the cysteine amino acids in GHBP are mutated and the disulfide bridges are disrupted, the ability of the ligand to bind to the active site of the GHBP is significantly lessened.
All of the adsorption sites are equivalent, and each site can only accommodate one molecule. The surface is energetically homogeneous, and adsorbed molecules do not interact. There are no phase transitions. At the maximum adsorption, only a monolayer is formed. Adsorption only occurs on localized sites on the surface, not with other adsorbates. These four assumptions are seldom all true: there are always imperfections on the surface, adsorbed molecules are not necessarily inert, and the mechanism is clearly not the same for the first molecules to adsorb to a surface as for the last. The fourth condition is the most troublesome, as frequently more molecules will adsorb to the monolayer; this problem is addressed by the BET isotherm for relatively flat (non-microporous) surfaces. The Langmuir isotherm is nonetheless the first choice for most models of adsorption and has many applications in surface kinetics (usually called Langmuir–Hinshelwood kinetics) and thermodynamics. Langmuir suggested that adsorption takes place through this mechanism:
Sources: en.wikipedia.org
Narrated by David Malone, produced by Simone Pilkington, directed by Tim Tate, made by Granada Television 21 December The Whale That Swam to London, an Equinox Special; it featured Rodney Coates of Seiche Underwater Acoustics, of Holsworthy in Devon, the former Professor of Acoustical Oceanography from 1990-96 at the University of Birmingham. Narrated by Dilly Barlow, produced by Nick Curwin, directed by Toby Macdonald, made by Firefly Film and Television Productions.
== Awards and recognition == Eberlin was named among the Forbes "30 Under 30" list in 2015. She won the Marion Milligan Mason Award of the American Association for the Advancement of Science in 2016. The award is given every two years to promising young female researchers in chemistry. She won the MacArthur "Genius" Fellowship from the John D. and Catherine T. MacArthur Foundation in 2018 for her research on the use of mass spectrometry "to differentiate more quickly and accurately diseased from healthy tissues during surgery". She is the first UT Austin professor to win MacArthur grant this century. The award consists of a $625,000 no-strings-attached grant. According to the foundation, this award goes to "extraordinarily talented and creative individuals as an investment in their potential". She also won the Moore Inventor Fellowship in 2018. She received the 2020 Curt Brunnée Award from the International Mass Spectrometry Foundation. She was named on the Power List by the Analytical Scientist in 2014, 2018, 2019, 2021, 2022, 2023, and 2024. She received the 2024 Norman Hackerman Award from the Welch Foundation and the Biemann Medal from the American Society for Mass Spectrometry in 2025.
=== Withdrawal === Carisoprodol, meprobamate, and related drugs such as tybamate may produce physical dependence of the barbiturate type after prolonged use. Withdrawal after extensive use may require hospitalization in medically compromised patients. In severe cases the withdrawal can mimic the symptoms of alcohol withdrawal, including the potentially lethal status epilepticus. Psychological dependence has also been linked to carisoprodol use. Psychological dependence is more common in those who use carisoprodol non-medically and those who have a history of substance use (particularly sedatives or alcohol). It may reach clinical significance before physiological tolerance and dependence have occurred and (as with benzodiazepines) has been demonstrated to persist in varying degrees of severity for months or years after discontinuation. Discontinuation of carisoprodol, as with all GABA-ergics, can result in cognitive changes that persist for weeks, months, or rarely even years, including greatly increased anxiety and depression, social withdrawal, hair-trigger agitation/aggression, chronic insomnia, new or aggravated (often illogical) phobias, reduced IQ, short- and long-term memory loss, and dozens of other sequelae. The effects, severity, and duration appear to be slightly dose-dependent but are mainly determined by the patient's pattern of use (taken as prescribed, taken in bulk doses, mixed with other drugs, a combination of the above, etc.).
Wadden, Thomas A.; Chao, Ariana M.; Machineni, Sriram; Kushner, Robert; Ard, Jamy; Srivastava, Gitanjali; Halpern, Bruno; Zhang, Shuyu; Chen, Jiaxun; Bunck, Mathijs C.; Ahmad, Nadia N.; Forrester, Tammy (2023). "Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity: The SURMOUNT-3 phase 3 trial". Nature Medicine. 29 (11): 2909–2918. doi:10.1038/s41591-023-02597-w. PMC 10667099. PMID 37840095. Wadden, Thomas A.; Chao, Ariana M.; Moore, Molly; Tronieri, Jena S.; Gilden, Adam; Amaro, Anastassia; Leonard, Sharon; Jakicic, John M. (2023). "The Role of Lifestyle Modification with Second-Generation Anti-obesity Medications: Comparisons, Questions, and Clinical Opportunities". Current Obesity Reports. 12 (4): 453–473. doi:10.1007/s13679-023-00534-z. PMC 10748770. PMID 38041774. Wadden, Thomas A.; Brown, Gregory K.; Egebjerg, Christina; Frenkel, Ofir; Goldman, Bryan; Kushner, Robert F.; McGowan, Barbara; Overvad, Maria; Fink-Jensen, Anders (2024). "Psychiatric Safety of Semaglutide for Weight Management in People Without Known Major Psychopathology". JAMA Internal Medicine. 184 (11): 1290–1300. doi:10.1001/jamainternmed.2024.4346. PMC 11372653. PMID 39226070.
== C == Calcium channel A type of ion channel located on the cell membrane that allows the selective entry of calcium ions (Ca²⁺) into the neuron, playing a crucial role in neurotransmitter release, gene expression, and synaptic plasticity. Capsaicin A compound found in chili peppers that activates TRPV1 receptors on sensory neurons, leading to the sensation of heat or burning. It is used in research and in topical analgesics for chronic pain. Caudate nucleus A C-shaped structure located in the basal ganglia, involved in motor control, learning, memory, and reward processing. It works closely with the putamen and globus pallidus. Central nervous system (CNS) Consists of the brain and spinal cord, responsible for processing and coordinating sensory data and motor commands. Cerebellum A brain structure located at the back of the skull that plays a central role in motor coordination, balance, posture, and some cognitive functions such as attention and language. Cerebral cortex The outermost layer of the cerebrum, composed of gray matter. It is involved in higher-order brain functions such as sensory perception, language, decision-making, and voluntary motor control. Cerebral hemisphere One of the two halves of the cerebrum, divided into left and right hemispheres. Each hemisphere specializes in different functions but communicates via the corpus callosum. Cerebrospinal fluid (CSF) A clear fluid found in the brain and spinal cord that cushions neural tissue, removes waste, and provides nutrients. It circulates through the ventricular system and subarachnoid space.
Sources: en.wikipedia.org
Bavaria (The geographically distinct Palatinate, which was part of Bavaria, 1816–1946, is now part of Rheinland Pfalz). Bremen Hamburg Hesse Saxony Thuringia The other 11 states of the Weimar Republic either merged into one another or were separated into smaller entities:
=== General information === "Pakistan". The World Factbook (2025 ed.). Central Intelligence Agency. Pakistan from UCB Libraries GovPubs Pakistan from BBC News Wikimedia Atlas of Pakistan Key Development Forecasts for Pakistan from International Futures Geographic data related to Pakistan at OpenStreetMap
== Further reading == Foreman, John C.; Johansen, Torben; Gibb, Alasdair J., eds. (2010). Textbook of Receptor Pharmacology. doi:10.1201/9781420052558. ISBN 978-0-429-14730-2. Brunton L (2011). Brunton LL, Chabner B, Knollmann BC (eds.). Goodman and Gilman's The Pharmacological Basis of Therapeutics (12 ed.). New York: McGraw-Hill. ISBN 978-0-07-162442-8. Whalen K (2014). Lippincott Illustrated Reviews: Pharmacology.
DNA, RNA and proteins are most common sequence-controlled polymers in living creatures. Inspired by them, polymerization methods, utilizing DNA or RNA as templates to control sequences of polymer, are developed. At first, taking DNA or RNA as templates, scientists developed a series of peptide nucleic acid (PNA)-based polymers, without using DNA polymerases. But this method is limited to polymerization scale and yield. After that, polymerase chain reaction (PCR) is developed, which currently is still the most extensively used sequence-regulated method. By employing enzymes, the yields and scales are greatly increased, but the specificity of enzymes towards natural peptides limits this technique to a certain degree. Nowadays, more attention is paid to utilization of ribosomes to directly mimic the transcription and translation process. This technology called protein engineering is considered as the most promising biological polymerization method for synthesis of sequence-controlled polymers.
Misuse by injection or use in the nose still occurs, and more recently the efficacy of naloxone in preventing misuse by injection has been brought into question and preparations including naloxone could even be less safe than preparations containing solely buprenorphine. Rates of misuse in the U.S. appear to be lower than with other opioids. The combination formulation was approved for medical use in the US in 2002, and in the European Union in 2017. A generic version was approved in the US in 2018. In 2019, it was the 272nd most commonly prescribed medication in the US, with more than 1 million prescriptions.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.