If you have been reading about electrospray ionization 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.
Updated 2026-04-28. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
| 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 |
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
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.
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.
Benazepril (Lotensin) Cilazapril (Inhibace) Enalapril (Vasotec/Renitec/Berlipril/Enap/Enalapril Profarma) Imidapril (Tanatril) Lisinopril (Listril/Lopril/Novatec/Prinivil/Zestril, Lisidigal) Moexipril (Univasc) Perindopril (Coversyl/Aceon/Perindo) Quinapril (Accupril) Ramipril (Altace/Prilace/Ramace/Ramiwin/Triatec/Tritace/Ramitac) Trandolapril (Mavik/Odrik/Gopten) Ceronapril (never marketed) Fosinopril (Fositen/Monopril) ACE inhibitor peptides can be derived from natural sources such as algae, fruit, seeds, dairy and animal products. A comprehensive resource on anti-hypertensive peptides is available in the form of a database. It contains around 1700 unique antihypertensive peptides. Arfalasin (HOE 409) is an angiotensin antagonist.
TMEM261 contains a domain of unknown function, DUF4536 (pfam15055), predicted as a helical membrane spanning domain about 45aa (Cys 47- Ser 92) in length with no known domain relationships. Two further transmembrane helical domains are predicted of lengths 18aa (Val 52-Ala 69) and 23aa (Pro 81-Ala 102]). There is also a low complexity region spanning 25aa (Thr 14-Ala 39). The tertiary structure for TMEM261 has not yet been determined. However, its protein secondary structure is mostly composed of coiled-coil regions with beta strands and alpha helices found within the transmembrane and domain of unknown function regions. The N-terminal region of TMEM261 is composed of a disordered region which contains the low complexity region that is not highly conserved amongst orthologues. A N-myristoylation domain is shown to be present in most TMEM261 protein variants. Post-translational modifications include myristoylation of the N-terminal Glycine residue (Gly2) of the TMEM261 protein as well as phosphorylation of Threonine 31.
Jannie Hofmeyr published the first catalog of control patterns in metabolic control analysis (MCA). His doctoral research. concerned the use of graphical patterns to elucidate chains of interaction in metabolic regulation, later published in the European Journal of Biochemistry. In his thesis, he cataloged 25 patterns for various biochemical networks. In later work, his research group, together with Carl D Christensen and Johann Rohwer, developed a Python based tool called SymCA that was part of the PySCeSToolbox toolkit that could generate patterns automatically and symbolically from a description of the network. This software was used to generate the patterns shown below. The control equations, especially the numerators of the equations, can give information on the relative importance and routes by which perturbations travel through a biochemical network
== Historical uses == Following its discovery by Marie and Pierre Curie in 1898, radium (principally 226Ra) has had a number of uses. In the early 20th century, when the hazards of radiation were not well-known, radium was commonly used in consumer items such as toothpaste and hair creams. Radium was also formerly used as a radiation source for cancer treatment, but has since been replaced in this role by safer and more easily available alternatives. Until the 1960s, radium was used in luminous paint for watch dials and aircraft instruments.
== Distribution and habitat == Panaeolus cyanescens is a coprophilous (dung-inhabiting) species which occurs in both the Neotropics and Paleotropics. It has been found in Vietnam, Africa (including South Africa, Mauritius, Madagascar and Democratic Republic of the Congo), Australia, Belize, the Caribbean (Bermuda, Grenada, Barbados Jamaica, Trinidad, and Puerto Rico), Costa Rica, India, Malaysia, Indonesia, Sri Lanka, Cambodia, Thailand, Japan, Mexico, Oceania (Fiji and Samoa), the Philippines, South America (Bolivia, Brazil, Paraguay, Colombia, Venezuela, and Ecuador), South Korea, and the United States (California, Hawaii, Louisiana, Mississippi, Alabama, Florida, Tennessee, Texas, Kentucky, Virginia, Georgia, and North Carolina).
Sources: en.wikipedia.org
Burger King Holdings was the parent company of Burger King when it went public in 2002. Burger King derived its income from several sources, including property rental and sales through company owned restaurants; however, a substantial portion of its revenue was dependent on franchise fees. During the transitional period after 3G Capital acquired the company, Burger King's board of directors was co-chaired by John W. Chidsey, formerly CEO and chairman of the company, and Alex Behring, managing partner of 3G Capital. By April 2011, the new ownership had completed the restructuring of Burger King's corporate management and Chidsey tendered his resignation, leaving Behring as CEO and chair. Burger King Corporation is currently an independently operated subsidiary of RBI. RBI's present organizational structure includes five primary segments: Tim Hortons, Burger King, Firehouse Subs, Popeyes Louisiana Kitchen and International. International encompasses the aggregated outcomes from the operations of each brand outside the United States and Canada. Josh Kobza, the CEO of RBI, was appointed in 2023. Before taking over as CEO in February 2023, Kobza served as CFO, CTO, and COO of RBI. Tom Curtis, the president of Burger King U.S. and Canada, was appointed in 2021 and oversees the operation of the Burger King Corporation in the United States and Canada. In North America, Burger King Corporation is responsible for licensing operators and administering stores.
=== Light utility vehicles === Austin Champ Land Rover series - primary light utility vehicle throughout the Cold War Land Rover 1/2 ton Lightweight - late 1960s onwards Land Rover 101 Forward Control - Gun tractor and ambulance versions Land Rover Defender - mid-1980s onwards
== Contraindications == Benzhydrocodone/APAP is contraindicated in patients with significant respiratory depression, bronchial asthma in an unmonitored setting, known or suspected gastrointestinal obstructions (including paralytic ileus). It is also contraindicated in patients that have experienced hypersensitivity to hydrocodone, acetaminophen or any other component in the formulation.
AlphaFold has been used to predict structures of proteins of SARS-CoV-2, the causative agent of COVID-19. The structures of these proteins were pending experimental detection in early 2020. Results were reviewed by scientists at the Francis Crick Institute in the United Kingdom before being released to the broader research community. The team also confirmed accurate prediction against the experimentally determined SARS-CoV-2 spike protein that was shared in the Protein Data Bank, an international open-access database, before releasing the computationally determined structures of the under-studied protein molecules. The team acknowledged that although these protein structures might not be the subject of ongoing therapeutical research efforts, they will add to the community's understanding of the SARS-CoV-2 virus. Specifically, AlphaFold 2's prediction of the structure of the ORF3a protein was very similar to the structure determined by researchers at University of California, Berkeley using cryo-electron microscopy. This specific protein is believed to assist the virus in breaking out of the host cell once it replicates. This protein is also believed to play a role in triggering the inflammatory response to the infection.
11-Aminoundecanoic acid is an organic compound with the formula H2N(CH2)10CO2H. This compound is classified as an amine and a fatty acid. 11-Aminoundecanoic acid is a precursor to Nylon-11. 11-Aminoundecanoic acid is a white crystalline and odorless solid with low solubility in water. As practiced by Arkema, 11-aminoundecanoic acid is prepared industrially from undecylenic acid, which is derived from castor oil. The synthesis proceeds in four separate reactions: Crude castor oil consists of about 80% triglycerides, from the ricinoleic acid, itself representing about 90% of the oil. It is quantitatively transesterified with methanol to methyl ricinoleate (the methyl ester of ricinoleic acid) in the presence of the basic sodium methoxide at 80 °C within 1 h reaction time in a stirred reactor.
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.
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.