This is a working overview of Semax, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-06. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
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.
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.
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.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
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.
=== Sleep === MCH and the hormone orexin have an antagonistic relationship with one another with regards to the sleep cycle, with orexin being almost entirely active during wake periods and MCH being more active during sleep periods. MCH also promotes sleep, and within a sleep period increased levels of MCH seem to increase the amount of time spent in REM sleep and slow waves sleep. Increased levels of MCH can also increase the amount of time spent in both REM and NREM, which in turn increases total sleep duration. Increased levels of sugar promotes MCH and its effect on sleep and conserving energy.
== Medical uses == Brimonidine is indicated for the lowering of intraocular pressure in people with open-angle glaucoma or ocular hypertension. It is also used to reduce redness of the eye. The gel is indicated for the topical treatment of persistent (nontransient) facial erythema of rosacea in adults 18 years of age or older. A 2017 Cochrane review found insufficient evidence to determine if brimonidine slows optic nerve damage.
Cold Spring Tavern was established as a stagecoach stop in 1865. Originally known as the "Cold Spring Relay Station", it was a horse changeover and meals break station. The tavern is located 20 minutes north of Santa Barbara, California, in Cold Spring Canyon, which is about a mile off Highway 154 along Stagecoach Road (in the San Marcos Pass area).
Sales caps are also placed on the properties of the CLT to maintain affordability for generations of future buyers. Most of the skepticism surrounding CLTs is rooted in their reliance on external funding. As CLT organizations grow and their boards become more professionalized, they are often distanced from their original ideals of community-based land control which the organizations were founded upon. Most CLTs are not built upon economically self-sustaining models, so they are forced to compete for external funding, taking away the CLT's autonomy, as all of the power is transferred into the hands of grant-funding organizations and private foundations. This problem could be avoided if CLTs could somehow source their funding from community investors or funders who share their ideals of community empowerment.
Sources: en.wikipedia.org
== Development and current usage == Livia S. Eberlin, Ph.D., an Assistant Professor of Chemistry at the University of Texas at Austin, first reported the invention of the MasSpec Pen in 2017. Within her laboratory, the device has been used to analyze human tissue biopsies, including normal and cancerous breast, lung, ovarian, and thyroid samples. The MasSpec Pen is currently being evaluated for use on freshly excised tissue biopsies and for intraoperative use during oncology surgeries. The MasSpec Pen has been licensed to Genio Technologies, Inc., a subsidiary of MS Pen Technologies, Inc.
=== Economics === Tavaborole began phase III clinical trials in December 2010 and was approved by the US FDA in July 2014. Originally developed by Anacor, it is now marketed in the United States by Novartis subsidiary Sandoz. Anacor was paid US$65 million and also entered into a profit sharing scheme for future sales.
Beta decay leaves the mass number unchanged, so the change of nuclear spin must be an integer. However, the electron spin is 1/2, hence angular momentum would not be conserved if beta decay were simply electron emission. From 1920 to 1927, Charles Drummond Ellis (along with Chadwick and colleagues) further established that the beta decay spectrum is continuous. In 1933, Ellis and Nevill Mott obtained strong evidence that the beta spectrum has an effective upper bound in energy. Niels Bohr had suggested that the beta spectrum could be explained if conservation of energy was true only in a statistical sense, thus this principle might be violated in any given decay. However, the upper bound in beta energies determined by Ellis and Mott ruled out that notion. Now, the problem of how to account for the variability of energy in known beta decay products, as well as for conservation of momentum and angular momentum in the process, became acute. In a famous letter written in 1930, Wolfgang Pauli attempted to resolve the beta-particle energy conundrum by suggesting that, in addition to electrons and protons, atomic nuclei also contained an extremely light neutral particle, which he called the neutron. He suggested that this "neutron" was also emitted during beta decay (thus accounting for the known missing energy, momentum, and angular momentum), but it had simply not yet been observed. In 1931, Enrico Fermi renamed Pauli's "neutron" the "neutrino" ('little neutral one' in Italian).
Sources: en.wikipedia.org
in his eagerness to weaken it, has cut off all possibility of understanding between the two Masonic Bodies existing and recognized in the Republic of Cuba." They also stated that since the signing of the Treaty of Friendship and Mutual Recognition in 1876, whenever a sanction was issued by the Supreme Council, that the Grand Lodge would show solidarity in issuing the same sanction. If Urquía Carreño did not step down, it would not only be a violation of Masonic Law, but also break almost a century and a half of tradition. If the Treaty of Friendship broke down, they said, it would only be an invitation for the State Security Unit to further infiltrate the brotherhood. Urquía Carreño still refused to step down. After this, certain Lodge Masters sent letters to the United States government, requesting that if Urquía Carreño tried to claim asylum there, to deny him this right for his alleged involvement and collaboration with the State Security Unit.
==== Specialty selection ==== Specialties differ in length of training, availability of residencies, and options. Specialist residency programs require participation for completion ranging from three years for family medicine to seven years for neurosurgery. This time does not include any fellowship that may be required to be completed after residency to further sub-specialize. In regard to options, specialty residency programs can range nationally from over 700 (family medicine) and over 580 (internal medicine) to 33 programs for integrated thoracic surgery and 28 programs for osteopathic neuromusculoskeletal medicine. Residents choose the teaching hospital where they want to perform their residency based upon many factors, including the medical specialties offered by the hospital and reputation and credentials of the hospital. The following table shows medical specialties and the residency training times for medical specialties, as reported by the American Medical Association in 2021.
In the flaxseed variety Linum usitatissimum, a precursor peptide was found using Blast searching that potentially contains five core peptides separated by putative recognition sequences. Proteusins are named after "Proteus", a Greek shape-shifting sea god. Until now, the only known members in the family of Proteusins are called polytheonamides. They were originally presumed to be nonribosomal natural products due to the presence of many D-amino acids and other non-proteinogenic amino acids. However, a metagenomic study revealed the natural products as the most extensively modified class of RiPPs known to date. Six enzymes are responsible for installing a total of 48 posttranslational modifications onto the polytheonamide A and B precursor peptides, including 18 epimerizations. Polytheonamides are exceptionally large, as a single molecule is able to span a cell membrane and form an ion channel. Sactipeptides contain intramolecular linkages between the sulfur of Cys residues and the α-carbon of another residue in the peptide. A number of nonribosomal peptides bear the same modification. In 2003, the first RiPP with a sulfur-to-α-carbon linkage was reported when the structure of subtilosin A was determined using isotopically enriched media and NMR spectroscopy.
Sources: en.wikipedia.org
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.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.