Everything below concerns Lyophilisation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-02-23. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
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.
==== Growth ==== Postnatally, the mammary ducts elongate into the mammary fat pad. Then, starting around four weeks of age, mammary ductal growth increases significantly with the ducts invading towards the lymph node. Terminal end buds, the highly proliferative structures found at the tips of the invading ducts, expand and increase greatly during this stage. This developmental period is characterized by the emergence of the terminal end buds and lasts until an age of about 7–8 weeks. By the pubertal stage, the mammary ducts have invaded to the end of the mammary fat pad. At this point, the terminal end buds become less proliferative and decrease in size. Side branches form from the primary ducts and begin to fill the mammary fat pad. Ductal development decreases with the arrival of sexual maturity and undergoes estrous cycles (proestrus, estrus, metestrus, and diestrus). As a result of estrous cycling, the mammary gland undergoes dynamic changes where cells proliferate and then regress in an ordered fashion.
== History == The first modern report of sickle cell disease may have been in 1846, where the autopsy of an executed runaway slave was discussed; the key finding was the absence of the spleen. Reportedly, African slaves in the United States exhibited resistance to malaria, but were prone to leg ulcers. The abnormal characteristics of the red blood cells, which later lent their name to the condition, were first described by Ernest E. Irons (1877–1959), intern to Chicago cardiologist and professor of medicine James B. Herrick (1861–1954), in 1910. Irons saw "peculiar elongated and sickle-shaped" cells in the blood of a man named Walter Clement Noel, a 20-year-old first-year dental student from Grenada. Noel had been admitted to the Chicago Presbyterian Hospital in December 1904 with anaemia. Noel was readmitted several times over the next three years for "muscular rheumatism" and "bilious attacks" but completed his studies and returned to the capital of Grenada (St. George's) to practice dentistry. He died of pneumonia in 1916 and is buried in the Catholic cemetery at Sauteurs in the north of Grenada. Shortly after the report by Herrick, another case appeared in the Virginia Medical Semi-Monthly with the same title, "Peculiar Elongated and Sickle-Shaped Red Blood Corpuscles in a Case of Severe Anemia." This article is based on a patient admitted to the University of Virginia Hospital on 15 November 1910. In the later description by Verne Mason in 1922, the name "sickle cell anemia" is first used.
Machamer (1964), philosopher and historian of science; professor at the University of Pittsburgh Mike Wallace (1964), historian and winner of the 1999 Pulitzer Prize for History for Gotham: A History of New York City to 1898 Jonathan Goldberg (1964), professor at Emory University Michael M. Gunter (1964), professor at Tennessee Technological University, authority in Kurdish studies Miles Orvell (1964), professor at Temple University, former editor of the Encyclopedia of American Studies Jonathan M. Weiss (1964), scholar of French literature and politics George R. Goldner (1965), former curator at the Metropolitan Museum of Art J. Bruce Jacobs (1965), Australian orientalist who specialized in Taiwan studies, professor at Monash University Richard Kagan (1965), historian, professor of Spanish history at Johns Hopkins University Richard Taruskin (1965), musicologist Walter Reich (1965), former director of United States Holocaust Memorial Museum and professor at George Washington University Mark Steiner (1965), professor of philosophy at the Hebrew University of Jerusalem Raymond Geuss (1966), specialist in Jürgen Habermas Steven Handel (1966), restoration ecologist, professor at Rutgers University Michael Hechter (1966), professor of political science at Arizona State University Ira Katznelson (1966), political scientist and historian, professor at Columbia University Mark D. Naison (1966), former political activist; professor of history at Fordham University T. J.
Federal Government systems for the electronic exchange of clinical health information. In 1999, it was identified by the HL7 Standards Development Organization as a preferred code set for laboratory test names in transactions between health care facilities, laboratories, laboratory testing devices, and public health authorities.
Sources: en.wikipedia.org
=== Periodic limb movement disorder === Selegiline has been studied in the treatment of periodic limb movement disorder (PLMD) in a single small open-label clinical study. It was reported to be effective as assessed by polysomnography, reducing periodic limb movements during sleep by about 60%. Selegiline has not been studied for the related condition restless legs syndrome (RLS) as of 2023. The drug has not been studied well enough in PLMD or RLS to be widely used in their treatment.
18 September Scientists at CERN in Switzerland, using the ATLAS particle detector, observed quantum entanglement between quarks for the first time, and was also the highest-energy observation of entanglement so far. The largest known pair of astrophysical jets is discovered within the radio galaxy Porphyrion, extending 23 million light-years from end to end. This surpasses Alcyoneus, the previous record holder at 16 million light-years. 19 September – A recently discovered near-Earth object called 2024 PT5 is calculated to become a "mini-moon" with a temporary orbit around Earth from September 29 until November 25. It will return in the year 2055. 23 September Scientists publish the first multi-century, multi-model forecast of Antarctic Ice Sheet loss derived from global climate models, which indicates that the West Antarctic ice sheet may undergo a near-total collapse by 2300. Researchers demonstrate an asteroid deflection method using an X-ray pulse using a miniaturized mock asteroid for up to ~4 km diameter asteroids for which DART-like impacts are thought to be insufficient. 24 September – Researchers at ETH Zurich demonstrate an image-based AI model able to solve Google's reCAPTCHA v2, one of the world's most powerful tools for determining whether a user is human in order to deter bot attacks and spam. 30 September – Researchers develop a new method merging confocal fluorescence microscopy with microfluidic laminar flow, that can detect nanoparticles and viruses quickly. It can be achieved by using the 3D-printed microscopy approach, Brick-MIC.
== Other reactions == Ornithine, through the action of ornithine decarboxylase (EC 4.1.1.17), serves as the starting point for the synthesis of polyamines such as putrescine. In bacteria such as E. coli, ornithine can be synthesized from L-glutamate.
== Bibliography == Clark D (2010). Germs, Genes, & Civilization: how epidemics shaped who we are today. Upper Saddle River, N.J: FT Press. ISBN 978-0-13-701996-0. OCLC 473120711. Crawford D (2007). Deadly Companions: how microbes shaped our history. Oxford New York: Oxford University Press. ISBN 978-0-19-956144-5. OCLC 183198723. Hall B (2008). Strickberger's Evolution: the integration of genes, organisms and populations. Sudbury, Mass: Jones and Bartlett. ISBN 978-0-7637-0066-9. OCLC 85814089. Krasner R (2014). The Microbial Challenge: a public health perspective. Burlington, Mass: Jones & Bartlett Learning. ISBN 978-1-4496-7375-8. OCLC 794228026. Pommerville JC (2014). Fundamentals of Microbiology (10th ed.). Boston: Jones and Bartlett. ISBN 978-1-284-03968-9. Wheelis M (2008). Principles of modern microbiology. Sudbury, Mass: Jones and Bartlett Publishers. ISBN 978-0-7637-1075-0. OCLC 67392796.
=== Gibbs–Donnan effect === In ion exchange chromatography, the Gibbs–Donnan effect is observed when the pH of the applied buffer and the ion exchanger differ, even up to one pH unit. For example, in anion-exchange columns, the ion exchangers repeal protons so the pH of the buffer near the column differs is higher than the rest of the solvent. As a result, an experimenter has to be careful that the protein(s) of interest is stable and properly charged in the "actual" pH. This effect comes as a result of two similarly charged particles, one from the resin and one from the solution, failing to distribute properly between the two sides; there is a selective uptake of one ion over another. For example, in a sulphonated polystyrene resin, a cation exchange resin, the chlorine ion of a hydrochloric acid buffer should equilibrate into the resin. However, since the concentration of the sulphonic acid in the resin is high, the hydrogen of HCl has no tendency to enter the column. This, combined with the need of electroneutrality, leads to a minimum amount of hydrogen and chlorine entering the resin.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.