The short version of lyophilization fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-11-19. Anything still debated is marked as such rather than presented as settled.
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.
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.
| 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 |
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
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.
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.
== Microbicidal activity == Each mentioned item in the list has different microbicidal activity, i.e. some viruses can be more or less resistant. For example, Poliovirus is resistant to a solution of 3% H2O2 even after a contact time of 10 minutes, however 7.5% H2O2 takes 30 minutes to inactivate over 99.9% of Poliovirus. Generally, hydrogen peroxide is considered as a potent virucide in appropriate concentrations, specifically in other forms such gaseous. Another example is povidone-iodine (PVP-I), which is found to be effective against herpes simplex virus or SARS-CoV-2, and other viruses, but coxsackievirus and polio was rather resistant or less sensitive to inactivation.
The thyroid gland is a butterfly-shaped organ composed of two lobes, left and right, connected by a narrow tissue band, called an "isthmus". It weighs 25 grams in adults, with each lobe being about 5 cm long, 3 cm wide, and 2 cm thick and the isthmus about 1.25 cm in height and width. The gland is usually larger in women than in men, and increases in size during pregnancy. The thyroid is near the front of the neck, lying against and around the front of the larynx and trachea. The thyroid cartilage and cricoid cartilage lie just above the gland, below the Adam's apple. The isthmus extends from the second to third rings of the trachea, with the uppermost part of the lobes extending to the thyroid cartilage and the lowermost around the fourth to sixth tracheal rings. The infrahyoid muscles lie in front of the gland and the sternocleidomastoid muscle to the side. Behind the outer wings of the thyroid lie the two carotid arteries. The trachea, larynx, lower pharynx and esophagus all lie behind the thyroid. In this region, the recurrent laryngeal nerve and the inferior thyroid artery pass next to or in the ligament. Typically, four parathyroid glands, two on each side, lie on each side between the two layers of the thyroid capsule, at the back of the thyroid lobes. The thyroid gland is covered by a thin fibrous capsule, which has an inner and an outer layer. The inner layer extrudes into the gland and forms the septa that divide the thyroid tissue into microscopic lobules.
Beyond the very youngest orphans, this study found that ISD tends to decrease with increasing gene age, and that this is primarily due to amino acid composition rather than GC content. Within shorter time scales, using de novo genes that have the most validation suggests that younger genes are more disordered in Lachancea, but less disordered in Saccharomyces. Intrinsic structural disorder and aggregation propensity did not show significant differences with age in some studies of mammals and primates, but did in other studies of mammals. One large study of the entire Pfam protein domain database showed enrichment of younger protein domain for disorder-promoting amino acids across animals, but enrichment on the basis of amino acid availability in plants.
Many kinds of isomerism exist in coordination complexes. Just as in organic chemistry, isomers are of two types: diastereomers (also called diastereoisomers) and enantiomers. Enantiomers are non-superimposable mirror images. Diastereomers are all other types of isomers.
Competitive inhibitors can bind to E, but not to ES. Competitive inhibition increases Km (i.e., the inhibitor interferes with substrate binding), but does not affect Vmax (the inhibitor does not hamper catalysis in ES because it cannot bind to ES). Uncompetitive inhibitors bind to ES. Uncompetitive inhibition decreases both Km and Vmax. The inhibitor affects substrate binding by increasing the enzyme's affinity for the substrate (decreasing Km) as well as hampering catalysis (decreases Vmax). Non-competitive inhibitors have identical affinities for E and ES (Ki = Ki'). Non-competitive inhibition does not change Km (i.e., it does not affect substrate binding) but decreases Vmax (i.e., inhibitor binding hampers catalysis). Mixed-type inhibitors bind to both E and ES, but their affinities for these two forms of the enzyme are different (Ki ≠ Ki'). Thus, mixed-type inhibitors affect substrate binding (increase or decrease Km) and hamper catalysis in the ES complex (decrease Vmax). When an enzyme has multiple substrates, inhibitors can show different types of inhibition depending on which substrate is considered. This results from the active site containing two different binding sites within the active site, one for each substrate. For example, an inhibitor might compete with substrate A for the first binding site, but be a non-competitive inhibitor with respect to substrate B in the second binding site. Traditionally reversible enzyme inhibitors have been classified as competitive, uncompetitive, or non-competitive, according to their effects on Km and Vmax.
Sources: en.wikipedia.org
In 1974, the Toronto Zoo was moved from its original downtown location to its current location in the Rouge River valley. The new location enabled the zoo to increase its overall area from 3 hectares (7.4 acres) to over 300 hectares (740 acres). The zoo was transformed at that time from a 19th-century style zoo with a few animals cramped behind iron bars into a zoo where space was provided to animals and the setting attempted to duplicate the animals' natural environments. There are a large number of golf courses in the district, with a mix of public and private courses. Dentonia Park is a public course established in 1967 and is situated in the Taylor-Massey Creek ravine beside the Victoria Park subway station. Formerly a private club, the Tam O'Shanter Golf Course was established in 1973 as a public course and is located alongside Highland Creek. Private clubs include the Toronto Hunt Club which was the first golf course in Scarborough, established in 1895 alongside Lake Ontario. and the Scarboro Golf and Country Club was established in 1912. The Cedarbrae Golf & Country Club was established in 1922 and moved to its current Rouge River Valley location at Steeles Ave East in 1954. On May 17, 2006, the Nike Malvern Sports Complex was opened in the Malvern neighbourhood. Nike Canada donated CA$500,000 to build the complex, which includes a basketball court, a practice soccer pitch, and a running track. The track was constructed from 50,000 used running shoes. The complex was built on the grounds of the St. Mother Teresa Catholic Academy and is open to the public.
Aurich, comprising former East Frisia Hanover, comprising about the former Principality of Calenberg in the Duchy of Brunswick-Lüneburg Hildesheim, comprising the former Brunswick-Lüneburg Principality of Grubenhagen and the former Prince-Bishopric of Hildesheim Lüneburg, comprising the former Brunswick-Lüneburg Principality of Lüneburg and the remainder of Saxe-Lauenburg areas Osnabrück, comprising the former County of Bentheim, the former Lower County of Lingen, and the former Prince-Bishopric of Osnabrück Stade, comprising the former Duchies of Bremen-Verden The Hanoverian subdivisions into high-bailiwicks and bailiwicks remained unchanged until 1 April 1885, when they were replaced by Prussian-style provinces (Regierungsbezirke) and districts (Kreise).
Carbapenem-resistant Enterobacteriaceae (CRE) or carbapenemase-producing Enterobacteriaceae (CPE) are gram-negative bacteria that are resistant to the carbapenem class of antibiotics, considered the drugs of last resort for such infections. They are resistant because they produce an enzyme called a carbapenemase that disables the drug molecule. The resistance can vary from moderate to severe. Enterobacteriaceae are common gastrointestinal commensals and infectious agents. Experts fear CRE as the new "superbug". The bacteria can kill up to half of patients who get bloodstream infections. Tom Frieden, former head of the Centers for Disease Control and Prevention has referred to CRE as "Nightmare bacteria". Examples of enzymes found in certain types of CRE are KPC (Klebsiella pneumoniae carbapenemase) and NDM (New Delhi Metallo-beta-lactamase). KPC and NDM are enzymes that break down carbapenems and make them ineffective. Both of these enzymes, as well as the enzyme VIM (Verona Integron-Mediated Metallo-β-lactamase) have also been reported in Pseudomonas.
== Prevalence == The prevalence of HLA-B27 varies markedly in the global population. In the United States, the estimated prevalence is 6-8%. 4% of North Africans, 2–9% of Chinese, and 0.1–0.5% of persons of Japanese descent possess the gene that codes for this antigen. Among the Sami in Northern Scandinavia (Sápmi), 24% of people are HLA-B27 positive, while 1.8% have associated ankylosing spondylitis, compared to 14-16% of Northern Scandinavians in general. In Finland, an estimated 14% of the population is positive for HLA-B27, while more than 95% of patients with ankylosing spondylitis and approximately 70–80% of patients with reactive arthritis have the genetic marker.
Sources: en.wikipedia.org
== Side effects == Common adverse reactions include nausea, headache, fatigue, vomiting, diarrhea, Anorexia (symptom) (loss of appetite), and insomnia (trouble sleeping). Rare but serious side effects include hypersensitivity reaction such as rash, elevated AST and ALT, depression, anxiety, fever/chills, URI, lactic acidosis, hypertriglyceridemia, and lipodystrophy.
In castrated immature male rats, vosilasarm (at 10 mg/kg/day orally, the highest assessed dose) maximally stimulated prostate weight to 67%, seminal vesicle weight to 59%, and levator ani muscle weight to 117% compared to that induced with testosterone propionate 1 mg/kg/day. Moreover, when combined with testosterone propionate, vosilasarm partially antagonized the weight increases of the prostate gland and seminal vesicles, reducing them to 84% and 78% (both from 100%), respectively. Conversely however, the combination of testosterone propionate and vosilasarm was additive in terms of levator ani muscle weight stimulation, increasing it to 124%. Vosilasarm was found to stimulate muscle at a dose much lower than that required to stimulate the prostate. A dose of 0.3 mg/kg/day stimulated levator ani muscle weight to a similar extent relative to the levator ani weight in non-castrated controls. Conversely, a 33-fold higher dose of 10 mg/kg/day was required to stimulate prostate weight to a similar extent as that in non-castrated controls. Similarly, in gonadally intact immature rats, 0.3 mg/kg/day vosilasarm stimulated levator ani muscle weight to a similar extent as testosterone propionate 0.5 mg/kg/day, but a dose of 30 mg/kg/day (100-fold higher) was required to stimulate the prostate to a similar extent as testosterone propionate 0.5 mg/kg/day.
=== Production === Generators provide radiation shielding for transport and to minimize the extraction work done at the medical facility. A typical dose rate at 1 metre from 99mTc generator is 20–50 μSv/h during transport. These generators' output declines with time and must be replaced weekly, since the half-life of 99Mo is still only 66 hours. Since the half-life of the parent nuclide (99Mo) is much longer than that of the daughter nuclide (99mTc), 50% of equilibrium activity is reached within one daughter half-life, 75% within two daughter half-lives. Hence, removing the daughter nuclide (elution process) from the generator ("milking" the cow) is reasonably done as often as every 6 hours in a 99Mo/99mTc generator.
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.
The most common approach combines reverse-phase liquid chromatography with mass spectrometry. Chromatography separates the components while mass spectrometry confirms the molecular mass. Peptide sequencing or tandem mass analysis can further verify the amino acid order.