This is a working overview of proteolysis, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-01-04. Anything still debated is marked as such rather than presented as settled.
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.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
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.
| 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 |
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
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.
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.
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.
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.
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.
Δh = The head loss due to pipe friction over the given length of pipe (SI units: m); g = The local acceleration due to gravity (m/s2). It is useful to present head loss per length of pipe (dimensionless):
=== Human health === Food engineers must adapt food technologies and operations to the recent consumer trend toward the consumption of healthy and nutritious food. To supply foods with these qualities, and for the benefit of human health, food engineers must work collaboratively with professionals in other domains, such as medicine, biochemistry, chemistry, and consumerism. New technologies and practices must be developed to increase the production of foods that have a positive impact on human health.
== Early life == She was the only child of utilities magnate George Crawford (a former chairman of Columbia Gas & Electric Company) and his wife, Annie-Laurie Warmack. She was born on her father's personal railway carriage in Manassas, Virginia, en route from Hot Springs, Virginia, to New York, for which she was known as "Choo-Choo" as a child before being nicknamed "Sunny" because of her nature. Upon her father's death, when she was three years old, she inherited a reported US$100 million. Her mother, the daughter of the founder of the International Shoe Company, later married Russell Aitken, a sculptor and writer.
Sources: en.wikipedia.org
=== Features === They are ovoid cells with granules. They have gastrin receptors. Some produce nesfatin-1. Ghrelin cells are not terminally differentiated in the pancreas: they are progenitor cells that can give rise to A-cells, PP cells and Beta-cells there.
Antipyrine-benzocaine otic consists of antipyrine and benzocaine, and is used to relieve ear pain and remove earwax. Cepacol consists of menthol and benzocaine, and is used to treat sore throat. A solution of benzocaine and menthol is marketed for the treatment of bee stings, mosquito bites, jellyfish stings, and other insect bites
== Non-drug inhibitors == Many natural products (including anti-oxidants) that have been promoted to have anti-cancer and anti-inflammatory activity have also been shown to inhibit NF-κB. There is a controversial US patent (US patent 6,410,516) that applies to the discovery and use of agents that can block NF-κB for therapeutic purposes. This patent is involved in several lawsuits, including Ariad v. Lilly. Recent work by Karin, Ben-Neriah and others has highlighted the importance of the connection between NF-κB, inflammation, and cancer, and underscored the value of therapies that regulate the activity of NF-κB. Extracts from a number of herbs and dietary plants are efficient inhibitors of NF-κB activation in vitro. Nobiletin, a flavonoid isolated from citrus peels, has been shown to inhibit the NF-κB signaling pathway in mice. Likewise, various withanolides of Withania somnifera (Ashwagandha) have been found to have inhibiting effects on NF-κB through inhibition of proteasome mediated ubiquitin degradation of IκBα.
Sources: en.wikipedia.org
Catatonia, on the other hand, is associated with normal EEG or diffuse slowing. Delirium is characterized by fluctuating disturbed perception and consciousness in the ill individual. It has hypoactive and hyperactive or mixed forms. People with hyperactive delirium present similarly to those with excited catatonia and have symptoms of restlessness, agitation, and aggression. Those with hypoactive delirium present with similarly to stuporous catatonia, withdrawn and quiet. However, catatonia also includes other distinguishing features including posturing and rigidity as well as a positive response to benzodiazepines. Patients with locked-in syndrome present with immobility and mutism; however, unlike patients with catatonia who are unmotivated to communicate, patients with locked-in syndrome try to communicate with eye movements and blinking. Furthermore, locked-in syndrome is caused by damage to the brainstem. Stiff-person syndrome and catatonia are similar in that they may both present with rigidity, autonomic instability, and a positive response to benzodiazepines. However, stiff-person syndrome may be associated with anti-glutamic acid decarboxylase (anti-GAD) antibodies and other catatonic signs such as mutism and posturing are not part of the syndrome. Untreated late-stage Parkinson's disease may present similarly to stuporous catatonia with symptoms of immobility, rigidity, and difficulty speaking.
With nearly every Syndicate member dead, the Colonists began to clear up any evidence of alien life and began to create human replacements called "Super Soldiers", on which the Colonists had been working covertly as an alternative slave race should the hybridization experiments be unsuccessful. To create Super Soldiers, the Colonists infect humans with a new strain of their virus, which slowly destroys and then rebuilds the body of the host. This process seems to involve a lengthy surgical procedure on abductees as opposed to simple infection (as with the black oil). As they have normal red blood and can replace individuals within powerful positions, they provide an ideal way for the Colonists to infiltrate humanity to ensure that the plans for colonization are uninterrupted. They are identifiable however by small spiny protrusions on the backs of their necks or by detailed analysis of a blood sample which shows their DNA exists as a complex with iron. Although they cannot shapeshift, Super Soldiers are practically unstoppable. They can survive being crushed by a garbage compactor, decapitation, and can rip through steel with their bare hands. The only known way to kill them takes advantage of their metallic biochemistry: their bodies are torn apart by the magnetic fields present near large deposits of magnetite ore. The Super Soldiers quietly fill the positions of power previously occupied by Syndicate members and rarely use human conspirators.
=== Metal ion complexation === With metal ions, thiolates behave as ligands to form transition metal thiolate complexes. The term mercaptan is derived from the Latin mercurium captans (capturing mercury) because the thiolate group bonds so strongly with mercury compounds. According to hard/soft acid/base (HSAB) theory, sulfur is a relatively soft (polarizable) atom. This explains the tendency of thiols to bind to soft elements and ions such as mercury, lead, or cadmium. The stability of metal thiolates parallels that of the corresponding sulfide minerals. Sodium aurothiolate is an antiarthritic drug.
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.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.