The short version of proteolysis fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-05-06. Anything still debated is marked as such rather than presented as settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analog of the tetrapeptide tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Reported consistently across pharmacopoeial descriptions |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| Solubility | Freely soluble in water | Aqueous buffers; poor in nonpolar solvents |
| Typical storage temperature | -20 degrees Celsius | Lyophilized powder; protect from moisture |
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.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
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.
=== Weissenbacher-Zweymüller syndrome === At least one identified mutation in the COL11A2 gene is responsible for Weissenbacher-Zweymüller syndrome. This mutation causes the amino acid glycine to be replaced with the amino acid glutamic acid at position 955 in the alpha 2 chain of type XI collagen (written as Gly955Glu). This mutation prevents collagen molecules from being assembled properly, which disrupts the structure of type XI collagen. These changes result in the characteristic signs and symptoms of Weissenbacher-Zweymüller syndrome.
=== Synthetic scaffolds === The use of natural materials in scaffolds has its disadvantages. Usually, they are expensive, not available in large quantities and they have the risk of disease transmission. This has led to the development of synthetic scaffolds. When producing synthetic scaffolds there is full control over their properties. For example, they can be made to have good mechanical properties and the right biodegradability. When it comes to synthetic scaffolds thickness, porosity and pore size are important factors for controlling connective tissue formation. Examples of synthetic scaffolds are:
=== Long-lived fission products === On scales greater than 105 years, fission products, chiefly 99Tc, again represent a significant proportion of the remaining, though lower radioactivity, along with longer-lived actinides like neptunium-237 and plutonium-242, if those have not been destroyed. The most abundant long-lived fission products have total decay energy around 100–300 keV, only part of which appears in the beta particle; the rest is lost to a neutrino that has no effect. In contrast, actinides undergo multiple alpha decays, each with decay energy around 4–5 MeV. Only seven fission products have long half-lives, and these are much longer than 30 years, in the range of 200,000 to 16 million years. These are known as long-lived fission products (LLFP). Three have relatively high yields of about 6%, while the rest appear at much lower yields. (This list of seven excludes isotopes with very slow decay and half-lives longer than the age of the universe, which are effectively stable and already found in nature, as well as a few nuclides like technetium-98 and samarium-146 that are "shadowed" from beta decay and can only occur as direct fission products, not as beta decay products of more neutron-rich initial fission products. The shadowed fission products have yields on the order of one millionth as much as iodine-129.)
Sources: en.wikipedia.org
Biochemically, GcMAF results from sequential deglycosylation of the vitamin D-binding protein (the Gc protein), which is naturally promoted by lymphocytes (B and T cells). The resulting protein may be a macrophage activating factor (MAF). MAFs are lymphokines that control the expression of antigens on the surface of macrophages, and one of their functions is to make macrophages become cytotoxic to tumors.
== Further reading == Semley J. "People Are Already Taking This Unapproved New Weight-Loss Drug". Wired. Gina Kolat, Rebecca Robbins (May 21, 2026). "Experimental Drug Yields Dramatic Weight Loss". People who got the injection, retatrutide, lost 28 percent of their body weight on average after 80 weeks, Eli Lilly said.
Along with mirtazapine, although to a lesser extent in comparison, mianserin has sometimes been described as a noradrenergic and specific serotonergic antidepressant (NaSSA). However, the actual evidence in support of this label has been regarded as poor.
Sources: en.wikipedia.org
In large retail stores, pneumatic tube systems were used to transport sales slips and money from the salesperson to a centralized tube room, where cashiers could make change, reference credit records, and so on. Many banks with drive-throughs also use pneumatic tubes.
Some microorganisms alter net surface charges. Staphylococcus aureus transports D-alanine from the cytoplasm to the surface teichoic acid which reduces the net negative charge by introducing basic amino groups. S. aureus also modifies its anionic membranes via MprF with L-lysine, increasing the positive net charge. The interaction of antimicrobial peptides with membrane targets can be limited by capsule polysaccharide of Klebsiella pneumoniae. Salmonella species reduce the fluidity of their outer membrane by increasing hydrophobic interactions between an increased number of Lipid A acyl tails by adding myristate to Lipid A with 2-hydroxymyristate and forming hepta-acylated Lipid A by adding palmitate. The increased hydrophobic moment is thought to retard or abolish antimicrobial peptide insertion and pore formation. The residues undergo alteration in membrane proteins. In some Gram-negative bacteria, alteration in the production of outer membrane proteins correlates with resistance to killing by antimicrobial peptides. Non-typeable Hemophilus influenzae transports AMPs into the interior of the cell, where they are degraded. Furthermore, H. influenzae remodels its membranes to make it appear as if the bacterium has already been successfully attacked by AMPs, protecting it from being attacked by more AMPs. ATP-binding cassette transporters import antimicrobial peptides and the resistance-nodulation cell-division efflux pump exports antimicrobial peptides.
The opium poppy is the principal source of opium, the dried latex produced by the seed pods. Opium contains a class of naturally occurring alkaloids known as opiates, that include morphine, codeine, thebaine, oripavine, papaverine and noscapine. The specific epithet somniferum means "sleep-bringing", referring to the sedative properties of some of these opiates. The opiate drugs are extracted from opium. The latex oozes from incisions made on the green seed pods and is collected once dry. Tincture of opium or laudanum, consisting of opium dissolved in alcohol or a mixture of alcohol and water, is one of many unapproved drugs regulated by the U.S. Food and Drug Administration (FDA). Its marketing and distribution persists because its historical use preceded the Federal Food, Drug & Cosmetic Act of 1938. Tincture of opium B.P., containing 1% w/v of anhydrous morphine, also remains in the British Pharmacopoeia, listed as a Class A substance under the Misuse of Drugs Act 1971. Morphine is the predominant alkaloid found in the cultivated varieties of opium poppy that are used for opium production. Other varieties produce minimal opium or none at all, such as the latex-free Sujata type. Non-opium cultivars that are planted for drug production feature a high level of thebaine or oripavine. Those are refined into drugs like oxycodone. Raw opium contains about 8–14% morphine by dry weight, or more in high-yield cultivars.
Sexually active women of reproductive potential should use contraception while receiving azacitidine and for one week after the last dose, and sexually active men with female partners of reproductive potential should use contraception during treatment and for three months following the last dose. A study undertaken to evaluate the immediate and long-term effects of a single-day exposure to Azacytidine (5-AzaC) on neurobehavioral abnormalities in mice found, that the inhibition of DNA methylation by 5-AzaC treatment causes neurodegeneration and impairs extracellular signal-regulated kinase (ERK1/2) activation and the activity-regulated cytoskeleton-associated (Arc) protein expression in neonatal mice and induces behavioral abnormalities in adult mice, as DNA methylation-mediated mechanisms appear to be necessary for the proper maturation of synaptic circuits during development, and disruption of this process by 5-AzaC could lead to abnormal cognitive function. Azacitidine can also cause nausea, vomiting, fevers, diarrhea, redness at its injection sites, constipation, bruising, petechiae, rigors, weakness, abnormally low potassium levels in the bloodstream, and many other side effects, some of which can be severe or even fatal.
Sources: en.wikipedia.org
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.
The first four residues of Selank reproduce the tuftsin sequence Thr-Lys-Pro-Arg. A Pro-Gly-Pro extension at the C-terminus was added to slow enzymatic breakdown and extend residence time.
It holds marketing authorization in Russia, where nasal drop formulations are sold. No equivalent approval exists in the European Union, the United States, or most other countries.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.