This is a working overview of proteolysis, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-04-06 and is reviewed periodically as new material appears.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
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.
| 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 |
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.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
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.
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.
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.
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.
Cooper's ligaments (also known as the suspensory ligaments of Cooper and the fibrocollagenous septa) are connective tissue in the breast that help maintain structural integrity. They are named for Astley Cooper, who first described them in 1840. Their anatomy can be revealed using transmission diffraction tomography. Cooper's suspensory ligament should not be confused with the pectineal ligament (sometimes called the inguinal ligament of Cooper) which shares the same eponym. Also, the intermediate fibers and/or the transverse part of the ulnar collateral ligament are sometimes called Cooper's ligament(s).
==== Rhizome lotus ==== Rhizome lotus cultivars produce a higher yield and higher quality rhizomes than seed or flower lotus cultivars. Furthermore, this group grows tall and produces few to no flowers. Cultivars can be classified by harvest time or by the depth of rhizomes into these types:
== Medical uses == Recombinant human parathyroid hormone (Natpara) is indicated as an adjunct to calcium and vitamin D to control hypocalcemia in people with hypoparathyroidism. Recombinant human parathyroid hormone (Natpar) is indicated as adjunctive treatment of adults with chronic hypoparathyroidism who cannot be adequately controlled with standard therapy alone. Recombinant human parathyroid hormone (Preotact) is indicated for the treatment of osteoporosis in postmenopausal women at high risk of fractures, but the marketing authorization has been withdrawn at the manufacturer's request.
Sources: en.wikipedia.org
=== Gastrointestinal === Its mechanism of action is oxygen radical scavenging, anti-oxidation, and acceleration of gastrointestinal wound healing. ZnC adheres to damaged gastric and intestinal mucosa and releases zinc and carnosine locally, helping repair and stabilize epithelial tissues. It exhibits ROS-quenching activities. It can remain in the stomach without rapid dissociation and adhere specifically to ulcerous lesions, after which L-carnosine and zinc are released to heal the ulcer. It has been shown to stimulate mucus production and to maintain the integrity of the gastric mucosal barrier. It maintains homeostasis of the gastric mucosa by prostaglandin-independent cytoprotective effects due to anti-oxidative membrane stabilizing actions, and it promotes the repair of damaged tissues by wound healing action. ZnC inhibits pro-inflammatory cytokines like TNF-α and IL-1β and reduces oxidative stress markers in tissues.[1] It exerts cytoprotection through regulating heat shock proteins and chemokines, and by stabilizing mast cells. It does so without affecting the secretion of gastric acid. It has a potential to stimulate Hsp70 expression, with overexpression of Hsp70 being found to prevent the development of inflammatory process in the large intestinal mucosa provoked by various damaging factors. It decreases p53, p21 and Bax expression and apoptosis in the intestine after irradiation. It possesses antioxidant, anti-inflammatory, and genomic stability enhancement effects, thereby having potential in preventing gastrointestinal cancer development.
== Function == In the dogfish shark, the main function of BHBDH is to help with the breakdown of ketone bodies in the cells. This function is supported by experimental evidence of starved dogfish sharks after they are fed. When starved, the ketone levels in the shark bodies increases, especially after long-term starvation. Once they are fed, the presence of ketone bodies in the body declines rapidly. The rapid decline is correlated with significant elevations of BHBDH activity, which points towards this enzyme being very important to process ketone bodies.
Although no sovereign Polish state existed between 1795 and 1918, the idea of Polish independence was kept alive throughout the 19th century. There were a number of uprisings and other armed undertakings waged against the partitioning powers. Military efforts after the partitions were first based on the alliances of Polish émigrés with post-revolutionary France. Jan Henryk Dąbrowski's Polish Legions fought in French campaigns outside of Poland between 1797 and 1802 in hopes that their involvement and contribution would be rewarded with the liberation of their Polish homeland. The Polish national anthem, "Poland Is Not Yet Lost", or "Dąbrowski's Mazurka", was written in praise of his actions by Józef Wybicki in 1797. The Duchy of Warsaw, a small, semi-independent Polish state, was created in 1807 by Napoleon in the wake of his defeat of Prussia and the signing of the Treaties of Tilsit with Emperor Alexander I of Russia. The Army of the Duchy of Warsaw, led by Józef Poniatowski, participated in numerous campaigns in alliance with France, including the successful Austro-Polish War of 1809, which, combined with the outcomes of other theaters of the War of the Fifth Coalition, resulted in an enlargement of the duchy's territory. The French invasion of Russia in 1812 and the German Campaign of 1813 saw the duchy's last military engagements. The Constitution of the Duchy of Warsaw abolished serfdom as a reflection of the ideals of the French Revolution, but it did not promote land reform.
The Norma Oficial Mexicana (NOM) applies to all processes and activities related to the supply of agave, production, bottling, marketing, information, and business practices linked to the distilled alcoholic beverage known as tequila. Tequila must be produced using agave of the species Tequilana Weber Blue variety, grown in the federal states and municipalities indicated in the Declaration. Furthermore, the NOM establishes the technical specifications and legal requirements for the protection of the Appellation of Origin of "Tequila" in accordance with the current General Declaration of Protection of the Appellation of Origin of "Tequila", the Law, the Industrial Property Law, the Federal Consumer Protection Law and other related legal provisions. All authentic, regulated tequilas will have a NOM identifier on the bottle. The important laws since 1990 were NOM-006-SCFI-1993, the later updates NOM-006-SCFI-1994 and NOM-006-SCFI-2005 and the most recent revision published on December 13, 2012, NOM-006-SCFI-2012. The number after NOM is the distillery number, assigned by the government. NOM does not indicate the location of the distillery, merely the parent company or, in the case where a company leases space in a plant, the physical plant where the tequila was manufactured.
Sources: en.wikipedia.org
== Uses == Historically, shell cordovan was used for razor strops to hone razors in barber shops. It is used mostly in the manufacture of shoes, including high-end shoemaking, and is also used for wallets and watch straps due to its visual appeal and durability. In archery, it is used to protect the fingers and is considered smooth and durable, ideal for a finger tab. Outside leather crafting, "cordwain" denotes a leather-grain embossed cover paper used for folders, covers, and similar applications in commercial printing.
A study in Europe suggested the gene marker is only relevant for East Asians. This has clinical relevance as it is agreed upon that prior to starting a medication such as allopurinol in a patient of Chinese descent, HLA-B*58:01 testing should be considered. Based on the Asian findings, similar studies in Europe showed 61% of allopurinol-induced SJS/TEN patients carried the HLA-B58 (phenotype frequency of the B*5801 allele in Europeans is typically 3%). One study concluded: "Even when HLA-B alleles behave as strong risk factors, as for allopurinol, they are neither sufficient nor necessary to explain the disease." Other HLA associations with the development of SJS, SJS/TEN, or TEN and the intake of specific drugs as determined in certain populations are given in HLA associations with SCARs.
The Boston keratoprosthesis is the most widely used synthetic cornea to date with over 900 procedures performed worldwide in 2008. The Boston KPro was developed at the Massachusetts Eye and Ear Infirmary under the leadership of Claes Dohlman.
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.
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.