This is a working overview of Heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-02-09. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
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.
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 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.
== History == The monarchical office of German Emperor was established on 1 January 1871 with the entry into force of the constitution of the newly unified German Empire, which designated the King of Prussia as the federal president (Bundespräsidium). On 18 January 1871, during the Franco-Prussian War, King Wilhelm I was ceremonially proclaimed German Emperor in the Hall of Mirrors at the Palace of Versailles. The title German Emperor (German: Deutscher Kaiser) was carefully chosen by Minister President of Prussia and Chancellor of the North German Confederation Otto von Bismarck after discussion until (and after) the day of the proclamation. Wilhelm I accepted this title grudgingly as he would have preferred "Emperor of Germany" which was, however, unacceptable to the federated monarchs, and which would also have signalled a claim to lands outside of his reign (Austria, Switzerland, Luxembourg etc.). The title Emperor of the Germans, as had been proposed at the Frankfurt Parliament in 1848, was ruled out as he considered himself chosen "By the Grace of God", not by the people as in a democracy. Through the constitutional accession of the southern German states on 1 January 1871, the North German Confederation of 1867 was expanded and transformed into the German Empire.
All LSF reactions are chemoselective but not every chemoselective reaction fulfills the requirements of the definition for LSF. High chemoselectivity is required for a useful LSF with a predictable reaction outcome because complex molecules typically feature several distinct functional groups that need to be tolerated. In this sense, chemoselectivity is sometimes referred to as functional group tolerance. Furthermore, high chemoselectivity avoids often undesired over-functionalization of the valuable substrate, which is used as a limiting reagent in LSF reactions. Every C–H bond functionalization on a complex molecule classifies as LSF, except when a directing or activating group must be installed in a previous step of the synthesis to accomplish the transformation. For functional group manipulations, the distinction between LSF and functional-group-tolerant reactions is more subtle. For example, peptide bioconjugation reactions make use of the native functionality in amino acid side chains, and thus classify as LSF. In contrast, bioorthogonal 1,3-dipolar cycloadditions (see also copper-free click chemistry and Huisgen cycloaddition) generally require prior introduction of azide or cycloalkyne functionalities to biomolecules. Hence, such transformations do not classify as LSF despite their excellent functional group tolerance.
=== Malta === The Parliament of Malta consists of the president of Malta and the House of Representatives of 69 members (article 51 of the Constitution), referred to as "members of Parliament" (article 52(1) of the Constitution). When appointed from outside the House, the speaker is also considered a member of the Parliament. The Constitution lists the qualifications and disqualifications from serving as a member of Parliament. Privileges of members of Parliament and their Code of Ethics are laid out in the House of Representatives (Privileges and Powers) Ordinance.
where A is mass number, Z is atomic number, mH is the atomic mass of a hydrogen atom, mn is the mass of a neutron, and c is the speed of light. Thus, the mass of an atom is less than the mass of its constituent protons and neutrons, assuming the average binding energy of its electrons is negligible. The binding energy B is expressed in energy units, using Einstein's mass-energy equivalence relationship. The binding energy also provides an estimate of the total energy released from fission. The curve of binding energy is characterized by a broad maximum near mass number 60 at 8.6 MeV, then gradually decreases to 7.6 MeV at the highest mass numbers. Mass numbers higher than 238 are rare. At the lighter end of the scale, peaks are noted for helium-4, and the multiples such as beryllium-8, carbon-12, oxygen-16, neon-20 and magnesium-24. Binding energy due to the nuclear force approaches a constant value for large A, while the Coulomb acts over a larger distance so that electrical potential energy per proton grows as Z increases. Fission energy is released when a A is larger than approx. 60. Fusion energy is released when lighter nuclei combine. Carl Friedrich von Weizsäcker's semi-empirical mass formula may be used to express the binding energy as the sum of five terms, which are the volume energy, a surface correction, Coulomb energy, a symmetry term, and a pairing term:
Whistleblowing tradition in what would soon become the United States had a start in 1773 with Benjamin Franklin leaking a few letters in the Hutchinson affair. The release of the communications from royal governor Thomas Hutchinson to Thomas Whately led to a firing, a duel and arguably, both through the many general impacts of the leak and its role in convincing Franklin to join the radicals' cause, the taking of another important final step toward the American Revolution.
Sources: en.wikipedia.org
The king brown snake (Pseudechis australis) is a species of highly venomous snake of the family Elapidae, native to northern, western, and Central Australia. The king brown snake is the largest terrestrial venomous snake in Australia. Despite its common name, it is a member of the genus Pseudechis (black snakes) and only distantly related to true brown snakes. Its alternative common name is the mulga snake, although it lives in many habitats apart from mulga. First described by English zoologist John Edward Gray in 1842, it is a robust snake up to 3.3 m (11 ft) long. It is variable in appearance, with individuals from northern Australia having tan upper parts, while those from southern Australia are dark brown to blackish. Sometimes, it is seen in a reddish-green texture. The dorsal scales are two-toned, sometimes giving the snake a patterned appearance. Its underside is cream or white, often with orange splotches. The species is oviparous. The snake is considered to be a least-concern species according to the International Union for Conservation of Nature, though may have declined with the spread of the cane toad. Its venom is not as potent as those of Australia's other dangerous snakes, but can still cause severe effects if delivered in large enough quantities. Its main effect is on striated muscle tissue, causing paralysis from muscle damage, and also commonly affects blood clotting (coagulopathy). Often, extensive pain and swelling occur, rarely with necrosis, at the bite site. Deaths from its bites have been recorded, with the most recent being in 1969.
=== Chemistry === Like the other noble gases, krypton is chemically highly unreactive. The rather restricted chemistry of krypton in the +2 oxidation state parallels that of the neighboring element bromine in the +1 oxidation state; due to the scandide contraction it is difficult to oxidize the 4p elements to their group oxidation states. Until the 1960s no noble gas compounds had been synthesized. Following the first successful synthesis of xenon compounds in 1962, synthesis of krypton difluoride (KrF2) was reported in 1963. In the same year, KrF4 was reported by Grosse, et al., but was subsequently shown to be a mistaken identification. Under extreme conditions, krypton reacts with fluorine to form KrF2 according to the following equation:
Ripasudil had no effect on respiratory or neurological function. Although no carcinogenicity studies were performed on the drug, developers believed it to be non-carcinogenic due to its rapid elimination and therefore lack of accumulation in tissue, as well as the lack of inflammatory response in the eye post-administration.
On 27 April 1791, Robespierre opposed plans to reorganize the National Guard and restrict its membership to active citizens, largely property owners. He demanded the reconstitution of the army on a democratic basis to allow passive citizens. He felt that the army had to become the instrument of defence of the Revolution and no longer be a threat to it. On 28 April, despite Robespierre's intensive campaign, the principle of an armed bourgeois militia was definitively enacted in the Assembly. Along with other Jacobins, he urged in his magazine the creation of a revolutionary army in Paris, consisting of 20,000 men, with the goal to defend "liberty" (the revolution), maintain order in the sections, and educate the members in democratic principles; an idea he borrowed from Jean-Jacques Rousseau and Machiavelli. According to Jean Jaures, he considered this even more important than the right to strike. Following the king's veto of the Assembly's efforts to raise a militia of volunteers, the reinstatement of Brissotin ministers and suppression of non-juring priests, the monarchy faced an abortive Demonstration of 20 June 1792. Sergent-Marceau and Panis, the administrators of police, urged the sans-culottes to lay down their weapons, telling them it was illegal to present a petition in arms, although their march to the Tuileries was not banned. They invited the officials to join the procession and march along with them.
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.