A practical reference on heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
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.
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.
| 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 |
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.
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.
=== Rocks === These are asteroids and other non-planetary bodies hollowed out for habitation and usually spun for centrifugal artificial gravity. Rocks (with the exception of those used for secretive purposes) are described as having faster-than-light space drives, and thus can be considered a special form of spaceship. Like Orbitals, they are usually administered by one or more Minds. Rocks do not play a large part in most of the Culture stories, though their use as storage for mothballed military ships (Pittance) and habitats (Phage Rock, one of the founding communities of the Culture) are both key plot points in Excession.
=== Neck === The neck, clavicle area and the back of the neck are very sensitive, and can be stimulated by licking, kissing or light caressing. Some people also like being bitten gently in these areas, often to the point that a "hickey", or "love-bite" is formed.
Adrenodoxin reductase: This enzyme is present ubiquitously in most organisms. It transfers two electrons from NADPH to FAD. In vertebrates, it serves as the first enzyme in the chain of mitochondrial P450 systems that synthesize steroid hormones.
=== Cause === As well as attempting to find disease-modifying agents for osteoarthritis, there is emerging evidence that a system-based approach is necessary to find the causes of osteoarthritis. A study conducted by scientists at the University of Twente found that osmolarity induced intracellular molecular crowding might drive the disease pathology.
The continental policy of England [after 1525] was fixed. It was to be pacific, mediating European affairs, favorable to a balance which should prevent any power from having a hegemony on the continent or controlling the Channel coasts. The naval security of England and the balance of power in Europe were the two great political principles which appeared in the reign of Henry VIII and which, pursued unwaveringly, were to create the greatness of England. In 1579, the first English translation of Francesco Guicciardini's Storia d'Italia ("History of Italy") popularised the Italian balance of power theory in England. This translation was dedicated to Elizabeth I of England and claimed that "God has put into your hand the balance of power and justice, to poise and counterpoise at your will the actions and counsels of all the Christian kings of your time". Thomas Carlyle referred to statesmen "in shadow-hunting, shadow-hunted hour ... looking with intense anxiety into a certain spectral something they call the Balance of Power." Statesman Richard Cobden labeled the balance of power "a chimera" due to its unclear meaning: "It is not a fallacy, a mistake, an imposture—it is an undescribed, indescribable, incomprehensible nothing." The only point on which writers on the balance of power agree "is in the fundamental delusion that such a system was ever acceded to by the nations of Europe." They imply long, uninterrupted, peaceful and prosperous co-existence.
Sources: en.wikipedia.org
== Principle == Peptides are very useful as therapeutic and diagnostic substances. Their use is getting more popular, and display systems offer a useful way to engineer peptides and optimise their binding capabilities. Cells express surface proteins which can be involved in a whole host of responses including recognition of other cells, interaction with other cells, and cell signalling. Many types of bacteria have cell surface proteins such as the enteropathogenic E. coli intimin protein which is involved in binding to host cells, or the OmpA protein of E. coli cells which is important in keeping the structure of the outer membrane. Many surface proteins are involved in bacterial cell attachment and invasion of the host cell. By using bacterial display, target proteins on the host cell can be identified. These surface proteins need to first be translocated across the bacterial cell membranes from the cytoplasm to the cell surface. Gram-negative bacteria have an additional periplasmic space, which Gram-positive bacteria lack, so they have a harder task of translocating proteins. The display of heterologous proteins on the bacterial cell surface normally requires the fusion of the protein with a surface protein, called a scaffold.
=== Type II Diabetes === Patients with Type II diabetes will have elevated glucagon levels during a fast and after eating. These elevated glucagon levels over stimulate the liver to undergo gluconeogenesis, leading to elevated blood glucose levels. Consistently high blood glucose levels can lead to organ damage, neuropathy, blindness, cardiovascular issues and bone and joint problems. It is not entirely clear why glucagon levels are so high in patients with Type II diabetes. One theory is that the alpha cells have become resistant to the inhibitory effects of glucose and insulin and do not respond properly to them. Another theory is that nutrient stimulation of the gastrointestinal tract, thus the secretion of gastric inhibitory polypeptide and Glucagon-like peptide-1, is a very important factor in the elevated secretion of glucagon.
== Neurons == The PVN contains magnocellular neurosecretory cells whose axons extend into the posterior pituitary, parvocellular neurosecretory cells that project to the median eminence, ultimately signalling to the anterior pituitary, and several populations of other cells that project to many different brain regions including parvocellular preautonomic cells that project to the brainstem and spinal cord.
A mammary gland is an exocrine gland that produces milk in mammals, including humans. Mammals get their name from the Latin word mamma, "breast". The mammary glands are arranged in organs such as the breasts in primates (for example, humans and chimpanzees), the udder in ruminants (for example, cows, goats, sheep, and deer), and the dugs of other animals (for example, dogs, cats, rabbits and pigs) to feed young offspring. Lactorrhea, the occasional production of milk by the glands, can occur in any mammal, but in most mammals, lactation, the production of enough milk for nursing, occurs only in phenotypic females who have gestated in recent months or years. It is directed by hormonal guidance from sex steroids. In a few mammalian species, male lactation can occur. With humans, male lactation can occur only under specific circumstances. Mammals are divided into 3 groups: monotremes, metatherians, and eutherians. In the case of monotremes, their mammary glands are modified sebaceous glands and without nipples. Concerning most metatherians and eutherians, only females have functional mammary glands, with the exception of some bat species. Their mammary glands can be termed as breasts or udders. In the case of breasts, each mammary gland has its own nipple (e.g., human mammary glands). In the case of udders, pairs of mammary glands comprise a single mass, with more than one nipple (or teat) hanging from it.
Sources: en.wikipedia.org
The regulation of proline biosynthesis can depend on the initial controlling step through negative feedback inhibition. In E. coli, proline allosterically inhibits Glutamate 5-kinase which catalyzes the reaction from L-glutamate to an unstable intermediate L-γ-Glutamyl phosphate. Arginine synthesis also utilizes negative feedback as well as repression through a repressor encoded by the gene argR. The gene product of argR, ArgR an aporepressor, and arginine as a corepressor affect the operon of arginine biosynthesis. The degree of repression is determined by the concentrations of the repressor protein and corepressor level.
Finite strain theory, also called large strain theory, large deformation theory, deals with deformations in which both rotations and strains are arbitrarily large. In this case, the undeformed and deformed configurations of the continuum are significantly different and a clear distinction has to be made between them. This is commonly the case with elastomers, plastically-deforming materials and other fluids and biological soft tissue. Infinitesimal strain theory, also called small strain theory, small deformation theory, small displacement theory, or small displacement-gradient theory where strains and rotations are both small. In this case, the undeformed and deformed configurations of the body can be assumed identical. The infinitesimal strain theory is used in the analysis of deformations of materials exhibiting elastic behavior, such as materials found in mechanical and civil engineering applications, e.g. concrete and steel. Large-displacement or large-rotation theory, which assumes small strains but large rotations and displacements.
Healthcare in Canada is delivered through the provincial and territorial systems of publicly funded health care, informally called Medicare. It is guided by the provisions of the Canada Health Act of 1984 and is universal. Universal access to publicly funded health services "is often considered by Canadians as a fundamental value that ensures national healthcare insurance for everyone wherever they live in the country". Around 30 percent of Canadians' healthcare is paid for through the private sector. This mostly pays for services not covered or partially covered by Medicare, such as prescription drugs, dentistry and optometry. Approximately 65 to 75 percent of Canadians have some form of supplementary health insurance; many receive it through their employers or access secondary social service programs.
== Art == Although some historians dates the start of the trepang industry to 1720, Regina Ganter of Griffith University suggests that the start of the industry may be around 1640. Artistic evidence, like the Arnhem land rock, also suggests that contact may go as far back as the 1500s. The land rock depicts the extensive boat voyages that spanned thousands of miles around the Australian cost line. The north-west monsoon, which arrived each December, also dictated the semi-permanent locations where the Makassan people would settle. These images likely contribute to narrative stories, which are associated with the ancestral story telling tradition of the indigenous people of Arnhem Land. Artist Nandabitta Maminyamandja (1911 - 1981) of the Anindilyakwa people painted Macassan prau and trepang curing in 1974. This work is natural pigments on eucalyptus bark and is now on display in the National Gallery of Australia. The subject matter includes the communication that the trepanging industry fostered, most importantly early trade interactions. In 1883, the trepanging trade started to decline with the South Australian governments implementation of the trepanging license. Trepanging-related art work was consistent with the influx of missionaries into the area, as there was a greater demand for secular stories. The missionaries did not encourage the production of ceremonial stories, and they established clear regulations around the subject matter that was depicted and distributed.
=== Pigments and chloroplast colors === Inside the photosystems embedded in chloroplast thylakoid membranes are various photosynthetic pigments, which absorb and transfer light energy. The types of pigments found are different in various groups of chloroplasts, and are responsible for a wide variety of chloroplast colorations. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photosynthesis.
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.
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.