heptapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-06-04. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| 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 |
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.
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.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
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 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.
==== Deficit in spatial learning ==== In 1998, Giese and colleagues studied knockout mice that have been genetically engineered to prevent CaMKII autophosphorylation. They observed that mice had trouble finding the hidden platform in the Morris water maze task. The Morris water maze task is often used to represent hippocampus-dependent spatial learning. The mice's inability to find the hidden platform implies deficits in spatial learning. However, these results were not entirely conclusive because memory formation deficit could also be associated with sensory motor impairment resulting from genetic alteration.
Mixing red, green, and blue sources to produce white light needs electronic circuits to control the blending of the colors. Since LEDs have slightly different emission patterns, the color balance may change depending on the angle of view, even if the RGB sources are in a single package, so RGB diodes are seldom used to produce white lighting. Nonetheless, this method has many applications because of the flexibility of mixing different colors, and in principle, this mechanism also has higher quantum efficiency in producing white light. There are several types of multicolor white LEDs: di-, tri-, and tetrachromatic white LEDs. Several key factors that play among these different methods include color stability, color rendering capability, and luminous efficacy. Often, higher efficiency means lower color rendering, presenting a trade-off between the luminous efficacy and color rendering. For example, the dichromatic white LEDs have the best luminous efficacy (120 lm/W), but the lowest color rendering capability. Although tetrachromatic white LEDs have excellent color rendering capability, they often have poor luminous efficacy. Trichromatic white LEDs are in between, having both good luminous efficacy (>70 lm/W) and fair color rendering capability. One of the challenges is the development of more efficient green LEDs. The theoretical maximum for green LEDs is 683 lumens per watt, but as of 2010 few green LEDs exceed even 100 lumens per watt. The blue and red LEDs approach their theoretical limits. Multicolor LEDs offer a means to form light of different colors.
In Russia, Acting Governor of Kursk Oblast, Alexei Smirnov, claimed that drone attacks caused fires in two districts, including at an oil depot in Polevaya, Kursk Oblast. Smirnov wrote on Telegram that three storage tanks caught fire, requiring 82 firefighters and 32 units of equipment. Another two drones were reported shot down over the oblast by the defence ministry. Smirnov claimed that falling debris damaged residential buildings and injured one person. The fires were detected by NASA's FIRMS.
=== Ears === Some people find whispering or breathing softly in the ear to be pleasurable and relaxing, as well as licking, biting, caressing and/or kissing it especially the area of and behind the earlobe.
Sources: en.wikipedia.org
== Early years == Of German descent, Christopher Richard Stein was born on 4 January 1947 in Churchill, Oxfordshire, to Eric Stein (1908–1965) and Dorothy Gertrude née Jackson (1909–1999). He was born and brought up on a farm. Stein was educated at Wells Court, a preparatory school just outside Tewkesbury, then Wells House, the Court's bigger sister-school at Malvern Wells, and then Uppingham School. He took A-levels in English, history and geography, but failed all of them. He moved to a cram school in Brighton, gaining E grades in English and history. Stein partially completed a hotel management traineeship with British Transport Hotels at its Great Western Royal Hotel in Paddington. He worked there as a chef for six months. Distraught by his father's suicide, at age 19 he went to Australia, where he worked as a labourer in an abattoir and as a clerk in a naval dockyard. To "take some time out" he travelled to New Zealand, where he picked asparagus, and Mexico. His 21st birthday was spent in Kaikōura, New Zealand, where he ate a rock lobster and slept under a bridge. Being on his own, he read widely, reflected on his attitude to education, and applied successfully to New College, Oxford, where he earned an English degree in 1971. Shortly after that, he moved to Padstow.
=== Peptide nucleic acids (PNA) === Peptide nucleic acids are synthetic oligonucleotides that resist protease degradation and are used to induce repair at site-specific triplex formation regions on DNA genomic sites. PNAs are able to bind with high affinity and sequence specificity to a complementary DNA sequence through Watson-Crick base-pairing and are able to form triple helices through parallel orientation Hoogsteen bonds, with the PNA facing the 5'-end of the DNA strand. The PNA-DNA triplex is stable because PNAs consist of a neutrally charged pseudopeptide backbone which binds to the double stranded DNA (dsDNA) sequence. Similar to homopyrimidine in TFOs, homopyrimidine in PNAs is able to form a bond with the complementary homopurine in the target sequence of dsDNA. These DNA analogues are able to bind to dsDNA by exploiting ambient DNA conditions and different predicting modes of recognition. This is different from TFOs which bind though the major groove recognition of the dsDNA. One of the predicting modes of recognition used for recognition is through a duplex invasion. Within mixed A–T/G–C dsDNA sequence is targeted by a pair of pseudo-complementary (pc) PNAs which are able to bind to dsDNAs via double invasion through the simultaneous formation of diaminopurine (D) and thiouracil (Us) which substitute for adenine and thymine, respectively. The pc PNA pair form a D-T and Us -A and G-C or C-G Watson-Crick paired PNA-DNA helix with each of complementary DNA strands.
Clinical trials of isotretinoin, etidronate with oral corticosteroids, and perhexiline maleate have failed to demonstrate effectiveness, though the variable course of the disease and small prevalence induces uncertainty. A handful of pharmaceutical companies focused on rare diseases are currently in varying stages of investigation into different therapeutic approaches for FOP. In August 2015, the U.S. Food and Drug Administration (FDA) Office of Orphan Products Development granted La Jolla Pharmaceuticals orphan drug designation for two novel compounds for FOP. The compounds are small-molecule protein kinase inhibitors designed to selectively block ACVR1 (ALK2). In August 2015, Clementia Pharmaceuticals began the enrollment of children (ages 6 and above) into its Phase II clinical trial investigating palovarotene for the treatment of FOP. Preclinical studies demonstrated that palovarotene, a retinoic acid receptor gamma agonist, blocked abnormal bone formation in animal models by inhibition of secondary messenger systems in the BMP pathway. Clementia licensed palovarotene from Roche Pharmaceuticals, which previously evaluated the compound in more than 800 individuals including healthy volunteers and patients with chronic obstructive pulmonary disease. Palovarotene received Fast Track designation from the FDA and orphan designations for the treatment of FOP from both the FDA and the European Medicines Agency (EMA). In the pivotal phase 3 MOVE trial published in 2023, Sohonos was shown to reduce new heterotropic ossification by 54-60%.
Sources: en.wikipedia.org
== Availability in foods and supplements == Lithium ascorbate can be found some dietary supplements with varying doses - from 200 mcg/tab up to 5000 mcg/tab of elemental lithium. Attempts are being made to include lithium ascorbate in premixes for animals (in doses of 5–10 mg/kg of body weight) in order to prevent the negative impact of stresses of various etiologies, to increase the intensity of growth and safety of farm animals and poultry.
Extinct dinosaurs, as well as modern birds, include genera that are herbivorous and others carnivorous, including seed-eaters, fish-eaters, insectivores, and omnivores. While dinosaurs were ancestrally bipedal (as are all modern birds), some evolved into quadrupeds, and others, such as Anchisaurus and Iguanodon, could walk as easily on two or four legs. Cranial modifications like horns and crests are common dinosaurian traits, and some extinct species had bony armor. Although the best-known genera are remarkable for their large size, many Mesozoic dinosaurs were human-sized or smaller, and modern birds are generally small in size. Dinosaurs today inhabit every continent, and fossils show that they had achieved global distribution by the Early Jurassic epoch at latest. Modern birds inhabit most available habitats, from terrestrial to marine, and there is evidence that some non-avian dinosaurs (such as Microraptor) could fly or at least glide, and others, such as spinosaurids, had semiaquatic habits.
Similarly to gas chromatography MS (GC-MS), liquid chromatography-mass spectrometry (LC/MS or LC-MS) separates compounds chromatographically before they are introduced to the ion source and mass spectrometer. It differs from GC-MS in that the mobile phase is liquid, usually a mixture of water and organic solvents, instead of gas. Most commonly, an electrospray ionization source is used in LC-MS. Other popular and commercially available LC-MS ion sources are atmospheric pressure chemical ionization and atmospheric pressure photoionization. There are also some newly developed ionization techniques like laser spray.
The relationship between Druze and Christians in the region, especially during Druze-Maronite conflicts in the Lebanese Civil War (1975–1990), did not adversely affect the peaceful coexistence between Druze and Christians in Galilee. Rare exceptions include incidents such as the one on April 11, 1981, when a soccer match between two neighboring Arab towns escalated into violence. Kafr Yasif, predominantly Christian, played against Julis, predominantly Druze. A brawl among fans resulted in the deaths of a teenager from each town. Subsequently, residents of Julis retaliated with attacks on Kafr Yasif in the days following the match. Another sectarian incident occurred in 2005, when Druze attacked Christians in Maghar following rumors that some Christian youths had created and shared photo images of Druze girls depicted as nude models on the internet. However, clashes between the two communities are rare. Christian shops, vehicle, house and the church were vandalized. The clashes forced around 2,000 of the Christians to flee their homes. However, a police investigation revealed that a Druze youth had spread lies to his friends about the pictures, leading to the escalation of tensions. Dan Ronen the commander of Northern District commander called the violence "a pogrom". According to Jack Khoury, the clash in Maghar may stem from animosity between the wealthier Christian population and the poorer Druze.
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.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.