The short version of Heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-10-15. 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. 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.
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.
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 |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
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.
This group, named after the Ivuna meteorite (Tanzania), have chemical compositions that are close to that measured in the solar photosphere (aside from gaseous elements, and elements such as lithium which are underrepresented in the Sun's photosphere by comparison to their abundance in CI chondrites). In this sense, they are chemically the most primitive known meteorites. CI chondrites typically contain a high proportion of water (up to 22%), and organic matter in the form of amino acids and PAHs. Aqueous alteration promotes a composition of hydrous phyllosilicates, magnetite, and olivine crystals occurring in a black matrix, and a possible lack of chondrules. It is thought they have not been heated above 50 °C (122 °F), indicating that they condensed in the cooler outer portion of the solar nebula. Five CI chondrites have been observed to fall: Ivuna, Orgueil, Alais, Tonk, and Revelstoke. Four others have been found by Japanese field parties in Antarctica. In general, the extreme fragility of CI chondrites causes them to be highly susceptible to terrestrial weathering, and they do not survive on Earth's surface for long after they fall.
=== Policies === Out of office Heseltine called for money, including the receipts from council house sales, to be spent on infrastructure investment instead of tax cuts. He also called for reductions in tax relief on mortgage interest payments and pension contributions, in the hope of encouraging investment into industry rather than into property and finance, echoing views being promoted by Will Hutton at the time. Heseltine also took an interest in the reduction of long-term unemployment, advocating Swedish-style Workfare. A pamphlet by Richard Layard on the topic would have been published under Heseltine's name had it not been for his return to government at the end of 1990. Several of Heseltine's advisers at this time were SDP supporters, and in some cases later defected to Labour; Crick commented (in 1997) that Heseltine's views at this time were very similar to those later advocated by Tony Blair's New Labour.
Dithiothreitol (DTT) is an organosulfur compound with the formula (CH(OH)CH2SH)2. A colorless compound, it is classified as a dithiol and a diol. DTT is redox reagent also known as Cleland's reagent, after W. Wallace Cleland. The reagent is commonly used in its racemic form. Its name derives from the four-carbon sugar, threose. DTT has an epimeric ('sister') compound, dithioerythritol (DTE).
Sources: en.wikipedia.org
He also holds patents for several processes he has developed. Ajayaghosh is associated with several science journals around the world. He is an associate editor of Physical Chemistry Chemical Physics (PCCP), published by the Royal Society of Chemistry and a senior editor of the Bulletin of the Chemical Society of Japan. He is a former member of the advisory board of RSC Advances and sits in the editorial board of Chemistry: An Asian Journal. He has also guided several master's and doctoral scholars in their studies and has been involved in programs for the popularization of science and science awareness campaigns.
Panic disorder with or without agoraphobia. Body dysmorphic disorder Repetitive self-injurious/self-harming behaviours in those with intellectual disability specifically. The subtype of systemised paranoia characterised by somatic phenomena. Compulsive nail-biting (onychophagia). Cataplexy associated with narcolepsy. This is a TGA and MHRA-labeled indication for clomipramine. Self-bloodletting Premature ejaculation, where it may be more effective than paroxetine Depersonalization-derealization disorder Chronic pain with or without organic disease, particularly headache of the tension type. Developmental stuttering Sleep paralysis, with or without narcolepsy Enuresis (involuntary urinating in sleep) in children. The effect may not be sustained following treatment, and alarm therapy may be more effective in both the short-term and the long-term. Combining a tricyclic (such as clomipramine) with anticholinergic medication may be more effective for treating enuresis than the tricyclic alone. Trichotillomania In combination with lithium and tryptophan for severe, particularly treatment-resistant depression. This combination, in a similar vein, has also been used for clomipramine-resistant obsessive-compulsive disorder. When electro-convulsive therapy is performed alongside this treatment-regime (as may be the case in severe depression and accompanied with thyroxine,) however, great care must be taken with lithium. The overall risk of seizures may have to be weighted against the refractory severity of the current illness and necessity of the amalgamation of treatment(s).
== Connection and treatment of autism == Effective therapies to manage autism remain scarce. According to the exorphin theory of autism, an increase in the levels of exorphin is linked to symptoms of autism. Based on this concept, experiments have attempted to reduce the symptoms of autism by using large amounts of protease to break down exorphins before they are absorbed. Experiments have also attempted to enhance and utilize enzymes existing in the gut to break down exorphins in a similar fashion, since the production of exorphins within the gut is inevitable.
Different views (also known as projections) of the chest can be obtained by changing the relative orientation of the body and the direction of the x-ray beam. The most common views are posteroanterior, anteroposterior, and lateral. In a posteroanterior (PA) view, the x-ray source is positioned so that the x-ray beam enters through the posterior (back) aspect of the chest and exits out of the anterior (front) aspect, where the beam is detected. To obtain this view, the patient stands facing a flat surface behind which is an x-ray detector. A radiation source is positioned behind the patient at a standard distance (most often 6 feet, 1,8m), and the x-ray beam is fired toward the patient. In anteroposterior (AP) views, the positions of the x-ray source and detector are reversed: the x-ray beam enters through the anterior aspect and exits through the posterior aspect of the chest. AP chest x-rays are harder to read than PA x-rays and are therefore generally reserved for situations where it is difficult for the patient to get an ordinary chest x-ray, such as when the patient is bedridden. In this situation, mobile X-ray equipment is used to obtain a lying down chest x-ray (known as a "supine film"). As a result, most supine films are also AP. Lateral views of the chest are obtained in a similar fashion as the posteroanterior views, except in the lateral view, the patient stands with both arms raised and the left side of the chest pressed against a flat surface.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
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.