Pro-Gly-Pro is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-08-13. Numbers and descriptions here follow the published literature rather than marketing material.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
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.
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.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
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.
Arg Pro Lys Pro Gln Gln Phe Phe Gly Leu Met (RPKPQQFFGLM) with an amide group at the C-terminus. Substance P is released from the terminals of specific sensory nerves. It is found in the brain and spinal cord and is associated with inflammatory processes and pain.
Novich, wrote: "Trainers of the old school who supplied treatments which had cocaine as their base declared with assurance that a rider tired by a six-day race would get his second breath after absorbing these mixtures." John Hoberman, a professor at the University of Texas in Austin, Texas, said six-day races were "de facto experiments investigating the physiology of stress as well as the substances that might alleviate exhaustion."
The International Union of Pure and Applied Chemistry (IUPAC) recommends the use of numeric prefixes to indicate the position of substituents, generally by identifying the parent hydrocarbon chain and assigning the carbon atoms based on their substituents in order of precedence. For example, there are at least two isomers of the linear form of pentanone, a ketone that contains a chain of exactly five carbon atoms. There is an oxygen atom bonded to one of the middle three carbons (if it were bonded to an end carbon, the molecule would be an aldehyde, not a ketone), but it is not clear where it is located. In this example, the carbon atoms are numbered from one to five, which starts at one end and proceeds sequentially along the chain. Now the position of the oxygen atom can be defined as on carbon atom number two, three or four. However, atoms two and four are exactly equivalent - which can be shown by turning the molecule around by 180 degrees. The locant is the number of the carbon atom to which the oxygen atom is bonded. If the oxygen is bonded to the middle carbon, the locant is 3. If the oxygen is bonded to an atom on either side (adjacent to an end carbon), the locant is 2 or 4; given the choice here, where the carbons are exactly equivalent, the lower number is always chosen. So the locant is either 2 or 3 in this molecule.
=== Incompressible isotropic case === For an incompressible and isotropic Newtonian fluid in laminar flow only in the direction x (i.e. where viscosity is isotropic in the fluid), the shear stress is related to the strain rate by the simple constitutive equation
A vascular plant begins from a single celled zygote, formed by fertilisation of an egg cell by a sperm cell. From that point, it begins to divide to form a plant embryo through the process of embryogenesis. As this happens, the resulting cells will organise so that one end becomes the first root, while the other end forms the tip of the shoot. In seed plants, the embryo will develop one or more "seed leaves" (cotyledons). By the end of embryogenesis, the young plant will have all the parts necessary to begin in its life. Once the embryo germinates from its seed or parent plant, it begins to produce additional organs (leaves, stems, and roots) through the process of organogenesis. New roots grow from root meristems located at the tip of the root, and new stems and leaves grow from shoot meristems located at the tip of the shoot. Branching occurs when small clumps of cells left behind by the meristem, and which have not yet undergone cellular differentiation to form a specialised tissue, begin to grow form the tip of a new root or shoot. Growth from any such meristem at the tip of a root or shoot is termed primary growth and results in the lengthening of that root or shoot. Secondary growth results in widening of a root or shoot from divisions of cells in a cambium. In addition to growth by cell division, a plant may grow through cell elongation. This occurs when individual cells or groups of cells grow longer. Not all plant cells will grow to the same length.
Sources: en.wikipedia.org
=== Other GLUT proteins === There are 14 total GLUT proteins separated into 3 classes based on sequence similarities. Class 1 consists of GLUT 1-4 and 14, class 2 contains GLUT 5, 7, 9 and 11, and class 3 has GLUT 6, 8, 10, 12 and 13. Although there are some sequence differences between all GLUT proteins, they all have some basic structural components. For example, both the N and C termini in GLUT proteins are exposed to the cytoplasm of the cell, and they all have 12 transmembrane segments.
== Function == Actin's primary role in the cell is to form linear polymers called microfilaments that serve various functions in the cell's structure, trafficking networks, migration, and replication. The multifaceted role of actin relies on a few of the microfilaments' properties: First, the formation of actin filaments is reversible, and their function often involves undergoing rapid polymerization and depolymerization. Second, microfilaments are polarized – i.e. the two ends of a filament are distinct from one another. Third, actin filaments can bind to many other proteins, which together help modify and organize microfilaments for their diverse functions. In most cells actin filaments form larger-scale networks which are essential for many key functions:
=== Experimental or banned methods === Photodynamic therapy for hair removal (experimental) X-ray hair removal is an efficient, and usually permanent, hair removal method, but also causes severe health problems, occasional disfigurement, and even death. It is illegal in the United States.
The Mediterranean seeps appear to represent a rich habitat characterized by megafauna species richness (e.g., gastropods) or the exceptional size of some species such as sponges (Rhizaxinella pyrifera) and crabs (Chaceon mediterraneus), compared with their background counterparts. This contrasts with the low macro- and mega-faunal abundance and diversity of the deep eastern Mediterranean. Seep communities in the Mediterranean that include endemic chemosynthetic species and associated fauna differ from the other known seep communities in the world at the species level but also by the absence of the large-size bivalve genera Calyptogena or Bathymodiolus. The isolation of the Mediterranean seeps from the Atlantic Ocean after the Messinian crisis led to the development of unique communities, which are likely to differ in composition and structure from those in the Atlantic Ocean. Further expeditions involved quantitative sampling of habitats in different areas, from the Mediterranean Ridge to the eastern Nile deep-sea fan. Cold seeps discovered in the Sea of Marmara in 2008 have also revealed chemosynthesis-based communities that showed a considerable similarity to the symbiont-bearing fauna of eastern Mediterranean cold seeps.
Sources: en.wikipedia.org
=== MOT === MOT is a measure of how many million sperm cells per ml are highly motile, that is, approximately of grade a (>25 micrometer per 5 sek. at room temperature) and grade b (>25 micrometer per 25 sek. at room temperature). Thus, it is a combination of sperm count and motility. With a straw or a vial volume of 0.5 milliliter, the general guideline is that, for intracervical insemination (ICI), straws or vials making a total of 20 million motile spermatozoa in total is recommended. This is equal to 8 straws or vials 0.5 mL with MOT5, or 2 straws or vials of MOT20. For intrauterine insemination (IUI), 1–2 MOT5 straws or vials is regarded sufficient. In WHO terms, it is thus recommended to use approximately 20 million grade a+b sperm in ICI, and 2 million grade a+b in IUI.
Pyrolysis is the basis of several methods for producing fuel from biomass, i.e. lignocellulosic biomass. Crops studied as biomass feedstock for pyrolysis include native North American prairie grasses such as switchgrass and bred versions of other grasses such as Miscantheus giganteus. Other sources of organic matter as feedstock for pyrolysis include greenwaste, sawdust, waste wood, leaves, vegetables, nut shells, straw, cotton trash, rice hulls, and orange peels. Animal waste including poultry litter, dairy manure, and potentially other manures are also under evaluation. Some industrial byproducts are also suitable feedstock including paper sludge, distillers grain, and sewage sludge. In the biomass components, the pyrolysis of hemicellulose happens between 210 and 310 °C. The pyrolysis of cellulose starts from 300 to 315 °C and ends at 360–380 °C, with a peak at 342–354 °C. Lignin starts to decompose at about 200 °C and continues until 1000 °C. Synthetic diesel fuel by pyrolysis of organic materials is not yet economically competitive. Higher efficiency is sometimes achieved by flash pyrolysis, in which finely divided feedstock is quickly heated to between 350 and 500 °C (660 and 930 °F) for less than two seconds. Syngas is usually produced by pyrolysis. The low quality of oils produced through pyrolysis can be improved by physical and chemical processes, which might drive up production costs, but may make sense economically as circumstances change.
== See also == Ergine (lysergic acid amide; LSA; lysergamide) Aztec use of entheogens § Ololiuqui and Tlitliltzin Morning glory § Chemistry and ethnobotany List of entheogens List of psychoactive plants
=== Ultrasound === Hepatomegaly is consistently identified with an abdominal ultrasound; however, it is also commonly found in diabetic cats without hypersomatotropism. Other findings from an abdominal ultrasound include: renomegaly, pelvic dilation, an enlarged pancreas, splenomegaly and bilateral adrenomegaly. The size of the adrenal glands can be useful in diagnosis, studies have found that the size of the adrenal gland in diabetic cats without hypersomatotropism does not differ significantly from non-diabetic cats; however, adrenomegaly is not pathognomonic to hypersomatotropism and can occur with other conditions in cats such as pituitary-dependent hypercortisolism.
== Polymyositis as a distinct diagnosis == The discovery of several myositis-specific autoantibodies during the past decades has enabled the description of other discrete subsets of diagnosis, specifically the discovery of Antisynthetase syndrome in reducing the number of diagnoses of polymyositis.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.