This is a working overview of Pro-Gly-Pro, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
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.
| 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 |
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.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
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.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
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.
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.
== Aquaculture == In aquaculture, microbubble aerators have been used to maintain elevated dissolved oxygen concentrations in fish and shrimp culture systems. Studies have reported improved fish growth performance, reduced stress, and altered microbial community composition in pond and recirculating aquaculture systems treated with microbubble or nanobubble aeration compared with conventional aeration.
== Examples of GxPs == Good agricultural and collection practices, or GACP(s) Good agricultural practice, or GAP Good auditing practice, or GAP Good automated laboratory practice, or GALP Good automated manufacturing practice, or GAMP Good business practice, or GBP Good cell culture practice, or GCCP Good clinical data management practice, or GCDMP Good clinical laboratory practice, or GCLP Good clinical practice, or GCP Good documentation practice, or GDP, or GDocP (to distinguish from "good distribution practice") Good distribution practice, or GDP Good engineering practice, or GEP Good financial practice, or GFP Good guidance practice, or GGP Good hygiene practice, or GHP Good laboratory practice, or GLP Good machine learning practice, or GMLP Good management practice, or GMP Good manufacturing practice, or GMP Good microbiological practice, or GMiP Good participatory practice, or GPP Good pharmacovigilance practice, or GPvP or even GVP Good pharmacy practice, or GPP Good policing practice, or GPP Good recruitment practice, or GRP Good research practice, or GRP Good safety practice, or GSP Good storage practice, or GSP Good tissue practice, or GTP
DMF is effective at separating and suspending carbon nanotubes, and is recommended by the NIST for use in near infrared spectroscopy of such. DMF can be utilized as a standard in proton NMR spectroscopy allowing for a quantitative determination of an unknown compound. In the synthesis of organometallic compounds, it is used as a source of carbon monoxide ligands. DMF is a common solvent used in electrospinning. DMF is commonly used in the solvothermal synthesis of metal–organic frameworks. DMF-d7 in the presence of a catalytic amount of potassium tert-butoxide under microwave heating is a reagent for deuteration of polyaromatic hydrocarbons.
=== Protocol example === A ZooMS protocol (Fig. 1) typically consists of an extraction, denaturation, digestion and filtration step, followed by mass spectrometric analysis. Various destructive and non-destructive extraction protocols have already been discussed in some detail above. The key is to extract the protein preserved in the sample and then bring it into solution, usually an ammonium bicarbonate buffer. Denaturation is done to unfold the proteins and make them more accessible for the enzymatic digestion. It is done by heating the solubilised sample at around 65 °C. Then an enzyme, trypsin, is added to the solution. Trypsin cleaves the protein after every arginine or lysine amino acid in its sequence, resulting in peptide fragments of predictable masses. After digestion the sample is filtered with C18 filters to get rid of non-proteinaceous material and the sample is now ready for mass spectrometric analysis, which for ZooMS generally means MALDI-TOF MS.
Sources: en.wikipedia.org
=== Neurological === Chronic headaches are common in patients with Ehlers–Danlos syndrome, whether related to dysautonomia, temporomandibular joint dysfunction (TMD), muscle tension, tethered cord syndrome, craniocervical instability, and alantoaxial instability. Arnold–Chiari malformation is also more frequently found in patients with EDS because of the instability at the juncture between skull and spine. This causes herniation of the posterior fossa below the foramen magnum. Ligaments in the neck are unable to heal properly, so the neck structure cannot support the skull, which can then sink into the brainstem, blocking the flow of cerebrospinal fluid, which in turn causes autonomic dysfunction. Increased pressure created by the malformation can lead to a flattened pituitary gland, hormone changes, sudden severe headaches, ataxia, and poor proprioception. Ophthalmological manifestations include nearsightedness, retinal tearing and retinal detachment, keratoconus, blue sclera, dry eye, Sjogren's syndrome, lens subluxation, angioid streaks, epicanthal folds, strabismus, corneal scarring, brittle cornea syndrome, cataracts, carotid-cavernous sinus fistulas, and macular degeneration. Otological complications may also occur. Hearing loss is common, both conductive and sensorineural, and is most often bilateral. Otosclerosis and instability of the bones in the inner ear may also contribute to hearing loss.
The wound-healing process is not only complex but fragile, and it is susceptible to interruption or failure leading to the formation of non-healing chronic wounds. Factors that contribute to non-healing chronic wounds are diabetes, venous or arterial disease, infection, and metabolic deficiencies of old age. Wound care encourages and speeds wound healing via cleaning and protection from reinjury or infection. Depending on each patient's needs, it can range from the simplest first aid to entire nursing specialties such as wound, ostomy, and continence nursing and burn center care.
=== Reactivity === Thorium is a highly reactive and electropositive metal. With a standard reduction potential of −1.90 V for the Th4+/Th couple, it is somewhat more electropositive than zirconium or aluminium. Finely divided thorium metal can exhibit pyrophoricity, spontaneously igniting in air. When heated in air, thorium turnings ignite and burn with a brilliant white light to produce the dioxide. In bulk, the reaction of pure thorium with air is slow, although corrosion may occur after several months; most thorium samples are contaminated with varying degrees of the dioxide, which greatly accelerates corrosion. Such samples slowly tarnish, becoming grey and finally black at the surface. At standard temperature and pressure, thorium is slowly attacked by water, but does not readily dissolve in most common acids, with the exception of hydrochloric acid, where it dissolves leaving a black insoluble residue of ThO(OH,Cl)H. It dissolves in concentrated nitric acid containing a small quantity of catalytic fluoride or fluorosilicate ions; if these are not present, passivation by the nitrate can occur, as with uranium and plutonium.
Sources: en.wikipedia.org
== Awards and honors == 1988-1990 - Wentink Award for Graduate Student of the Year, Cornell University 1991-1992 - Alexander von Humboldt Fellowship for Study in Germany 1997 - NIH First Award 1998 - NSF Career Award 1998 - Eli Lilly Young Investigator Grantee 1999 - DuPont Young Investigator Award 1999 - Camille Dreyfus Teacher-Scholar Award 2000 - Alfred Sloan Foundation Fellow 2002 - Merck Faculty Development Award 2003-2004 - John Simon Guggenheim Memorial Fellow 2017 - ACS Maryland Chemist of the Year
== Latent TGF-β complex == All three TGF-βs are synthesized as precursor molecules containing a propeptide region in addition to the TGF-β homodimer. After it is synthesized, the TGF-β homodimer interacts with a latency-associated peptide (LAP), a protein derived from the N-terminal region of the TGF-β gene product, forming a complex called small latent complex (SLC). This complex remains in the cell until it is bound by another protein called Latent TGF-β-Binding Protein (LTBP), forming a larger complex called large latent complex (LLC). It is this LLC that gets secreted to the extracellular matrix (ECM). In most cases, before the LLC is secreted, the TGF-β precursor is cleaved from the propeptide but remains attached to it by noncovalent bonds. After its secretion, it remains in the extracellular matrix as an in activated complex containing both the LTBP and the LAP which need to be further processed in order to release active TGF-β. The attachment of TGF-β to the LTBP is by disulfide bond which allows it to remain inactive by preventing it from binding to its receptors . Because different cellular mechanisms require distinct levels of TGF-β signaling, the inactive complex of this cytokine gives opportunity for a proper mediation of TGF-β signaling. There are four different LTBP isoforms known, LTBP-1, LTBP-2, LTBP-3 and LTBP-4. Mutation or alteration of LAP or LTBP can result in improper TGF-β signaling. Mice lacking LTBP-3 or LTBP-4 demonstrate phenotypes consistent to phenotypes seen in mice with altered TGF-β signaling.
Homologous sequences are orthologous if they are inferred to be descended from the same ancestral sequence separated by a speciation event: when a species diverges into two separate species, the copies of a single gene in the two resulting species are said to be orthologous. Orthologs, or orthologous genes, are genes in different species that originated by vertical descent from a single gene of the last common ancestor. The term "ortholog" was coined in 1970 by the molecular evolutionist Walter Fitch. For instance, the plant Flu regulatory protein is present both in Arabidopsis (multicellular higher plant) and Chlamydomonas (single cell green algae). The Chlamydomonas version is more complex: it crosses the membrane twice rather than once, contains additional domains and undergoes alternative splicing. However, it can fully substitute the much simpler Arabidopsis protein, if transferred from algae to plant genome by means of genetic engineering. Significant sequence similarity and shared functional domains indicate that these two genes are orthologous genes, inherited from the shared ancestor. Orthology is strictly defined in terms of ancestry. Given that the exact ancestry of genes in different organisms is difficult to ascertain due to gene duplication and genome rearrangement events, the strongest evidence that two similar genes are orthologous is usually found by carrying out phylogenetic analysis of the gene lineage. Orthologs often, but not always, have the same function.
The father tongue hypothesis proposes the idea that humans tend to speak their father's language. The hypothesis is based on a 1997 proposal that linguistic affiliation correlates more closely with Y-chromosomal variation than with mitochondrial DNA variation. The initial work was performed on African and European samples by a team of population geneticists, led by Laurent Excoffier. On the basis of these, and similar findings by other geneticists, the hypothesis was elaborated by the Dutch historical linguist George van Driem in 2010 that the teaching by a mother of her spouse's tongue to her children is a mechanism by which language has preferentially been spread over time. Focusing on prehistoric language shift in already settled areas, examples worldwide show that as little as 10–20% of prehistoric male immigration can (but need not) cause a language switch, indicating an elite imposition such as may have happened with the appearance of the first farmers or metalworkers in the Neolithic, Bronze and Iron Ages.
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.
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.