A practical reference on Pro-Gly-Pro: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-08-19. Anything still debated is marked as such rather than presented as settled.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
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.
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.
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.
Octopuses are generally predatory and feed on prey such as crustaceans, bivalves, gastropods, fish, and other cephalopods, including members of the same species. Major items in the diet of the giant Pacific octopus include bivalves such as the cockle Clinocardium nuttallii, clams and scallops and crustaceans such as crabs. It typically rejects moon snails because they are too large; limpets, rock scallops, chitons and abalone, because they are too securely fixed to the rock. Small cirrate octopuses such as those of the genera Grimpoteuthis and Opisthoteuthis typically prey on polychaetes, copepods, amphipods and isopods. Octopuses typically locate prey by feeling through their environment; some species hide and ambush their target. When prey tries to escape, the octopus jets after it. Octopuses may drill into the shells of crustaceans, bivalves and gastropods. It used to be thought that drilling was done by the radula, but it has now been shown that minute teeth at the tip of the salivary papilla are involved, and an enzyme in the toxic saliva is used to dissolve the calcium carbonate of the shell. This can take hours and once the shell is penetrated, the prey dies almost instantaneously. With crabs, tough-shelled species are more likely to be drilled, and soft-shelled crabs are torn apart. Some species have other modes of feeding. Grimpoteuthis either lacks or has a small radula and swallows prey whole.
aureus, it is suggested by many public health institutions, including the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC), to treat first with empirical therapies for S. aureus, with an emphasis on evaluating the response to initial treatment and laboratory diagnostic techniques to isolate cases of drug resistance. Due to the possibility of potential severe or fatal consequences of resistant strains, initial treatment often includes concomitant administration of multiple antimicrobial agents that are not known to show cross-resistance, so as to reduce the possibility of a resistant strain remaining inadequately treated by a single agent during the evaluation of drug response. Once a specific resistance profile has been isolated via clinical laboratory findings, treatment is often modified as indicated. Vancomycin has long been considered a drug of last resort, due to its efficiency in treating multiple drug-resistant infectious agents and the requirement for intravenous administration. Recently, resistance to even vancomycin has been shown in some strains of S. aureus (sometimes referred to as vancomycin resistant S. aureus (VRSA) or vancomycin intermediate-resistance S. aureus (VISA)), often coinciding with methicillin/penicillin resistance, prompting the inclusion of newer antibiotics, such as linezolid, that have shown efficacy in highly drug-resistant strains. There are also strains of enterococci that have developed resistance to vancomycin, referred to as vancomycin resistant enterococcus (VRE).
=== Athletics and promotions === Hooters is involved in the sports world. Previous sponsorships include the Miami Hooters, a now defunct Arena Football League team. Hooters formerly sponsored the USAR Hooters Pro Cup, an automobile racing series, and the NGA Pro Golf Tour, a minor league golf tour.
During World War II, Germany used submarines to devastating effect in the Battle of the Atlantic, where it attempted to cut Britain's supply routes by sinking more merchant ships than Britain could replace. These merchant ships were vital to supply Britain's population with food, industry with raw material, and armed forces with fuel and armaments. Although the U-boats had been updated in the interwar years, the major innovation was improved communications, encrypted using the Enigma cipher machine. This allowed for mass-attack naval tactics (Rudeltaktik, commonly known as "wolfpack"), which ultimately ceased to be effective when the U-boat's Enigma was cracked. By the end of the war, almost 3,000 Allied ships (175 warships, 2,825 merchantmen) had been sunk by U-boats. Although successful early in the war, Germany's U-boat fleet suffered heavy casualties, losing 793 U-boats and about 28,000 submariners out of 41,000, a casualty rate of about 70%. The Imperial Japanese Navy operated the most varied fleet of submarines of any navy, including Kaiten crewed torpedoes, midget submarines (Type A Ko-hyoteki and Kairyu classes), medium-range submarines, purpose-built supply submarines and long-range fleet submarines. They also had submarines with the highest submerged speeds during World War II (I-201-class submarines) and submarines that could carry multiple aircraft (I-400-class submarines). They were also equipped with one of the most advanced torpedoes of the conflict, the oxygen-propelled Type 95.
Sources: en.wikipedia.org
== History == Relugolix was first described in 2004. It superseded sufugolix (developmental code name TAK-013), which was developed by the same researchers. Relugolix was approved for the treatment of uterine fibroids in Japan in January 2019. It was the second orally active GnRH antagonist to be introduced for medical use, following elagolix (brand name Orilissa) in July 2018. Relugolix was approved for the treatment of prostate cancer in the United States on 18 December 2020. The FDA approved relugolix based on evidence from a clinical trial (NCT03085095) of 930 participants 48 to 97 years old with advanced prostate cancer. The trial was conducted at 155 sites in the United States, Canada, and countries in South America, Europe and the Asia Pacific region. All participants in the trial had advanced prostate cancer. Participants were randomly assigned to receive either one relugolix tablet daily (on the first day they received three tables) or an active control (leuprolide acetate) which was given as an injection under the skin every three months. The participants and healthcare providers were aware of which treatment was being given. The treatment lasted for 48 weeks. The efficacy of relugolix was assessed by the percentage of participants who achieved and maintained low testosterone level equal to castration.
Peter Sprague, Pierre Lamond and the affectionately called Charlie Sporck worked hand-in-hand, with support of the board of directors to transform the company into a multinational and world-class semiconductor concern. Immediately after becoming CEO, Sporck started a historic price war among semiconductor companies, which then trimmed the number of competitors in the field. Among the casualties to exit the semiconductor business were General Electric and Westinghouse. Cost control, overhead reduction and a focus on profits implemented by Sporck was the key element to National surviving the price war and subsequently in 1981 becoming the first semiconductor company to reach the US$1 billion annual sales mark. However, the foundation that made National successful was its expertise in analog electronics, TTL (transistor–transistor logic) and MOSFET (metal–oxide–semiconductor field-effect transistor) integrated circuit technologies. As they had while employed in Fairchild, Sporck and Lamond directed National Semiconductor towards the growing industrial and commercial markets and began to rely less on military and aerospace contracts. Those decisions coupled with inflationary growth in use of computers provided the market for the expansion of National. Meanwhile, sources of funds associated with Sprague coupled with creative structuring of cash flow buffering due to Sporck and Lamond provided the financing required for that expansion. Lamond and Sporck had also managed to attract and extract substantial funds to finance the expansion.
=== World War I and the American dye industry 1913 – 1930 === Through 1914, the US dye market was dominated by German imports, there were only a few small companies and German subsidiaries. With World War I, however, German dye factories now had to switch to making explosives and German shipping was cut off by British blockades. Prices quickly went up and U. S. companies built plants to meet demand. American pharmaceutical giants, even at that time, like Dow, DuPont, and others began to produce dyes and were extremely successful with simple sulphur and vat dyes. Dow Chemical developed a synthetic process for indigo in 1915, and American industry and universities worked together to reverse engineer German chemical production secrets. After the war some American munitions factories converted to dye-works, intuiting that if the reverse was possible for the German chemical industry during the war, then it ought to be feasible.
Sources: en.wikipedia.org
==== Other ==== Work is underway to develop a sCO2 closed-cycle gas turbine to operate at temperatures near 550 °C. This would have implications for bulk thermal and nuclear generation of electricity, because the supercritical properties of carbon dioxide at above 500 °C and 20 MPa enable thermal efficiencies approaching 45 percent. This could increase the electrical power produced per unit of fuel required by 40 percent or more. Given the volume of carbon fuels used in producing electricity, the environmental impact of cycle efficiency increases would be significant. Supercritical CO2 is an emerging natural refrigerant, used in new, low carbon solutions for domestic heat pumps. Supercritical CO2 heat pumps are commercially marketed in Asia. EcoCute systems from Japan, developed by Mayekawa, develop high temperature domestic water with small inputs of electric power by moving heat into the system from the surroundings. Supercritical CO2 has been used since the 1980s to enhance recovery in mature oil fields. "Clean coal" technologies are emerging that could combine such enhanced recovery methods with carbon sequestration. Using gasifiers instead of conventional furnaces, coal and water is reduced to hydrogen gas, carbon dioxide and ash. This hydrogen gas can be used to produce electrical power In combined cycle gas turbines, CO2 is captured, compressed to the supercritical state and injected into geological storage, possibly into existing oil fields to improve yields.
The in-gel digestion step is a part of the sample preparation for the mass spectrometric identification of proteins in course of proteomic analysis. The method was introduced in 1992 by Rosenfeld. Innumerable modifications and improvements in the basic elements of the procedure remain. The in-gel digestion step primarily comprises the four steps; destaining, reduction and alkylation (R&A) of the cysteines in the protein, proteolytic cleavage of the protein and extraction of the generated peptides.
=== No development reported === ACH-36 – undefined mechanism of action [22] Alprazolam sublingual – GABAA receptor positive allosteric modulator and benzodiazepine [23] Antalarmin (CP-154526) – corticotropin-releasing hormone (CRH) inhibitor [24] Buspirone controlled release (Buspirone ER) – serotonin 5-HT1A receptor partial agonist and other actions [25] BW-723C86 – serotonin 5-HT2B and 5-HT2C receptor agonist [26] Cannabidiol dry powder inhalation (RLS-103) – cannabinoid receptor modulator and other actions [27] Darigabat (CVL-865; PF-06372865; PF-6372865) – GABAA receptor positive allosteric modulator [28] Divaplon (RU-32698) – GABAA receptor positive allosteric modulator and nonbenzodiazepine/imidazolpyrimidine [29] Fananserin (RP-62203) – serotonin 5-HT2A receptor antagonist and dopamine D4 receptor antagonist [30] FR260010 (FR-260010) – serotonin 5-HT2C receptor antagonist [31] [32] GSK-588045 (GSK588045) – serotonin 5-HT1A, 5-HT1B, and 5-HT1D receptor antagonist [33] GSK-1360707 – serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI) [34] GT-001 – GABAA receptor positive allosteric modulator [35] Guanfacine extended release (Connexyn; Intuniv; Intuniv XR; S-877503; SHP-503; SPD-503) – α2-adrenergic receptor agonist [36] Itriglumide (CR-2945) – cholecystokinin B (CCKB) receptor antagonist [37] Lohocla-201 (Kindolor) – various actions [38] LY-293284 – serotonin 5-HT1A receptor agonist [39] NMRA-511 (BTRX-323511; NMRA-323511) – vasopressin V1A receptor antagonist [40] Paroxetine (Aropax; BRL-29060; Deroxat; Divarius; FG-7051; Frosinor; Motivan; NNC-207051; Paxil; Seroxat; SI-211103; Tagonis) – selective serotonin reuptake inhibitor (SSRI) [41] Psilocybin (MYCO-001; MYCO-003) – non-selective serotonin receptor agonist and psychedelic hallucinogen [42] PT-00114 (PT100114) – corticotropin-releasing hormone (CRH) inhibitor [43] Research programme: allosteric modulators - Addex Therapeutics – various actions [44] Research programme: AMPA receptor agonists - RespireRx (ampakines; CX compounds) – AMPA receptor agonists and brain-derived neurotrophic factor (BDNF) stimulants [45] Research programme: anxiety and neurological disorder therapeutics - AstraZeneca – various actions [46] Research programme: cannabis-based therapeutics - Skye Bioscience – cannabinoid receptor agonists [47] Research programme: neuropeptide S receptor modulators - Pfizer (WYE-198232) – neuropeptide receptor agonists [48] Research programme: oxytocin receptor agonist - Wyeth – oxytocin receptor agonists [49] RGH-618 – metabotropic glutamate mGlu5 receptor negative allosteric modulator [50] Riluzole (PK-26124; Rilutek; RP-54274) – various actions [51] Risperidone (JNJ-410397-AAA; R-64766; R064766; Risperdal; Risperdal Consta; Risperdal Depot) – atypical antipsychotic (non-selective monoamine receptor modulator) [52] Saripidem (SL-850274) – GABAA receptor positive allosteric modulator and nonbenzodiazepine/imidazopyridine [53] SB-242084 (SB242084) – serotonin 5-HT2C receptor antagonist [54] SRX-246 (API-246) – vasopressin V1A receptor antagonist [55] SYT-510 – anandamide reuptake inhibitor [56] Tebideutorexant (JNJ-3215; JNJ-61393215; Orexin-1) – orexin OX1 receptor antagonist [57] WAY-100135 – serotonin 5-HT1A receptor antagonist [58] Ziprasidone (CP-88059-01; CP-88059-1; Geodon; ME-2112; RQ-00000003; Zeldox) – atypical antipsychotic (non-selective monoamine receptor modulator) [59]
== Side effects == Loxapine can cause side effects that are generally similar to that of other antipsychotic medications. These include, e.g., gastrointestinal problems (like constipation and abdominal pain), cardiovascular problems (like tachycardia), moderate likelihood of drowsiness (relative to other antipsychotics), and movement problems (i.e. extrapyramidal symptoms [EPS]). At lower dosages its propensity for causing EPS appears to be similar to that of atypical antipsychotics. Although it is structurally similar to clozapine, it has much lower risk of agranulocytosis (which, even with clozapine, is 0.8%); however, mild and temporary fluctuations in blood leukocyte levels can occur. Abuse of loxapine has been reported. The inhaled formulation of loxapine carries a low risk for a type of airway adverse reaction called bronchospasm that is not thought to occur when loxapine is taken by mouth.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.