The short version of Pro-Gly-Pro fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-12-01 and is reviewed periodically as new material appears.
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.
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.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
| Property | Value | Notes |
|---|---|---|
| Solubility | Freely soluble in water | Also in aqueous buffers |
| Typical purity (HPLC) | 95 percent or higher | Lot-dependent |
| Dry powder storage | Minus 20 degrees Celsius | Sealed, dry, protected from light |
| Solution storage | 2 to 8 degrees Celsius | Short-term use |
| Identity confirmation | Mass spectrometry | ESI or MALDI-TOF |
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.
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.
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.
== Related heterocycles == Benzimidazole, an analog with a fused benzene ring Dihydroimidazole or imidazoline, an analog where the 4,5-double bond is saturated Pyrrole, an analog with only one nitrogen atom in position 1 Oxazole, an analog with the nitrogen atom in position 1 replaced by oxygen Thiazole, an analog with the nitrogen atom in position 1 replaced by sulfur Pyrazole, an analog with two adjacent nitrogen atoms Triazoles, analogs with three nitrogen atoms
=== Radiotherapy dose enhancer === Considerable interest has been shown in the use of gold and other heavy-atom-containing nanoparticles to enhance the dose delivered to tumors. Since the gold nanoparticles are taken up by the tumors more than the nearby healthy tissue, the dose is selectively enhanced. The biological effectiveness of this type of therapy seems to be due to the local deposition of the radiation dose near the nanoparticles. This mechanism is the same as occurs in heavy ion therapy.
They played their last ever international on 21 June 2006, a 3–2 loss to Ivory Coast. Following the World Cup, this team has been inherited by Serbia, while a new one was to be organized to represent Montenegro in future international competitions.
=== Etymology === Rheumatoid arthritis is derived from the Greek word ῥεύμα-rheuma (nom.), ῥεύματος-rheumatos (gen.) ("flow, current"). The suffix -oid ("resembling") gives the translation as joint inflammation that resembles rheumatic fever. Rhuma, which means watery discharge, might refer to the fact that the joints are swollen or that the disease may be made worse by wet weather.
Sources: en.wikipedia.org
As a second lieutenant in 1966, Noriega spent many months taking courses at the School of the Americas. The school was located at the United States Army's Fort Gulick in the Panama Canal Zone. Journalist John Dinges has suggested that Torrijos sent Noriega to the school to help him "shape up" and live up to Torrijos's expectations. Despite performing poorly in his classes, he was promoted to the rank of first lieutenant in 1966, and Torrijos found him a job as an intelligence officer in the "North Zone" of the National Guard. Shortly afterward, he returned to the School of the Americas for more training. At the school, Noriega participated in courses on infantry operations, counterintelligence, intelligence, and jungle warfare. He also took a course in psychological operations at Fort Bragg in North Carolina. Noriega's job required him to penetrate and disrupt the trade unions that had formed in the United Fruit Company's workforce, and he proved adept at this work. His new superior officer Boris Martínez was a fervent anti-communist, and enforced strict discipline on Noriega. Reports have suggested that he continued to pass intelligence to the U.S. during this period, about the plantation workers' activities. In 1967 the administration of U.S. President Lyndon B. Johnson concluded that Noriega would be a valuable asset, as he was a "rising star" in the Panamanian military. Later, as the de facto leader of Panama, Noriega maintained a close relationship with the School of the Americas, partly due to the school's presence in Panama.
At the time, Senator Hatch's son was working for a firm hired to lobby Congress and the FDA on behalf of ephedra manufacturers. In addition to the activities of the Ephedra Education Council, Metabolife spent more than $4 million between 1998 and 2000 lobbying against state regulation of ephedra in Texas. Business Week reported that efforts to regulate ephedra and other potentially harmful supplements had been "beaten down by deep-pocketed industry lobbying." In 2000, the FDA withdrew the proposed labeling changes and restrictions.
Although they vary in particulars, polymyositis, dermatomyositis and inclusion body myositis are idiopathic inflammatory myopathies (IIM) primarily characterized by chronic inflammation of human skeletal muscle tissue that ultimately causes the necrosis of muscle cells. This degeneration leads to muscle tissue wasting, weakness and fatigue among other serious effects. Until recently, exercise has been avoided as a type of therapy, and even forbidden due to the risk of triggering or amplifying inflammation. However, several studies have been conducted to test this assumption and have shown that aerobic exercise as well as resistance training can maintain and even improve the quality of life for IIM-affected individuals without increased inflammatory response.
Sources: en.wikipedia.org
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.
Freeze-dried material is kept frozen, often at minus 20 degrees Celsius, and protected from light and moisture. Dissolved peptide is refrigerated for short-term use. Repeated freeze-thaw cycles are avoided.
A certificate of analysis typically lists purity by HPLC, the confirmed mass, appearance, and sometimes water or counter-ion content. It documents results for a specific batch. Details vary by supplier.
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.