A practical reference on Pro-Gly-Pro: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-02-12 and is reviewed periodically as new material appears.
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.
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.
| 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 |
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.
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.
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.
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After these convictions, it was announced that a new system for unsafe food recall would be implemented by the end of 2007. By the end of August 2007, Xinhua reported that China had instituted new product recall and customer notification systems. Further customer protection measures were introduced in response to the 2008 Chinese milk scandal. A Xinhua article from September 2008 lists the following information as "Lessons Learned" from the milk scandal: "Sanlu, the center of the scandal, provided a bad example of crisis management. When it was first exposed, Sanlu refused to take the blame and passed the buck to innocent dairy farmers, which ignited great anger nationwide. A further official investigation showed Sanlu had lied about its contaminated baby formula for months while thousands of infants got sick and at least three died. Sanlu didn't openly admit its products were toxic until Sept. 11. It eventually recalled baby formula manufactured on and before Aug. 6."
He also served as a member of the executive committee of the American Society for Testing and Materials (A.S.T.M.) Committee E-19 on Chromatography (1966–1973); as a foreign member of the executive committee of the (British) Chromatographic Society (1992–1997); and as an executive committee member of the Chromatography Subdivision of the Division of Analytical Chemistry of the American Chemical Society (A.C.S.).
One year later, the National Committee for Mental Hygiene (NCMH) was founded by a small group of reform-minded scholars and scientists—including Beers himself—which marked the beginning of the "mental hygiene" movement. The movement emphasized the importance of childhood prevention. World War I catalyzed this idea with an additional emphasis on the impact of maladjustment, which convinced the hygienists that prevention was the only practical approach to handle mental health issues. However, prevention was not successful, especially for chronic illness; the condemnable conditions in the hospitals were even more prevalent, especially under the pressure of the increasing number of chronically ill and the influence of the depression. In 1961, the Joint Commission on Mental Health published a report called Action for Mental Health, whose goal was for community clinic care to take on the burden of prevention and early intervention of the mental illness, therefore to leave space in the hospitals for severe and chronic patients. The court started to rule in favor of the patients' will on whether they should be forced to treatment. By 1977, 650 community mental health centers were built to cover 43 percent of the population and serve 1.9 million individuals a year, and the lengths of treatment decreased from 6 months to only 23 days. However, issues still existed. Due to inflation, especially in the 1970s, the community nursing homes received less money to support the care and treatment provided.
Sources: en.wikipedia.org
Yeolmu radishes and cucumbers are summer vegetables made into kimchi, yeolmu-kimchi (열무김치) which is eaten in several bites. Brined fish or shellfish can be added, and freshly ground dried chili peppers are often used.
The total number of deaths in the Romanian revolution was 1,104, of which 162 were from the protests that led to the overthrow of Ceaușescu (16–22 December 1989) and 942 during the fighting that occurred after the seizure of power by the new FSN. The number of wounded was 3,352, of which 1,107 occurred while Ceaușescu was still in power and 2,245 after the FSN took power. Official figures place the death toll of the revolution at 689 people, many of whom were civilians. Figures by FSN officials in January 1990 claimed that as many as 7,000 people died during four days of bitter street fighting in December.
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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.
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.