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 2026-05-19 and is reviewed periodically as new material appears.
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.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
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.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
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.
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.
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.
The Mustang was initially developed for the RAF, which was its first user. As the first Mustangs were built to British requirements, these aircraft used factory numbers and were not P-51s; the order comprised 320 NA-73s, followed by 300 NA-83s, all of which were designated Mustang Mark I by the RAF. The first RAF Mustangs supplied under Lend-Lease were 93 Mk Ia designated as P-51s by the USAAF, followed by 50 P-51As used as Mustang Mk IIs. Aircraft supplied to Britain under Lend-Lease were required for accounting purposes to be on the USAAC's books before they could be supplied to Britain, but the British Aircraft Purchasing Commission signed its first contract for the North American NA-73 on 24 April 1940, before Lend-Lease was in effect. After the arrival of the initial aircraft in the UK in October 1941, the first squadron of Mustang Mk Is entered service in January 1942, the first being No. 26 Squadron RAF. Due to poor high-altitude performance, the Mustangs were used by Army Co-operation Command, rather than Fighter Command, and were used for tactical reconnaissance and ground-attack duties. On 10 May 1942, Mustangs first flew over France, near Berck-sur-Mer. On 27 July 1942, 16 RAF Mustangs undertook their first long-range reconnaissance mission over Germany. During the amphibious Dieppe Raid on the French coast (19 August 1942), four British and Canadian Mustang squadrons, including 26 Squadron, saw action covering the assault on the ground. By 1943–1944, British Mustangs were used extensively to seek out V-1 flying bomb sites.
Fabrication and coating of nanodevices and medical implants to increase biocompatibility. Emulsifiers in food industry and personal care products. Hydrophobins' high stability can be very useful in the coating of surfaces of prolonged use or under harsh conditions. The easy dissociation of a class II hydrophobin monolayer might be desirable and this can easily be achieved by the use of detergents and alcohols. The use of hydrophobins in protein purification, drug delivery and cell attachment has been reported. For more about the potential biotechnological applications of hydrophobins see Hektor & Scholtmeijer (2005) and Cox & Hooley (2009).
== Research use == Separate from its utility as an educational, self-learning, or teaching tool for people with diabetes and their relatives / carers, students and health-care professionals — various research groups around the world have found the freeware AIDA diabetes simulator of use as a way of generating large quantities of realistic blood glucose data for developing and testing out their own diabetes computing prototypes (e.g. for training artificial neural networks, or other decision support research prototypes). Various published examples of this research approach can be found in the scientific literature.
=== EC 1.21.98 With other, known, physiological acceptors === EC 1.21.98.1: cyclic dehypoxanthinyl futalosine synthase EC 1.21.98.2: dichlorochromopyrrolate synthase EC 1.21.98.3: anaerobic magnesium-protoporphyrin IX monomethyl ester cyclase EC 1.21.98.4: PqqA peptide cyclase
Sources: en.wikipedia.org
After terminating their exclusive distribution agreement with PepsiCo, Bang alleged that PepsiCo was misrepresenting itself as the exclusive distributor of their products, and threatened lawsuits against suppliers and distributors who did not purchase Bang products directly from them. An emergency arbitrator ruled in December 2020 that Pepsi remains the exclusive distributor of Bang. Bang and PepsiCo mutually transitioned from their exclusive distribution agreement in June 2022, with then-CEO Jack Owoc claiming that "all disputes with PepsiCo have been fully settled and resolved".
the Secretary mentioned that he was being pressed by the Foreign Office to bring forward the question of Zionism, an early settlement of which was regarded as of great importance." 31 October 1917: "[Balfour] stated that he gathered that everyone was now agreed that, from a purely diplomatic and political point of view, it was desirable that some declaration favourable to the aspirations of the Jewish nationalists should now be made. The vast majority of Jews in Russia and America, as, indeed, all over the world, now appeared to be favourable to Zionism. If we could make a declaration favourable to such an ideal, we should be able to carry on extremely useful propaganda both in Russia and America."
According to the Ebers Papyrus, a sulfur ointment was used in ancient Egypt to treat granular eyelids. There are ancient Egyptian necklaces, dated between the Ptolemaic period and the early Roman period, with beads made of sulfur, shaped like flowers and cow heads. Sulfur is one of the ingredients of niello, a dark material used to decorate metallic items. Pliny the Elder mentioned, in the first century AD, that the Romans used a type of niello inherited from the Egyptians, who, according to him, made a dark pigment to depict Anubis on silver vessels. He lists a recipe where copper and silver are mixed with sulfur and heated to produce this material. In Roman jewelry, sulfur was used as a filler in hollow gold items, especially in gold rings. This practice was widespread enough to be included by Artemidorus in the section of the Oneirocritica about gold finger-rings, where he mentions rings "that are hollow and filled with brimstone". Modern analysis has confirmed this, detecting sulfur in ancient Roman gold artifacts. In the 2nd century BC, Cato the Elder gave a recipe to protect vines against caterpillars, which contains sulfur as an ingredient, in his De Agri Cultura, an early example of its use as pest control. Pliny the Elder further discussed sulfur in his Natural History, saying that its best-known source is the island of Melos. He listed four types of sulfur: one used for medicinal purposes, one used by fullers, one used to bleach wool and one used for lamp wicks.
Sources: en.wikipedia.org
== Use in biological research == Imidazole is a suitable buffer for pH 6.2 to 7.8,. Pure imidazole has essentially no absorbance at protein relevant wavelengths (280 nm), however lower purities of imidazole can give notable absorbance at 280 nm. Imidazole can interfere with the Lowry protein assay. Imidazole is often used in protein purification, where recombinant proteins with polyhistidine tags are immobilized onto nickel resins and eluted with a high imidazole concentration.
== See also == Gluconeogenesis – A process where glucose can be synthesized by non-carbohydrate sources. Glycobiology Glycogen Glycoinformatics Glycolipid Glycome Glycomics Glycosyl Macromolecule Saccharic acid
=== mRNA === Ψ is also found in mRNAs which are the template for protein synthesis. Ψ residues in mRNA can affect the coding specificity of stop codons UAA, UGA, and UAG. In these stop codons, both a U→Ψ modification and a U→C mutation promote nonsense suppression. In the SARS-CoV2 vaccine from BioNTech/Pfizer, also known as BNT162b2, tozinameran or Comirnaty, all U's have been substituted with N1-methylpseudouridine, a nucleoside related to Ψ that contains a methyl group added to N1 atom.
Sources: en.wikipedia.org
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.