The short version of peptide purity fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
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.
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.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Among Catholics, the positive rating decreased from 48% to 24%, and among evangelicals, from 30% to 21%. In the Northeast, traditionally a region of greater support for the president, approval fell from 49% to 33%. The survey was carried out between 10 and 11 February, with 2,007 voters from 113 cities, and has a margin of error of two percentage points. On 29 May, the study "Vida Digital de Lula", launched by the Ativaweb agency, identified that Lula lost one million followers on the social networks Instagram and Facebook. According to the study, the reasons would be the triggering of the INSS fraud scheme initiated in 2019 and the taxation of the Tax on Financial Operations (IOF). According to the portal O Antagonista, one of the reasons would be the embarrassments caused by first lady Janja. The AtlasIntel survey carried out on 30 May showed that disapproval rates of Lula's government reached the record level of 53.7%, according to the survey conducted in partnership with Bloomberg. This is the highest rate of dissatisfaction with the current administration since January 2024, due to the start of the investigations into the INSS fraud scheme. Approval of the PT government remained stable at 45.5% – in April, it was 46.1%, and in March, 44.9%. The Quaest survey released on 16 July indicated a recovery in the rating, according to the survey, because the difference between approval and disapproval was 17 points in June and 10 now. Disapproval, however, remained above approval, with 53% disapproval and 43% approval.
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Miroslav Aleksić became mayor of Trstenik in 2012 as a member of the United Regions of Serbia (Ujedinjeni regioni Srbije, URS). The URS largely became dormant after the 2014 Serbian parliamentary election, and Aleksić left the party later in the year and became acting leader of a breakaway group initially called the People's Party of Serbia (Narodna stranka Srbije, NSS). The group was formally constituted as the People's Movement of Serbia in January 2015, and Aleksić was chosen as its leader in February. The party contested the 2016 parliamentary election as part of the Alliance for a Better Serbia list led by Boris Tadić, Čedomir Jovanović and Nenad Čanak. Aleksić received the eighth position on the electoral list and was elected when the alliance won thirteen mandates. The People's Movement of Serbia operated in a parliamentary alliance with Tadić's Social Democratic Party, which also contested the 2016 elections in the Alliance for a Better Serbia. Aleksić served as the parliamentary group's deputy leader. Both the alliance with the Social Democratic Party and Aleksić's deputy leadership of the parliamentary group continued after the party was restructured as the People's Party.
== Suicide == Since 2013, the National Suicide Observatory has published data on suicide trends in France. Sociological and demographic factors influence the incidence and outcome of suicide across genders.
On July, the Ministry of Education announced that the federal programme for creation of civic-military schools would be stopped, and that each state would have the option to keep or extinguish the programme. On the same month, Lula also signed in the Education Ministry's "full-time school program" after modifications to the original project, which dealt with increasing government investments in these schools, as well as reforming many part-time ones to also allow for the offering of these options, were approved by the Chamber of Deputies. On 6 November 2023, education minister Camilo Santana announced that people with FIES debts could now renegotiate them with the federal government, the attitude is similar to the Desenrola Brasil programme, also created during the Lula government in an effort to reduce indebtedness among the people, especially those of lower classes. The government announced on 12 March 2024 the construction of 100 new Federal Institutes of Education, Science and Technology in all federative units in Brazil by 2026. The ministry of education announced that it would be Investing ~R$3.9 billion in the construction of these units, with the funds being made possible through the New PAC. The government estimates the creation of 140 thousand new enrollments, the majority in technical courses integrated into secondary education (high school). The region that will receive the most Institutes will be the Northeast, with 38 new units planned, while the State that will receive the largest number of Institutes will be São Paulo, with 12 new units.
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=== Maluku province === Alune people Ambonese people Haruku people Hitu people Saparua people Aru people Ujir people Babar people Banda people Bati people Buano people Buru people Ambelau people Kayeli people Lisela people Masarete people Rana people Wai Apu people Wai Loa people Geser people Gorom people Kei people Tanimbar Kei people Kisar people Leti people Manipa people Masela people Mausu Ane people Meher people Nuaulu people Oirata people Tanimbarese people Teon–Nila–Serua (TNS) Nila people Serua people Teon people Teor people Von people Wemale people Wetar people Yamatitam people
December 13: Constitution of 22 Frimaire Year VIII (establishing the Consulate) grants citizenship only to men over 21, born and residing in France, and registered in their commune's civic registry, effectively excluding women. 1800
The meat of a lamb is taken from the animal between one month and one year old, with a carcass weight of between 5.5 and 30 kg (12 and 66 lb). This meat generally is more tender than that from older sheep and appears more often on tables in some Western countries. Hogget and mutton have a stronger flavour than lamb because they contain a higher concentration of species-characteristic fatty acids and are preferred by some. Mutton and hogget also tend to be tougher than lamb (because of connective tissue maturation) and are therefore better suited to casserole-style cooking, as in Lancashire hotpot, for example. Lamb is often sorted into three kinds of meat: forequarter, loin, and hindquarter. The forequarter includes the neck, shoulder, front legs, and the ribs up to the shoulder blade. The hindquarter includes the rear legs and hip. The loin includes the ribs between the two. Lamb chops are cut from the rib, loin, and shoulder areas. The rib chops include a rib bone; the loin chops include only a chine bone. Shoulder chops are usually considered inferior to loin chops; both kinds of chops are usually grilled. Breast of lamb (baby chops) can be cooked in an oven. Leg of lamb is a whole leg; saddle of lamb is the two loins with the hip. Leg and saddle are usually roasted, though the leg is sometimes boiled. Forequarter meat of sheep, as of other mammals, includes more connective tissue than some other cuts, and, if not from a young lamb, is best cooked slowly using either a moist method, such as braising or stewing, or by slow roasting or American barbecuing.
==== Psilocybin ==== Psilocybin has been shown in several studies to improve symptoms in people with treatment-resistant depression. In 2018 and 2019, the FDA designated psilocybin as a "breakthrough therapy" for drug-resistant depression and major depressive disorder.
Sources: en.wikipedia.org
=== Controlled atmospheres === Helium is used as a protective gas in growing silicon and germanium crystals, in titanium and zirconium production, and in gas chromatography, because it is inert. Because of its inertness, thermally and calorically perfect nature, high speed of sound, and high value of the heat capacity ratio, it is also useful in supersonic wind tunnels and impulse facilities.
StoreDot is a developer of lithium-ion (Li-ion) batteries for electric vehicles founded in 2012 by Doron Myersdorf, Simon Litsyn, and Gil Rosenman. It is based in Herzliya, Israel. The company was founded around developing peptide-based mobile phone displays and data storage. The company reported it was ready to commercially release these products: peptide-based displays by 2016; peptide-based batteries for mobile phones that fully charge in 30 seconds by 2016; germanium-based mobile phone batteries by 2019; electric car and aerial drone batteries that fully charge in five minutes by 2020; scooter batteries that fully charge in under five minutes by 2021; and silicon-graphite-electrode batteries in 2025. None of the aforementioned products have been commercially released as of February 2026. Financial journalists estimated in February 2026 that StoreDot has funding for a few more months of operations. StoreDot stated in 2026 it needs two more years of development in order to commercialize its product.
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2,4,6-Triisopropylbenzenesulfonyl azide (trisyl azide) is an organic chemical used as a reagent to supply azide for electrophilic amination reactions, such as for the asymmetric synthesis of unnatural amino acids. Introduction of an azide on the α carbon of carboxylic acid derivatives using trisyl azide is an efficient alternative to electrophilic halogenation followed by nucleophilic substitution using anionic azide. Using an oxazolidinone as chiral auxiliary typically gives good induction of the stereochemistry at the α position. Subsequent reduction converts the α-azide to an α-amine.
It can be "fingerprinted" as different in origin from manmade depleted uranium by the 234U content, which is 55 ppm in uranium from the Oklo Mine as well as all other natural sources, but will be lower in depleted uranium in accordance with the degree of depletion.
Sources: en.wikipedia.org
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.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
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.