peptide purity raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-01-23 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Modeled on tuftsin |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues |
| Approximate molecular mass | Around 750 Da | Depends on counter-ion and hydration |
| Common forms | Lyophilized powder | Also described as aqueous solution |
| Primary origin of research | Russian laboratories | Mid-1990s onward |
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.
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.
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.
2 March Chinese People's Liberation Army troops attacked Soviet border guards on Zhenbao Island, marking a new low in relations between North Vietnam's principal allies. Village and hamlet elections were held throughout South Vietnam, largely free of PAVN/VC interference.
Physical properties of the drug (hydrophobicity, pKa, solubility) The drug formulation (immediate release, excipients used, manufacturing methods, modified release – delayed release, extended release, sustained release, etc.) Whether the formulation is administered in a fed or fasted state Gastric emptying rate Circadian differences Interactions with other drugs/foods: Interactions with other drugs (e.g., antacids, alcohol, nicotine) Interactions with other foods (e.g., grapefruit juice, pomello, cranberry juice, brassica vegetables) Transporters: Substrate of efflux transporters (e.g. P-glycoprotein) Health of the gastrointestinal tract Enzyme induction/inhibition by other drugs/foods: Enzyme induction (increased rate of metabolism), e.g., Phenytoin induces CYP1A2, CYP2C9, CYP2C19, and CYP3A4 Enzyme inhibition (decreased rate of metabolism), e.g., grapefruit juice inhibits CYP3A → higher nifedipine concentrations Individual variation in metabolic differences Age: In general, drugs are metabolized more slowly in fetal, neonatal, and geriatric populations Phenotypic differences, enterohepatic circulation, diet, gender Disease state E.g., hepatic insufficiency, poor renal function Each of these factors may vary from patient to patient (inter-individual variation), and indeed in the same patient over time (intra-individual variation). In clinical trials, inter-individual variation is a critical measurement used to assess the bioavailability differences from patient to patient in order to ensure predictable dosing.
Similarly to the SIR model, also, in this case, we have a Disease-Free-Equilibrium (N,0,0,0) and an Endemic Equilibrium EE, and one can show that, independently from biologically meaningful initial conditions
=== June === 1 June – Mark Rocket becomes the first New Zealander to reach space after flying on the Blue Origin NS-32 suborbital spaceflight. 2 June: The 2025 King's Birthday Honours are announced. Notable recipients include comedian Dai Henwood, Suzy Cato, Louise Wallace and Jude Dobson. Australian mining company Siren Gold is granted a permit to explore gold and antimony in the Marlborough Sounds. 3 June: Online retailer Trade Me acquires a 50 percent stake in media company Stuff's Stuff Digital division. Former National Party minister and MP Steven Joyce becomes chair of media company NZME's board while Canadian billionaire Jim Grenon becomes the company's director following a board meeting. The 90,000 Pawprint Petition calling for a ban on the public sale of fireworks is presented to the New Zealand Parliament. WorkSafe New Zealand launches a new road cone online tipline. The Kaipara District Council confirms that Dargaville's water supply pipeline is fully repaired following four days of disruptions caused by four separate ruptures. 4 June – The navigation radar of HMAS Canberra's accidentally disrupts Internet service and radio signals over a large area spanning Taranaki in the North Island to the Marlborough District in the South Island. When made aware, Canberra's crew changed her systems to non-interfering frequencies. 5 June: Police charged three individuals with manslaughter in relation to the Loafers Lodge fire.
=== Polysaccharide chiral stationary phases === The naturally occurring polysaccharide form the basis for an important group of columns designed for chiral separation. The main polysaccharides are cellulose, amylose, chitosan, dextran, xylan, curdlan, and inulin. Polysaccharide-based stationary phase have a high loading capacity, many chiral centers and complicated stereochemistry, and can be used for the separation of a wide range of compounds. Polysaccharide-based chiral stationary phases have a wide application due to their high separation efficiency, selectivity, sensitivity and reproducibility under normal and reversed-phase conditions, as well as their broad applicability for structurally diversified compounds. The mechanism of chiral interaction on the polysaccharide-based chiral stationary phase has not yet been elucidated. However, the following interactions are believed to play a role in the retention: (i) Hydrogen bonding interactions of the polar chiral analyte with carbamate groups on the CSP; (ii) π-π interactions between phenyl groups on the CSP and aromatic groups of the solute; (i) Dipole-dipole interactions (ii) Steric interactions due to the helical structure of the CSP. These effects on the retention process originate also from the functionality of the derivatives of the polysaccharide, its average molecular weight, and size distribution, the solvent used to immobilize it on the macroporous silica support, and the nature of the macroporous silica support itself.
Sources: en.wikipedia.org
=== Quantum tunneling === These traditional "over the barrier" mechanisms have been challenged in some cases by models and observations of "through the barrier" mechanisms (quantum tunneling). Some enzymes operate with kinetics which are faster than what would be predicted by the classical ΔG‡. In "through the barrier" models, a proton or an electron can tunnel through activation barriers. Quantum tunneling for protons has been observed in tryptamine oxidation by aromatic amine dehydrogenase. Quantum tunneling does not appear to provide a major catalytic advantage, since the tunneling contributions are similar in the catalyzed and the uncatalyzed reactions in solution. However, the tunneling contribution (typically enhancing rate constants by a factor of ~1000 compared to the rate of reaction for the classical 'over the barrier' route) is likely crucial to the viability of biological organisms. This emphasizes the general importance of tunneling reactions in biology. However, as stated above, this does not represent a true catalytic effect, since the same enhancement exists in the corresponding reference reaction in solution. In 1971-1972 the first quantum-mechanical model of enzyme catalysis was formulated. However, this study did not include any representation of the enzyme environment, nor did it provide a relevant potential energy surface. Consequently, it cannot be considered a true quantum mechanical study of enzyme catalysis. Such investigations became feasible only with the development of combined quantum mechanical/molecular mechanical (QM/MM) methods.
=== Industrial applications === Since 1975, ion chromatography has been widely used in many branches of industry. The main advantages are reliability, very good accuracy and precision, high selectivity, high speed, high separation efficiency, and low cost of consumables. The most significant development related to ion chromatography are new sample preparation methods; improving the speed and selectivity of analytes separation; lowering of limits of detection and limits of quantification; extending the scope of applications; development of new standard methods; miniaturization and extending the scope of the analysis of a new group of substances. Allows for quantitative testing of electrolyte and proprietary additives of electroplating baths. It is an advancement of qualitative hull cell testing or less accurate UV testing. Ions, catalysts, brighteners and accelerators can be measured. Ion exchange chromatography has gradually become a widely known, universal technique for the detection of both anionic and cationic species. Applications for such purposes have been developed, or are under development, for a variety of fields of interest, and in particular, the pharmaceutical industry. The usage of ion exchange chromatography in pharmaceuticals has increased in recent years, and in 2006, a chapter on ion exchange chromatography was officially added to the United States Pharmacopia-National Formulary (USP-NF).
Such systems may use taxonomic thesauri to track accepted names and synonyms and to keep checklists aligned with changing taxonomy. Hardisty and colleagues have proposed the concept of "digital extended specimens" as an infrastructure for linking biodiversity records derived from physical specimens to a broader network of related digital objects and third-party data resources. Digitization improves access to specimen data, but it cannot by itself resolve cryptic diversity, which often requires direct examination and sequencing of preserved material. Despite these advances, many regions, particularly in the tropics, still lag behind in collecting and digitizing fungal diversity.
=== Mass analysis === Fragmentation caused by ETD allows more complete protein sequence information to be obtained from ETD spectra than from CID tandem mass spectrometry. Because many peptide backbone c- and z- type ions are detected, almost complete sequence coverage of many peptides can be discerned from ETD fragmentation spectra. Sequences of 15-40 amino acids at both the N-terminus and the C-terminus of the protein can be read using mass-to-charge values for the singly and doubly charged ions. These sequences, together with the measured mass of the intact protein, can be compared to database entries for known proteins and to reveal post-translational modifications.
=== Prehistory and Imperial China === The earliest known human traces in what is now Hong Kong are dated by some to 35,000-39,000 years ago during the Paleolithic period. The claim is based on an archaeological investigation in Wong Tei Tung in the Sai Kung Peninsula in 2003. The archaeological works revealed knapped stone tools from deposits dated by optical luminescence dating. During the Middle Neolithic period, about 6,000 years ago, the region had been widely occupied by humans. Neolithic to Bronze Age Hong Kong settlers were semi-coastal people. Early inhabitants are believed to have been Austronesians in the Middle Neolithic period, and later the Yue people. As hinted by the archaeological works in Sha Ha, Sai Kung, rice cultivation had been introduced since the Late Neolithic period. Bronze Age Hong Kong featured coarse pottery, hard pottery, quartz and stone jewelry, as well as small bronze implements.
Sources: en.wikipedia.org
Cannabis tea (also known as weed tea, pot tea, a cannabis decoction) is a cannabis-infused drink prepared by steeping various parts of the cannabis plant in hot or cold water. Cannabis tea is commonly recognized as an alternative form of preparation and consumption of the cannabis plant, more popularly known as marijuana, pot, or weed. This plant has long been recognized as an herbal medicine employed by health professionals worldwide to ease symptoms of disease, as well as a psychoactive drug used recreationally and in spiritual traditions. Though less commonly practiced than popular methods like smoking or consuming edibles, drinking cannabis tea can produce comparable physical and mental therapeutic effects. Such effects are largely attributed to the THC and CBD content of the tea, levels of which are drastically dependent on individual preparation techniques involving volume, amount of cannabis, and boiling time. Also in common with these administration forms of cannabis is the heating component performed before usage. Due to the rather uncommon nature of this particular practice of cannabis consumption in modern times (in contrast to historical use) as well as the legality of cannabis throughout the world, the research available on the composition of cannabis tea is limited and based broadly around what is known of cannabis as it exists botanically.
=== Glycogenesis === Glycogenesis refers to the process of synthesizing glycogen. In humans, glucose can be converted to glycogen via this process. Glycogen is a highly branched structure, consisting of the core protein Glycogenin, surrounded by branches of glucose units, linked together. The branching of glycogen increases its solubility, and allows for a higher number of glucose molecules to be accessible for breakdown at the same time. Glycogenesis occurs primarily in the liver, skeletal muscles, and kidney. The Glycogenesis pathway consumes energy, like most synthetic pathways, because an ATP and a UTP are consumed for each molecule of glucose introduced.
Robert Joseph Wittman (born February 3, 1959) is an American politician and environmental health specialist serving as the U.S. representative for Virginia's 1st congressional district since 2007. A member of the Republican Party, his district contains portions of the Richmond suburbs and Hampton Roads area, as well as the Northern Neck and Middle Peninsula.
==== Greece ==== The production of potassium alum from alunite is archaeologically attested on the island Lesbos. This site was abandoned in the 7th century but dates back at least to the 2nd century CE.
=== The genetic code is solved === The genetic code consists of the translation of particular nucleotide sequences in mRNA to specific amino acid sequences in proteins (polypeptides). The ability to work out the genetic code emerged from the convergence of three different areas of study: (i) new methods to generate synthetic RNA molecules of defined composition to serve as artificial mRNAs, (ii) development of in vitro translation systems that could be used to translate the synthetic mRNAs into protein, and (iii) experimental and theoretical genetic work which established that the code was written in three letter "words" (codons). Today, our understanding of the genetic code permits the prediction of the amino sequence of the protein products of the tens of thousands of genes whose sequences are being determined in genome studies.
Sources: en.wikipedia.org
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.
It originates from research in Russia, associated with the Institute of Molecular Genetics of the Russian Academy of Sciences. The first descriptions date to the mid-1990s. Most published studies come from Russian laboratories.
No, Selank itself does not occur naturally. Its backbone is based on tuftsin, which is produced in the body, but the seven-residue version is a synthetic construct. It is supplied as a manufactured peptide.
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.