A practical reference on heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-05-12 and is reviewed periodically as new material appears.
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.
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 |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
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.
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.
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.
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.
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.
More potential nutrients from the grape must (though the bacteria will be competing with the yeast for these) Lower sulfur dioxide and ethanol levels which can otherwise inhibit the LAB Higher fermentation temperatures which are more conducive to LAB growth and an earlier completion of MLF: The optimal temperatures for malolactic fermentation are between 20 and 37 °C (68 and 99 °F), while the process is significantly inhibited at temperatures below 15 °C (59 °F). Wine stored in the barrels in the cellar during the winter following fermentation will often have a very prolonged malolactic fermentation due to the cool cellar temperatures. Early completion of malolactic fermentation means the winemaker can make a postfermentation SO2 earlier to protect the wine from oxidation and spoilage microbes (such as Acetobacter). Since sulfur dioxide can inhibit MLF, delaying LAB inoculation till after alcoholic fermentation may mean a delay in sulfur addition till early spring when cellar temperatures warm up enough to encourage the completion of MLF. Less diacetyl production The disadvantages for early inoculation include:
=== Mid-infrared === With the advent of cheap microcomputers it became possible to have a computer dedicated to controlling the spectrometer, collecting the data, doing the Fourier transform and presenting the spectrum. This provided the impetus for the development of FTIR spectrometers for the rock-salt region. The problems of manufacturing ultra-high precision optical and mechanical components had to be solved. A wide range of instruments are now available commercially. Although instrument design has become more sophisticated, the basic principles remain the same. Nowadays, the moving mirror of the interferometer moves at a constant velocity, and sampling of the interferogram is triggered by finding zero-crossings in the fringes of a secondary interferometer lit by a helium–neon laser. In modern FTIR systems the constant mirror velocity is not strictly required, as long as the laser fringes and the original interferogram are recorded simultaneously with higher sampling rate and then re-interpolated on a constant grid, as pioneered by James W. Brault. This confers very high wavenumber accuracy on the resulting infrared spectrum and avoids wavenumber calibration errors.
the cAMP signal pathway and the phosphatidylinositol signal pathway. When a ligand binds to the GPCR it causes a conformational change in the GPCR, which allows it to act as a guanine nucleotide exchange factor (GEF). The GPCR can then activate an associated G protein by exchanging the GDP bound to the G protein for a GTP. The G protein's α subunit, together with the bound GTP, can then dissociate from the β and γ subunits to further affect intracellular signaling proteins or target functional proteins directly depending on the α subunit type (Gαs, Gαi/o, Gαq/11, Gα12/13). GPCRs are an important drug target, and approximately 34% of all Food and Drug Administration (FDA) approved drugs target 108 members of this family. The global sales volume for these drugs is estimated to be 180 billion US dollars as of 2018. It is estimated that GPCRs are targets for about 50% of drugs currently on the market, mainly due to their involvement in signaling pathways related to many diseases i.e. mental, metabolic including endocrinological disorders, immunological including viral infections, cardiovascular, inflammatory, senses disorders, and cancer. The long ago discovered association between GPCRs and many endogenous and exogenous substances, resulting in e.g. analgesia, is another dynamically developing field of the pharmaceutical research.
Several case studies studying deletions in the 7p22.3 genomic region, where the SNX8 gene is located, found that it contributes to neurodevelopmental problems with considerable impairments in the motor, cognitive and socio-emotional areas, with malformations in the heart and craniofacial structures, with developmental, intellectual and language delay, with mild intellectual disability and with cognitive impairment associated with autism in some cases. This idea is supported by the fact that the overlapping deleted regions of the different patients of these studies contained SNX8, which suggests that it is one of the accountable genes.
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While arsenic presents no radiological hazard, it is extremely chemically toxic. If it is desired to get rid of arsenic (no matter its origin), thermal neutron irradiation of the only stable isotope 75As will yield short lived 76As which quickly decays to stable 76Se. If arsenic is irradiated with sufficient fast neutrons to cause notable "knockout" (n,2n) or even (n,3n) reactions, Isotopes of germanium will be produced instead.
In molecular biology, subcloning is a technique used to move a particular DNA sequence from a parent vector to a destination vector. Subcloning is not to be confused with molecular cloning, a related technique.
=== Since 1994 === A new interim constitution, introduced in 1994 after four years of negotiation, finally introduced all-race democracy and enfranchised men and women of all races on equal terms, the minimum age remaining 18 years. Parliament was reconstituted to consist of a Senate and a National Assembly.
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Katherine J. Franz (born 1972) is an American chemist. She is the chair of the department of chemistry at Duke University. She studies metal ion coordination in biological systems and looks to use the insight to manage species such as copper and iron. Franz was awarded the American Chemical Society Award for Encouraging Women into Careers in the Chemical Sciences.
=== Invasion routes === Hematogenous spread, or spread through blood vessels, occurs either through the venous plexus of Batson or by arterial dissemination. This occurs with arterioles as a result of tumor cells being lodged in vessels that feed the meninges and later causing leakage into the meninges and CSF. This same situation also appear with spinal arteries where leakage of tumor cells is into the nerve roots. More regarding the effects of NM on spinal cord is discussed later. Tumor cells may also seed the choroid plexus, where CSF is produced, and ultimately gaining direct access to the CSF. Seeding of the choroid plexus is most common in patients with third and lateral ventricular hydrocephalus. Venous spread may occur when intra-abdominal or thoracic pressure increases and venous flow is retrograde which then allows tumor cells in the systemic venous system to enter the vertebral venous system. Centripetal migration from systemic tumors along perineural, invasion of nerve space, or perivascular spaces. Malignant cells can migrate along spinal or cranial nerve epineurium-perineurium, invade the subpial space, and travel along blood vessels into the endoneurial space, or invade the nerve parenchyma. Infiltration happens most often at the base of the brain, dorsal surface, and especially at the cauda equina, which is largely due to the effect of gravity. Once in the CSF, malignant cells can extend along the membrane surfaces or spread freely in the CSF and attach to other locations.
This was an increase from the 228,834 reports submitted in the previous year). Most of these reports are submitted by banks and similar financial institutions (there were 186,897 reports from the banking sector in the year ended 30 September 2010). Although 5,108 different organisations submitted suspicious activity reports to the authorities in the year ended 30 September 2010, just four organisations submitted approximately half of all reports, and the top 20 reporting organisations accounted for three-quarters of all reports. The offence of failing to report a suspicion of money laundering by another person carries a maximum penalty of five years' imprisonment. The Criminal Finances Act 2017 introduced unexplained wealth orders, another tool to combat money laundering, whereby the owner of an asset greater than £50,000 may be required to show how the purchase was financed. On 1 May 2018, the UK House of Commons, without opposition, passed the Sanctions and Anti–Money Laundering Bill, which will set out the UK government's intended approach to exceptions and licenses when the nation becomes responsible for implementing its own sanctions and will also require notorious overseas British territory tax havens such as the Cayman Islands and the British Virgin Islands to establish public registers of the beneficial ownership of firms in their jurisdictions by the end of 2020. The legislation was passed by the House of Lords on 21 May and received Royal Asset on 23 May.
== Treatment == Management of chronic granulomatous disease revolves around two goals: 1) diagnose the disease early so that antibiotic prophylaxis can be given to keep an infection from occurring, and 2) educate the patient about his or her condition so that prompt treatment can be given if an infection occurs.
Sources: en.wikipedia.org
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
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.