The short version of mass spectrometry fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-07-28 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.
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.
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.
| 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 |
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
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.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
== History == In the late 1970s and early 1980s the material was used with the brand names of Hylartin and Hylartin Vetused in human and veterinary clinical trials (race horses) to treat osteoarthritis. The first commercially sold sodium hyaluronate had been developed by Endre Alexander Balazs under the brand name of Healon, manufactured by Pharmacia AB in Sweden in 1980. In 1986, sodium hyaluronate was used as an intra-articular injection to treat osteoarthritis of the knee with the product Hyalart/Hyalgan by Fidia of Italy.
== Commercial performance == Ellipse debuted at number 5 on the Billboard 200 chart and spent a total of 9 weeks on the chart, while also debuting at number 4 on the Billboard Canadian Albums chart and spending a total of 2 weeks on that chart. She also earned three more top 5 entries (including a chart topping entry) in other Billboard charts As of 2011, the album had sold 161,000 copies in the United States. The album sold 48,025 copies worldwide in its first week, which is the most copies Imogen has sold in a singular week.
==== IgE receptor structure ==== FcεR1 is a high affinity IgE-receptor that is expressed on the surface of the mast cell. FcεR1 is a tetramer made of one alpha (α) chain, one beta (β) chain, and two identical, disulfide-linked gamma (γ) chains. The binding site for IgE is formed by the extracellular portion of the α chain that contains two domains that are similar to Ig. One transmembrane domain contains an aspartic acid residue, and one contains a short cytoplasmic tail. The β chain contains, a single immunoreceptor tyrosine-based activation motif ITAM, in the cytoplasmic region. Each γ chain has one ITAM on the cytoplasmic region. The signaling cascade from the receptor is initiated when the ITAMs of the β and γ chains are phosphorylated by a tyrosine kinase. This signal is required for the activation of mast cells. Type 2 helper T cells,(Th2) and many other cell types lack the β chain, so signaling is mediated only by the γ chain. This is due to the α chain containing endoplasmic reticulum retention signals that causes the α-chains to remain degraded in the ER. The assembly of the α chain with the co-transfected β and γ chains mask the ER retention and allows the α β γ complex to be exported to the golgi apparatus to the plasma membrane in rats. In humans, only the γ complex is needed to counterbalance the α chain ER retention.
=== Pharmacodynamics === Relative to other benzodiazepines, lorazepam is thought to have a high affinity for GABA receptors, which may also explain its marked amnesic effects. Its main pharmacological effects are the enhancement of the effects of the neurotransmitter GABA at the GABAA receptor. Benzodiazepines, such as lorazepam, enhance the effects of GABA at the GABAA receptor via increasing the frequency of opening of the chloride ion channel on the GABAA receptors; which results in the therapeutic actions of benzodiazepines. They, however, do not on their own activate the GABAA receptors but require the neurotransmitter GABA to be present. Thus, the effect of benzodiazepines is to enhance the effects of the neurotransmitter GABA. The magnitude and duration of lorazepam effects are dose-related, meaning larger doses have stronger and longer-lasting effects, because the brain has spare benzodiazepine drug receptor capacity, with single, clinical doses leading only to an occupancy of some 3% of the available receptors.
Sources: en.wikipedia.org
=== Canada === In Canada, Canadian medical graduates (CMGs), which includes final-year medical students and unmatched previous-year medical graduates, apply for residency positions via the Canadian Resident Matching Service (CaRMS). The first year of residency training is known as "Postgraduate Year 1" (PGY1). CMGs can apply to many post-graduate medical training programs including family medicine, emergency medicine, internal medicine, pediatrics, general surgery, obstetrics-gynecology, neurology, and psychiatry, amongst others. Some residency programs are direct-entry (family medicine, dermatology, neurology, general surgery, etc.), meaning that CMGs applying to these specialties do so directly from medical school. Other residencies have sub-specialty matches (internal medicine and pediatrics) where residents complete their first 2–3 years before completing a secondary match (Medicine subspecialty match (MSM) or Pediatric subspecialty match (PSM)). After this secondary match has been completed, residents are referred to as fellows. Some areas of subspecialty matches include cardiology, nephrology, gastroenterology, immunology, respirology, infectious diseases, rheumatology, endocrinology and more. Direct-entry specialties also have fellowships, but they are completed at the end of residency (typically 5 years).
=== Phase 3 === Gepirone (Ariza; BMY-13805; Exxua; Gepirone ER; MJ-13805; Org-33062; TGFK-07AD; TGFK07AD; Travivo; Variza) – serotonin 5-HT1A receptor partial agonist [1] Lysergic acid diethylamide (LSD; lysergide; MM-120; MM120) – non-selective serotonin receptor agonist and psychedelic hallucinogen [2] [3] Toludesvenlafaxine extended release (4-methylbenzoate desvenlafaxine; ansofaxine; desvenlafaxine prodrug; LPM-570065; LY-03005; Ruoxinlin) – serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI) [4] Vilazodone (EMD-68843; SB-659746A; Viibryd) – serotonin reuptake inhibitor (SRI) and serotonin 5-HT1A receptor partial agonist [5]
== Cross-Linked Enzyme Aggregates (CLEAs) == The use of cross-linked enzyme crystals (CLECs) as industrial biocatalysts was pioneered by Altus Biologics in the 1990s. CLECs proved to be significantly more stable to denaturation by heat, organic solvents and proteolysis than the corresponding soluble enzyme or lyophilized (freeze-dried) powder. CLECs are robust, highly active immobilized enzymes of controllable particle size, varying from 1 to 100 micrometer. Their operational stability and ease of recycling, coupled with their high catalyst and volumetric productivities, renders them ideally suited for industrial biotransformations. However, CLECs have an inherent disadvantage: enzyme crystallization is a laborious procedure requiring enzyme of high purity, which translates to prohibitively high costs. The more recently developed cross-linked enzyme aggregates (CLEAs), on the other hand, are produced by simple precipitation of the enzyme from aqueous solution, as physical aggregates of protein molecules, by the addition of salts, or water miscible organic solvents or non-ionic polymers. The physical aggregates are held together by covalent bonding without perturbation of their tertiary structure, that is without denaturation. Subsequent cross-linking of these physical aggregates renders them permanently insoluble while maintaining their pre-organized superstructure, and, hence their catalytic activity. This discovery led to the development of a new family of immobilized enzymes: cross-linked enzyme aggregates (CLEAs).
Sources: en.wikipedia.org
In Islam, embalming of the dead is not practiced, except in cases of necessity, such as when a body is being transported internationally and the law requires it to be embalmed. Muslims bury their deceased without delay (preferably within 24 hours), to allow the soul to transition to the afterlife as soon as possible. Buddhists generally do not favor embalming, but it is not strictly prohibited in most Buddhist traditions. The practice of embalming varies among different Buddhist schools and cultures. In Theravada Buddhism, embalming is allowed but not considered essential. However, in Tibetan Buddhism, embalming is typically discouraged and should not take place. The increasingly global nature of communities and far longer delays between death and final disposition caused by modern requirements and often distant families mean that embalming is frequently required either by law or common sense due to issues of transportation and holding requirement. Thus most religious authorities relent to its necessity in specific circumstances
==== Enzyme-linked immunosorbent assay ==== The enzyme-linked immunosorbent assay (ELISA) technique used for the analysis of YTXs is a recently developed method by Briggs et al. This competitive, indirect immunoassay uses polyclonal antibodies against YTX to determine its concentration in the sample. The assay is commercially available, and is a rapid technique for the analysis of YTXs in shellfish, algal cells, and culture samples. ELISA has several advantages: it is very sensitive, has a limit of quantification of 75 μg/kg, is relatively cheap, and is easy to carry out. The major disadvantage to this method is it cannot differentiate between the different YTX analogues and takes a long time to generate results.
Interestingly, the full-length CUX1 protein purified from insect cells exhibited DNA binding kinetics similar to that of CR1CR2, suggesting that the Cut homeodomain may not be active in the context of the full-length protein.
elementary reaction Any chemical reaction in which one or more chemical species react directly to form products in a single reaction step and with a single transition state, i.e. without any intermediates. Contrast stepwise reaction.
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 synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.