peptidase 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 2026-07-23 and is reviewed periodically as new material appears.
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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
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.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
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.
Gastrointestinal problems can be part of CMT, as can difficulty chewing, swallowing, and speaking (due to atrophy of vocal cords). A tremor can develop as muscles waste. Pregnancy has been known to exacerbate CMT, as well as severe emotional stress. Patients with CMT must avoid periods of prolonged immobility, such as when recovering from a secondary injury, as prolonged periods of limited mobility can drastically accelerate symptoms of CMT. Pain is a common symptom experienced by individuals with Charcot–Marie–Tooth disease, often resulting from postural abnormalities, skeletal deformities, muscle fatigue, and cramping. This pain can typically be managed through a combination of physical therapy, orthopedic interventions, and the use of corrective or assistive devices. In cases where these approaches do not provide sufficient relief, analgesic medications may be necessary to alleviate discomfort and improve quality of life. Although the disease is typically slowly progressive and not life-threatening, the degree of disability can vary. Some people may live relatively normal lives with mild symptoms, while others may require orthopedic supports, physical therapy, or even surgery to manage complications. The variation in symptoms and severity is influenced by the specific genetic mutation causing the condition. While some genes are linked to earlier onset and more severe forms of CMT, others result in milder forms with slower progression. Furthermore, even when the same gene is involved, the symptoms can differ between individuals.
The first group of Directives create a range of individual rights in EU employment relationships. The Employment Information Directive 1991 requires that every employee (however defined by member state law) has the right to a written statement of their employment contract. While there is no wage regulation, the Institutions for Occupational Retirement Provision Directive 2003 requires that pension benefits are protected through a national insurance fund, that information is provided to beneficiaries, and minimum standards of governance are observed. Most member states go far beyond these requirements, particularly by requiring a vote for employees in who manages their money. Reflecting basic standards in the Universal Declaration of Human Rights and ILO Conventions, the Working Time Directive 2003 requires a minimum of 4 weeks (totalling 28 days) paid holidays each year, a minimum of 20-minute paid rest breaks for 6-hour work shifts, limits on night work or time spent on dangerous work, and a maximum 48-hour working week unless a worker individually consents. The Parental Leave Directive 2010 creates a bare minimum of 4 months of unpaid leave for parents (mothers, fathers, or legal guardians) to care for children before they turn 8 years old, and the Pregnant Workers Directive 1992 creates a right for mothers to a minimum of 14 weeks' paid leave to care for children.
==== Dengue epidemic ==== In 2024, the number of deaths from dengue in the country surged (6,041), an increase of 400% compared with 2023 (1,179), surpassing the deaths from COVID-19 (5,960) in that year (2024). Dengue deaths in 2024 exceeded the total for the previous eight years (4,992). The explosion in dengue cases led opposition deputies from the PL to nickname Lula "presidengue" and share false and exaggerated data about the number of deaths resulting from this small-scale epidemic.
== Structural studies == As of late 2007, 8 structures have been solved for this class of enzymes, with PDB accession codes PDB: 1VKN, PDB: 2CVO, PDB: 2G17, PDB: 2I3A, PDB: 2I3G, PDB: 2NQT, PDB: 2OZP, and PDB: 2Q49.
Sources: en.wikipedia.org
==== Engineered bacteria-based platform ==== Bacteria have long been used in cancer treatment. Bifidobacterium and Clostridium selectively colonize tumors and reduce their size. Recently synthetic biologists reprogrammed bacteria to sense and respond to a particular cancer state. Most often bacteria are used to deliver a therapeutic molecule directly to the tumor to minimize off-target effects. To target the tumor cells, peptides that can specifically recognize a tumor were expressed on the surfaces of bacteria. Peptides used include an affibody molecule that specifically targets human epidermal growth factor receptor 2 and a synthetic adhesin. The other way is to allow bacteria to sense the tumor microenvironment, for example hypoxia, by building an AND logic gate into bacteria. Then the bacteria only release target therapeutic molecules to the tumor through either lysis or the bacterial secretion system. Lysis has the advantage that it can stimulate the immune system and control growth. Multiple types of secretion systems can be used and other strategies as well. The system is inducible by external signals. Inducers include chemicals, electromagnetic or light waves. Multiple species and strains are applied in these therapeutics. Most commonly used bacteria are Salmonella typhimurium, Escherichia coli, Bifidobacteria, Streptococcus, Lactobacillus, Listeria and Bacillus subtilis. Each of these species have their own property and are unique to cancer therapy in terms of tissue colonization, interaction with immune system and ease of application.
== Circular economy == Recent research has begun to investigate the relationship between fermentation and creating a circular economy in effort to address the current climate crisis and the increasing demands for resources as the population grows. The production of fuels, materials, and other chemicals has led to a notable increase in greenhouse gasses and a subsequent increase in global temperatures. The current, linear economy relies heavily on fossil fuels and nonrenewable energy to produce chemicals and materials. In a circular economy, the use of renewable resources would be employed to produce chemicals; moreover, this type of economy focuses on reusing end-of-life chemicals and materials. Investigation into alternative biofuels and biomaterials has become increasingly popular with fermentation as a notable method. The primary source of biomass for fermentation is using biomass feedstocks which contain a mix of carbohydrates, proteins, oils and fats, and lignin. Carbohydrates such as sucrose and starch (sources include sugarcane, corn, and cassava) are the most commonly used substrate for fermentation; however, in the discussion of biofuels, there are concerns regarding land competition between food and fuel biomass. Attention has been turned towards second-generation biomass feedstock such as silvergrass or wood chips.
== Diagonals == If e, f, g and h are the tangent lengths from A, B, C and D respectively to the points where the incircle is tangent to the sides of a tangential quadrilateral ABCD, then the lengths of the diagonals p = AC and q = BD are
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
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.