peptidase is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
| Property | Value | Notes |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
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.
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.
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.
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.
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.
== Presentation == Abdominal discomfort begins two to six hours after eating unripe ackee fruit, followed by sudden onset vomiting. In severe cases, profound dehydration, seizures, coma, and death may ensue. Children and those who are malnourished are more susceptible to the disease. Clinically the diagnosis is that of a toxic encephalopathy.
== Diagnosis == Typical scleroderma is classically defined as symmetrical skin thickening, with about 70% of cases also presenting with Raynaud's phenomenon, nail-fold capillary changes, and antinuclear antibodies. Affected individuals may experience systemic organ involvement. No single test for scleroderma works all of the time; hence, diagnosis is often a matter of exclusion. Atypical scleroderma may show any variation of these changes without skin changes or with finger swelling only. Laboratory testing can show antitopoisomerase antibodies, like anti-scl70 (causing a diffuse systemic form), or anticentromere antibodies (causing a limited systemic form and the CREST syndrome). Other autoantibodies can be seen, such as anti-U3 or anti-RNA polymerase. Antidouble-stranded DNA autoantibodies are likely to be present in serum.
=== Concentration quotients === In aqueous solution, equilibrium constants are usually determined in the presence of an "inert" electrolyte such as sodium nitrate, NaNO3, or potassium perchlorate, KClO4. The ionic strength of a solution is given by
Sources: en.wikipedia.org
== Prevention == Many types of dwarfism are currently impossible to prevent because they are genetically caused. Genetic conditions that cause dwarfism may be identified with genetic testing, by screening for the specific variations that result in the condition. However, due to the number of causes of dwarfism, it may be impossible to determine definitively if a child will be born with dwarfism. Dwarfism resulting from malnutrition or a hormonal abnormality may be treated with an appropriate diet or hormonal therapy. Growth hormone deficiency may be remedied via injections of human growth hormone during childhood.
11B is more sensitive than 10B and yields sharper signals. The nuclear spin of 10B is 3 and that of 11B is 3/2. Quartz tubes must be used because borosilicate glass interferes with measurement. 13C, a spin-1/2 nucleus, is widely used, despite its relative paucity in naturally occurring carbon (approximately 1.1%). It is stable to nuclear decay. Since there is a low percentage in natural carbon, spectrum acquisition on samples which have not been enriched in 13C takes a long time. Frequently used for labeling of compounds in synthetic and metabolic studies. Has low sensitivity and moderately wide chemical shift range, yields sharp signals. Low percentage makes it useful by preventing spin–spin couplings and makes the spectrum appear less crowded. Slow relaxation of 13C not bonded to hydrogen means that spectra are not integrable unless long acquisition times are used. 14N, spin-1, is a medium sensitivity nucleus with wide chemical shift range. Its large quadrupole moment interferes with acquisition of high-resolution spectra, limiting usefulness to smaller molecules and functional groups with a high degree of symmetry such as in the head-groups of lipids. 15N, spin-1/2, is relatively commonly used. Can be used for isotopically labeling compounds. Very insensitive but yields sharp signals. Low percentage in natural nitrogen together with low sensitivity requires high concentrations or expensive isotope enrichment. 17O, spin-5/2, low sensitivity and very low natural abundance (0.037%), wide chemical shift range (up to 2000 ppm).
The 1980s saw several new technologies that promised to change the way creatinine testing was done. Enzymatic and ion-exchange methods provided better accuracy but had other drawbacks. Enzymatic methods reduced some interferences but other new ones were discovered. High-performance liquid chromatography, HPLC, was more sensitive and specific, and had become the new reference method endorsed by the American Association for Clinical Chemistry. HPLC addressed the shortcomings of Jaffe-based methods, but was labor-intensive, expensive, and therefore impractical for routine analysis of the most frequently ordered renal analyte in medical labs. Simple, easily automated and cost-effective, Jaffe-based methods have persisted into the 21st century, despite their imperfections. By 2006, isotope dilution mass spectrometry (IDMS) became the reference method. To improve the accuracy in creatinine testing, new standards were developed by the National Institute of Standards and Technology (NIST). The College of American Pathologists (CAP) and the National Kidney Disease Education Program (NKDEP) collaborated with NIST to develop a new control reference called standard reference material 967 (SRM 967). SRM 967 aims to standardize calibration of creatinine testing, including Jaffe methods. Use of both IDMS and SRM 967 are currently recommended by the National Institutes of Health.
==== 1600–1699 ==== Department of Transport (Fees) (Amendment) Order 1993 (S.I. 1993/1601) Motor Vehicles (Driving Licences) (Amendment) Regulations 1993 (S.I. 1993/1602) Motor Vehicles (Driving Licences) (Large Goods and Passenger-Carrying Vehicles) (Amendment) Regulations 1993 (S.I. 1993/1603) Education (School and Placing Information) (Scotland) Amendment, Etc., Regulations 1993 (S.I. 1993/1604) Education (Provision of Information as to Schools) (Scotland) Regulations 1993 (S.I. 1993/1605) Food Protection (Emergency Prohibitions) (Paralytic Shellfish Poisoning) (No.7) Order 1993 (S.I. 1993/1606) Swanage Light Railway (Extension) Order 1993 (S.I. 1993/1607) Council Tax Limitation (Wales) (Maximum Amount) Order 1993 (S.I. 1993/1608) Further Education (Prescription of Different Date for Property Agreements) (Scotland) Order 1993 (S.I. 1993/1614) Health Boards (Membership and Procedure) (No. 2) Amendment Regulations 1993 (S.I. 1993/1615) Education (Student Loans) (Amendment) Regulations 1993 (S.I. 1993/1620) Community Action (Miscellaneous Provisions) Order 1993 (S.I. 1993/1621) Air Navigation (General) Regulations 1993 (S.I. 1993/1622) Debts of Overseas Governments (Determination of Relevant Percentage) (Amendment) Regulations 1993 (S.I. 1993/1623) Charities (Exemption from Accounting Requirements) (Scotland) Regulations 1993 (S.I. 1993/1624) Right to Purchase (Prescribed Persons) (Scotland) Order 1993 (S.I. 1993/1625) Sheep Annual Premium and Suckler Cow Premium Quotas Regulations 1993 (S.I.
Sources: en.wikipedia.org
Yet the foundations for what would come to be known as "The Frankfurt School" were soon laid: Horkheimer resumed his chair in social philosophy, and the Institute for Social Research, rebuilt, became a lightning rod for critical thought.
== GST-tags and the GST pull-down assay == GST can be added to a protein of interest to purify it from solution in a process known as a pull-down assay. This is accomplished by inserting the GST DNA coding sequence next to that which codes for the protein of interest. Thus, after transcription and translation, the GST protein and the protein of interest will be expressed together as a fusion protein. Because the GST protein has a strong binding affinity for GSH, beads coated with the compound can be added to the protein mixture; as a result, the protein of interest attached to the GST will stick to the beads, isolating the protein from the rest of those in solution. The beads are recovered and washed with free GSH to detach the protein of interest from the beads, resulting in a purified protein. This technique can be used to elucidate direct protein–protein interactions. A drawback of this assay is that the protein of interest is attached to GST, altering its native state. A GST-tag is often used to separate and purify proteins that contain the GST-fusion protein. The tag is 220 amino acids (roughly 26 kDa) in size, which, compared to tags such as the Myc-tag or the FLAG-tag, is quite large. It can be fused to either the N-terminus or C-terminus of a protein. In addition to functioning as a purification tag, GST acts as a chaperone for the attached protein, promoting its correct folding, as well as preventing it from becoming aggregated in inclusion bodies when expressed in bacteria.
==== MeSH E05.318.308 – data collection ==== MeSH E05.318.308.225 – geriatric assessment MeSH E05.318.308.250 – health surveys MeSH E05.318.308.250.149 – behavioral risk factor surveillance system MeSH E05.318.308.250.300 – dental health surveys MeSH E05.318.308.250.300.300 – dental plaque index MeSH E05.318.308.250.300.350 – dmf index MeSH E05.318.308.250.300.675 – oral hygiene index MeSH E05.318.308.250.300.725 – periodontal index MeSH E05.318.308.250.475 – health status indicators MeSH E05.318.308.250.475.365 – apache MeSH E05.318.308.250.475.547 – severity of illness index MeSH E05.318.308.250.475.547.500 – karnofsky performance status MeSH E05.318.308.250.475.730 – sickness impact profile MeSH E05.318.308.250.580 – mass screening MeSH E05.318.308.250.580.174 – anonymous testing MeSH E05.318.308.250.580.350 – genetic screening MeSH E05.318.308.250.580.510 – mass chest x-ray MeSH E05.318.308.250.580.560 – multiphasic screening MeSH E05.318.308.250.580.580 – neonatal screening MeSH E05.318.308.250.580.925 – vision screening MeSH E05.318.308.250.600 – nutrition surveys MeSH E05.318.308.250.600.350 – diet surveys MeSH E05.318.308.250.700 – population surveillance MeSH E05.318.308.250.700.650 – sentinel surveillance MeSH E05.318.308.335 – health care surveys MeSH E05.318.308.420 – interviews MeSH E05.318.308.420.200 – focus groups MeSH E05.318.308.502 – narration MeSH E05.318.308.585 – nutrition assessment MeSH E05.318.308.585.550 – nutrition surveys MeSH E05.318.308.585.550.350 – diet surveys MeSH E05.318.308.750 – questionnaires MeSH E05.318.308.940 – records MeSH E05.318.308.940.250 – birth certificates MeSH E05.318.308.940.350 – death certificates MeSH E05.318.308.940.375 – dental records MeSH E05.318.308.940.425 – hospital records MeSH E05.318.308.940.968 – medical records MeSH E05.318.308.940.968.500 – medical record linkage MeSH E05.318.308.940.968.625 – medical records systems, computerized MeSH E05.318.308.940.968.750 – medical records, problem-oriented MeSH E05.318.308.940.968.875 – trauma severity indices MeSH E05.318.308.940.968.875.125 – abbreviated injury scale MeSH E05.318.308.940.968.875.250 – glasgow coma scale MeSH E05.318.308.940.968.875.260 – glasgow outcome scale MeSH E05.318.308.940.968.875.500 – injury severity score MeSH E05.318.308.940.984 – nursing records MeSH E05.318.308.970 – registries MeSH E05.318.308.970.725 – seer program MeSH E05.318.308.985 – vital statistics MeSH E05.318.308.985.450 – life expectancy MeSH E05.318.308.985.475 – life tables MeSH E05.318.308.985.525 – morbidity MeSH E05.318.308.985.525.080 – basic reproduction number MeSH E05.318.308.985.525.375 – incidence MeSH E05.318.308.985.525.750 – prevalence MeSH E05.318.308.985.550 – mortality MeSH E05.318.308.985.550.250 – cause of death MeSH E05.318.308.985.550.287 – child mortality MeSH E05.318.308.985.550.325 – fatal outcome MeSH E05.318.308.985.550.362 – fetal mortality MeSH E05.318.308.985.550.400 – hospital mortality MeSH E05.318.308.985.550.475 – infant mortality MeSH E05.318.308.985.550.500 – maternal mortality MeSH E05.318.308.985.550.900 – survival rate MeSH E05.318.308.985.775 – pregnancy rate MeSH E05.318.308.985.775.500 – birth rate
== Biological Functions == 2,5-DKPs have been shown to play a role in interspecies bacterial quorum sensing. For example, the 2,5-DKP cyclo(Phe-Pro) has been shown to play a role in the regulation of gene expression in multiple different species of bacteria including V. fishceri, V. cholera, Lactobacillus reuteri, Staphylococcus aureus, among others.
In August 2019, the FDA approved fedratinib (Inrebic) as a treatment for adults with intermediate-2 or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis (MF). In March 2022, the FDA approved pacritinib (Vonjo) with an indication to treat adults who have intermediate or high-risk primary or secondary myelofibrosis and who have platelet (blood clotting cells) levels below 50,000/μL. Momelotinib (Ojjaara) was approved for medical use in the United States in September 2023. It is indicated for the treatment of intermediate or high-risk myelofibrosis, including primary myelofibrosis or secondary myelofibrosis [post-polycythemia vera and post-essential thrombocythemia], in adults with anemia. Currently a few drugs are under clinical trial for their use in myelofibrosis. This includes Tasquinimod, which targets the alarmin protein S1009a and has been shown to have beneficial effects in pre-clinical models.
Sources: en.wikipedia.org
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.