This is a working overview of GABA-A modulation, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-06 and is reviewed periodically as new material appears.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
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.
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 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.
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.
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.
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.
== Distribution coefficient and log D == The distribution coefficient, log D, is the ratio of the sum of the concentrations of all forms of the compound (ionized plus un-ionized) in each of the two phases, one essentially always aqueous; as such, it depends on the pH of the aqueous phase, and log D = log P for non-ionizable compounds at any pH. For measurements of distribution coefficients, the pH of the aqueous phase is buffered to a specific value such that the pH is not significantly perturbed by the introduction of the compound. The value of each log D is then determined as the logarithm of a ratio—of the sum of the experimentally measured concentrations of the solute's various forms in one solvent, to the sum of such concentrations of its forms in the other solvent; it can be expressed as
Cycling between supercritical and subcritical CO2 at tectonic fault zones might have led to peptides integrating with and stabilizing lipid membranes. This is suggested to have driven membrane protein evolution, as it shown that a selected peptide (H-Lys-Ser-Pro-Phe-Pro-Phe-Ala-Ala-OH) causes the increase of membrane permeability to water. David Deamer and Bruce Damer states that the prebiotic chemistry does not require ultraviolet irradiation as the chemistry could also have occurred under shaded areas that protected biomolecules from photolysis.
=== Mexican women === Immigration of Mexican citizens into the United States caused much controversy in how well they had adjusted to the American life and culture. Because of this, starting in the early 20th century, they were deemed as a significant problem to the community as they were believed to be mentally weak due to their prolonged adjustment to the American culture. The increase of city populations also led to the belief that mental health degraded, as more mental breakdowns seemed prevalent. This discrimination against Mexican and Mexican-Americans led to eugenics laws in which women were targeted and utilized in sterilization procedures. Starting in the year 1909, women of Mexican descent were used as targets for the eugenics movement to reinforce population control and purity. Women of all ages were victims of the many sterilization acts performed in hospitals, correction facilities, and asylums, but younger women were especially targeted. Pacific Colony (later known as Lanterman Developmental Center), a home designated for the mentally defective in LA, California, took in many young women and classified them as mentally defective and sexually delinquent starting in 1944. According to laws in California justifying sterilization acts, staff at this clinic deemed it was in the best interests of society to go forth with the procedure on some of the women who were sent here. In Los Angeles, between 1969 and 1973, Mexican and Chicana (Mexican-American) women were also disproportionately targeted by involuntary sterilizations.
Sources: en.wikipedia.org
BioB or biotin synthase is a radical SAM enzyme that employs one [4Fe-4S] center to thiolate dethiobitin, thus converting it to biotin or also known as vitamin B7. Vitamin B7 is a cofactor used in carboxylation, decarboxylation, and transcarboxylation reactions in many organisms. LipA or lipoyl synthase is radical SAM sulfurtransferase utilizing two [4Fe-4S] clusters to catalyze the final step in lipoic acid biosynthesis.
Diethylaminoethyl cellulose (DEAE-C) is a positively charged resin used in ion-exchange chromatography, a type of column chromatography, for the separation and purification of proteins and nucleic acids. Gel matrix beads are derivatized with diethylaminoethanol (DEAE) and lock negatively charged proteins or nucleic acids into the matrix. The proteins are released from the resin by increasing the salt concentration of the solvent or changing the pH of the solution as to change the charge on the protein.
Like garlic, shallots are formed in clusters of offsets with a head composed of multiple cloves. The skin colour of shallots can vary from golden brown to gray to rose red, and their off-white flesh is usually tinged with green or magenta. Shallots are extensively cultivated for culinary uses, propagated by offsets. In some regions ("long-season areas"), the offsets are usually planted in autumn (September or October in the Northern Hemisphere). In some other regions, the suggested planting time for the principal crop is early spring (typically in February or the beginning of March in the Northern Hemisphere). In planting, the tops of the bulbs should be kept a little above ground, and the soil surrounding the bulbs is often drawn away when the roots have taken hold. They come to maturity in summer, although fresh shallots can now be found year-round in supermarkets. Shallots should not be planted on ground recently manured. Shallots suffer damage from leek moth larvae, which mine into the leaves or bulbs of the plant.
Sources: en.wikipedia.org
The three substrates of this enzyme are hydroxy-1,4-benzoquinone, reduced nicotinamide adenine dinucleotide (NADH), and a proton. Its products are hydroxyquinol and oxidised NAD+. This enzyme participates in the metabolism of 2,4,5-trichlorophenoxyacetic acid in the bacteria Burkholderia cepacia.
The first clinical study of vosilasarm, a small (n=22) phase 1 study in women with metastatic breast cancer, was started in 2017 and completed in 2020, with results published in 2019, 2020, and 2022. As of March 2023, vosilasarm is in phase 1/2 clinical trials for the treatment of breast cancer. Aside from its development as a potential pharmaceutical drug, vosilasarm is on the World Anti-Doping Agency list of prohibited substances and is sold for physique- and performance-enhancing purposes by black-market Internet suppliers. Vosilasarm is often used in these contexts at doses that have not been evaluated in clinical trials, with unknown effectiveness and safety. Many products sold online that are purported to be a specific SARM either contain none or contain other unrelated substances. Social media has played an important role in facilitating the widespread non-medical use of SARMs.
Cells of one type may release the 5(S)-HETE that they make to nearby cells of a second type which then oxidize the 5(S)-HETE to 5-oxo-ETE. This transcellular production typically involves the limited variety of cell types that express active 5-lipoxygenase, lack HEDH activity because of their high levels of NADPH compared to NADP+ levels, and therefore accumulate 5(S)-HETE, not 5-oxo-ETE, upon stimulation. This 5(S)-ETE can leave these cells, enter various cell types that possess 5-HEDH activity along with lower NADPH to NADP+ levels, and thereby be converted to 5-oxo-ETE. Transcellular production of 5-oxo-eicosatetraenoates has been demonstrated in vitro with human neutrophils as the 5(S)-HETE producing cells and human PC-3 prostate cancer cells, platelets, and monocyte-derived dendritic cells as the oxidizing cells. It is theorized that this transcellular metabolism occurs in vivo and provides a mechanism for controlling 5-oxo-ETE production by allowing it to occur or be augmented at sites were 5-lipoxygenase-containing cells congregate with cell types possessing 5-HEDH and favorable NADPH/NADP+ ratios; such sites, it is theorized, might include those involving allergy, inflammation, oxidative stress, and rapidly growing cancers.
For instance, on average each gram of potassium contains 117 micrograms of 40K (all other naturally occurring isotopes are stable) that has a t1/2 of 1.277×109 years = 4.030×1016 s, and has an atomic mass of 39.964 g/mol, so the amount of radioactivity associated with a gram of potassium is 30 Bq.
Sources: en.wikipedia.org
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.