GABA-A modulation comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-06-08. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by RP-HPLC | Area percentage of the main peak |
| Identity confirmation | Electrospray ionization mass spectrometry | Observed mass compared with the theoretical value near 751.9 Da |
| Recommended dry storage | -20 °C, desiccated | -80 °C for multi-year archival material |
| Solution handling | Prepare fresh; avoid long storage | Sterile filtration reduces microbial load |
| Common synonyms | TKPRPGP; TP-7 | Sequence code and laboratory designation used interchangeably |
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.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
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.
=== Legal status === It was approved in both the European Union (brand name Revestive) and the United States (brand name Gattex) in 2012. It was granted orphan drug designation by the European Medicines Agency (EMA).
=== Taiwanese === The history of soy sauce making in Taiwan can be traced back to southeastern China, in the provinces of Fujian and Guangdong. Taiwanese soy sauce is known for its black bean variant, known as black bean soy sauce (黑豆蔭油), which producers claim to have stronger flavor and more nutrition. Most soy sauce makers in Taiwan make soy sauce from soybeans and wheat using machines, which is a technique introduced during Japanese rule. A smaller number of producers continue to handmake soy sauce in the traditional way.
Militias from the Cao Đài sect, which had initially joined the Viet Minh in their struggle against the return of the French, made a truce with France when their leader was captured on 6 June 1946. The Viet Minh later attacked the Cao Đài after open conflict had erupted with France, which led them to join the French side. The Viet Minh assassinated the Hòa Hảo leader Huỳnh Phú Sổ in April 1947. Vietnamese society also polarized along ethnic lines: the Nùng and Chinese Nùng minority assisted the French, while the Tày assisted the Việt Minh. The Khmer Krom also sided with France. Surviving Vietnamese nationalist partisans and politico-religious groups rallied behind the exiled Bảo Đại to reopen negotiations with France in opposition to communist domination. The State of Vietnam (SVN), with Bảo Đại as Chief of State, was established and positioned within the anticommunist Western Bloc. With the recognition of the DRV by China and the Soviet Union, and the recognition of the SVN by the United States in 1950, the civil war and the colonial war in Vietnam became internationalized and intertwined with the global Cold War.
There are many beta lactamases which vary in substrate specificity and host range. The enzymes active site is easily regenerated hydrolytically so it is re-usable many times, in that way can a comparatively small amount of beta-lactamases destroy a large amount of drug. Gram-positive bacteria, such as a staphylococci, have a high release of beta-lactamases into their extracellular space, where they meet the drug outside the cell wall. Gram-negative bacteria on the other hand follow a more conservative course. They secrete their beta-lactamases into the periplasmic space between the inner and outer membrane so they can't easily escape into the extracellular space, and don't have to be biosynthesized in high quantities.
=== Blocking of L-type calcium channels === Because the presence of calcium in the cytosol is required for muscle contraction, blockers of calcium channels prevent the muscles from building tension. Blockers of the L-type calcium channels, which occur in cardiac and smooth muscles, thus act as smooth muscle relaxants and inhibitors of cardiac contractions. Common blockers of L-type calcium channels are 1,4-dihydropyridines, which are used in treatment of cardiovascular diseases. Because of their activity as a relaxant, they can relax smooth muscles surrounding blood vessels, thus widening them and lowering the blood pressure.
Sources: en.wikipedia.org
=== Anaerobic oxidative decarboxylation === One well-studied example is HemN. HemN or anaerobic coproporphyrinogen III oxidase is a radical SAM enzyme that catalyzes the oxidative decarboxylation of coproporphyrinogen III to protoporphyrinogen IX, an intermediate in heme biosynthesis. Evidence support the idea that HemN utilizes two SAM molecules to mediate radical-mediated hydrogen transfer for the sequential decarboxylation of the two propionate groups of coproporphyrinogen III. Hyperthermophilic sulfate-reducing archaen Archaeoglobus fulgidus enables anaerobic oxidation of long chain n-alkanes. PflD is reported to be responsible for the capacity of A. fulgidus to grow on a wide range of unsaturated carbons and fatty acids. A detailed biochemical and mechanistic characterization of PflD is still undergoing but preliminary data suggest PflD may be a radical SAM enzyme.
=== Common resins === DEAE-C is commonly commercially available as DE52 and DE53. These resins are prepared preswollen although cellulose exchangers swell in a strong basic environment to increase access to binding sites. DE52 has a pKa of 11.5. The buffering range for diethanolamine is 8.4-8.8, though the range for DEAE-C varies between manufacturers.
=== New Zealand === The opposition Green Party of Aotearoa New Zealand's co-leader, Marama Davidson, stated "this is a unilateral attack that goes against any enduring pathway to international peace through justice." She called upon Prime Minister Christopher Luxon to condemn the United States for attacking Venezuela.
Temazepam, a strong hypnotic benzodiazepine, is illicitly manufactured in clandestine laboratories (called jellie labs) to supply the increasingly high demand for the drug internationally. Many clandestine temazepam labs are in Eastern Europe. The labs manufacture temazepam by chemically altering diazepam, oxazepam or lorazepam. "Jellie labs" have been identified and shut down in Russia, Ukraine, Latvia and Belarus.
Sources: en.wikipedia.org
Greater bulldog bats honk when on a collision course with each other. Bats also communicate by other means. Male little yellow-shouldered bats (Sturnira lilium) use a spicy odour secreted from their shoulder glands during the breeding season, retained and spread by specialised hairs. These hairs exist in other species, which are noticeable as collars around the necks in some Old World megabat males. Male greater sac-winged bats (Saccopteryx bilineata) have sacs in their wings in which they mix body secretions like saliva and urine to create a perfume that they sprinkle on roost sites, a behaviour known as "salting". The bats may sing while salting.
== Discovery == Collagen XXIII was first identified and isolated from rat prostate carcinoma cells by Jacqueline Banyard, Lere Bao and Bruce R. Zetter in 2003. They also identified this protein in human tissue. They concluded that at the nucleotide level, human and rat collagen XXIII alpha 1 show 76% identity. Furthermore, cellular localization of collagen XXIII was determined by immunofluorescence staining, using an antibody that recognizes the carboxyl terminus of the protein. It was demonstrated that the carboxyl terminus of collagen XXIII is present on the cell surface.
=== General references === Daxer, Albert; Misof, Klaus; Grabner, Barbara; Ettl, Armin; Fratzl, Peter (1998). "Collagen fibrils in the human corneal stroma: Structure and aging". Investigative Ophthalmology & Visual Science. 39 (3): 644–8. PMID 9501878. Daxer, Albert; Fratzl, Peter (1997). "Collagen fibril orientation in the human corneal stroma and its implication in keratoconus". Investigative Ophthalmology & Visual Science. 38 (1): 121–9. PMID 9008637. Fratzl, Peter; Daxer, Albert (1993). "Structural transformation of collagen fibrils in corneal stroma during drying. An x-ray scattering study". Biophysical Journal. 64 (4): 1210–4. Bibcode:1993BpJ....64.1210F. doi:10.1016/S0006-3495(93)81487-5. PMC 1262438. PMID 8494978.
However, there is no real demand in chemistry, physics, or engineering for isolating 234U, and the small amounts that may be wanted for research can be separated chemically from plutonium-238 that have been aged enough to accumulate its alpha decay product, which is 234U. Enriched uranium contains more 234U than natural uranium as a byproduct of the uranium enrichment process aimed at obtaining uranium-235, which concentrates lighter isotopes even more strongly than it does 235U. IAEA research paper TECDOC-1529 concludes the 234U content of enriched fuel is directly proportional to the degree of 235U—enrichment with 2% 235U resulting in 150 g 234U/ton HM (heavy metals, special meaning, relating to nuclear fuels), and the most common 4.5% 235U enrichment resulting in 400 g 234U/ton HM. The increased percentage of 234U in enriched natural uranium is not harmful to the operation of current nuclear reactors. Uranium-234 has a neutron-capture cross section of about 100 barns for thermal neutrons, and about 700 barns for its resonance integral—the average of neutrons having a range of intermediate energies. In a nuclear reactor non-fissile isotopes 234U and 238U both capture a neutron, thereby breeding fissile isotopes 235U and 239Pu, respectively. 234U is converted to 235U more easily and therefore at a greater rate than 238U is to 239Pu (via neptunium-239) because 238U has a much smaller neutron-capture cross section of just 2.7 barns.
The Houthis joined the war on 28 March launching a ballistic missile towards Israel while stating that they had launched ballistic missiles targeting "sensitive" military sites in Israel; the missile was intercepted and no casualties were reported. The Houthis subsequently launched a second missile at Eilat. In response, the internationally recognized Yemeni government condemned Iran's "frequent attempts to drag Yemen" into conflict "through its terrorist militias". On the same day, 2,500 US marines from the 31st Marine Expeditionary Unit arrived in the Middle East, expected to be part of US efforts to open the Strait of Hormuz. US Central Command (CENTCOM) stated that it had struck over 11,000 targets in Iran since the beginning of the war. On 28 March, joint US–Israeli airstrikes severely damaged several residential and civilian facilities, including the Iran University of Science and Technology. In response, Iran threatened to attack Israeli and American colleges across the Middle East. Airstrikes also struck a 10,000-cubic-metre (350,000 cu ft) water reservoir in Haftkel, in Khuzestan province. An Iranian missile struck a chemical plant in the Ne'ot Hovav industrial zone, injuring one person and causing fears of a hazardous leak. A convoy of the Iraqi Popular Mobilization Forces was seen entering Khorramshahr in southwestern Iran. Eleven-year-old child soldier Alireza Jafari was killed in an Israeli drone strike "while serving" at a checkpoint on a Tehran highway; Amnesty International called the organized Iranian recruitment of children as young as Jafari a war crime.
Sources: en.wikipedia.org
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.
A reported purity value reflects the share of the main peak in one chromatographic run and says nothing about identity. Confirming that the expected sequence is present requires a separate measurement such as mass spectrometry. Purity and identity are distinct questions.
A mass spectrum reports the molecular masses present in a sample and shows whether they match the value expected for selank, near 751.9 Da. It also flags common artifacts such as truncation or adduct formation. It does not establish correct stereochemistry or complete sequence order on its own.
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.