If you have been reading about certificate of analysis and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-01-10. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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 |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
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.
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.
Amnesty International has received reports of violence against lesbians in Jamaica, including rape and other forms of sexual violence. Lesbians reportedly have been attacked on the grounds of masculine physical appearance or other visible signs of sexuality. Some reports of abduction and rape come from inner-city communities, where local non-governmental organizations have expressed concerns about high incidents of violence against women.
polyadenylation The addition of a series of multiple adenosine ribonucleotides, known as a poly(A) tail, to the 3'-end of a primary RNA transcript. A class of post-transcriptional modification, polyadenylation serves different purposes for different classes of RNA and in different cell types and organisms. For eukaryotic messenger RNAs, the addition of a poly(A) tail is an important step in the processing of the raw transcript into a mature mRNA ready for export to the cytoplasm; primary transcripts are first cleaved 10–30 nucleotides downstream of a highly conserved AAUAAA sequence, then the poly(A) tail is generated from the chaining of multiple ATP molecules through the action of polynucleotide adenylyltransferase.For non-coding RNAs and in many bacteria, polyadenylation has the opposite function, instead promoting the RNA's degradation.
C6H5OH + Hg(O2CCH3)2 → C6H4(OH)–HgO2CCH3 + CH3CO2H C6H4(OH)–HgO2CCH3 + NaCl → C6H4(OH)–HgCl + NaO2CCH3 The first such reaction, including a mercuration of benzene itself, was first reported by Otto Dimroth in 1898.
Ukraine's Defense Ministry claimed that May 2024 was the deadliest month for Russia so far in the war, with Russian troop losses allegedly amounting to 38,940 killed, wounded, missing, or captured. They also claimed a record number of 1,160 Russian artillery systems destroyed.
Sources: en.wikipedia.org
Some analysts used the term to describe the worsening relations between Russia on one side and the West or NATO, or more specifically the United States on the other since the 2014 Russian annexation of Crimea and intervention in Eastern Ukraine, which started the Russo-Ukrainian war. Others argue that the term is not appropriate.
Drew often has issues with Berto over boundaries and the door being locked (at one point, prompting an intervention by Ryan and Amber) and because Berto slept with Natalie (while Amy was visiting Drew). When Drew returns to the room after a few weeks’ absence, Berto suggests the Drew voice his issues while chugging beer; Drew and Berto seem to get along afterwards. Natalie (Lyndon Smith) is Drew's love interest and dorm-mate at UC Berkeley during seasons 5 and 6. Chris Jefferies (Coby Ryan McLaughlin) is Julia's colleague at the law firm where she works during season 6. They dated in law school, and got back in a romantic relationship, until she reconciles with Joel. Before Julia and Joel reconcile, though, Adam recruits Chris for a basketball game during a family picnic where Chris only came to have Julia sign a paper; Joel is mad because she introduced him to the kids. Dr. Leland Gordon (Leland Crooke) is the physician who performs heart surgery on Zeek, and sees him when Zeek has a second cardiac episode. Dylan Jones (Ally Ioannides) is a newer student at Chambers Academy with ADHD and an abrupt personality, who befriends Max (whom she usually calls "Asperger's"). Max becomes romantically interested in her, but she does not reciprocate the feelings that Max has. Aaron Brownstein (Isaac Salzman) is a student at Chambers Academy with ADHD. He is in the culinary arts class, where students are always warning Adam Braverman (who teaches the class) when Aaron has matches or a knife.
Population coverage: some countries have large surveillance networks that cover most of their population, while others use a smaller subset of hospitals and laboratories to generate data intended to be representative of the broader population. Sampling: EARS-Net data are only collected for invasive isolates (from blood or cerebrospinal fluid). These samples may not be representative of the members of this species that can colonize and infect humans, so resistance rates for other infections, such as urinary tract infections may vary. In some settings, laboratory microbiology work may only be performed in cases where initial antibiotic treatment has failed, leading to an overestimation of resistance rates. Laboratory routines and capacity: interpretation of minimum inhibitory concentration may vary across laboratories and countries, depending on current practice. Recommendations around converting minimum inhibitory concentration to resistance status also change over time, making comparison of resistance rates over time challenging.
== Detectors == A time-of-flight mass spectrometer (TOFMS) consists of a mass analyzer and a detector. An ion source (either pulsed or continuous) is used for lab-related TOF experiments, but not needed for TOF analyzers used in space, where the sun or planetary ionospheres provide the ions. The TOF mass analyzer can be a linear flight tube or a reflectron. The ion detector typically consists of microchannel plate detector or a fast secondary emission multiplier (SEM) where first converter plate (dynode) is flat. The electrical signal from the detector is recorded by means of a time to digital converter (TDC) or a fast analog-to-digital converter (ADC). TDC is mostly used in combination with orthogonal-acceleration (oa)TOF instruments. Time-to-digital converters register the arrival of a single ion at discrete time "bins"; a combination of threshold triggering and constant fraction discriminator (CFD) discriminates between electronic noise and ion arrival events. CFD converts nanosecond-long Gaussian-shaped electrical pulses of different amplitudes generated on the MCP's anode into common-shape pulses (e.g., pulses compatible with TTL/ESL logic circuitry) sent to TDC. Using CFD provides a time point correspondent to a position of peak maximum independent of variation in the peak amplitude caused by variation of the MCP or SEM gain.
=== Analogues === A notable analogue of SDA is 4T-MMDA-2 (2-methoxy-4T-MDA), which was described by Alexander Shulgin in his book PiHKAL (Phenethylamines I Have Known and Loved). Other analogues of SDA include SDMA, MDA, MDMA, 5-APB, 5-APDB, and 6-APBT, among others.
Sources: en.wikipedia.org
SPINA-GBeta is a calculated biomarker for pancreatic beta cell function. It represents the maximum amount of insulin that beta cells can produce per time-unit (e.g. in one second). The method of calculation is based on a time-discrete nonlinear feedback model of insulin-glucose homeostasis that is rooted in the MiMe-NoCoDI modeling platform for endocrine systems.
=== Controversy === Several Hardee's ad campaigns in the 2000s have been criticized by groups including Parents Television Council for their sexually suggestive nature. A campaign titled "More Than a Piece of Meat" featured scantily clad women appearing to receive sexual gratification from consuming Hardee's products, and "Name Our Holes" – an ad campaign and website promoting Hardee's Biscuit Holes. In January 2015, Carl's Jr. released a commercial online featuring model Charlotte McKinney advertising its new All Natural Burger to air regionally during Super Bowl XLIX. The ad features McKinney walking around a farmers' market, implying that she is "all natural" and uses double entendres to suggest that she is naked with strategically placed items in the market until it reveals McKinney in a bikini eating the All Natural Burger. Critics suggested that the ad "sets feminism back four decades," while others, including McKinney's elderly grandfather, enjoyed the ad. Until the YouTube video of the ad was privatized by Carl's Jr. in March 2017, it had over 13 million views and 10 thousand likes.
(Full) agonists are able to activate the receptor and result in a strong biological response. The natural endogenous ligand with the greatest efficacy for a given receptor is by definition a full agonist (100% efficacy). Partial agonists do not activate receptors with maximal efficacy, even with maximal binding, causing partial responses compared to those of full agonists (efficacy between 0 and 100%). Antagonists bind to receptors but do not activate them. This results in a receptor blockade, inhibiting the binding of agonists and inverse agonists. Receptor antagonists can be competitive (or reversible), and compete with the agonist for the receptor, or they can be irreversible antagonists that form covalent bonds (or extremely high affinity non-covalent bonds) with the receptor and completely block it. The proton pump inhibitor omeprazole is an example of an irreversible antagonist. The effects of irreversible antagonism can only be reversed by synthesis of new receptors. Inverse agonists reduce the activity of receptors by inhibiting their constitutive activity (negative efficacy). Allosteric modulators: They do not bind to the agonist-binding site of the receptor but instead on specific allosteric binding sites, through which they modify the effect of the agonist. For example, benzodiazepines (BZDs) bind to the BZD site on the GABAA receptor and potentiate the effect of endogenous GABA. Note that the idea of receptor agonism and antagonism only refers to the interaction between receptors and ligands and not to their biological effects.
Both GLaDOS and the Weighted Companion Cube were nominated for the Best New Character Award on G4, with GLaDOS winning the award for "having lines that will be quoted by gamers for years to come." Ben Croshaw of Zero Punctuation praised the game as "absolutely sublime from start to finish ... I went in expecting a slew of interesting portal-based puzzles and that's exactly what I got, but what I wasn't expecting was some of the funniest pitch black humor I've ever heard in a game". He felt the short length was ideal as it did not outstay its welcome. Writing for GameSetWatch in 2009, columnist Daniel Johnson pointed out similarities between Portal and Erving Goffman's essay on dramaturgy, The Presentation of Self in Everyday Life, which equates one's persona to the front and backstage areas of a theater. The game was also made part of the required course material among other classical and contemporary works, including Goffman's work, for a freshman course "devoted to engaging students with fundamental questions of humanity from multiple perspectives and fostering a sense of community" for Wabash College in 2010. Portal has been cited as a strong example of instructional scaffolding that can be adapted for more academic learning situations, as the player, through careful design of levels by Valve, is first hand-held in solving simple puzzles with many hints at the correct solution, but this support is slowly removed as the player progresses in the game, and completely removed when the player reaches the second half of the game.
Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
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.