The short version of anxiolytic fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-03-09 and is reviewed periodically as new material appears.
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.
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 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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
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.
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.
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.
Hong Kong has twelve universities. The University of Hong Kong (HKU), ranked QS Asia #1, was founded as the city's first institute of higher education in 1911 during the early colonial period. The Chinese University of Hong Kong (CUHK) was established in 1963 to fill the need for a university that taught using Chinese as its primary language of instruction. Along with the Hong Kong University of Science and Technology (HKUST) established in 1991, these universities are consistently ranked among the top 20 or top 50 universities worldwide. The Hong Kong Polytechnic University (PolyU) and City University of Hong Kong (CityU), both granted university status in 1994, are consistently ranked among the top 50 or top 100 universities worldwide. The Hong Kong Baptist University (HKBU) was granted university status in 1994 and is a liberal arts institution. Hong Kong Metropolitan University (formerly as Open University of Hong Kong before 2021) (attaining status in 1997), Lingnan University (in 1999), Hong Kong Shue Yan University (in 2006), Education University of Hong Kong (in 2016), Hang Seng University of Hong Kong (in 2018) and Saint Francis University (in 2024) all attained full university status in subsequent years.
The news began spreading immediately: the West German Deutsche Presse-Agentur issued a bulletin at 19:04 which reported that East German citizens would be able to cross the inner German border "immediately". Excerpts from Schabowski's press conference were broadcast on West Germany's two main news programs that night—at 19:17 on ZDF's heute, which came on the air as the press conference was ending, and as the lead story at 20:00 on ARD's Tagesschau. As ARD and ZDF had broadcast to nearly all of East Germany since the late 1950s, were far more widely viewed than the East German channels, and had become accepted by the East German authorities, this is how most of the population heard the news. Later that night, on ARD's Tagesthemen, anchorman Hanns Joachim Friedrichs proclaimed, "This 9 November is a historic day. The GDR has announced that, starting immediately, its borders are open to everyone. The gates in the Wall stand open wide." In 2009, Ehrman claimed that a member of the Central Committee had called him and urged him to ask about the travel law during the press conference, but Schabowski called that absurd. Ehrman later recanted this statement in a 2014 interview with an Austrian journalist, admitting that the caller was Günter Pötschke, head of the East German news agency ADN, and he only asked if Ehrman would attend the press conference.
The taxonomic workforce remains insufficient for documenting lichen diversity. Lendemer (2021) found that only 14% of lichen-related research papers published in 2018–2020 included taxonomic work, while Lücking (2020) estimated that the current community of lichen taxonomists is only a fraction of what would be needed for a complete inventory. Expertise is particularly lacking in biodiversity-rich tropical regions where most undescribed species likely occur. However, infrastructure improvements are helping address these gaps. Since 2012–2013, mandatory registration of new fungal names in repositories like MycoBank has been widely adopted, with over 97% of new lichen species from 2018 to 2020 properly registered. Additionally, citizen scientists using platforms such as iNaturalist increasingly contribute to species discovery when collaborating with professional taxonomists. Nomenclatural challenges arise as lichen systematics increasingly encounters cryptic species. Environmental DNA studies reveal numerous uncharacterized fungal lineages, including potential lichenicolous fungi, but ICN rules require physical type specimens for species description. This creates difficulties for documenting diversity found only in environmental samples. The community generally discourages naming taxa known only from sequences to avoid proliferating dubious names. A related concern is taxonomic inflation—the risk that genomic data could lead to naming every population variant.
Sources: en.wikipedia.org
The Mystery of the Yellow Room (1913) The Mystery of the Yellow Room (1919) The Mystery of the Yellow Room (1930) El misterio del cuarto amarillo (1947) at IMDb The Mystery of the Yellow Room (1949) Mystère de la chambre jaune, Le (1965) at IMDb The Mystery of the Yellow Room (2003) An episode of Jonathan Creek features a stage adaptation of the novel and centres around a similar event happening to one of its actors. Radio:
Examples include alpha-Amanitin containing mushrooms, kava, and aflatoxin producing molds. Pyrrolizidine alkaloids, which occur in some plants, can be toxic. Green tea extract is a growing cause of liver failure due to its inclusion in more products.
== tRNA genes == Organisms vary in the number of tRNA genes in their genome. For example, the nematode worm C. elegans, a commonly used model organism in genetics studies, has 29,647 genes in its nuclear genome, of which 620 code for tRNA. The budding yeast Saccharomyces cerevisiae has 275 tRNA genes in its genome. The number of tRNA genes per genome can vary widely, with bacterial species from groups such as Fusobacteria and Tenericutes having around 30 genes per genome while complex eukaryotic genomes such as the zebrafish (Danio rerio) can bear more than 10 thousand tRNA genes. In the human genome, which, according to January 2013 estimates, has about 20,848 protein-coding genes in total, there are 497 nuclear genes encoding cytoplasmic tRNA molecules, and 324 tRNA-derived pseudogenes—tRNA genes thought to be no longer functional (although pseudo tRNAs have been shown to be involved in antibiotic resistance in bacteria). One study has shown that the copy number of tRNA genes varies among individuals. As with all eukaryotes, there are 22 mitochondrial tRNA genes in humans. Mutations in some of these genes have been associated with severe diseases like the MELAS syndrome. Regions in nuclear chromosomes, very similar in sequence to mitochondrial tRNA genes, have also been identified (tRNA-lookalikes). These tRNA-lookalikes are also considered part of the nuclear mitochondrial DNA (genes transferred from the mitochondria to the nucleus).
The polymerase chain reaction (PCR) is a laboratory method widely used to amplify copies of specific DNA sequences rapidly, to enable detailed study. PCR was invented in 1983 by American biochemist Kary Mullis at Cetus Corporation. Mullis and biochemist Michael Smith, who had developed other essential ways of manipulating DNA, were jointly awarded the Nobel Prize in Chemistry in 1993. PCR is fundamental to many of the procedures used in genetic testing, research, including analysis of ancient samples of DNA, and identification of infectious agents. Using PCR, copies of very small amounts of DNA sequences are exponentially amplified in a series of cycles of temperature changes. PCR is now a common and often indispensable technique used in medical laboratory research for a broad variety of applications including biomedical research and forensic science. The majority of PCR methods rely on thermal cycling. Thermal cycling exposes reagents to repeated cycles of heating and cooling to permit different temperature-dependent reactions—specifically, DNA melting and enzyme-driven DNA replication. PCR employs two main reagents—primers (which are short single strand DNA fragments known as oligonucleotides that are a complementary sequence to the target DNA region) and a thermostable DNA polymerase. In the first step of PCR, the two strands of the DNA double helix are physically separated at a high temperature in a process called nucleic acid denaturation. In the second step, the temperature is lowered and the primers bind to the complementary sequences of DNA.
Sources: en.wikipedia.org
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.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
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.