peptide stability 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.
Updated 2026-08-01. 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.
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.
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.
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.
| 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 |
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.
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.
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.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
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.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
== Awareness == In the US, July is widely recognized as Sarcoma Awareness Month. The UK has a Sarcoma Awareness Week in July led by Sarcoma UK, the bone and soft-tissue cancer charity. American YouTuber Technoblade was diagnosed with sarcoma in August 2021, and died from his illness in June 2022 after the sarcoma metastasized. He had raised over $500,000 in a charity stream. Many YouTubers have raised awareness and donated to charities such as the Sarcoma Foundation of America after Technoblade's diagnosis and passing. To date, Technoblade's fans have raised over $1,000,000 for sarcoma research. TikTok has provided a voice for many creators to chronicle their experiences with sarcoma. "Dance You Outta My Head", by American singer Cat Janice, went viral on TikTok in early 2024 before the singer died of sarcoma, prompting awareness of this rare disease. Kimberley Nix, a Canadian physician, chronicled her journey with undifferentiated pleomorphic sarcoma, from her diagnosis to eventual death, on TikTok under the username @cancerpatientmd. Nix died on 8 May 2024 at the age of 31, and her death was announced in a video uploaded posthumously to her TikTok page. In many of her videos, she links viewers to her Own.Cancer fundraiser, which has raised almost C$118,000 as of 17 May 2024.
In their discovery of elements 99 and 100, the American teams had competed with a group at the Nobel Institute for Physics, Stockholm, Sweden. In late 1953 to early 1954, the Swedish group succeeded in synthesizing light isotopes of element 100, in particular 250Fm, by bombarding uranium with oxygen nuclei. These results were also published in 1954. Nevertheless, the priority of the Berkeley team was generally recognized, as its publications preceded the Swedish article, and they were based on the previously undisclosed results of the 1952 thermonuclear explosion; thus the Berkeley team was given the privilege to name the new elements. As the effort which had led to the design of Ivy Mike was codenamed Project PANDA, element 99 had been jokingly nicknamed "Pandemonium" but the official names suggested by the Berkeley group derived from two prominent scientists, Einstein and Fermi: "We suggest for the name for the element with the atomic number 99, einsteinium (symbol E) after Albert Einstein and for the name for the element with atomic number 100, fermium (symbol Fm), after Enrico Fermi." Both Einstein and Fermi died between the time the names were originally proposed and when they were announced. The discovery of these new elements was announced by Albert Ghiorso at the first Geneva Atomic Conference held on 8–20 August 1955. The symbol for einsteinium was first given as "E" and later changed to "Es" by IUPAC.
== External links == Histocompatibility+Antigens+Class+I at the U.S. National Library of Medicine Medical Subject Headings (MeSH) MHC+Class+I+Genes at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
The class of compounds causing pungency in plants such as chili peppers is called capsaicinoids, which display a linear correlation between concentration and Scoville scale, and may vary in content during ripening. Capsaicin is the major capsaicinoid in chili peppers. The Scoville Heat Unit may be used to express the approximate pungency of other, unrelated TRPV1 agonists, sometimes with extrapolation for much hotter compounds. One such substance is resiniferatoxin, an alkaloid present in the sap of some species of Euphorbia plants (spurges). Since it is 1,000 times as hot as capsaicin, it would have a Scoville scale rating of 16 billion. In the table below, non-capsaicinoid compounds are italicized. The ratings for piperine (150,000 SHU) and gingerol (60,000 SHU) for example are comparative estimates and are not official Scoville ratings. While the ratings are expressed in Scoville Heat Units (SHU), they do not technically belong on the official Scoville scale because the scale is scientifically designed and defined exclusively for capsaicinoids found in chili peppers.
== Medical implications == By culturing P. fluorescens, mupirocin (an antibiotic) can be produced, which has been found to be useful in treating skin, ear, and eye disorders. Mupirocin free acid and its salts and esters are agents currently used in creams, ointments, and sprays as a treatment of methicillin-resistant Staphylococcus aureus infection. Pseudomonas fluorescens demonstrates hemolytic activity, and as a result, has been known to infect blood transfusions. Pseudomonas fluorescens produces the antibiotic obafluorin. Recent case studies have reported instances of pneumonia caused by Pseudomonas fluorescens. These studies are significant as they identify P. fluorescens from lung biopsy specimens, providing insights into its pathogenic potential and informing treatment strategies based on antibiotic susceptibility testing. Ongoing research into the antimicrobial resistance mechanisms of the Pseudomonas fluorescens complex is exploring both intrinsic and acquired resistance to antimicrobial agents in strains isolated from various environments. This research is crucial for understanding the evolution of antimicrobial resistance and the role of P. fluorescens as a potential reservoir of clinically important resistance genes. Pseudomonas fluorescens is being studied for its biotechnological applications, particularly in the production of medium-chain-length polyhydroxyalkanoates (MCL-PHAs). These biodegradable polymers have potential uses in medical devices and drug delivery systems.
Sources: en.wikipedia.org
=== Effects on sugar absorption and insulin secretion === Gymnemic acid compounds in Gymnema sylvestre can also attach to receptors on the intestinal walls, helping to reduce absorption of sugar molecules in the gut. This process can lower blood sugar and promote insulin secretion and release. However, its antidiabetic properties were not confirmed in rats.
== Clinical significance == Activation of the ERK1/2 pathway by aberrant RAS/RAF signalling, DNA damage, and oxidative stress leads to cellular senescence. Low doses of DNA damage resulting from cancer therapy cause ERK1/2 to induce senescence, whereas higher doses of DNA damage fail to activate ERK1/2, and thus induce cell death by apoptosis.
Some cultures have long celebrated and even worshipped the vulva. During the Uruk period (c. 4000–3100 BC), the ancient Sumerians regarded the vulva as sacred and a vast number of Sumerian poems praising the vulva of Inanna, the goddess of love, sex, and fertility, have survived. In Sumerian religion, the goddess Ninimma is the divine personification of the vulva. Vaginal fluid is always described in Sumerian texts as tasting "sweet" and, in a Sumerian bridal hymn, a young maiden rejoices that her vulva has grown hair. Clay models of vulvas were discovered in the temple of Inanna at Ashur. Some major Hindu traditions such as Shaktism, a goddess-centered tradition, revere the vulva and vagina under the name yoni. The goddess as Devi is worshipped as the supreme deity. The yoni is a representation of the female deity and is found in many temples as a focus for prayer and offerings. It is also represented symbolically as a mudra in spiritual practices, including yoga. Sheela na gigs are figurative carvings of naked women displaying an exaggerated vulva. They are found in ancient and medieval European contexts. They are displayed on many churches, but their origin and significance is debatable. A main line of thinking is that they were used to ward off evil spirits. Another view is that the sheela na gig was a divine assistant in childbirth. Starr Goode explores the image and possible meanings of the Sheela na gig and Baubo images in particular, but writes also about the recurring image worldwide.
== Literary and cinematic portrayals == Lobotomies have been featured in several literary and cinematic presentations that both reflected society's attitude toward the procedure and, at times, changed it. Writers and filmmakers have played a pivotal role in turning public sentiment against the procedure.
Sources: en.wikipedia.org
==== Stems ==== Young lotus stems are used as a salad ingredient in Vietnamese cuisine and as a vegetable ingredient for some soup and curry in Thailand, such as keang som sai bua (Thai: แกงส้มสายบัว, lotus stem sour soup) and keang kati sai bua (แกงกะทิสายบัว, lotus stem in coconut milk curry). In northern and eastern regions of India, the stalk of the flower is used to prepare a soup, kamala gaṭṭē kī sabzī (Hindi: कमल गट्टे की सब्ज़ी) and an appetizer, kamala kakaṛī pakauṛē (Hindi: कमल ककड़ी पकौड़े). In South Indian states, the lotus stem is sliced, marinated with salt to dry, and the dried slices are fried and used as a side dish. In Kerala (Malayalam: താമര) and Tamil Nadu, this end product is called thamara vathal. In the Philippines, an indigenous variety called tukal is used as the main ingredient in dishes with coconut milk. The stems and petals can be bought in markets when in season.
There is still much ongoing differential (DNA sequence based) comparison research that is trying to separate out the simplest forms of chordates. As some lineages that lack a backbone or notochord might have lost these structures over time, this complicates the classification of chordates. Some chordate lineages may only be identified by DNA analysis as there is no physical trace of any chordate-like structures. Attempts to work out the evolutionary relationships of the chordates have produced several hypotheses. The current consensus is that chordates are monophyletic (meaning, all chordates are descend from a single, common ancestor, which can be considered a chordate) and that the vertebrates' nearest relatives are tunicates. In 2016, identification of two conserved signature indels (CSIs) in the proteins cyclophilin-like protein and mitochondrial inner membrane protease ATP23, which are exclusively shared by all vertebrates, tunicates and cephalochordates also provided strong evidence of the monophyly of Chordata. All of the earliest chordate fossils have been found in the Early Cambrian Chengjiang fauna, and include three species that are regarded as fish, and hence vertebrates. Because the fossil record of early chordates is poor, only molecular phylogenetics offers a reasonable prospect of dating their emergence. However, the use of molecular phylogenetics for dating evolutionary transitions is controversial. It has proven difficult to produce a detailed classification within the living chordates.
=== Detection of metals === The compounds suspected of containing a metal are traditionally analyzed by the destruction of the organic matrix by chemical or thermal oxidation. This leaves the metal to be identified and quantified in the inorganic residue, and it can be detected using such methods as the Reinsch test, emission spectroscopy or X-ray diffraction. Unfortunately, while this identifies the metals present it removes the original compound, and so hinders efforts to determine what may have been ingested. The toxic effects of various metallic compounds can vary considerably.
=== 2000 census === As of the census of 2000, there were 40,852 people, 16,108 households, and 10,808 families residing in the city. The population density was 2,571.8/sq mi. There were 17,374 housing units at an average density of 1,093.8 per square mile. The racial makeup of the city was 91.68% White, 0.53% African American, 1.22% Native American, 1.14% Asian, 0.21% Pacific Islander, 2.65% from other races, and 2.56% from two or more races. Hispanic or Latino of any race were 6.09% of the population. There were 16,108 households, out of which 33.3% had children under the age of 18 living with them, 51.1% were married couples living together, 11.7% had a female householder with no husband present, and 32.9% were non-families. 26.1% of all households were made up of individuals, and 10.4% had someone living alone who was 65 years of age or older. The average household size was 2.49 and the average family size was 2.99. In the city, the population was 26.4% under the age of 18, 9.6% from 18 to 24, 29.3% from 25 to 44, 21.9% from 45 to 64, and 12.7% who were 65 years of age or older. The median age was 35 years. For every 100 females, there were 94.5 males. For every 100 females age 18 and over, there were 91.7 males. The median income for a household in the city was $39,409, and the median income for a family was $46,094. Males had a median income of $36,457 versus $24,480 for females. The per capita income for the city was $18,570.
Based upon the aforementioned observation in protein structure, it has been proposed that a possible therapeutic approach to Alzheimer's might involve shifting the conformational preference of IDE to the open state, and thus increasing Aβ degradation, preventing aggregation, and, ideally, preventing the neuronal loss that leads to disease symptoms.
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.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.