The short version of heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-06-11 and is reviewed periodically as new material appears.
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.
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.
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.
| 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 |
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
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.
=== Serotonin norepinephrine reuptake inhibitor === Venlafaxine (Effexor) from the SNRI class may be moderately more effective than SSRIs; however, it is not recommended as a first-line treatment because of the higher rate of side effects, and its use is specifically discouraged in children and adolescents.
Cement manufacture causes environmental impacts at all stages of the process. These include emissions of airborne pollution in the form of dust, gases, noise and vibration when operating machinery and during blasting in quarries, and damage to countryside from quarrying. Equipment to reduce dust emissions during quarrying and manufacture of cement is widely used, and equipment to trap and separate exhaust gases are coming into increased use. Environmental protection also includes the re-integration of quarries into the countryside after they have been closed down by returning them to nature or re-cultivating them.
When fungal spores germinate, they initially form preliminary associations with common free-living algae in their vicinity. Additionally, the fungus can recruit compatible algal cells from neighboring lichen thalli—essentially extracting these partners—to help establish a complete symbiotic relationship. Native across Europe, parts of Asia, and coastal North Africa, X. parietina has a more limited and primarily coastal distribution in North America and Australia, where genetic evidence suggests human-mediated introduction. In recent decades, it has expanded inland in these regions, particularly in urban environments and areas affected by agricultural runoff, road salt application, and nitrogen deposition. The lichen grows slowly (averaging 2.6 mm (1⁄8 in) per year) but possesses considerable regenerative abilities, with fragments capable of developing into new thalli. It participates in a complex web of ecological interactions, hosting at least 41 species of lichen-dwelling fungi, while certain gastropods and microscopic rotifers contribute to its dispersal by consuming and excreting viable spores. The species has high diversity even within local populations, with distinct patterns linked to both geographic location and substrate type. This genetic variability, combined with the lichen's flexible associations with different photobiont strains, contributes to its ecological success. X. parietina serves as a bioindicator for monitoring air quality due to its capacity to accumulate environmental contaminants.
Sibabrata Mukhopadhyay, Mumu Chakraborty, Arun Bandyopadhyay, Dipak Kar, Tanima Banerjee, Aditya Konar, Debaprasad Jana, Siddhartha Roy, Santu Bandyopadhyay, Balram Ghosh, Mabalirajan Ulaganathan, Rakesh Johri, Subhash Sharma, Gurdarshan Singh, Bholanath Paul, Vasanta Madhava Sharma Gangavaram, Jhillu Singh Yadav, Radha Krishna Palakodety (August 2013). "Method for treatment of bronchial asthma (Patent US8519154B2)". {{cite journal}}: Cite journal requires |journal= (help)CS1 maint: multiple names: authors list (link) Sujoy K Das Gupta, Abhik Saha, Archana Sharma, Siddhartha Roy, Bhabatarak Bhattacharya (January 2012). "Peptide antagonists for inhibiting heat shock protein (Hsp 16.3) of Mycobacterium tuberculosis (Patent 7569537)". Retrieved 15 October 2016.{{cite web}}: CS1 maint: multiple names: authors list (link) S. Bandyopadhay, B. Ghosh, Parasuraman Jaisankar, Bikas C Pal, Siddhartha Roy, Nath Paul, Arjun Ram, U. Mabalirajan, Nahid Ali, Arun Bandyopadhyay, Aditya Konar, J. B. Chakraborty, I. C. Mukherjee, Jaydeep Chaudhuri, Sanjit Kumar Mahato, A. Manna, Roma Sinha, Pradyot Bhattacharya, J. Vinayagam, Sudeshna Chowdhury (January 2012). "Substituted catechols as inhibitors of IL-4 and IL-5 for the treatment of bronchial asthma (WO Patent 2,012,140,574)". doi:10.13140/RG.2.1.2784.6488. Retrieved 15 October 2016. {{cite journal}}: Cite journal requires |journal= (help)CS1 maint: multiple names: authors list (link) 1st S. Bandyopadhay, B. Ghosh, Parasuraman Jaisankar, Bikas C Pal, Siddhartha Roy, Nath Paul, Arjun Ram, U.
Sources: en.wikipedia.org
== Series 1 == The first series covers volumes 1 and 2 of the original novels, adding two stories from the prequel novel The Star Crusher (episodes 9 and 11) and an original story (parts of episodes 13 and 14). The main theme is Reinhard von Lohengramm's rise to power, mirrored by Yang Wen-li's unwillingness to go beyond his military duties and assume a similar position in the Free Planets Alliance.
In the Crimean war (1853–1856), mustard poultices were used for chest and abdominal complaints, including dysentery and cholera. During the American Civil War (1861–1865), poultices were applied to wounds when antiseptics such as iodine were unavailable. Honey-based poultices were used to aid wound healing during the world wars, taking advantage of honey's antimicrobial properties. Decline and survival in traditional medicine
"Sometimes Always", taken from Stoned & Dethroned, became the band's most commercially successful single in the US as it peaked at No. 96 on the Billboard Hot 100. The band departed from WEA after ten years, and then signed with Sub Pop Records in the US and re-signed with Creation Records in the UK for the release of the album Munki in 1998. The band broke up the following year as a result of an onstage altercation the year prior; William Reid prematurely left a tour after fighting with an intoxicated Jim Reid. They eventually reunited in 2007, and in 2017, they released Damage and Joy, their first studio album in 19 years and seventh overall. Their next album, Glasgow Eyes, was released in 2024 and became the band's first top 10 album in the UK since 1988.
=== Anisotropy of the interface kinetics === Even if the temperature gradient within the slurry is perfectly vertical, it is common to see tilting or curvature of the lamellae as they grow through the suspension. To explain this, it is possible to define two distinct growth directions for each ice crystal. There is the direction determined by the temperature gradient, and the one defined by the preferred growth direction crystallographically speaking. These angles are often at odds with one another, and their balance will describe the tilt of the crystal. The non-overlapping growth directions also help to explain why dendritic textures are often seen in freeze-casts. This texturing is usually found only on the side of each lamella; the direction of the imposed temperature gradient. The ceramic structure left behind shows the negative image of these dendrites. In 2013, Deville et al. made the observation that the periodicity of these dendrites (tip-to-tip distance) actually seems to be related to the primary crystal thickness.
=== Genetics === Type 1 diabetes is partially caused by genetics, and family members of type 1 diabetics have a higher risk of developing the disease themselves. In the general population, the risk of developing type 1 diabetes is around 1 in 250. For someone whose parent has type 1 diabetes, the risk rises to 1–9%. If a sibling has type 1 diabetes, the risk is 6–7%. If someone's identical twin has type 1 diabetes, they have a 30–70% risk of developing it themselves. About half of the disease's heritability is due to variations in three HLA class II genes involved in antigen presentation: HLA-DRB1, HLA-DQA1, and HLA-DQB1. The variation patterns associated with increased risk of type 1 diabetes are called HLA-DR3 and HLA-DR4-HLA-DQ8, and are common in people of European descent. A pattern associated with reduced risk of type 1 diabetes is called HLA-DR15-HLA-DQ6. Large genome-wide association studies have identified dozens of other genes associated with type 1 diabetes risk, mostly genes involved in the immune system.
Sources: en.wikipedia.org
Another ancient way of preparing potatoes in the Andes was by mimicking native wildlife, specifically, wild relatives of the llama. They would lick clay before eating wild poisonous potatoes which would help negate the toxins. The people of the Andes copied this by creating a mixture of clay and water to dunk the potatoes into so they could eat them as well. The need for this mixture mostly disappeared with the selective breeding of non-poisonous potatoes but the practice remains in use where the old species of poisonous potatoes are still grown. Chuño is still produced in the Andean Altiplano, specifically in the Suni and Puna regions, which are the only regions with suitable eco-climatic conditions, and is consumed in Argentina, Bolivia, Chile and Peru. According to the botanist R.N. Salaman, in prehistoric times, chuño was ground into flour and incorporated into all kinds of stews and chupes, a kind of hearty soup of very ancient origin, but still cooked. Another traditional product of the Altiplano is tocosh, obtained from the fermentation of potatoes left in a stream of water for at least six months. This product, considered to have probiotic properties, is used in the preparation of a local dessert, the mazamorra de papas.
==== Insulin ==== Perhaps the most common medication administered subcutaneously is insulin. While attempts have been made since the 1920s to administer insulin orally, the large size of the molecule has made it difficult to create a formulation with absorption and predictability that comes close to subcutaneous injections of insulin. People with type 1 diabetes almost all require insulin as part of their treatment regimens, and a smaller proportion of people with type 2 diabetes do as well — with tens of millions of prescriptions per year in the United States alone. Insulin historically was injected from a vial using a syringe and needle, but may also be administered subcutaneously using devices such as injector pens or insulin pumps. An insulin pump consists of a catheter which is inserted into the subcutaneous tissue, and then secured in place to allow insulin to be administered multiple times through the same injection site.
Catechol oxidase is a copper oxidase that contains a type 3 di-copper cofactor and catalyzes the oxidation of ortho-diphenols into ortho-quinones coupled with the reduction of molecular oxygen to water. It is present in a variety of species of plants and fungi including Ipomoea batatas (sweet potato) and Camellia sinensis (Indian tea leaf). Metalloenzymes with type 3 copper centers are characterized by their ability to reversibly bind dioxygen at ambient conditions. In plants, catechol oxidase plays a key role in enzymatic browning by catalyzing the oxidation of catechol to o-quinone in the presence of oxygen, which can rapidly polymerize to form the melanin that grants damaged fruits their dark brown coloration.
==== Antistasin binding to factor Xa ==== Antistasin contains an N- and a C-terminal domain which are similar in their amino acid sequences with ~40% identity and ~56% homology. Each of them contains a short β-sheet structure and 5 disulfide bonds. Only the N-terminal domain is necessary to inhibit Xa while the C-terminal domain does not contribute to the inhibitory properties due to differences in the 3 dimensional structure, even though the C-terminal domain has a strongly analogue pattern to the actual active site. The interaction of antistasin with FXa involves both the active site and the inactive surface of FXa. The reactive site of antistasin formed by Arg-34 and Val-35 in the N-terminal domain suits the binding site of FXa, most likely the S1 pocket. At the same time, Glu-15 located outside the reactive site of antistasin fits to positively charged residues on the surface of FXa. The multiple binding is thermodynamically advantageous and leads to sub-nanomolar inhibition (Ki = 0.3–0.6 nM).
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.
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.