The short version of heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
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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.
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.
| 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 |
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
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.
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.
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.
== Carbon footprint == Whirlpool Corporation reported Total CO2e emissions (Direct + Indirect) for the twelve months ending December 31, 2020 at 663 Kt (-21 /-3.1% y-o-y) and is committed to reaching net zero emissions by 2030.
A clinical study that includes a comparison (control) group. The comparison group receives a placebo, another treatment, or no treatment at all. (NCI) An experiment or clinical trial that includes a comparison (control) group. (NCI) Controlled trials
=== Hezbollah and Hamas === At a 22 July 2006 demonstration (and later in a Socialist Worker op-ed), Galloway stated that "Hizbollah is not and has never been a terrorist organisation. It is the legitimate national resistance movement of Lebanon". He further said: "The invasion of Lebanon by Israel, for that's what it is, is a monstrous injustice. I side with the resistance to that injustice. Hizbollah is leading that resistance. ... I glorify the Hizbollah national resistance movement, and I glorify the leader of Hizbollah, Sayyed Hassan Nasrallah". In 2009, Galloway received a Palestinian passport from Hamas leader Ismail Haniyeh. Hamas is designated as a terrorist organisation by Israel, the European Union, the United Kingdom, and the United States. He was denied entry into Canada on national security grounds, with Alykhan Velshi, then a spokesman for Jason Kenney, Canada's immigration minister, commenting: "We're going to uphold the law, not give special treatment to this infandous street-corner Cromwell who actually brags about giving 'financial support' to Hamas, a terrorist organisation banned in Canada." After a 2010 investigation into the actions of Velshi and other staffers in Kenney's office and into decisions made by bureaucrats prior to Galloway's visit, Justice Richard Mosley ruled that the government's decision to ban Galloway was politically motivated. A week after Mosley's ruling, Galloway travelled to Canada.
Sources: en.wikipedia.org
Taliban claimed that three people including a woman were killed by Pakistani airstrikes in Nangarhar and Paktia. On the same day, armed clashes broke out between Taliban and Pakistan border guards along the Torkham border crossing. Afghanistan's Ministry of Defense said that clashes in border areas of Nangarhar, Paktia, Khost, and Kandahar provinces killed 32 Pakistani soldiers and wounded dozens more. The ministry did not provide figures for casualties among Taliban forces. The ministry also said it had carried out airstrikes on Pakistan's military sites in Khyber Pakhtunkhwa and Balochistan, without specifying the type of aircraft or aerial equipment used. Pakistan's Ministry of Information and Broadcasting rejected the claim and described it as false, stating that no evidence such as satellite imagery, flight data, ground footage, or eyewitness accounts had been provided to substantiate it. In Pakistan's Mohmand District, a drone crashed at Governor Model High School, causing no casualties or significant structural damage. Following the incident, Pakistani officials temporarily closed a number schools close to the border areas. Four civilians were wounded in Chitral District as a result of cross-border fire from Afghanistan. Later that day, Pakistani officials said that Operation Ghazab lil-Haq was ongoing and that, since the start of hostilities, 415 Afghan Taliban fighters had been killed and more than 580 wounded. According to the officials, Pakistan's forces had destroyed 182 Taliban posts, captured 31 others, and disabled 185 tanks and armoured personnel carriers.
== Further reading == Ahnström, M. L.; Seyfert, M.; Hunt, M. C.; Johnson, D. E. (2006). "Dry aging of beef in a bag highly permeable to water vapor". Meat Science. 73 (4): 674–679. doi:10.1016/j.meatsci.2006.03.006. PMID 22062568. DeGeer, S. L.; Hunt, M. C.; Bratcher, C. L.; Crozier-Dodson, B. A.; Johnson, D. E.; Stika, J. F. (2009). "Effects of dry aging of bone-in and boneless strip loins using two aging processes for two aging times". Meat Science. 83 (4): 768–774. doi:10.1016/j.meatsci.2009.08.017. PMID 20416624.
== History == No clear record of the breed's origin exists. They are most often claimed to have originated as the companions of temple priests in northern Burma in the Mount of Lugh. Many stories exist of how the cats first came to France, including pairs of cats being given as a reward for helping defend a temple, or being smuggled out of Burma and Sweden by a Vanderbilt. Another pair of Birmans (or a pregnant female called Poupée de Maldapour) were said to have been stolen and later imported to France by Thadde Haddisch. The first traces of historical Birmans go back to a Mme Leotardi in Nice, France. Birmans were almost wiped out as a breed during World War II. Only two cats were alive in Europe at the end of the war, a pair named Orloff and Xenia de Kaabaa, both belonging to Baudoin-Crevoisier. The foundation of the breed in postwar France were offspring of this pair. They had to be heavily outcrossed with long-hair breeds such as Persian and Siamese to rebuild the Birman breed. By the early 1950s, pure Birman litters were again being produced. The restored breed was recognized in Britain in 1965 and by the Cat Fanciers' Association (CFA) in 1966. The first Birman cats were seal point. The blue point colour was introduced in 1959 using blue Persian lines. New colours were later added by English breeders including chocolate, red, and tabby/lynx points. Birmans have also been used in the development of new breeds such as the Ragdoll.
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.
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.