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 2025-09-18 and is reviewed periodically as new material appears.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
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.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
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.
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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
==== Flight ==== Flies fly via straight sequences of movement interspersed by rapid turns called saccades. During these turns, a fly is able to rotate 90 degrees in less than 50 milliseconds. Characteristics of Drosophila flight may be dominated by the viscosity of the air, rather than the inertia of the fly body, but the opposite case with inertia as the dominant force may occur. However, subsequent work showed that while the viscous effects on the insect body during flight may be negligible, the aerodynamic forces on the wings themselves actually cause fruit flies' turns to be damped viscously.
Myoglobin and hemoglobin, the first two proteins whose structures were solved by X-ray crystallography, have very similar folds made up of about 70% α-helix, with the rest being non-repetitive regions, or "loops" that connect the helices. In classifying proteins by their dominant fold, the Structural Classification of Proteins database maintains a large category specifically for all-α proteins. Hemoglobin then has an even larger-scale quaternary structure, in which the functional oxygen-binding molecule is made up of four subunits.
==== Heating ==== A report given to the Food and Drug Administration by the Institute of Food Technologists thoroughly discusses the thermal processing of food. A notable step in development of heat application to food processing is pasteurization, developed by Louis Pasteur in the nineteenth century. Pasteurization is used to kill microorganisms that could pose risks to consumers or shorten the shelf life of food products. Primarily applied to liquid food products, pasteurization is regularly applied to fruit juice, beer, milk, and ice cream. Heat applied during pasteurization varies from around 60 °C to kill bacteria to around 80 °C to kill yeasts. Most pasteurization processes have been optimized recently to involve several steps of heating at various temperatures and minimize the time needed for the process. A more severe food heating mechanism is thermal sterilization. While pasteurization destroys most bacteria and yeast growing in food products, the goal of sterilization is to kill almost all viable organisms found in food products including yeast, mold, bacteria, and spore forming organisms. Done properly, this process will greatly extend the shelf life of food products and can allow them to be stored at room temperature. As detailed in The Handbook of Food Preservation, thermal sterilization typically involves four steps. First, food products are heated to between 110 and 125 °C, and the products are given time for the heat to travel through the material completely.
A varied diet is very important to the dwarf gourami, which is an omnivore that prefers both algae-based foods and meaty foods. An algae-based flake food, along with freeze-dried bloodworms, tubifex, and brine shrimp, will provide these fish with proper nutrition.
This new process led to an increase in output and profit for the company. Under Eli's supervision, the design for Building 22, a new five-floor plant that opened in Indianapolis in 1926, implemented the straight-line concept to improve production efficiency and lower production costs. One historian noted, "It was probably the most sophisticated production system in the American pharmaceutical industry." This more efficient manufacturing process also allowed the company to hire a regular workforce. Instead of recalling workers at peak times and laying them off when production demand fell, Lilly's regular workforce produced less-costly medicines in off-peak times using the same manufacturing facilities. During the 1920s, the introduction of new products brought the company financial success. In 1921, three University of Toronto scientists, John Macleod, Frederick Banting, and Charles Best, were working on the development of insulin for treatment of diabetes. Clowes proposed a collaboration with the researchers in December 1921, and then again March and May 1922. The researchers were hesitant to work with a commercial drug firm, particularly since they had the Connaught Laboratories' non-commercial facilities at hand. But as limits were reached at the scale to which Connaught could produce insulin, Clowes and Eli Lilly met with the researchers in 1922 to negotiate an agreement with the University of Toronto scientists to mass-produce insulin. The collaboration greatly accelerated the large-scale production of the extract.
Sources: en.wikipedia.org
=== Degradation === In mammals, norepinephrine is rapidly degraded to various metabolites. The initial step in the breakdown can be catalyzed by either of the enzymes monoamine oxidase (mainly monoamine oxidase A) or COMT. From there, the breakdown can proceed by a variety of pathways. The principal end products are either Vanillylmandelic acid or a conjugated form of MHPG, both of which are thought to be biologically inactive and are excreted in the urine.
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== Distribution == Cold seeps were discovered in 1983 by Charles Paull and colleagues on the Florida Escarpment in the Gulf of Mexico at a depth of 3,200 meters (10,500 ft). Since then, seeps have been discovered in many other parts of the world's oceans. Most have been grouped into five biogeographic provinces: Gulf of Mexico, Atlantic, Mediterranean, East Pacific, and West Pacific, but cold seeps are also known from under the ice shelf in Antarctica, the Arctic Ocean, the North Sea, Skagerrak, Kattegat, the Gulf of California, the Red Sea, the Indian Ocean, off southern Australia, and in the inland Caspian Sea. In the Pacific Northwest, a cold seep called Pythia's Oasis was discovered in 2015. With the recent discovery of a methane seep in the Southern Ocean, cold seeps are now known in all major oceans. Cold seeps are common along continental margins in areas of high primary productivity and tectonic activity, where crustal deformation and compaction drive emissions of methane-rich fluid. Cold seeps are patchily distributed, and they occur most frequently near ocean margins from intertidal to hadal depths. In Chile, cold seeps are known from the intertidal zone, in Kattegat, the methane seeps are known as "bubbling reefs" and are typically at depths of 0–30 m (0–100 ft), and off northern California, they can be found as shallow as 35–55 m (115–180 ft). Most cold seeps are located considerably deeper, well beyond the reach of ordinary scuba diving, and the deepest seep community known is found in the Japan Trench at a depth of 7,326 m (24,035 ft).
Black Detroiters tended to have far less access to New Deal mortgage support programs such as Federal Housing Authority and Veterans Administration insured mortgages. African-American neighborhoods were viewed by lenders and the federal programs as riskier, resulting—in this period—in much lower rates of homeownership for African-Americans than other residents of the city. The auto industry also gave rise to a large number of high paying management and executive jobs. There were also large numbers of attorneys, advertisers, and other workers who supported the industry's managerial force. These workers already by the 1920s had begun to move to neighborhoods well removed from the industry's factories and higher crime rates. This upper stratum moved to outlying neighborhoods, and further, to well-to-do suburbs such as Bloomfield Hills and Grosse Pointe. Oakland County, north of the city, became a popular place to live for executives in the industry. "By the second half of the twentieth century, it was one of the wealthiest counties in the United States, a place profoundly shaped by the concentration of auto-industry-derived wealth." Public policy was automobile oriented. Funds were directed to the building of expressways for automobile traffic, to the detriment of public transit and the inner-city neighborhoods through which the expressways were cut to get to the auto factories and the downtown office buildings.
Using the co-ordinates of the subunits and segments to determine the topographic location of the defect on the nose, the plastic surgeon plans, maps, and executes a rhinoplasty procedure. The unitary division of the nasal topography permits minimal, but precise, cutting, and maximal corrective-tissue coverage, to produce a functional nose of proportionate size, contour, and appearance for the patient. Hence, if more than 50 percent of an aesthetic subunit is lost (damaged, defective, destroyed) the surgeon replaces the entire aesthetic segment, usually with a regional tissue graft, harvested from either the face or the head, or with a tissue graft harvested from elsewhere on the patient's body.
Sources: en.wikipedia.org
In the expansion years of the 1950s and 1960s, franchisees were signing 20- or 25-year contracts under the older model. The chain expanded into Canada in 1956, opening restaurants in Winnipeg and Montreal. By 1960, A&W had 2,000 restaurants. In November 1956, F. R. "Fran" Loetterle became the president of the chain. In 1963, the chain opened its first store on Okinawa, which at the time was under American control. In the following years, the chain branched into other foreign markets, including Guam (first territory outside of the North American continent to open a restaurant, in 1961), opened by Scotty Moylan, Mexico, the Philippines (some sources say it opened in the 1990s) and Malaysia. The first restaurant in Malaysia (Malaya at the time) was opened on December 24 that year by Al and Geri Lieboff, a couple from Las Vegas, who got the franchising rights for Malaysia and Singapore. Setting up the chain seemed to be complicated, as they were unable to find a proper site, and in the recruitment process, Malayans had no consent to adorning Western "cabaret girl" style clothes. Already at the time of setup, kids were starting to favor chicken, burgers, and hot dogs rather than rice and curry, and within the next five years, would also see a rise in new locations up to 22 within five years. The first restaurant in Europe opened in Mannheim (near Stuttgart), West Germany in 1962.
=== Other locations === Every Halloween since 1969, a pumpkin has been impaled onto the spire of North Miami Public Library by a group named Coxie's Army. This has become a celebrated tradition, and is often accompanied by the hanging of a poem at the library's entrance. At the University of Montana, a pumpkin has been placed on the spire of the Main Hall every October since 1995. These pranks resulted in arrests on charges of trespassing in 2004 and 2016.
=== EC 2.8.1: Sulfurtransferases === EC 2.8.1.1: thiosulfate sulfurtransferase EC 2.8.1.2: 3-mercaptopyruvate sulfurtransferase EC 2.8.1.3: thiosulfate—thiol sulfurtransferase EC 2.8.1.4: tRNA sulfurtransferase EC 2.8.1.5: thiosulfate—dithiol sulfurtransferase EC 2.8.1.6: biotin synthase EC 2.8.1.7: cysteine desulfurase EC 2.8.1.8: lipoyl synthase EC 2.8.1.9: molybdenum cofactor sulfurtransferase EC 2.8.1.10: thiazole synthase EC 2.8.1.11: molybdopterin synthase sulfurtransferase EC 2.8.1.12: molybdopterin synthase EC 2.8.1.13: tRNA-uridine 2-sulfurtransferase EC 2.8.1.14: tRNA-5-taurinomethyluridine 2-sulfurtransferase EC 2.8.1.15: tRNA-5-methyluridine54 2-sulfurtransferase EC 2.8.1.16: L-aspartate semialdehyde sulfurtransferase
=== Justin Klineman === Justin Klineman (Joshua James) is Pierpoint's head of HR. He is first seen pressing Harper to send over her college transcripts, unaware she never graduated; Harper sends forged documents. Eric, aware of Harper's past, reports her deceit to HR at the end of series 2, and Justin fires her. In series 3, Justin and another HR rep confront Rishi over his lewd and inappropriate comments on the trading floor, which he angrily dismisses. After Pierpoint is acquired by Al-Mi'raj, a holding company for the Egyptian sovereign wealth, the London trading firm is shut down, and Justin presides over a slew of employee terminations including Eric's.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
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.