The short version of HPLC fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-09-22. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
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.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
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.
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.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Gerald A. LeBlanc is an American biologist, toxicologist, author, and academic. He is a Professor Emeritus in the Department of Biological Sciences at the North Carolina State University. LeBlanc's research interests span the fields of environmental toxicology and risk assessment with a focus on investigating the processes involved in the endocrine regulation of reproduction and development, as well as how environmental agents can disrupt these processes. He is the author of the book, Everyday Chemicals: Understanding the Risks and has published over 190 articles.
I don't think there was anything else like it at the time. Before TGI Fridays, four single twenty-five-year-old girls were not going out on Friday nights, in public and with each other, to have a good time. They went to people's apartments for cocktail parties or they might go to a real restaurant for a date or for somebody's birthday, but they weren't going out with each other to a bar for a casual dinner and drinks because there was no such place for them to go. TGI Fridays was one of the first to use promotions such as ladies' night, and Stillman achieved his hopes of meeting women; "Have you seen the movie Cocktail? Tom Cruise played me!...Why do girls want to date the bartender? To this day, I'm not sure that I get it." He and the restaurant benefited from its location—according to Stillman, 480 stewardesses lived in the apartment building next door—and received publicity in national magazines. TGI Fridays became so popular that it had to install ropes to create an area for those waiting in line, also unusual at the time for a restaurant. A competitor, Maxwell's Plum, opened across the street, and others soon followed. With fellow Bucknell University graduate Ben Benson, Stillman opened other restaurants, including Tuesday's, Thursday's, Wednesday's, and Ice Cream Sunday's. Franchising of TGI Fridays began two years after the Manhattan location opened, in a since-closed location in Memphis, Tennessee's Overton Square district. In 1971, Daniel R. Scoggin acquired the rights to eight major Midwest cities. In 1972, he opened with the first of a new prototype in Dallas.
Teneurin C-terminal associated peptides (TCAPs) are a family of highly conserved 40–41 amino acid peptides encoded within the C-terminus of the type II transmembrane proteins known as teneurins that are involved with cell adhesion. TCAPs are proposed to be liberated by proteolytic cleavage from the parent protein. Once released, TCAPs have been shown in have been shown in HEK293 cell assays and rodent models to act as to act as soluble neuromodulatory and metabolic regulators that influence neuronal morphology, synaptic connectivity, and stress responsiveness, in part via cytoskeletal remodeling, enhanced energy generating oxidative metabolism in some contexts, and based on in vitro studies, functional interaction with adhesion GPCRs of the latrophilin family.
Sources: en.wikipedia.org
Abiotic factors that can damage plants include heat, freezing, flooding, lightning strikes, ozone gas, and pollutant chemicals. Heat can kill any plant, given a sufficient temperature. Alpine plants tend to die at around 47 Celsius; temperate plants at around 51 Celsius; and tropical plants at nearly 58 Celsius: but there is some overlap depending on species. Similarly among cereal crops, temperate barley and oat die at around 49 Celsius, but tropical maize at 55 Celsius. Freezing affects plants variously, according to each species' ability to resist frost damage. Many forbs, including many garden flowers, are tender with little tolerance to frost, and die or are seriously damaged when frozen. Many woody plants are able to supercool, with tough buds and stems containing molecules that lower the freezing point or help to prevent the nucleation of ice crystals, and cell walls that mechanically protect cells against freezing. Flooding of soil quickly kills or injures many plants. The leaves become yellow (chlorosis) and die, progressively up the stem, within about five days after the roots are flooded. The roots lose the ability to absorb water and nutrients. Lightning strikes kill or injure plants, from root crops like beet and potato, which are instantly cooked in the ground, to trees such as coconut, through effects such as sudden heat and pressure shock waves created when water inside the plant flashes to steam. This can rupture stems and scorch any plant parts.
These are usually hydroxyapatite- or tricalcium phosphate-based granules formed into a coralline or trabecular structure to mimic the structure of cancellous bone. They act solely as an osteoconductive matrix. Some manufacturers have recently begun supplying these products with soluble bone-forming factors such as bone morphogenetic protein to attempt to create a synthetic product with osteoinductive properties. Titanium alloy implants (plates and screws) can be attached to the two bones to hold them together in a position which favors bone growth. A combination of the above methods is also commonly employed to facilitate bony fusion. At the completion of surgery and healing, which takes place over a period of several weeks to over a year, the two adjoining bones are fused and no motion takes place between them. This can have the effect of strengthening the bones, as in anterior cervical fusion.
=== October === 2 October Russell Brand faces a second police investigation, as Thames Valley Police announce they are looking into claims of harassment and stalking by the comedian. The price of a first class stamp rises from £1.10 to £1.25, the third increase in 18 months. Chancellor Jeremy Hunt confirms the National Minimum Wage will rise to £11 an hour from April 2024. The Met Office confirms that September 2023 was the joint warmest September on record for the UK, tying with 2006 with an average temperature of 15.2 °C. 3 October – Home Secretary Suella Braverman addresses the Conservative Party Conference and says a "hurricane" of migrants is coming to the UK. 4 October Rishi Sunak confirms that the West Midlands to Manchester portion of the High Speed 2 (HS2) rail link will be axed, which will free up £36bn to be spent on new transport projects in the North and Midlands. He also confirms that the southern portion of the line will run all the way from Birmingham to Euston, not just Old Oak Common as earlier reports had speculated. Sunak proposes that the age at which people can buy cigarettes and tobacco should rise by one year every year, so that eventually no-one can buy them, emulating a similar scheme announced recently in New Zealand. Sunak confirms plans to replace A Levels and T Levels in England with a new qualification called the Advanced British Standard.
"The IDO-like myoglobin is unexpectedly widely distributed among gastropodic molluscs, such as Sulculus, Nordotis, Battilus, Omphalius and Chlorostoma." The hemocyanin from arthropods and molluscs evolved from different ancestors, tyrosinase and insect storage proteins, respectively. They have different molecular weight and structure. However, the proteins both use copper binding sites to transport oxygen. The hexokinase, ribokinase, and galactokinase families of sugar kinases have similar enzymatic functions of sugar phosphorylation, but they evolved from three distinct nonhomologous families since they all have distinct three-dimensional folding and their conserved sequence patterns are strikingly different. Hemoglobins in jawed vertebrates and jawless fish evolved independently. The oxygen-binding hemoglobins of jawless fish evolved from an ancestor of cytoglobin which has no oxygen transport function and is expressed in fibroblast cells. Toxic agent, serine protease BLTX, in the venom produced by two distinct species, the North American short-tailed shrew (Blarina brevicauda) and the Mexican beaded lizard, undergo convergent evolution. Although their structures are similar, it turns out that they increased the enzyme activity and toxicity through different way of structure changes. These changes are not found in the other non-venomous reptiles or mammals. Another toxin BgK, a K+ channel-blocking toxin from the sea anemone Bunodosoma granulifera and scorpions adopt distinct scaffolds and unrelated structures, however, they have similar functions.
Sources: en.wikipedia.org
In February 2022, Carrey reprised his role as Ernie "Chip" Douglas, from the 1996 movie The Cable Guy, in a commercial for Verizon, which aired during the Super Bowl. In April 2022, Carrey announced that he was considering retirement, saying: "I have enough. I've done enough. I am enough." He said he would return to acting if "angels bring some sort of script that's written in gold ink that says to me that it's going to be really important for people to see". In February 2024, it was announced that Carrey would reprise his role as Dr. Ivo Robotnik in Sonic the Hedgehog 3. A copy of the script for Sonic the Hedgehog 3 was delivered to Carrey written in 24-carat ink in reference to his previous comments. Carrey also plays Ivo Robotnik's grandfather, Gerald Robotnik. Carrey reportedly told an Associated Press reporter that he agreed to return to the Sonic universe because "I need the money, frankly." He later clarified in interviews in December 2024 that he planned to "power rest" rather than retire, while also stating that he was open to continuing his role in the Sonic film series. In March 2026, Carrey was announced to return as Dr. Ivo Robotnik in Sonic the Hedgehog 4 (2027). In August 2026, Carrey was announced to star in the upcoming live-action film The Jetsons, but his role is yet to be confirmed.
Plaid Cymru expels Senedd member Rhys ab Owen after he was found to have inappropriately touched and sworn at two women while drunk at a party. Former Chancellor Nadhim Zahawi, who stood down from Parliament at the general election, is reported to be seeking financial backers in order to bid for the Daily Telegraph and The Spectator. 23 July – Seven Labour MPs, including former shadow chancellor John McDonnell and former shadow minister Rebecca Long-Bailey, have the Labour whip suspended for six months after voting against the government and in favour of an SNP amendment to scrap the two-child benefit cap. McDonnel said, "I'm following Keir Starmer's example as he said put country before party". The Home Office confirms that contract for the Bibby Stockholm, the vessel used to house asylum seekers, will not be renewed after January 2025. Documents released by The National Archives reveal that former prime minister Harold Wilson agreed to sell his private papers late in life in order to provide funds for his care. A deal agreed with Canada's McMaster University in 1990 attracted concern from the Cabinet Office because documents relating to his time in office remained private under the thirty year rule, which would not apply if they went to Canada. They were eventually sold to Oxford's Bodleian Library. 2024 Conservative Party leadership election: James Cleverly, who served as home secretary and foreign secretary in the Sunak government, announces his intention to run for the post of Conservative Party leader. 24 July – Starmer attends his first PMQs as prime minister.
Alpha particles emitted by polonium ionize air molecules that neutralize charges on the nearby surfaces. Some anti-static brushes contain up to 500 microcuries (20 MBq) of 210Po as a source of charged particles for neutralizing static electricity. In the US, devices with no more than 500 μCi (19 MBq) of (sealed) 210Po per unit can be bought in any amount under a "general license", which means that a buyer need not be registered by any authorities. Polonium needs to be replaced in these devices nearly every year because of its short half-life; it is also highly radioactive and therefore has been mostly replaced by less dangerous beta particle sources. Tiny amounts of 210Po are sometimes used in the laboratory and for teaching purposes—typically of the order of 4–40 kBq (0.11–1.08 μCi), in the form of sealed sources, with the polonium deposited on a substrate or in a resin or polymer matrix—are often exempt from licensing by the NRC and similar authorities as they are not considered hazardous. Small amounts of 210Po are manufactured for sale to the public in the United States as "needle sources" for laboratory experimentation, and they are retailed by scientific supply companies. The polonium is a layer of plating which in turn is plated with a material such as gold, which allows the alpha radiation (used in experiments such as cloud chambers) to pass while preventing the polonium from being released and presenting a toxic hazard. Polonium spark plugs were marketed by Firestone from 1940 to 1953.
== Perspectives == Synthetic biology is a field whose scope is expanding in terms of systems integration, engineered organisms, and practical findings. Engineers view biology as technology (in other words, a given system includes biotechnology or its biological engineering). Synthetic biology includes the broad redefinition and expansion of biotechnology, with the ultimate goal of being able to design and build engineered live biological systems that process information, manipulate chemicals, fabricate materials and structures, produce energy, provide food, and maintain and enhance human health, as well as advance fundamental knowledge of biological systems (see Biomedical engineering) and our environment. Researchers and companies working in synthetic biology are using nature's power to solve issues in agriculture, manufacturing, and medicine. Due to more powerful genetic engineering capabilities and decreased DNA synthesis and sequencing costs, the field of synthetic biology is rapidly growing. In 2016, more than 350 companies across 40 countries were actively engaged in synthetic biology applications; all these companies had an estimated net worth of $3.9 billion in the global market. Synthetic biology currently has no generally accepted definition. Here are a few examples: It is the science of genetic and physical engineering to produce new (and, therefore, synthetic) life forms.
To produce a Dayhoff matrix, pairs of aligned amino acids in verified alignments are used to build a count matrix, which is then used to estimate at mutation matrix at 1 PAM (considered an evolutionary unit). From this mutation matrix, a Dayhoff scoring matrix may be constructed. Along with a model of indel events, alignments generated by these methods can be used in an iterative process to construct new count matrices until convergence. One of Dayhoff's most important contributions to bioinformatics was her Atlas of Protein Sequence and Structure, a book reporting all known protein sequences (totaling 65) that she published in 1965. This book published a degenerate encoding of amino acids. It was subsequently republished in several editions. This led to the Protein Information Resource database of protein sequences, the first online database system that could be accessed by telephone line and available for interrogation by remote computers. The book has since been cited nearly 4,500 times. It and the parallel effort by Walter Goad which led to the GenBank database of nucleic acid sequences are the twin origins of the modern databases of molecular sequences. The Atlas was organized by gene families, and she is regarded as a pioneer in their recognition. Frederick Sanger's determination of the first complete amino acid sequence of a protein (insulin) in 1955, led a number of researchers to sequence various proteins from different species.
Sources: en.wikipedia.org
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.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.