A practical reference on Reversed-phase HPLC: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-05-24 and is reviewed periodically as new material appears.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
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.
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.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
The Affordable Insulin Now Act is a bill in the United States Congress intended to cap out-of-pocket insulin prices under private health insurance and Medicare at no more than $35 per month. The bill was first introduced on February 25, 2022, by Representative Angie Craig (D-MN). On March 31, 2022, the bill passed the House of Representatives, 232–193. A version of the bill contained in the Inflation Reduction Act (IRA) for private health insurance was blocked by Senate Republicans on August 8, 2022. However, the inflation reduction legislation did cap out-of-pocket insulin cost at $35 per monthly prescription for the following:
== Development of penicillin derivatives == The narrow range of treatable diseases or "spectrum of activity" of the penicillins, along with the poor activity of the orally active penicillin V, led to the search for derivatives of penicillin that could treat a wider range of infections. The isolation of 6-APA, the nucleus of penicillin, allowed for the preparation of semisynthetic penicillins, with various improvements over benzylpenicillin. Ampicillin was developed by the Beecham Research Laboratories in London. When introduced to clinical use in 1961 it was the first semisynthetic penicillin that could be taken orally that was effective against both Gram-negative and Gram-positive bacteria, whereas the original was only effective against Gram-positive.
In 2025, DFI Retail Group sold the Singaporean food retailing business (including Cold Storage brand) to Macrovalue Pte Ltd. In August 2026, Cold Storage launched Cold Storage On The Go, a convenience store format, at an Esso station on East Coast Road. The company planned to introduce the format at all 58 Esso stations in Singapore during 2026, replacing FairPrice Group's convenience stores.
Metallic zinc was isolated in India by 1300 AD. Before it was isolated in Europe, it was imported from India in about AD 1600. Postlewayt's Universal Dictionary, a contemporary source giving technological information in Europe, did not mention zinc before 1751 but the element was studied before then. Flemish metallurgist and alchemist P. M. de Respour reported that he had extracted metallic zinc from zinc oxide in 1668. By the start of the 18th century, Étienne François Geoffroy described how zinc oxide condenses as yellow crystals on bars of iron placed above zinc ore that is being smelted. In Britain, John Lane is said to have carried out experiments to smelt zinc, probably at Landore, prior to his bankruptcy in 1726. In 1738 in Great Britain, William Champion patented a process to extract zinc from calamine in a vertical retort-style smelter. His technique resembled that used at Zawar zinc mines in Rajasthan, but no evidence suggests he visited the Orient. Champion's process was used through 1851. German chemist Andreas Marggraf normally gets credit for isolating pure metallic zinc in the West, even though Swedish chemist Anton von Swab had distilled zinc from calamine four years previously. In his 1746 experiment, Marggraf heated a mixture of calamine and charcoal in a closed vessel without copper to obtain a metal. This procedure became commercially practical by 1752.
Meanwhile, the Central and Eastern European communist states politically deteriorated in response to the success of the Polish Solidarity movement and the possibility of Gorbachev-style political liberalisation. In 1989, revolts began across Central and Eastern Europe and China against Marxist–Leninist regimes. In China, the government refused to negotiate with student protestors, resulting in the 1989 Tiananmen Square massacre that stopped the revolts by force. The Pan-European Picnic, which was based on an idea by Otto von Habsburg to test the reaction of the Soviet Union, then triggered a peaceful chain reaction in August 1989, at the end of which there was no longer East Germany and the Iron Curtain and the Marxist–Leninist Eastern Bloc had collapsed. On the one hand, as a result of the Pan-European Picnic, the Marxist–Leninist rulers of the Eastern Bloc did not act decisively, but cracks appeared between them and on the other hand the media-informed Central and Eastern European population now noticed a steady loss of power in their governments.
Sources: en.wikipedia.org
== Structure == NGF is initially in a 7S, 130-kDa complex of 3 proteins – Alpha-NGF, Beta-NGF, and Gamma-NGF (2:1:2 ratio) when expressed. This form of NGF is also referred to as proNGF (NGF precursor). The gamma subunit of this complex acts as a serine protease, and cleaves the N-terminal of the beta subunit, thereby activating the protein into functional NGF. The term nerve growth factor usually refers to the 2.5S, 26-kDa beta subunit of the protein, the only component of the 7S NGF complex that is biologically active (i.e. acting as a signaling molecule).
Reduction of 4-nitrobenzoic acid Hoffman degradation of the monoamide derived from terephthalic acid. Food sources of PABA include liver, brewer's yeast (and unfiltered beer), kidney, molasses, mushrooms, and whole grains. Other food sources of PABA include spinach and oat seeds.
July 31: Communist insurgents in Malaya are defeated. August 3: Niger becomes independent from France. August 6: Cuban leader Fidel Castro orders the nationalisation of all American-owned property. August 9: The Pathet Lao (communist) revolt in Laos begins. August 11: Chad becomes independent from France. August 17: Gabon becomes independent from France. September 30: Sukarno gives a speech in front of the fifteenth United Nations General Assembly titled "To Build The World Anew" in which he criticizes the United Nations for not being neutral and questions location of the United Nations Headquarters in New York, United States. October 12: While addressing the United Nations, Soviet Leader Nikita Khrushchev becomes agitated at criticisms of Soviet policies in eastern European. Khrushchev removes his shoe and thumps it on the lectern. October 19: The US places a partial embargo on Cuba, banning the export of all items except food and medicine. November 13: the Guatemalan Civil War begins. November 28: Mauritania becomes independent from France. December 20: Formation of the National Liberation Front (often called Viet Cong) by North Vietnam. It is a communist insurgent movement that vows to overthrow the anti-communist South Vietnamese regime. It is supplied extensively by North Vietnam, China, and the USSR eventually.
On March 1, 2013, Governor Rick Snyder announced that the state would be assuming financial control of the city. A team was chosen to review the city's finances and determine whether the appointment of an emergency manager was warranted. Two weeks later, the state's Local Emergency Financial Assistance Loan Board (ELB) appointed an emergency financial manager, Kevyn Orr. Orr released his first report in mid-May. The results were generally negative regarding Detroit's financial health. The report said that Detroit is "clearly insolvent on a cash flow basis." The report said that Detroit would finish its current budget year with a $162 million cash-flow shortfall and that the projected budget deficit was expected to reach $386 million in less than two months. The report said that costs for retiree benefits were eating up a third of Detroit's budget and that public services were suffering as Detroit's revenues and population shrink each year. The report was not intended to offer a complete blueprint for Orr's plans for fixing the crisis; more details about those plans were expected to emerge within a few months. After several months of negotiations, Orr was ultimately unable to come to a deal with Detroit's creditors, unions, and pension boards and therefore filed for Chapter 9 bankruptcy protection in the Eastern District of Michigan U.S. Bankruptcy Court on July 18, 2013, the largest U.S. city ever to do so, with outstanding financial obligations to more than 100,000 creditors totaling approximately $18.5 billion. On December 10, 2014, Detroit successfully exited bankruptcy.
Sources: en.wikipedia.org
=== Poisoning === Fomepizole, a drug that competitively inhibits alcohol dehydrogenase, can be used in the setting of acute methanol or ethylene glycol toxicity. This prevents the conversion of the methanol or ethylene glycol to its toxic metabolites (such as formic acid, formaldehyde, or glycolate). The same effect is also sometimes achieved with ethanol, again by competitive inhibition of ADH.
=== Metal recovery === A recent study highlights the first report of thermo-responsive rare-earth elements (REE)-selective protein. The ELP and the REE-binding domain are genetically fused to form REE-selective and thermo-responsive genetically encoded ELP called RELP for the selective extraction and recovery of total REEs. RELP shows a selective and repeatable biosorption platform for REE recovery. The authors highlighted that technology can be adapted to recover other precious metals and commodities.
=== Structural convergence === Here is a list of examples in which unrelated proteins have similar tertiary structures but different functions. Whole protein structural convergence is not thought to occur but some convergence of pockets and secondary structural elements have been documented.
=== Fl–Fu === Edith M. Flanigen (born 1929), American chemist known for synthesizing emeralds and zeolites Nicolas Flamel (c. 1330–1418), French alchemist who was believed to have created and discovered the philosopher's stone Paul Flory (1910–1985), American chemist, 1974 Nobel Prize in Chemistry for work on the physical chemistry of macromolecules Maria Forsyth (PhD 1990), Australian chemist known for work on energy storage and on corrosion Margaret D.
== Contraindications == Ioxaglic acid is contraindicated in people with hyperthyreosis because of the drug's iodine content. It must not be used for myelography (spinal cord imaging), for hysterosalpingography in women who are pregnant or have an acute inflammation in the pelvic region, or for arthrography if the joint is infected.
Sources: en.wikipedia.org
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.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.