RP-HPLC purity raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-08-01. Anything still debated is marked as such rather than presented as settled.
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.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
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.
| 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 |
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.
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.
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.
Ion exchange chromatography can be used to separate proteins because they contain charged functional groups. The ions of interest (in this case charged proteins) are exchanged for another ions (usually H+) on a charged solid support. The solutes are most commonly in a liquid phase, which tends to be water. Take for example proteins in water, which would be a liquid phase that is passed through a column. The column is commonly known as the solid phase since it is filled with porous synthetic particles that are of a particular charge. These porous particles are also referred to as beads, may be aminated (containing amino groups) or have metal ions in order to have a charge. The column can be prepared using porous polymers, for macromolecules of a mass of over 100 000 Da, the optimum size of the porous particle is about 1 μm2. This is because slow diffusion of the solutes within the pores does not restrict the separation quality. The beads containing positively charged groups, which attract the negatively charged proteins, are commonly referred to as anion exchange resins. The amino acids that have negatively charged side chains at pH 7 (pH of water) are glutamate and aspartate. The beads that are negatively charged are called cation exchange resins, as positively charged proteins will be attracted. The amino acids that have positively charged side chains at pH 7 are lysine, histidine and arginine. The isoelectric point is the pH at which a compound—in this case a protein—has no net charge.
==== Other cooking shows ==== In 1996, Flay hosted The Main Ingredient with Bobby Flay on Lifetime Television. Twice a month, he hosts a cooking segment on CBS's The Early Show. He hosted the reality television show America's Next Great Restaurant on NBC from March to May 2011 in which in the end he picks one restaurant team with whom to open a restaurant. The show was canceled after the first season due to low ratings. Flay has been featured in several episodes of Great Chefs television including:
=== Applications for ecosystem process analysis === Isotopic tracers are used to examine processes in natural systems, especially terrestrial and aquatic environments. In soil science 15N tracers are used extensively to study nitrogen cycling, whereas 13C and 14C, stable and radioisotopes of carbon respectively, are used for studying turnover of organic compounds and fixation of CO2 by autotrophs. For example, Marsh et al. (2005) used dual labeled (15N- and 14C) urea to demonstrate utilization of the compound by ammonia oxidizers as both an energy source (ammonia oxidation) and carbon source (chemoautotrophic carbon fixation). Deuterated water is also used for tracing the fate and ages of water in a tree or in an ecosystem.
Sources: en.wikipedia.org
Sarah Jane Cressall. Founder and Chief Executive Officer, The Creation Station. For services to Creativity in Education, Entertainment and Business. Thomas Daniel Critchley. Data Scientist, Prime Minister's Office. For services to Evidence-Based Policy. Dr. Ruth Louise Cromie. Research Fellow, Wildfowl and Wetlands Trust. For services to Wetland and Waterbird Conservation. Professor Adrian Michael Cruise. Emeritus Professor, University of Birmingham. For services to Space Science. Dr. Robert Nicholas Cullinan. Director, National Portrait Gallery. For services to Art. Laurence Alexander Cummings. Conductor, Harpsichordist, Music Director of the Academy of Ancient Music and the London Handel Festival, and William Crotch Professor of Historical Performance, Royal Academy of Music. For services to Music. Lynn Cummings, JP. Commercial Category Lead, Department for Work and Pensions. For Public Service. Professor William Cushley. Chair, Expert Committee on Pesticides. For services to the Regulation of Plant Protection Products. Dr. Dipankar Dutta. Chair, South Asia Voluntary Enterprise. For services to Charity. Roy Henry Dennis, MBE. Wildlife Conservationist. For services to Wildlife. Paul Anthony Denton. For services to Charity. Dr. Darrell Carmel De Souza. Lately Principal and Chief Executive Officer, Harrow College and Uxbridge College. For services to Further Education. Morag Deyes, MBE. Artistic Director, Dance Base, Edinburgh. For services to Dance. Angela Jane Charlotte Dickson, MBE. Co-Founder, The Brain Tumour Charity. For services to People with Brain Tumours.
The 21st Century Cures Act enacted in December 2016 allows researchers to waive the requirement for informed consent when clinical testing "poses no more than minimal risk" and "includes appropriate safeguards to protect the rights, safety, and welfare of the human subject." The probability that a patient may sue researchers who utilize tissues that would typically be discarded is low, but as genetic research becomes more prevalent, this likelihood may increase. Ideally, researchers should obtain informed consent from individuals and aim for transparency in their intended use of the human tissue while protecting the privacy of the donor. CAP and other laboratory accreditation organizations (AO) have additional requirements and protocols for repurposing biospecimens that would otherwise be discarded. In July 2011, an Advance Notice of Proposed Rule Making (ANPRM), entitled "Human Subjects Research Protections: Enhancing Protections for Research Subjects and Reducing Burden, Delay, and Ambiguity for Investigators" was published in the Federal Register. The rise in direct-to-consumer (DTC) genetic testing has raised concerns about the secondary use of both patient samples and their data.
== Applications of commercially synthesized peptides == Biologically active peptides have been integrated into a growing number of active pharmaceutical ingredients (API’s) as well as standalone products such as vasopressin, gonadorelin, leuprolide, and goserelin. Completion of the Human Genome Project resulted in the identification of approximately 30,000 proteins encoded in the human genome and provided many more new target molecules for biomedical researchers to explore. To investigate the possibility of increasing the native potency of a given peptide or protein using a rational design approach, small and large amounts of peptides are needed, Some in the milligram scale. Once a desired activity or potency is identified, larger scale synthesis is need. For this, gram to multi-gram scale may be needed in order to initiate small animal studies. Often, after successful validation, an even larger scale of synthesis may be desired. These can range in scale from hundreds of grams to multi-kilo amounts.
The Kawakawa (Piper excelsum) plant, known also as "Māori kava", may be confused with kava. While the two plants look similar and have similar names, they are different, but related, species. Kawakawa is a small tree endemic to New Zealand, having importance to traditional medicine and Māori culture. As noted by the Kava Society of New Zealand, "in all likelihood, the kava plant was known to the first settlers of Aotearoa [New Zealand]. It is also possible that (just like the Polynesian migrants that settled in Hawaii) the Maori explorers brought some kava with them. Unfortunately, most of New Zealand is simply too cold for growing kava and hence the Maori settlers lost their connection to the sacred plant." Further, "in New Zealand, where the climate is too cold for kava, the Maori gave the name kawa-kawa to another Piperaceae M. excelsum, in memory of the kava plants they undoubtedly brought with them and unsuccessfully attempted to cultivate. The Maori word kawa also means "ceremonial protocol", recalling the stylized consumption of the drug typical of Polynesian societies". Kawakawa is commonly used in Maori traditional medicine for the treatment of skin infections, wounds, and cuts, and (when prepared as a tea) for stomach upsets and other minor illnesses.
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.
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.