peptide purity raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-06-03 and is reviewed periodically as new material appears.
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.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
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.
| 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 |
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.
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.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
=== Nitrile oxides === Nitrile oxides have the chemical formula RCNO. Their general structure is R−C≡N+−O−. The R stands for any group (typically organyl, e.g., acetonitrile oxide CH3−C≡N+−O−, hydrogen in the case of fulminic acid H−C≡N+−O−, or halogen (e.g., chloroformonitrile oxide Cl−C≡N+−O−). Nitrile oxides are quite different from nitriles and do not arise from direct oxidation of the latter. Instead, they can be synthesised by nitroalkane dehydration, oxime dehydrogenation, or halooxime elimination in base. They are highly reactive in 1,3-dipolar cycloadditions, such as to isoxazoles, and undergo type I dyotropic rearrangement to isocyanates. The heavier nitrile sulfides are extremely reactive and rare, but temporarily form during the thermolysis of oxathiazolones. They react similarly to nitrile oxides.
=== Main === Jean Smart as Deborah Vance, a revered Las Vegas stand-up comedian decades into her career Hannah Einbinder as Ava Daniels, a 25-year-old down-on-her-luck comedy writer forced to leave Los Angeles and work with Deborah Vance Carl Clemons-Hopkins as Marcus, the loyal workaholic COO of Deborah's company
=== Complications === Pressure ulcers can trigger other ailments, cause considerable suffering, and can be expensive to treat. Some complications include autonomic dysreflexia, bladder distension, bone infection, pyarthrosis, sepsis, amyloidosis, anemia, urethral fistula, gangrene and very rarely malignant transformation (Marjolin's ulcer – secondary carcinomas in chronic wounds). Sores may recur if those with pressure ulcers do not follow recommended treatment or may instead develop seromas, hematomas, infections, or wound dehiscence. Paralyzed individuals are the most likely to have pressure sores recur. In some cases, complications from pressure sores can be life-threatening. The most common causes of fatality stem from kidney failure and amyloidosis. Pressure ulcers are also painful, with individuals of all ages and all stages of pressure ulcers reporting pain.
Sources: en.wikipedia.org
1909: Alice Wilson became the first female geologist hired by the Geological Survey of Canada. She is widely credited as being the first Canadian female geologist. 1909: Danish physicist Kirstine Meyer became the first Danish woman to receive a doctorate degree in natural sciences. She wrote her dissertation on the topic of "the development of the temperature concept" within the history of physics.
Glass noodles, or fensi (traditional Chinese: 粉絲; simplified Chinese: 粉丝; pinyin: fěnsī; lit. 'flour thread'), sometimes called cellophane noodles, are a type of transparent noodle made from starch (such as mung bean starch, potato starch, sweet potato starch, tapioca, or canna starch) and water. They originated in China. A stabilizer such as chitosan or alum (illegal in some jurisdictions) may also be used. They are generally sold in dried form, soaked to reconstitute, then used in soups, stir-fried dishes, or spring rolls. They are called "glass noodles" because of their glass-like transparency when cooked. Glass noodles are not the same as rice vermicelli, which is made from rice and white in color rather than clear (after cooking in water).
CoA-glutathione + NADPH + H+ The 3 substrates of this enzyme are CoA, glutathione, and NADP+, whereas its 3 products are CoA-glutathione, NADPH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is glutathione:NADP+ oxidoreductase (CoA-acylating). Other names in common use include coenzyme A glutathione disulfide reductase, NADPH-dependent coenzyme A-SS-glutathione reductase, coenzyme A disulfide-glutathione reductase, and NADPH:CoA-glutathione oxidoreductase. This enzyme participates in cysteine metabolism. It employs one cofactor, FAD.
Nonbenzodiazepines (Z-drugs) are a class of psychoactive drugs that are "benzodiazepine-like" in nature. Nonbenzodiazepine pharmacodynamics are almost entirely the same as benzodiazepine drugs, and therefore entail similar benefits, side effects, and risks. Nonbenzodiazepines, however, have dissimilar or different chemical structures, and are unrelated to benzodiazepines on a molecular level. Examples include zopiclone (Imovane), eszopiclone (Lunesta), zaleplon (Sonata), and zolpidem (Ambien). Since the generic names of all drugs of this type start with Z, they are often referred to as Z-drugs. Research on nonbenzodiazepines is new and conflicting. A review by a team of researchers suggests the use of these drugs for people who have trouble falling asleep (but not staying asleep), as next-day impairments were minimal. The team noted that the safety of these drugs had been established, but called for more research into their long-term effectiveness in treating insomnia. Other evidence suggests that tolerance to nonbenzodiazepines may be slower to develop than with benzodiazepines. A different team was more skeptical, finding little benefit over benzodiazepines.
Sources: en.wikipedia.org
Tapentadol was invented at the German pharmaceutical company Grünenthal in the late 1980s led by Helmut Buschmann; the team started by analyzing the chemistry and activity of tramadol, which had been invented at the same company in 1962. Tramadol has several enantiomers, and each forms metabolites after processing in the liver. These tramadol variants have varying activities at the μ-opioid receptor, the norepinephrine transporter, and the serotonin transporter, and differing half-lives, with the metabolites having the best activity. Using tramadol as a starting point, the team aimed to discover a single molecule that minimized the serotonin activity, had strong μ-opioid receptor agonism and strong norepinephrine reuptake inhibition, and would not require metabolism to be active; the result was tapentadol. In 2003 Grünenthal partnered with two Johnson & Johnson subsidiaries, Johnson & Johnson Pharmaceutical Research and Development and Ortho-McNeil Pharmaceutical to develop and market tapentadol; Johnson & Johnson had exclusive rights to sell the drug in the US, Canada, and Japan while Grünenthal retained rights elsewhere. In 2008 tapentadol received approval by the US Food and Drug Administration; in 2009 it was classified by US Drug Enforcement Agency as a Schedule II drug, and entered the US market. Tapentadol was reported to be the "first new molecular entity of oral centrally acting analgesics" class approved in the United States in more than 25 years. In 2010 Grünenthal granted Johnson & Johnson the right to market tapentadol in about 80 additional countries.
== Mechanism of action == Like all opioid drugs, ADL-5859 activates opioid receptors, but where as traditional opioids (such as oxycodone) activate the three main receptors (mu, delta, and kappa), ADL-5859 appears to be selective and only activates the delta receptor. with a Ki of 20 nM
Verdin, Eric (2015-12-04). "NAD+ in aging, metabolism, and neurodegeneration". Science. 350 (6265): 1208–1213. Bibcode:2015Sci...350.1208V. doi:10.1126/science.aac4854. ISSN 0036-8075. PMID 26785480. S2CID 27313960. Verdin, Eric; Ott, Melanie (2015). "50 years of protein acetylation: from gene regulation to epigenetics, metabolism and beyond". Nature Reviews Molecular Cell Biology. 16 (4): 258–264. doi:10.1038/nrm3931. ISSN 1471-0080. PMID 25549891. S2CID 10192177. Gut, Philipp; Verdin, Eric (2013-10-24). "The nexus of chromatin regulation and intermediary metabolism". Nature. 502 (7472): 489–498. Bibcode:2013Natur.502..489G. doi:10.1038/nature12752. ISSN 1476-4687. PMID 24153302. S2CID 4471359. Shimazu, Tadahiro; Hirschey, Matthew D.; Newman, John; He, Wenjuan; Shirakawa, Kotaro; Le Moan, Natacha; Grueter, Carrie A.; Lim, Hyungwook; Saunders, Laura R. (2013-01-11). "Suppression of Oxidative Stress by β-Hydroxybutyrate, an Endogenous Histone Deacetylase Inhibitor". Science. 339 (6116): 211–214. Bibcode:2013Sci...339..211S. doi:10.1126/science.1227166. ISSN 0036-8075. PMC 3735349. PMID 23223453. Hirschey, Matthew D.; Shimazu, Tadahiro; Jing, Enxuan; Grueter, Carrie A.; Collins, Amy M.; Aouizerat, Bradley; Stančáková, Alena; Goetzman, Eric; Lam, Maggie M. (2011-10-21). "SIRT3 deficiency and mitochondrial protein hyperacetylation accelerate the development of the metabolic syndrome". Molecular Cell. 44 (2): 177–190. doi:10.1016/j.molcel.2011.07.019. ISSN 1097-4164. PMC 3563434. PMID 21856199.
=== Carl Hardee Sr. campaign === In March 2017, Hardee's began to move away from the sexualized ads by releasing a commercial featuring a white bearded character played by Charles Esten as "Carl Hardee Sr." who had come back into the office (much to the delight of the employees) to find his son (Drew Tarver), a.k.a. "Carl Jr." who was focusing on sex appeal over its food. The commercial marked a turning point in CKE's advertising, as the company wanted to move away from its provocative ads and focus more on food and as a competitor to Five Guys, Steak 'n Shake, and In-N-Out Burger. "Carl Hardee Sr." was also expected to become the new company spokesperson.
== External links == UniProt: Bisphosphoglycerate mutase - Homo sapiens (Human) UniProt-Information about bisphosphoglycerate mutase A live model of the effect of changing 2,3-bisphosphoglycerate on the oxyhaemoglobin saturation curve
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.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.