heptapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-12-28. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
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.
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.
Growth hormone deficiency (GHD) is a medical condition in which the body produces insufficient growth hormone. Growth hormone, also called somatotropin, is a polypeptide hormone which stimulates growth and cell reproduction. If this hormone is lacking, stunted or even halted growth may become apparent. Children with this disorder may grow slowly and puberty may be delayed by several years or indefinitely. Growth hormone deficiency has no single definite cause. It can be caused by mutations of specific genes, damage to the pituitary gland, Turner's syndrome, poor nutrition, or even stress (leading to psychogenic dwarfism). Laron syndrome (growth hormone insensitivity) is another cause. Those with growth hormone issues tend to be proportionate.
==== Magnetic resonance and radio-frequency pulses ==== A perturbation of nuclear spin orientations from equilibrium will occur only when an oscillating magnetic field is applied whose frequency νrf sufficiently closely matches the Larmor precession frequency νL of the nuclear magnetization. The populations of the spin-up and -down energy levels then undergo Rabi oscillations, which are analyzed most easily in terms of precession of the spin magnetization around the effective magnetic field in a reference frame rotating with the frequency νrf. The stronger the oscillating field, the faster the Rabi oscillations or the precession around the effective field in the rotating frame. After a certain time on the order of 2–1000 microseconds, a resonant RF pulse flips the spin magnetization to the transverse plane, i.e. it makes an angle of 90° with the constant magnetic field B0 ("90° pulse"), while after a twice longer time, the initial magnetization has been inverted ("180° pulse"). It is the transverse magnetization generated by a resonant oscillating field which is usually detected in NMR, during application of the relatively weak RF field in old-fashioned continuous-wave NMR, or after the relatively strong RF pulse in modern pulsed NMR.
=== Even-numbered saturated fatty acids === Theoretically, the ATP yield for each oxidation cycle where two carbons are broken down at a time is 17, as each NADH produces 3 ATP, FADH2 produces 2 ATP and a full rotation of Acetyl-CoA in citric acid cycle produces 12 ATP. In practice, it is closer to 14 ATP for a full oxidation cycle as 2.5 ATP per NADH molecule is produced, 1.5 ATP per each FADH2 molecule is produced and Acetyl-CoA produces 10 ATP per rotation of the citric acid cycle(according to the P/O ratio). This breakdown is as follows:
The 8th district includes most of the northern and northwestern exurbs of Houston, including Conroe, part of Huntsville, Willis, Magnolia, Brookshire and Hempstead, along with parts of west Houston including Briar Forest, the western end of the Energy Corridor and most of the Bear Creek and Addicks areas in west Harris County. The incumbent is Republican Morgan Luttrell, who was elected with 68.2% of the vote in 2024. Luttrell is not seeking reelection in the heavily Republican district, which gave Donald Trump 63.2% and Ted Cruz 60.1% of the vote in 2024 and is a plurality White district with a 31.3% Hispanic voting age population.
Sources: en.wikipedia.org
Optical: To improve visual acuity by replacing the opaque or distorted host tissue by clear healthy donor tissue. The most common indication in this category is pseudophakic bullous keratopathy, followed by keratoconus, corneal degeneration, keratoglobus and dystrophy, as well as scarring due to keratitis and trauma. Tectonic/reconstructive: To preserve corneal anatomy and integrity in patients with stromal thinning and descemetoceles, or to reconstruct the anatomy of the eye, e.g. after corneal perforation. Therapeutic: To remove inflamed corneal tissue unresponsive to treatment by antibiotics or anti-virals. Cosmetic: To improve the appearance of patients with corneal scars that have given a whitish or opaque hue to the cornea.
Aspartic acid was first discovered in 1827 by Auguste-Arthur Plisson and Étienne-Ossian Henry by hydrolysis of asparagine, which had been isolated from asparagus juice in 1806. Their original method used lead hydroxide, but various other acids or bases are now more commonly used instead. There are two forms or enantiomers of aspartic acid. The name "aspartic acid" can refer to either enantiomer or a mixture of two. Of these two forms, only one, "L-aspartic acid", is directly incorporated into proteins. The biological roles of its counterpart, "D-aspartic acid" are more limited. Where enzymatic synthesis will produce one or the other, most chemical syntheses will produce both forms, "DL-aspartic acid", known as a racemic mixture. In the human body, aspartate is most frequently synthesized through the transamination of oxaloacetate. The biosynthesis of aspartate is facilitated by an aminotransferase enzyme: the transfer of an amine group from another molecule such as alanine or glutamine yields aspartate and an alpha-keto acid.
== Bibliography == Audi, G.; Kondev, F. G.; Wang, M.; et al. (2017). "The NUBASE2016 evaluation of nuclear properties". Chinese Physics C. 41 (3) 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001. Beiser, A. (2003). Concepts of modern physics (6th ed.). McGraw-Hill. ISBN 978-0-07-244848-1. OCLC 48965418. Hoffman, D. C.; Ghiorso, A.; Seaborg, G. T. (2000). The Transuranium People: The Inside Story. World Scientific. ISBN 978-1-78-326244-1. Kragh, H. (2018). From Transuranic to Superheavy Elements: A Story of Dispute and Creation. Springer. ISBN 978-3-319-75813-8. Silva, Robert J. (2011). "Chapter 13. Fermium, Mendelevium, Nobelium, and Lawrencium". In Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements. Netherlands: Springer. doi:10.1007/978-94-007-0211-0_13. ISBN 978-94-007-0210-3. Zagrebaev, V.; Karpov, A.; Greiner, W. (2013). "Future of superheavy element research: Which nuclei could be synthesized within the next few years?". Journal of Physics: Conference Series. 420 (1) 012001. arXiv:1207.5700. Bibcode:2013JPhCS.420a2001Z. doi:10.1088/1742-6596/420/1/012001. ISSN 1742-6588. S2CID 55434734.
=== Serious === Diabetic ketoacidosis, a rare but potentially life-threatening condition, may occur more commonly with empagliflozin and other SGLT-2 inhibitors. While diabetic ketoacidosis is usually associated with elevated blood glucose levels, in people taking SGLT-2 inhibitors diabetic ketoacidosis may be seen with uncharacteristically normal blood glucose levels, a phenomenon called euglycemic diabetic ketoacidosis. The absence of elevated blood glucose levels in people on an SGLT-2 inhibitor may make it more difficult to diagnose diabetic ketoacidosis. The risk of empagliflozin-associated euglycemic diabetic ketoacidosis may be higher in the setting of illness, dehydration, surgery, and/or alcohol consumption. It is also seen in type 1 diabetes who take empagliflozin, which notably is an unapproved or "off-label" use of the medication. To lessen the risk of developing ketoacidosis (a serious condition in which the body produces high levels of blood acids called ketones) after surgery, the FDA has approved changes to the prescribing information for SGLT2 inhibitor diabetes medicines to recommend they be stopped temporarily before scheduled surgery. Empagliflozin should each be stopped at least three days before scheduled surgery. Symptoms of diabetic ketoacidosis include nausea, vomiting, abdominal pain, tiredness, and trouble breathing. Fournier's gangrene, a rare but serious infection of the groin, occurs more commonly in people taking empagliflozin and other SGLT-2 inhibitors.
== External links == The MEROPS online database for peptidases and their inhibitors: Stem Bromelain:C01.005[link removed], Fruit Bromelain:C01.028[link removed] Bromelains at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
Sources: en.wikipedia.org
=== Academic Health Center and UC Health (1980s-Present) === The medical school and health colleges had been referred to as the "University of Cincinnati Medical Center" from the early 1980s until 2005. In 2000 a fourth College, the College of Allied Health Sciences joined the University of Cincinnati Medical Center. In 2005, the name was changed from the University of Cincinnati Medical Center to the University of Cincinnati Academic Health Center. In 2010, the Academic Health Center (AHC) became part of the newly formed UC Health organization. UC Health was formed after the dissolution of the Health Alliance of Greater Cincinnati, which had operated the University of Cincinnati Medical Center from 1994 to 2010 and also operated West Chester Hospital starting in 2009. The 2010 dissolution of the alliance left the university with 100% ownership so the alliance was renamed to UC Health and placed under a parent company named UC Healthcare System.
Nalbuphine, sold under the brand names Nubain among others, is an opioid analgesic which is used in the treatment of pain. It is given by injection into a vein, muscle, or fat. Side effects of nalbuphine include sedation, sweatiness, clamminess, nausea, vomiting, dizziness, vertigo, dry mouth, and headache. Unlike other opioids, it has little to no capacity to cause euphoria or respiratory depression. There is also little to no incidence of dysphoria, dissociation, hallucinations, and related side effects at typical therapeutic doses. Nalbuphine is a mixed agonist/antagonist opioid modulator. Specifically, it acts as a moderate-efficacy partial agonist or antagonist of the μ-opioid receptor (MOR) and as a high-efficacy partial agonist of the κ-opioid receptor (KOR), whereas it has relatively low affinity for the δ-opioid receptor (DOR) and sigma receptors. Nalbuphine was patented in 1968 and was introduced for medical use in the United States in 1979. It is marketed in many countries throughout the world.
=== Enterohepatic circulation === Research by Aarons has focused on enterohepatic cycling (EHC) which refers to the process whereby a drug goes through the liver and biliary tract for excretion and is released into the small intestine, where it can be reabsorbed back into circulation and subsequently returned to the liver. This can cause liver damage and the half-life and duration of a drug to be increased. Aarons and his team stressed that knowing the extent of EHC is invaluable in deciding whether or not the in vitro characteristics of a drug - i.e. those taking place outside of a living organism - will have any effect on the overall process of absorption in vivo, or when it is taking place inside the organism. Aarons had earlier been involved in research on the area under the curve (AUC). This is a pharmacokinetic statistic used to describe the total exposure to a drug - specifically the concentration of a drug in body fluids such as blood - and is useful because it gives insight into the extent of exposure to a drug and its clearance rate from the body. The research was seen as important in the "design of sampling protocols for accurate determination of AUC(0– ∞) for drugs subject to enterohepatic cycling."
Congress reconvenes and formally certifies Joe Biden as the next president of the United States on the morning of January 7. President Trump formally concedes to an orderly transition of power to Joe Biden. During the Electoral College vote count, Senator Ted Cruz and Representative Paul Gosar object to Arizona's election results, the first time a vote is forced to accept or reject the objection since 2004. Representative Scott Perry and Senator Josh Hawley subsequently object to Pennsylvania's election results. January 7 Tesla and SpaceX CEO Elon Musk becomes the world's richest person, with a net worth exceeding $185 billion, surpassing Amazon CEO Jeff Bezos. Facebook indefinitely bans President Donald Trump from all of its platforms, citing his role in the January 6 Capitol riot. Twitter permanently suspends Trump's personal account the next day, January 8. Betsy DeVos resigns as Education Secretary in protest of President Trump's role in the January 6 Capitol riot. January 8 Amid an industry crackdown on extremist content following the January 6 Capitol riot, Google removes the mobile app of social networking service Parler from Google Play. Apple suspends the app from its App Store the next day, January 9. Parler goes offline a day later, January 10, when Amazon ceases to provide its cloud computing services. After 36 years, Alex Trebek's final episode of Jeopardy! airs. Ken Jennings becomes the temporary host on January 11 as the search for a new permanent host continues.
== Synthetic inorganic chemistry == Although some inorganic species can be obtained in pure form from nature, most are synthesized in chemical plants and in the laboratory. Inorganic synthetic methods can be classified roughly according to the volatility or solubility of the component reactants. Soluble inorganic compounds are prepared using methods of organic synthesis. For metal-containing compounds that are reactive toward air, Schlenk line and glove box techniques are followed. Volatile compounds and gases are manipulated in "vacuum manifolds" consisting of glass piping interconnected through valves, the entirety of which can be evacuated to 0.001 mm Hg or less. Compounds are condensed using liquid nitrogen (b.p. 78 K) or other cryogens. Solids are typically prepared using tube furnaces, the reactants and products being sealed in containers, often made of fused silica (amorphous SiO2) but sometimes more specialized materials such as welded Ta tubes or Pt "boats". Products and reactants are transported between temperature zones to drive reactions.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.