The short version of Tuftsin analog fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-11 and is reviewed periodically as new material appears.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
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.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
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.
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.
Most perceivable colors can be formed by mixing different amounts of three primary colors. This allows precise dynamic color control. Their emission power decays exponentially with rising temperature, resulting in a substantial change in color stability. Such problems hinder industrial use. Multicolor LEDs without phosphors cannot provide good color rendering because each LED is a narrowband source. LEDs without phosphors, while a poorer solution for general lighting, are the best solution for displays, whether they are LCD-backlit or direct LED-based pixels. Dimming a multicolor LED source to match the characteristics of incandescent lamps is difficult because manufacturing variations, age, and temperature change the actual color value output. To emulate the appearance of dimming in incandescent lamps, LEDs may require a feedback system with color sensor to actively monitor and control the color.
== Discovery == The first hint that led to the discovery of the SCF complex came from genetic screens of Saccharomyces cerevisiae, also known as budding yeast. Temperature-sensitive cell division cycle (Cdc) mutants—such as Cdc4, Cdc34, and Cdc53—arrested in G1 with unreplicated DNA and multiple elongated buds. The phenotype was attributed to a failure to degrade Sic1, an inhibitor of S cyclin-CDK complexes. These findings indicated that proteolysis is important in the G1/S transition. Next, biochemical studies revealed that Cdc34 is an E2 enzyme that physically interacts with an E3 ubiquitin ligase complex containing Skp1, Cdc4, and several other proteins. Skp1's known binding partners—specifically Skp2, Cyclin F, and Cdc4—were found to share an approximately 40 residue motif that was coined the F-box motif. The F-box hypothesis that followed these discoveries proposed that F-box proteins recruit substrates targeted for degradation, and that Skp1 links the F-box protein to the core ubiquitination complex. Subsequent genetic studies in Caenorhabditis elegans later contributed to the elucidation of other SCF complex components.
=== China === Journalist Joshua Kurlantzick writes that China has been engaging in a "charm offensive" in the 21st century to improve relations with many other countries, especially in the developing world. Kurlantzick contends that the Chinese government has leveraged the construction of large works of architecture abroad to better its standing with these countries. He also criticizes many of these projects, such as large-sized buildings and government ministries, as white-elephant projects. Kurlantzick cites examples of Chinese-led construction in Mozambique and East Timor as examples.
== Etymology == The word "aptamer" is a neologism coined by Andrew D. Ellington and Jack Szostak in their first publication on the topic. They did not provide a precise definition, stating "We have termed these individual RNA sequences 'aptamers', from the Latin aptus, to fit." The word itself, however, derives from the Greek word ἅπτω, to connect or fit (as used by Homer (c. 8th century BC)) and μέρος, a component of something larger.
Sources: en.wikipedia.org
=== Geothermal springs === Bruce Damer and David Deamer argue that cell membranes cannot be formed in salty seawater, and must therefore have originated in freshwater environments like pools replenished by a combination of geothermal springs and rainfall. Before the continents formed, the only dry land on Earth would be volcanic islands, where rainwater would form ponds where lipids could form the first stages towards cell membranes. During multiple wet-dry cycles, biopolymers would be synthesized and are encapsulated in vesicles after condensation. Zinc sulfide and manganese sulfide in these ponds would have catalyzed organic compounds by abiotic photosynthesis. Experimental research at geothermal springs successfully synthesized polymers and were encapsulated in vesicles after exposure to UV light and multiple wet-dry cycles. At temperatures of 60 to 80 °C at geothermal fields, biochemical reactions can occur. These predecessors of true cells are assumed to have behaved more like a superorganism rather than individual structures, where the porous membranes would house molecules which would leak out and enter other protocells. Only when true cells had evolved would they gradually adapt to saltier environments and enter the ocean. 6 of the 11 biochemical reactions of the rTCA cycle can occur in hot metal-rich acidic water which suggests metabolic reactions might have originated in this environment, this is consistent with the enhanced stability of RNA phosphodiester, aminoacyl-tRNA bonds, and peptides in acidic conditions.
(editor) (2017) Handbook on Navier-Stokes Equations Theory and Applied Analysis, Nova Science Publisher ISBN 978-1-53610-292-5 Döring, C.E. and J.D. Gibbon, J.D. (1995) Applied analysis of the Navier-Stokes equations, Cambridge University Press, ISBN 0-521-44557-4 Basset, Alfred Barnard (1888) Hydrodynamics Volume I and II, Cambridge: Delighton, Bell and Company Fox, R. W.; McDonald, A. T.; and Pritchard, P. J. (2004) Introduction to Fluid Mechanics, John Wiley and Sons, ISBN 0-471-20231-2 Foias, C.; Mainley, O.; Rosa, R.; and Temam, R. (2004) Navier–Stokes Equations and Turbulence, Cambridge University Press, ISBN 0-521-36032-3 Lions, P-L. (1998) Mathematical Topics in Fluid Mechanics Volume 1 and 2, Clarendon Press, ISBN 0-19-851488-3 Deville, M. O. and Gatski, T. B. (2012) Mathematical Modeling for Complex Fluids and Flows, Springer, ISBN 978-3-642-25294-5 Kochin, N. E.; Kibel, I. A.; and Roze, N. V. (1964) Theoretical Hydromechanics, John Wiley & Sons, Limited Lamb, Horace (1879) Hydrodynamics, Cambridge University Press White, Frank M. (2006), Viscous Fluid Flow, McGraw-Hill, ISBN 978-0-07-124493-0
The mummies of Asia are usually considered to be accidental. The decedents were buried in just the right place where the environment could act as an agent for preservation. This is particularly common in the desert areas of the Tarim Basin and Iran. Mummies have been discovered in more humid Asian climates; however, these are subject to rapid decay after being removed from the grave.
== Signs and symptoms == Symptoms vary according to individuals' hydration level and sensitivity to the rate and/or magnitude of decline of their blood glucose concentration. A crash is usually felt within four hours of heavy carbohydrate consumption. Along with the symptoms of hypoglycemia, symptoms of reactive hypoglycemia include:
==== Myelopathy ==== Copper deficiency myelopathy in humans was discovered and first described by Schleper and Stuerenburg in 2001. They described a patient with a history of gastrectomy and partial colonic resection who presented with severe tetraparesis and painful paraesthesias and who was found on imaging to have dorsomedial cervical cord T2 hyperintensity. Upon further analysis, it was found that the patient had decreased levels of serum coeruloplasmin, serum copper, and CSF copper. The patient was treated with parenteral copper and the patient's paraesthesias did resolve. Since this discovery, awareness of copper-deficiency myelopathy and its treatment has increased. Patients typically present difficulty walking (gait difficulty) caused by sensory ataxia (irregular muscle coordination) due to dorsal column dysfunction or degeneration of the spinal cord (myelopathy). Patients with ataxic gait have problems balancing and display an unstable wide walk. They often feel tremors in their torso, causing sideways jerks and lunges. In brain MRI, there is often an increased T2 signalling at the posterior columns of the spinal cord in patients with myelopathy caused by copper deficiency. T2 signalling is often an indicator of neurodegeneration. There are some changes in the spinal cord MRI involving the thoracic cord, the cervical cord, or sometimes both. Copper deficiency myelopathy is often compared to subacute combined degeneration (SCD).
Sources: en.wikipedia.org
==== Renewed clashes ==== The conflict between Houthis and Salafis in Saada Governorate was renewed in October and November. Saada government officials accused Houthi fighters of attacking a Salafi mosque in Dammaj in an attempt to drive the Sunnis out, while the Houthis accused the Salafis of using the religious institute as a staging ground for foreign Sunni fighters. The government attempted to intervene to stop the fighting. Sectarian fighting in Al Jawf Governorate lasted throughout the year. Dhamar Governorate also saw clashes between the Houthis and Salafis toward the end of the year.
== In humans == Zinc has been used therapeutically at a dose of 150 mg/day for months, or in some cases for years, and in one case at a dose of up to 2000 mg/day zinc for months. A decrease in copper levels and hematological changes have been reported; however, those changes were completely reversed with the cessation of zinc intake. Zinc has been popularly used as zinc gluconate or zinc acetate lozenges for treating the common cold, and therefore the safety of usage at about 100 mg/day level is a relevant question. Unlike iron, the elimination of zinc is concentration-dependent.
=== Electricity and Wi-Fi === In August 2002, Starbucks provided free Wi-Fi in the United Kingdom, although in the past, a Starbucks rewards card was required. On July 1, 2010, Starbucks offered free Wi-Fi in all of its stores in the U.S. and Canada. In August 2010, Starbucks began offering free Wi-Fi in Germany via BT Openzone. In October 2012, Starbucks and Duracell Powermat announced a pilot program to install Powermat charging surfaces in the tabletops in selected Starbucks stores in the Boston area. Furthermore, Starbucks announced its support in the Power Matters Alliance (PMA) and its membership in the PMA board, along with Google and AT&T, in an effort to create "a real-world ecosystem of wireless power" through a universal wireless charging standard that customers could use to recharge smartphones. In 2013, it switched providers in the U.S. from AT&T to Google. In August 2016, startup company FluxPort introduced Qi inductive charging pads at select locations in Germany.
They have a similar consistency and, in their raw form, have a similar texture but a sweeter, nuttier flavor. When raw and sliced thinly, they are fit for a salad. Their inulin form of carbohydrates give the tubers a tendency to become soft and mushy if boiled, but they retain their texture better when steamed. The inulin cannot be broken down by the human digestive system but bacteria metabolize it in the colon. This can cause flatulence and, in some cases, gastric pain. John Gerard's Herbal, printed in 1621, quotes the English botanist John Goodyer on Jerusalem artichokes:
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.