This is a working overview of Selank, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-07-04. Anything still debated is marked as such rather than presented as settled.
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.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
| 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 |
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.
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.
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.
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.
== Interleukin antagonists == Interleukins are a cytokine that play a major role in the immune system. IL-12 and IL-23 help with the activation and differentiation of natural killer cells and CD4+ T lymphocyte, both of which contribute to inflammation. Interleukin antagonists, the most recent class of biologics available for use in IBD, inhibit the action of IL-12 and IL-23 by binding to the p40 protein subunit that is found on both of these cytokines.
=== Children === The infant lamina propria is composed of only one layer, as compared to three in the adult, and there is no vocal ligament. The vocal ligament begins to be present in children at about four years of age. Two layers appear in the lamina propria between the ages of six and twelve, and the mature lamina propria, with the superficial, intermediate and deep layers, is only present by the conclusion of adolescence. As vocal fold vibration is a foundation for vocal formants, this presence or absence of tissue layers influences a difference in the number of formants between the adult and pediatric populations. In females, the voice is three tones lower than the child's and has five to twelve formants, as opposed to the pediatric voice with three to six. The length of the vocal fold at birth is approximately six to eight millimeters and grows to its adult length of eight to sixteen millimeters by adolescence. The infant vocal fold is half membranous or anterior glottis, and half cartilaginous or posterior glottis. The adult fold is approximately three-fifths membranous and two-fifths cartilaginous.
=== Aging and obesity === NF-κB is increasingly expressed with obesity and aging, resulting in reduced levels of the anti-inflammatory, pro-autophagy, anti-insulin resistance protein sirtuin 1. NF-κB increases the levels of the microRNA miR-34a, which inhibits nicotinamide adenine dinucleotide (NAD) synthesis by binding to its promoter region, resulting in lower levels of sirtuin 1. NF-κB and interleukin 1 alpha mutually induce each other in senescent cells in a positive feedback loop causing the production of senescence-associated secretory phenotype (SASP) factors. NF-κB and the NAD-degrading enzyme CD38 also mutually induce each other. NF-κB is a central component of the cellular response to damage. NF-κB is activated in a variety of cell types that undergo normal or accelerated aging. Genetic or pharmacologic inhibition of NF-κB activation can delay the onset of numerous aging related symptoms and pathologies. This effect may be explained, in part, by the finding that reduction of NF-κB reduces the production of mitochondria-derived reactive oxygen species that can damage DNA.
==== Addiction ==== Arguably, some people pursue ineffective shortcuts to feeling good. These shortcuts create positive feelings, but are problematic, in part because of the lack of effort involved. Some examples of these shortcuts include shopping, drugs, chocolate, loveless sex, and TV. These are problematic pursuits because all of these examples have the ability to become addictive. When happiness comes to us so easily, it comes with a price we may not realize. This price comes when taking these shortcuts is the only way to become happy, otherwise viewed as an addiction. A review by Amy Krentzman on the Application of Positive Psychology to Substance Use, Addiction, and Recovery Research, identified, in the field of positive psychology, three domains that allow an individual to thrive and contribute to society. One of these, A Pleasant Life, involves good feelings about the past, present, and future. To tie this with addiction, they chose an example of alcoholism. Research on positive affect and alcohol showed a majority of the population associates drinking with pleasure. The pleasure one feels from alcohol is known as somatic pleasure, which is immediate but a short lived sensory delight. The researchers wanted to make clear pleasure alone does not amount to a life well lived; there is more to life than pleasure. Secondly, the Engaged Life is associated with positive traits such as strength of character.
Sources: en.wikipedia.org
C in order to vaporize the entering solvent and create dopant molecules. Dopant molecules are added to help facilitate the ionization of the sample. Some of the common solvents include: nitrogen, toluene, acetone, and anisole. The desorption process can occur by two mechanisms: thermal desorption or momentum transfer/liquid spray. Thermal desorption uses heat to volatilize the sample and increase the surface temperature of the substrate. As the substrate's surface temperature is increased, the higher the sensitivity of the instrument. While studying the substrate temperature, it was seen that the solvent did not have a noticeable effect on the final temperature or heat rate of the substrate. Momentum transfer or liquid spray desorption is based on the solvent interaction with the sample, causing the release of specific ions. The momentum transfer is propagated by the collision of the solvent with the sample along with the transfer of ions with the sample. The transfer of positive ions, such as protons and charge transfers, are seen with the solvents: toluene and anisole. Toluene goes through a charge exchange mechanism with the sample, while acetone promotes a proton transfer mechanism with the sample. A beam of 10 eV photons that are given off by a UV lamp is directed at the newly desorbed molecules, as well as the dopant molecules. Photoionization then occurs, which knocks out the molecule's electron and produces an ion. This technique alone is not highly efficient for different varieties of molecules, particularly those that are not easily protonated or deprotonated.
Righthanded β-helices, typified by the pectate lyase enzyme shown at left or P22 phage tailspike protein, have a less regular cross-section, longer and indented on one of the sides; of the three linker loops, one is consistently just two residues long and the others are variable, often elaborated to form a binding or active site. A two-sided β-helix (right-handed) is found in some bacterial metalloproteases; its two loops are each six residues long and bind stabilizing calcium ions to maintain the integrity of the structure, using the backbone and the Asp side chain oxygens of a GGXGXD sequence motif. This fold is called a β-roll in the SCOP classification.
Prior to founding the Center for Biomedical Mass Spectrometry at Boston University School of Medicine in 1994, Costello was a senior research scientist and the associate director of the National Institutes of Health Research Resource for Mass Spectrometry at Massachusetts Institute of Technology for 20 years. She is a William Fairfield Warren Distinguished Professor and the director of the Center for Biomedical Mass Spectrometry at the Boston University School of Medicine. Costello served as the president of the American Society for Mass Spectrometry (2002–2004), the Human Proteome Organization (2011–2012), and the International Mass Spectrometry Foundation (2014–2018). She currently serves on the board of directors of the US Human Proteome Organization, and the editorial board of Clinical Proteomics.
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.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.