Everything below concerns tuftsin. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
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.
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.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
== Biological function == NADPH oxidases (NOXes) are one of the major sources of cellular reactive oxygen species (ROS), and they still are the focus of extensive research interest due to their exclusive function in producing ROS under normal physiological conditions. The NADPH oxidase complex is dormant under normal circumstances but is activated to assemble in the membranes during respiratory burst. The activated NADPH oxidase generates superoxide which has roles in animal immune response and plant signalling. Superoxide can be produced in phagosomes which have ingested bacteria and fungi, or it can be produced outside of the cell. In macrophages, superoxide kills bacteria and fungi by mechanisms that are not yet fully understood. Superoxide spontaneously dismutates to form peroxide which is then protonated to produce hydrogen peroxide. Opinions are polarised as to how the oxidase kills microbes in neutrophils. On the one hand it is thought that hydrogen peroxide acts as substrate for myeloperoxidase to produce hypochlorous acid. It may also inactivate critical metabolic enzymes, initiate lipid peroxidation, damage iron-sulphur clusters, and liberate redox-active iron, which allows the generation of indiscriminate oxidants such as the hydroxyl radical.
=== Sources === Chapple, Christopher Key (1993), Nonviolence to Animals, Earth, and Self in Asian Traditions, State University of New York Press Cort, John E., ed. (1998), Open Boundaries: Jain Communities and Cultures in Indian History, SUNY Press, ISBN 0-7914-3785-X Cort, John E. (2001a), Jains in the World: Religious Values and Ideology in India, Oxford University Press, ISBN 978-0-19-513234-2 Dundas, Paul (2002) [1992], The Jains (Second ed.), London and New York: Routledge, ISBN 978-0-415-26605-5 Jaini, Padmanabh S. (1998) [1979], The Jain Path of Purification, Delhi: Motilal Banarsidass, ISBN 978-81-208-1578-0 Laidlaw, James (1995), Riches and Renunciation. Religion, economy, and society among the Jains, Oxford, ISBN 978-0-19-828031-6 Sangave, Vilas Adinath (1980), Jain Community: A Social Survey (2nd ed.), Bombay: Popular Prakashan, ISBN 978-0-317-12346-3 Shah, Umakant Premanand (1987), Jaina-rūpa-maṇḍana: Jaina iconography, Abhinav Publications, ISBN 81-7017-208-X Vallely, Anne (2002), Guardians of the Transcendent: An Ethnography of a Jain Ascetic Community, University of Toronto Press, ISBN 978-0-8020-8415-6 Wiley, Kristi L. (2009) [1949], The A to Z of Jainism, vol. 38, Scarecrow Press, ISBN 978-0-8108-6337-8
The complete laboratory synthesis of B12 was achieved by Robert Burns Woodward and Albert Eschenmoser in 1972. The work required the effort of 91 postdoctoral fellows (mostly at Harvard) and 12 PhD students (at ETH Zurich) from 19 nations. The synthesis constitutes a formal total synthesis, since the research groups only prepared the known intermediate cobyric acid, whose chemical conversion to vitamin B12 was previously reported. This synthesis of vitamin B12 is of no practical consequence due to its length, taking 72 chemical steps and giving an overall chemical yield well under 0.01%. Although there have been sporadic synthetic efforts since 1972, the Eschenmoser–Woodward synthesis remains the only completed (formal) total synthesis.
Sources: en.wikipedia.org
{\displaystyle {\begin{aligned}\sigma _{xx}&=-{\frac {2P}{\pi }}{\frac {x^{2}z}{\left(x^{2}+z^{2}\right)^{2}}}\\\sigma _{zz}&=-{\frac {2P}{\pi }}{\frac {z^{3}}{\left(x^{2}+z^{2}\right)^{2}}}\\\sigma _{xz}&=-{\frac {2P}{\pi }}{\frac {xz^{2}}{\left(x^{2}+z^{2}\right)^{2}}}\end{aligned}}}
Albany ( AL-bə-nee) is a city in and the county seat of Linn County, Oregon, and is the 11th most populous city in the state. Albany is located in the Willamette Valley at the confluence of the Calapooia River and the Willamette River in both Linn and Benton counties, just east of Corvallis and south of Salem. It is predominantly a farming and manufacturing city that settlers founded around 1848. As of the 2020 United States census, the population of Albany, Oregon was 56,472. Albany has a home rule charter, a council–manager government, and a full-time unelected city manager. The city provides the population with access to over 30 parks and trails, a senior center, and many cultural events such as the Northwest Art & Air Festival, River Rhythms, Summer Sounds and Movies at Monteith. In addition to farming and manufacturing, the city's economy depends on retail trade, health care, and social assistance. In recent years the city has worked to revive the downtown shopping area, with help from the Central Albany Revitalization Area.
Nickel is a silvery-white metal with a slight golden tinge that takes a high polish. It is one of only four elements that are ferromagnetic at or near room temperature; the others are iron, cobalt and gadolinium. Its Curie temperature is 355 °C (671 °F), meaning that bulk nickel is non-magnetic above this temperature. The unit cell of nickel is a face-centered cube; it has lattice parameter of 0.352 nm, giving an atomic radius of 0.124 nm. This crystal structure is stable to pressures of at least 70 GPa. Nickel is hard, malleable and ductile, and has a relatively high electrical and thermal conductivity for transition metals. The high compressive strength of 34 GPa, predicted for ideal crystals, is never obtained in the real bulk material due to formation and movement of dislocations. However, it has been reached in Ni nanoparticles.
Sources: en.wikipedia.org
The South African government was angered by this escalation of the war, and withdrew its military and diplomatic support for the Rhodesian regime. Pressure from South Africa led Prime Minister Smith to accept the principle of black majority rule in Rhodesia in September 1976. The Selous Scouts unsuccessfully attempted to assassinate Joshua Nkomo, the leader of ZIPRA, while he was in Zambia. While the attacks made outside of Rhodesia by the Selous Scouts were usually militarily successful, they worsened the country's political position. This was because they resulted in civilians and members of the armed forces in the neighbouring countries being killed.
=== Solar cells === Selenium was used as the photoabsorbing layer in the first solid-state solar cell, which was demonstrated by the English physicist William Grylls Adams and his student Richard Evans Day in 1876. Only a few years later, Charles Fritts fabricated the first thin-film solar cell, also using selenium as the photoabsorber. As silicon solar cells emerged in the 1950s, research on selenium thin-film solar cells declined. The record efficiency of 5.0% demonstrated by Tokio Nakada and Akio Kunioka in 1985 remained unchanged for more than 30 years. In 2017, researchers from IBM achieved a new record efficiency of 6.5% by redesigning the device structure. Following this achievement, selenium has gained renewed interest as a wide bandgap photoabsorber with the potential of being integrated in tandem with lower bandgap photoabsorbers. In 2024, the first selenium-based tandem solar cell was demonstrated, showcasing a selenium top cell monolithically integrated with a silicon bottom cell. A significant deficit in the open-circuit voltage is currently the limiting factor to further improve the efficiency, necessitating defect-engineering strategies for selenium thin-films to enhance the carrier lifetime. Recent theoretical studies using first-principles defect calculations have shown that selenium exhibits intrinsic point defect tolerance, suggesting that interfaces and extended defects are the primary factors limiting device performance.
=== Trypsin-like === Trypsin-like proteases cleave peptide bonds following a positively charged amino acid (lysine or arginine). This specificity is driven by the residue which lies at the base of the enzyme's S1 pocket (generally a negatively charged aspartic acid or glutamic acid).
Sources: en.wikipedia.org
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.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
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.