The short version of mass spectrometry fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-07-09 and is reviewed periodically as new material appears.
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.
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.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
| 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 |
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
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.
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.
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.
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.
== Causes == Mitochondrial disorders may be caused by mutations (acquired or inherited), in mitochondrial DNA (mtDNA), or in nuclear genes that code for mitochondrial components. They may also be the result of acquired mitochondrial dysfunction due to adverse effects of drugs, infections, or other environmental causes.
Charles Jerrard. For services to the British Limbless Ex-Service Men's Association in Romford, Essex. Andy Derrick Johnson, Section Leader, Mathematics and Technology Department, Southwark College, London. For services to Education. George Refoy Johnston, Vice Chairman, Eildon Housing Association. For services to Housing. Samuel Hans Johnston, Process and General Supervisory Grade D, Ministry of Defence. Carol Theresa Jones, lately Senior Personal Secretary, the Highways Agency, Department of Transport. David Charles Newhams Jones, lately Journalist, Ashton Reporter. For services to Journalism in Lancashire. David Lloyd Jones, lately Chief Executive, Arfon Borough Council. For services to Local Government. Howard Leslie Jones, Maintenance Technician, Stanlow Manufacturing Complex, Shell UK Ltd. For services to Health and Safety. Ivy Jones. For services to the community in Tayside. Janice Jones. For services to the community, particularly Young Children, in Adamsdown, Cardiff. Robert Meinon Jones. For services to Choral Music in the District of Ffestiniog, Gwynedd. Lieutenant Colonel Robert Ian Hywel-Jones, , Senior Executive Officer, Foreign and Commonwealth Office. Trevor Mostyn Jones. For services to the Environment in North East England. Vera Daisy Jones. For political and public service. Wendy Keene. For political service. Eileen Grace Kelly. For services to the community in Pulborough, West Sussex. Donald Fraser Kennedy, Honorary Chairman, Dalneigh Senior Citizen's Club. For services to Elderly People in Inverness. Richard Leighton Keys.
== Overview == The series focuses on Olivia Pope and her crisis management firm, Olivia Pope & Associates, and its staff, as well as staff at the White House in Washington D.C. as political scandals occur and they must try to deal with them.
The legislative branch of government is a unicameral legislative assembly, whose tenure is five years. The legislative assembly may make laws for any of the matters in the State List of the Constitution of India except "public order" and "police", which will remain the preserve of the central Government of India. The Lieutenant Governor also has the power to promulgate ordinances which have the same force as the acts of the legislative assembly. Elections for the Jammu and Kashmir Legislative Assembly were held in September and October 2024.
Mining of an active deep sea hydrothermal vent ecosystem would depend on the recolonization of chemosynthetic bacteria, and therefore the continuation of the hydrothermal vent fluid as it is the main hydrothermal energy source. It is very difficult to get an idea of the effects of mining on the hydrothermal vent fluid because there have been no large scale studies done. However, there have been studies on the recolonization of these vent ecosystems after volcanic destruction. From these we can develop insight on the potential effects of mining destruction, and have learned it took 3–5 years for bacteria to recolonize the area, and around 10 years for megafauna to return. It was also found that there was a shift in the composition of species in the ecosystem compared to before the destruction, and the presence of immigrant species. This shift in biodiversity poses issues to certain critically endangered species that thrive in harsh deep sea environment, like mollusks. Though further research into the effects of sustained seafloor SMS mining on species recolonization is needed. Shallow hydrothermal vents have also been proposed as a potential model for climate change in extreme environments, specifically by tracking changes to highly specialized organisms local to the vent. Major impacts of climate change such as ocean acidification, increasing temperature and heavy metal deposition, on local hydrothermal vent ecosystems are areas of interest for these models. Deep sea mining's impact on efficacy of these models is an area of future interest.
Sources: en.wikipedia.org
== Curtius rearrangement == The Bergmann degradation makes use of the azide degradation described by the Curtius rearrangement. Curtius also attempted to degrade benzoylated amino acids; however, his method involved splitting the carbamate with strongly energetic treatment with acids, which lead to decomposition of the resultant aldehyde and acid amides. This convinced Bergmann that Curtius' azide degradation could be followed by treatment with benzyl alcohol (his carbobenzoxy method) to isolate the resultant amino acid aldehyde and residual peptide amide for sequencing purposes.
In 1908, King Carlos I and Luís Filipe, Prince Royal, were assassinated by republican partisans. In 1910, the monarchy was replaced with a republic. During World War I, Portugal fought for the Allies. The war increased political instability and deepened the economic crisis creating further chaos and unrest during the First Republic. These conditions led to the overthrow of the Republic in 1926 and the establishment of the Ditadura Militar, later the Ditadura Nacional, which evolved into the authoritarian nationalist corporative dictatorship of the Estado Novo, under António de Oliveira Salazar. During the Estado Novo, Portugal remained neutral in World War II, after which the postwar end of colonial legitimacy and the growth of the existing independence movements, rooted in the Great Depression, increasingly challenged Portuguese rule overseas. From the 1940s onward, the regime tightened control over colonial affairs and expanded overseas administration, increasing costs and delaying inefficient development programmes. It maintained a fragmented economic and customs empire that favored the metropole. The regime retained policies intended to preserve the colonies such as forced labour until 1961 and settlement schemes that served metropolitan economic, social and strategic purposes. Indigenous peoples, already second-class citizens, saw limited improvements in living conditions. This further fuelled nationalist movements, ultimately leading to the Portuguese Colonial War from 1961 to 1974.
== Questionable techniques == Some forensic techniques, believed to be scientifically sound at the time they were used, have turned out later to have much less scientific merit or none. Some such techniques include:
Valve enlisted Gearbox Software to develop three expansions for Half-Life: Opposing Force (1999), Blue Shift (2001) and Decay (2001). In 1998, Valve acquired TF Software, a group that had made the popular Team Fortress mod for Quake, and remade it for GoldSrc as Team Fortress Classic in 1999. Valve released the software development kit (SDK) for the GoldSrc engine, facilitating numerous user-created mods. They acquired the developers of one popular mod, Counter-Strike, to create a standalone Counter-Strike game. Happy with Valve's success, Harrington sold his stake in Valve to Newell in 2000. Valve's publishing agreement meant Sierra owned the Half-Life intellectual property and held exclusive publishing rights to future Valve games. In 2001, Valve renegotiated by threatening to cease game development and develop other software, using an offer of a partnership from Amazon to create a digital storefront as a bargaining chip. After the agreement with Sierra was amended, Valve gained the Half-Life intellectual property and online distribution rights for its games.
=== Restriction enzymes then gel electrophoresis === Restriction enzymes are first used to recognize and then cut specific nucleic acid sequences. These cut pieces of DNA can be run through a gel electrophoresis to allow diagnostics of the organism by referencing back to previous gel electrophoresis results.
Sources: en.wikipedia.org
The samples were found to be "masses of virtually pure collagen" and not to have the "biochemical characteristics of invertebrate collagen, nor the collagen fiber arrangement of octopus mantle." The results suggest the samples are "the remains of the skin of an enormous warm-blooded vertebrate." The authors conclude that "there is no evidence to support the existence of Octopus giganteus" and concur with Verrill (1897) and Lucas (1897) that the St. Augustine carcass was "the remains of a whale, likely the entire skin [blubber layer] . . . nothing more or less."
=== Biotransformation === n-Hexane is biotransformed to 2-hexanol and further to 2,5-hexanediol in the body. The conversion is catalyzed by the enzyme cytochrome P450 utilizing oxygen from air. 2,5-Hexanediol may be further oxidized to 2,5-hexanedione, which is neurotoxic and produces a polyneuropathy. In view of this behavior, replacement of n-hexane as a solvent has been discussed. n-Heptane is a possible alternative.
=== Chemical reactions === CO2 is a potent electrophile having an electrophilic reactivity that is comparable to benzaldehyde or strongly electrophilic α,β-unsaturated carbonyl compounds. However, unlike electrophiles of similar reactivity, the reactions of nucleophiles with CO2 are thermodynamically less favored and are often found to be highly reversible. The reversible reaction of carbon dioxide with amines to make carbamates is used in CO2 scrubbers and has been suggested as a possible starting point for carbon capture and storage by amine gas treating. Only very strong nucleophiles, like the carbanions provided by Grignard reagents and organolithium compounds react with CO2 to give carboxylates:
Some pregnant women and care providers choose to forgo routine screening due to the absence of risk factors; however, this is not advised due to the large proportion of women who develop gestational diabetes despite having no risk factors present and the dangers to the mother and baby if gestational diabetes remains untreated.
== Function == This gene encodes a multifunctional protein. It has two enzymatically active domains with catalytic activities - peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidyl-alpha-hydroxyglycine alpha-amidating lyase (PAL). These catalytic domains work sequentially to catalyze neuroendocrine peptides to active alpha-amidated products. The reaction pathway catalyzed by PAM is accessed via quantum tunneling and substrate preorganization. Multiple alternatively spliced transcript variants encoding different isoforms have been described for this gene, but some of their full-length sequences are not yet known. The PHM subunit effects hydroxylation of a C-terminal glycine residue:
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.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.