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Peptide Identity And Structure — Worked Examples

By Editorial Desk · published 2026-05-07 · last reviewed 2026-06-15 · Wiki

Selank raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.

Reviewed 2026-06-15. Anything still debated is marked as such rather than presented as settled.

Peptide Identity and Structure

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.

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.

Selank Origin and Chemical Identity

Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.

Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.

Selank at a glance

PropertyValueNotes
Peptide sequenceThr-Lys-Pro-Arg-Pro-Gly-ProSeven residues; tuftsin plus a Pro-Gly-Pro tail
Molecular formulaC33H57N11O9Commonly reported value for the free peptide
Monoisotopic massRoughly 751.4 DaAverage molecular mass near 751.9 Da
AppearanceWhite to off-white powderTypically supplied as a lyophilized solid
Solubility classFreely soluble in waterAlso dissolves in saline and other polar solvents

Selank Handling, Stability, and Analysis

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.

Related pages on this site

Background and Molecular Identity

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.

Stability, Handling, and Analytical Control

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.

Administration, Testing and Availability

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.

Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.

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.

Reference notes

in-frame 1. (of a gene or sequence) Read or transcribed in the same reading frame as another gene or sequence; not requiring a shift in reading frame to be intelligible or to result in a functional peptide. 2. (of a mutation) Not causing a frameshift.

In November 1965, when asked to comment by Time after the number of Americans killed in Vietnam passed 1,000, Kissinger praised Johnson for having to make "difficult and lonely decisions". Kissinger compared Johnson to the sheriff played by Gary Cooper in the 1952 film High Noon, depicting Johnson as a heroic figure making necessary, but unpopular decisions. In a 1967 peace initiative, he would mediate between Washington and Hanoi. In June 1967, at an academic conference in Paris, Kissinger met a French biologist, Herbert Marcovitch, who mentioned that one of his friends was Raymond Aubrac, a Communist hero of the French resistance, who in turn was one of the few Westerners who were friends with Ho Chi Minh. Ho had something of an aversion to Westerners and tried to avoid meeting them as much as possible, and Aubrac was unique in being allowed to correspond with Ho. Wanting to play a role in diplomacy, Kissinger contacted the State Department with a plan for Marovitch and Aubrac to go to Hanoi with a peace offer. The Secretary of State, Dean Rusk, was opposed to Kissinger's plan. However, W. Averell Harriman of the "peace shop" was interested and got President Johnson to approve the approach, which was code-named Operation Pennsylvania. In July 1967, Aubrac and Marcovitch went to Hanoi to see Ho, who told him that he was willing to open peace talks with the United States, provided that the Americans "unconditionally" stopped bombing North Vietnam.

In the 1700s, ivory dentures were developed from walrus, elephant or hippopotamus tusks. Alexis Duchateu crafted the first porcelain dentures in 1770. These were prone to cracking and appeared too white to be natural teeth. Duchateus was a pharmacist, since Denturist, as an occupation was yet to be established. In the 1800s, the incidence of dental decay and tooth loss began to increase rapidly. The industrialisation period meant the consumption of sugar among British citizens increased by 500 percent. A need for an alternative form of dentures was needed. In 1815, the Battle of Waterloo gave rise to the highly demanded "Waterloo teeth". These were dentures crafted primarily from the teeth of dead soldiers seated in a base of animal ivory. Waterloo dentures gave the appearance of natural teeth and were not as prone to breakage as porcelain dentures. In 1820, Claudius Ash was given the task of crafting a new and improved form of dentures. Ash was a silversmith and goldsmith. He constructed porcelain on 18-karat gold plates. The springs that held the dentures together were also made of gold. Dentures that were previously made from natural teeth or porcelain were both aesthetically and functionally inferior in comparison to Ash's design. In the 1850s, Ash and his company developed Vulcanite (hardened rubber that seated porcelain teeth). His company was the leading supplier of this form of dentures in Europe. Charles Goodyear was awarded the patent for Vulcanite-based dentures in 1851. Dentures, at the time, were primarily focused on aesthetics.

== Contraindications == Benzodiazepines require special precaution if used in the elderly, during pregnancy, in children, alcohol or drug-dependent individuals and individuals with comorbid psychiatric disorders. Phenazepam should not be taken with alcohol or any other CNS depressants. Phenazepam should not be used therapeutically for periods of longer than one month including tapering on and off the drug as recommended for any benzodiazepine in the British national formulary. Some patients may require longer term treatment. Phenazepam was found to be a component in some "herbal incense" mixtures in Australia and New Zealand in 2011, namely "Kronic". The particular product variety was withdrawn from the market shortly after and replaced with a new formulation.

=== Excessive sleepiness === Selegiline has been evaluated for the treatment of narcolepsy in three small clinical studies. It was found to be effective in these studies. A dosage of 10 mg/day had no effect on symptoms, but 20 to 30 mg/day improved alertness, mood, and somewhat reduced cataplexy, clinical effects that have been described as comparable to the same dosages of amphetamine. Animal research indicates that the beneficial effects of high doses of selegiline in narcolepsy are likely due to conversion into its active metabolites, levoamphetamine and levomethamphetamine. Selegiline has also been evaluated for treatment of hypersomnia (excessive sleeping or sleepiness) in people with myotonic dystrophy, but its effectiveness was very uncertain.

Sources: en.wikipedia.org

Notes from published material

=== The Buck Institute for Research on Aging === In November 2016, Verdin became president and CEO of the Buck Institute for Research on Aging. The Buck Institute is the first independent research center focused solely on aging. As of 2022, it had an operating budget of $65 million a year and around 300 employees. The Buck's first human clinical trial, Buck Institute Ketone Ester (BIKE), was announced in 2023. In 2025, Verdin was named a scientific ambassador for Alliance for Longevity Science, Arts & Entertainment (ALSAE), a partner organization of the Buck Institute.

Nidanas 1, 2 and 3 which cast beings downward into the whirl of transmigration Nidanas 4 to 7 represent what undergoes transmigration, "the aspects of the person undergoing phenomenal life" (Wayman). Nidanas 8, 9, 10 produce new karma Nidanas 11 and 12 are the fruits or results of karma produced previously According to Gombrich, the "contorted" three lives interpretation is rendered unnecessary by the analysis provided by Jurewicz and other scholars which show that the 12 link chain is a composite list.

== Adverse effects == The most common adverse side effects of clonidine are dry mouth and sedation. Many side effects are dose-related and tend to diminish with tolerance that develops from continued use. For the same reason that clonidine has efficacy for treating hypertension, hypotension (i.e., low blood pressure) and bradycardia (i.e., slow heart rate) are predictable dose-dependent effects. However, with overdose in children, the degree of central nervous system depression does not clearly correlate with the ingested dose.

==== Host genetic factors ==== The organism that is the target of an infecting action of a specific infectious agent is called the host. The host harboring an agent that is in a mature or sexually active stage phase is called the definitive host. The intermediate host comes in contact during the larvae stage. A host can be anything living and can attain to asexual and sexual reproduction. The clearance of the pathogens, either treatment-induced or spontaneous, can be influenced by the genetic variants carried by individual patients. For instance, for genotype 1 hepatitis C treated with Pegylated interferon-alpha-2a or Pegylated interferon-alpha-2b (brand names Pegasys or PEG-Intron) combined with ribavirin, it has been shown that genetic polymorphisms near the human IL28B gene, encoding interferon lambda 3, are associated with significant differences in the treatment-induced clearance of the virus. This finding, originally reported in Nature, showed that genotype 1 hepatitis C patients carrying certain genetic variant alleles near the IL28B gene are more likely to achieve a sustained virological response after treatment than others. Later report from Nature demonstrated that the same genetic variants are also associated with the natural clearance of the genotype 1 hepatitis C virus.

During the many years I spent on the Left, the cause of self-determination for Kurdistan was high on the list of principles and priorities – there are many more Kurds than there are Palestinians and they have been staunch fighters for democracy in the region. He also wore a lapel pin with the flag of Kurdistan on it, to show his solidarity with the Kurds.

Sources: en.wikipedia.org

Further detail

The Journal of Psychiatric Research is a monthly peer-reviewed medical journal covering research in four major areas of psychiatry: clinical studies on normal and pathological human behavior; basic studies in psychiatry and related fields; clinical laboratory techniques such as neuroimaging, spectroscopy and other computer techniques used in research; advances in research methodology, including the clinical use of recent research findings. The journal was established in 1961 and is published by Elsevier. The current editor-in-chief is Eric Hollander (Albert Einstein College of Medicine). According to the Journal Citation Reports, the journal has a 2015 impact factor of 4.465.

== Further reading == López-Alonso, JP; Diez-Garcia, F; Font, J; Ribó, M; Vilanova, M; Scholtz, JM; González, C; Vottariello, F; Gotte, G; Libonati, M; Laurents, DV (2009). "Carbodiimide EDC Induces Cross-Links That Stabilize RNase A C-dimer against Dissociation: EDC Adducts Can Affect Protein Net Charge, Conformation and Activity". Bioconjugate Chemistry. 20 (8): 1459–1473. doi:10.1021/bc9001486. PMID 19606852. Nakajima, N; Ikada, Y (1995). "Mechanism of Amide Formation by Carbodiimide for Bioconjugation in Aqueous Media". Bioconjugate Chemistry. 6 (1): 123–130. doi:10.1021/bc00031a015. PMID 7711098.

For biomedical research purposes, atherosclerosis has been defined as the presence of atherosclerotic lesions in the coronary arteries, carotid arteries, cerebral arteries, limb arteries, or other vessels. The definitions of the different histological types of atheromatous plaques are also well-established. In the clinical practice of medicine, as well as in the field of epidemiology, the widely agreed upon diagnostic criteria for atherosclerosis are those for the diseases resulting from atherosclerosis, including atherosclerotic cardiovascular disease and peripheral artery disease. In recent years, developments in nuclear imaging techniques such as PET and SPECT have provided non-invasive methods of estimating the severity of atherosclerotic plaques.

== Technological achievements == In addition to being credited with the development of one of the first anti-virus programs, "Vaccine", Tippett pioneered and commercialized a string of now-common technologies including what is now called the "Recovery Disk," processor image signatures, using hash-tables for trusted file execution and anomaly detection, aspects of mail merge and "un-do." He ran a bulletin board system for CP/M software before the first IBM PC was created and was president of the Cleveland Osborne Group (a user group for the computers of the Osborne Computer Corporation) in the early 1980s. As chief scientist for ICSA.net, Tippett was one of a handful of experts to identify and address the ILOVEYOU virus that broke in May 2000 and provided key information to the Department of Justice about David Smith, the writer of the Melissa virus. He was featured on the cover of the August 2000 issue of Time Digital magazine.

Sources: en.wikipedia.org

Frequently asked questions

What is the primary sequence of Selank?

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.

Is Selank found naturally in the body?

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.

Why does the peptide contain three proline residues?

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.

What is Selank?

Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.

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