A practical reference on mass spectrometry: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-06-05 and is reviewed periodically as new material appears.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by RP-HPLC | Area percentage of the main peak |
| Identity confirmation | Electrospray ionization mass spectrometry | Observed mass compared with the theoretical value near 751.9 Da |
| Recommended dry storage | -20 °C, desiccated | -80 °C for multi-year archival material |
| Solution handling | Prepare fresh; avoid long storage | Sterile filtration reduces microbial load |
| Common synonyms | TKPRPGP; TP-7 | Sequence code and laboratory designation used interchangeably |
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.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical 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.
Soluble gas neurotransmitters are difficult to study because they act rapidly and are immediately broken down, existing for only a few seconds. The most prevalent transmitter is glutamate, which is excitatory at well over 90% of the synapses in the human brain. The next most prevalent is gamma-Aminobutyric Acid, or GABA, which is inhibitory at more than 90% of the synapses that do not use glutamate. Although other transmitters are used in fewer synapses, they may be very important functionally: the great majority of psychoactive drugs exert their effects by altering the actions of some neurotransmitter systems, often acting through transmitters other than glutamate or GABA. Addictive drugs such as cocaine and amphetamines exert their effects primarily on the dopamine system. The addictive opiate drugs act primarily as functional analogs of opioid peptides, which, in turn, regulate dopamine levels.
{\displaystyle {\begin{aligned}{\frac {D\omega _{i}}{Dt}}&={\frac {\partial \omega _{i}}{\partial t}}+v_{j}{\frac {\partial \omega _{i}}{\partial x_{j}}}\\&=\omega _{j}{\frac {\partial v_{i}}{\partial x_{j}}}-\omega _{i}{\frac {\partial v_{j}}{\partial x_{j}}}+e_{ijk}{\frac {1}{\rho ^{2}}}{\frac {\partial \rho }{\partial x_{j}}}{\frac {\partial p}{\partial x_{k}}}+e_{ijk}{\frac {\partial }{\partial x_{j}}}\left({\frac {1}{\rho }}{\frac {\partial \tau _{km}}{\partial x_{m}}}\right)+e_{ijk}{\frac {\partial B_{k}}{\partial x_{j}}}\end{aligned}}}
== New York Giants == The New York Giants Fearsome Foursome consisting of ends Andy Robustelli and Jim Katcavage, and tackles Rosey Grier and Dick Modzelewski, first played together on the Giants 1956 NFL Championship Team. They were considered pioneers in inaugurating a defensive era in professional football. The Giants' Fearsome Foursome broke up as a group before the start of the 1963 season, when the Giants traded Grier to the Los Angeles Rams for John LoVetere. Other than during Grier's Army service in 1957, and a period of injury for Katcavage at the end of the 1960 season, the four played together in every minute of every game from 1956 to 1962. Robustelli is in the Pro Football Hall of Fame. In addition to winning the championship in 1956, the Giants went to four other NFL championship games, losing to the Baltimore Colts in 1958 (known as "the Greatest Game Ever Played"), and 1959 and the Green Bay Packers in 1961 and 1962. They were "largely responsible" for the Giants' success during these years. In the 1957 season the New York Daily News, a major New York city tabloid, ran an article and sketches of the New York Giants' line consisting of ends Andy Robustelli and Jim Katcavage, and tackles Rosey Grier and Dick Modzelewski and a headline that read "A Fearsome Foursome." They were known as the Fearsome Foursome by at least 1959, supported by an actual photograph of the four.
== Diagnosis == The diagnosis of androgenic alopecia can usually be established based on clinical presentation in men. In women, the diagnosis usually requires a more complex diagnostic evaluation. Further evaluation of the differential requires exclusion of other causes of hair loss, and assessing for the typical progressive hair loss pattern of androgenic alopecia. Trichoscopy can be used for further evaluation. Biopsy may be needed to exclude other causes of hair loss, and histology would demonstrate perifollicular fibrosis. The Hamilton–Norwood scale has been developed to grade androgenic alopecia in males by severity.
== Medical uses == Several treatment guidelines recommend adding ezetimibe in select high-risk persons in whom LDL goals cannot be achieved by maximally tolerated statin alone. Adding ezetimibe to statin treatment of high blood cholesterol has no effect on overall mortality or cardiovascular mortality, although it significantly reduces the risk of myocardial infarction and stroke. Combining ezetimibe with simvastatin had no effect on overall mortality but did lower the risk of heart attack or stroke in people with prior heart attack. Initiation of ezetimibe along with high-intensity statin therapy at the time of an acute coronary syndrome (ACS) event was associated with significantly better cholesterol reduction at day 7, 1-month, 3-months, and 1-year post-ACS event; which translated into significantly lower recurrent cardiovascular events (death from any cause, major ACS, non-fatal stroke, non-fatal myocardial infarction, and ischemic stroke) post the index event of ACS. Ezetimibe is indicated in the United States as an add-on to dietary measures to reduce levels of certain lipids in people with:
Sources: en.wikipedia.org
=== Sexual stimulation and arousal === The clitoris has an abundance of nerve endings, and is the human female's most erogenous part of the body. When sexually stimulated, it may incite sexual arousal, which may result from mental stimulation (sexual fantasy), activity with a sexual partner, or masturbation, and can lead to orgasm. The most effective sexual stimulation of this organ is usually manually or orally, which is often referred to as direct clitoral stimulation; in cases involving sexual penetration, these activities may also be referred to as additional or assisted clitoral stimulation. Direct stimulation involves physical stimulation to the external anatomy of the clitoris – glans, hood, and shaft. Stimulation of the labia minora, due to it being connected with the glans and hood, may have the same effect as direct clitoral stimulation. Though these areas may also receive indirect physical stimulation during sexual activity, such as when in friction with the labia majora, indirect clitoral stimulation is more commonly attributed to penile-vaginal penetration. Penile-anal penetration may also indirectly stimulate the clitoris by the shared sensory nerves (especially the pudendal nerve, which gives off the inferior anal nerves and divides into two terminal branches: the perineal nerve and the dorsal nerve of the clitoris).
=== Multiplexed DIA (plexDIA) === The progress in data independent acquisition (DIA) enabled multiplexed quantitative proteomics with non-isobaric mass tags and a new method called plexDIA introduced in 2021. This new approach increases the number of data points by parallelizing both samples and peptides, thus achieving multiplicative gains. It has the potential to continue scaling proteomic throughput with new mass tags and algorithms. plexDIA is applicable to both bulk and single-cell samples and is particularly powerful for single-cell proteomics.
Protesters chanted slogans against "federalism" and demanded "full independence" for Syria, with slogans praising Hikmat al-Hijri. On 23 August, the National Guard was formed, with the aim of consolidating military efforts to confront what it described as "Salafist-jihadist gangs", with large military groups such as Anti-Terrorism Force, Al-Jabal Brigade, Sheikh al-Karama Forces, the As-Suwayda Operations Room, Al-Fahd Forces, with small groups, and the Jaysh al-Muwahhidin included. On 25 August, according to Enab Baladi, other groups that later joined include "Men of Dignity, the Unitarian Popular Resistance, Southern Shield Forces, Mountain Shield Forces, Lions of the Mountain Forces, Shield of Tawhid, Sahwat al-Khedr Shield, Mimas and Tal al-Lawz, Men of al-Lajat and Men of al-Kafr", while 164th Brigade joined on 24 August, and the Suwayda Military Council joined on 27 August.
The evolutionary adaptation from primary to secondary vascular tissues demonstrates how this monocot developed its tree-like form, combining water conservation through its dense crown with structural stability from its specialized stem growth. These features collectively enable the species to thrive in challenging high-altitude, arid conditions where few other trees can survive.
=== Migraine prophylaxis === Candesartan may be helpful in migraine prevention as it has better tolerability and fewer side effects compared to other first line medications. It has been recommended by multiple guidelines for migraine prophylaxis in adults with different levels of recommendations, however further studies on larger populations are needed.
Sources: en.wikipedia.org
=== General election 2005 === After the 2004 European Parliamentary election results became known, in which Galloway stood in London, but did not gain a seat, he announced that he would stand in East London at the next general election. On 2 December, he confirmed that he was aiming to be nominated as the Respect Party candidate for Bethnal Green and Bow. The ensuing electoral campaign in the seat proved to be a difficult one with heated exchanges between Galloway, Oona King (the incumbent Labour MP for Bethnal Green and Bow), and their respective supporters. Galloway and Respect threatened to sue King, whose mother is Jewish, if she repeated her assertion in the Evening Standard on 10 April 2005 which reported her as saying: "I have been told by several people that members of Respect have told Muslim voters 'not to vote for me because I am Jewish'". A major issue of the campaign was King's support for the Iraq War. Galloway was asked at a hustings early in the campaign why he was standing against one of only two black female MPs to which he replied that King had "voted to kill a lot of women in the last few years. Many of them had much darker skins than her". Claiming to be the ghost of Old Labour, Galloway told The Sunday Times contributor A. A. Gill that "we're here to haunt new Labour". Bethnal Green and Bow is "where Labour was founded. We're giving birth to the Labour Party all over again". Galloway said at a hustings event that the Labour Government had been pursuing a "war on Muslims" while King said her stance against Saddam Hussein had been "principled".
=== Spare receptors === In some receptor systems (e.g. acetylcholine at the neuromuscular junction in smooth muscle), agonists are able to elicit maximal response at very low levels of receptor occupancy (<1%). Thus, that system has spare receptors or a receptor reserve. This arrangement produces an economy of neurotransmitter production and release.
=== Other drug targets === Other known targets of dapansutrile include several phosphorylated kinases such as Src; Fyn; HcK; STAT3. Human monocyte derived macrophages (HMDM) cells were stimulated with lipopolysaccharide, and nigericin. Dapansutrile was then added and they found a 26%, 35%, 43% and 33% reduction of these phosphorylated kinases respectively.
PABA is an intermediate in the synthesis of folate by bacteria, plants, and fungi. Many bacteria, including those found in the human intestinal tract such as E. coli, generate PABA from chorismate by the combined action of the enzymes 4-amino-4-deoxychorismate synthase and 4-amino-4-deoxychorismate lyase. Plants produce PABA in their chloroplasts, and store it as a glucose ester (pABA-Glc) in their tissues. The malarial protozoan Plasmodium only make PABA when necessary, preferring to get it from the surroundings if able to. Some bacteria, including a few found in the human microbiome, are unable to make PABA for themselves but can use PABA to make folate. A few are very efficient at the PABA-to-folate conversion despite not making their own PABA. Sulfonamide drugs are structurally similar to PABA, and their antibacterial activity is due to their ability to interfere with the conversion of PABA to folate by the enzyme dihydropteroate synthetase. Thus, bacterial growth is limited through folate deficiency.
Sources: en.wikipedia.org
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.
A reported purity value reflects the share of the main peak in one chromatographic run and says nothing about identity. Confirming that the expected sequence is present requires a separate measurement such as mass spectrometry. Purity and identity are distinct questions.
A mass spectrum reports the molecular masses present in a sample and shows whether they match the value expected for selank, near 751.9 Da. It also flags common artifacts such as truncation or adduct formation. It does not establish correct stereochemistry or complete sequence order on its own.
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.