A practical reference on Pro-Gly-Pro: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-03-15. 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.
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.
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.
| 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 |
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.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Acemetacin acts as an inhibitor of cyclooxygenase (COX), producing the anti-inflammatory and analgetic (pain relieving) effects. In the body, it is partly metabolized to indomethacin, which also acts as a COX inhibitor. The same mechanism is responsible for the antipyretic and antiplatelet effects, which are however not clinically used, as well as for the typical NSAID adverse effects. An advantage of acemetacin is that it reduces gastric damage as compared to indometacin, possibly because acemetacin has less effect on the increase of leukotriene B4 synthesis and tumor necrosis factor (TNF) expression, leading to less induction of leukocyte-endothelial adherence.
=== Immigration === In April 2022, Schmitt repeated a Great Replacement–derived claim on Glenn Beck's program that the Democratic Party seeks to "fundamentally" change the country through illegal immigration to the United States. In a September 2025 speech, Schmitt criticized both legal and illegal immigration to the United States.
== Importance == Many urine tests (urinalysis) monitor the amount of urobilin in urine, as its levels can give insight on the effectiveness of urinary tract function. Normally, urine would appear as either light yellow or colorless. A lack of water intake, for example following sleep or dehydration, reduces the water content of urine, thereby concentrating urobilin and producing a darker color of urine. Obstructive jaundice reduces biliary bilirubin excretion, which is then excreted directly from the blood stream into the urine, giving a dark-colored urine but with a paradoxically low urobilin concentration, no urobilinogen, and usually with correspondingly pale faeces. Darker urine can also be due to other chemicals, such as various ingested dietary components or drugs, porphyrins in patients with porphyria, and homogentisate in patients with alkaptonuria.
=== Eating === The weakness of the muscles involved in swallowing may lead to swallowing difficulty (dysphagia). Typically, this means that some food may be left in the mouth after an attempt to swallow, or food and liquids may regurgitate into the nose rather than go down the throat (velopharyngeal insufficiency). Weakness of the muscles that move the jaw (muscles of mastication) may cause difficulty chewing. In individuals with myasthenia gravis, chewing tends to become more tiring when chewing tough, fibrous foods. Difficulty in swallowing, chewing, and speaking is the first symptom in about one-sixth of individuals.
Sources: en.wikipedia.org
During sexual arousal, the clitoris and the rest of the vulva engorge and change color as the erectile tissues fill with blood (vasocongestion), and the individual experiences vaginal contractions. The ischiocavernosus and bulbocavernosus muscles, which insert into the corpora cavernosa, contract and compress the dorsal vein of the clitoris (the only vein that drains the blood from the spaces in the corpora cavernosa), and the arterial blood continues a steady flow and having no way to drain out, fills the venous spaces until they become turgid and engorged with blood. This is what leads to clitoral erection. The prepuce has retracted and the glans becomes more visible. The glans doubles in diameter upon arousal and further stimulation becomes less visible as it is covered by the swelling of the clitoral hood. The swelling protects the glans from direct contact, as direct contact at this stage can be more irritating than pleasurable. Vasocongestion eventually triggers a muscular reflex, which expels the blood that was trapped in surrounding tissues, and leads to an orgasm. A short time after stimulation has stopped, especially if orgasm has been achieved, the glans becomes visible again and returns to its normal state, with a few seconds (usually 5–10) to return to its normal position and 5–10 minutes to return to its original size. If orgasm is not achieved, the clitoris may remain engorged for a few hours, which women often find uncomfortable. Additionally, the clitoris is very sensitive after orgasm, making further stimulation initially painful for some women.
Tandem mass spectrometry can be used for protein sequencing. When intact proteins are introduced to a mass analyzer, this is called "top-down proteomics" and when proteins are digested into smaller peptides and subsequently introduced into the mass spectrometer, this is called "bottom-up proteomics". Shotgun proteomics is a variant of bottom up proteomics in which proteins in a mixture are digested prior to separation and tandem mass spectrometry. Tandem mass spectrometry can produce a peptide sequence tag that can be used to identify a peptide in a protein database. A notation has been developed for indicating peptide fragments that arise from a tandem mass spectrum. Peptide fragment ions are indicated by a, b, or c if the charge is retained on the N-terminus and by x, y or z if the charge is maintained on the C-terminus. The subscript indicates the number of amino acid residues in the fragment. Superscripts are sometimes used to indicate neutral losses in addition to the backbone fragmentation, * for loss of ammonia and ° for loss of water. Although peptide backbone cleavage is the most useful for sequencing and peptide identification other fragment ions may be observed under high energy dissociation conditions. These include the side chain loss ions d, v, w and ammonium ions and additional sequence-specific fragment ions associated with particular amino acid residues.
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.
Sources: en.wikipedia.org
=== Cellulose nanofibers === Cellulose nanofibers (CNF), also called nanofibrillated cellulose (NFC), are nanosized cellulose fibrils with a high aspect ratio (length to width ratio). Typical fibril widths are 5–20 nanometers with a wide range of lengths, typically several micrometers. The fibrils can be isolated from natural cellulose, generally wood pulp, produced by mechanical fibrillation of cellulose fibres through high-pressure, high temperature and high velocity impact homogenization, grinding or microfluidization (see manufacture).
Important factors for well-being are self-esteem, or how a person evaluates themselves, and authenticity, or the degree to which a person's behavior is subjectively consistent with their sense of self. A further area explores the role of social and physical circumstances. This includes the effects of trust and cooperation on group well-being and dilemmas in which self-interest conflicts with group interest. Having close relationships and engaging in altruistic behavior are generally beneficial to a person's well-being. In addition to the study of the different components and causes of well-being, positive psychologists seek to understand how well-being changes over time. For example, they examine the effects of major negative events, such as the death of a child or bankruptcy, and the psychological features that help some people maintain their level of well-being despite significant adversity, such as self-regulation and an optimistic outlook. Another key topic is the problem of interventions or how to design and implement methods to reliably increase well-being. Researchers explore a wide range of strategies, including cognitive reframing, cultivating gratitude, acts of kindness toward others, and different forms of meditation. The possibility of creating long-term gains in well-being is challenged by the set-point theory—the hypothesis that each person has a stable level of subjective well-being.
== Physiological function == Thyroid hormones act to increase protein turnover. This might serve an adaptive function in regard to long-term calorie restriction with adequate protein. When calories are in short supply, reduction in protein turnover may ameliorate the effects of the shortage.
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.
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.