The short version of Pro-Gly-Pro fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-01-12 and is reviewed periodically as new material appears.
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.
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 studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
| 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 |
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
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.
In 1933, Fermi published his landmark theory for beta decay, where he applied the principles of quantum mechanics to matter particles, supposing that they can be created and annihilated, just as the light quanta in atomic transitions. Thus, according to Fermi, neutrinos are created in the beta-decay process, rather than contained in the nucleus; the same happens to electrons. The neutrino interaction with matter was so weak that detecting it proved a severe experimental challenge. Further indirect evidence of the existence of the neutrino was obtained by observing the recoil of nuclei that emitted such a particle after absorbing an electron. Neutrinos were finally detected directly in 1956 by the American physicists Clyde Cowan and Frederick Reines in the Cowan–Reines neutrino experiment. The properties of neutrinos were (with a few minor modifications) as predicted by Pauli and Fermi.
It had two taxiways and a 6,800-by-400-foot (2,070 by 120 m) runway. In June 1945, the 67th CB arrived to build a 35,000 man recreation center to be turned over to CBMU 608. In 1950, John C. Woods, who executed the Nazi war criminals convicted at the Nuremberg trials, died by accidental electrocution while stationed on Enewetak Atoll.
== Medical uses == Rusfertide is indicated for the treatment of erythrocytosis in adults with polycythemia vera. Polycythemia vera ia a rare blood disorder that causes the body to make too many red blood cells. The excess cells can thicken the blood and increase the risk of cardiovascular issues, such as blood clots, stroke and heart attack.
Sources: en.wikipedia.org
Following the September 11 attacks, SPME was used to test for toxins in the air at Ground Zero at the World Trade Center. In 2008, Pawliszyn was honoured for his invention of SPME with the EnCana Principal Award as someone who has made a significant impact in the world outside the lab. He also earned the American Chemical Society's Separations Science and Technology Award. In March 2010, Pawliszyn was promoted to the rank of University Professor of Chemistry at the University of Waterloo. A few months later, he was recognized for "innovation leadership" as part of the Ontario Premier's Innovation Awards for 2010. Through the same year, Pawliszyn was elected a Fellow of the Royal Society of Canada for "developing state-of-the-art, integrated and automated analytical methods and instruments for on-site analysis and monitoring of living and environmental systems." Upon becoming a fellow, Pawliszyn received the 2011 Dal Nogare award from the Chromatography Forum of Delaware Valley as a scientist who has made a significant contribution in the field of chromatography. The following year, Pawliszyn was honoured by the Canadian Society for Chemistry with the 2012 E.W.R. Steacie Award as a scientist who has made a "distinguished contribution to chemistry while working in Canada." In 2019, Pawliszyn was ranked the 9th most influential person in analytical science across the globe by Analytical Scientist. He also received the 2019 Talanta Medal for his numerous contributions to analytical chemistry and for his pioneering work in SPME.
During cancer T cell exhaustion plays a role in tumor protection. According to research some cancer-associated cells as well as tumor cells themselves can actively induce T cell exhaustion at the site of tumor. T cell exhaustion can also play a role in cancer relapses as was shown on leukemia. Some studies have suggested that it is possible to predict relapse of leukemia based on expression of inhibitory receptors PD-1 and TIM-3 by T cells. Many experiments and clinical trials have focused on immune checkpoint blockers in cancer therapy, with some of these approved as valid therapies that are now in clinical use. Inhibitory receptors targeted by those medical procedures are vital in T cell exhaustion and blocking them can reverse these changes.
=== Psychedelics === Jung's theories are considered to be a useful therapeutic framework for the analysis of unconscious phenomena that become manifest in the acute psychedelic state. This view is based on correspondence Jung had with researchers involved in psychedelic research in the 1950s, as well as more recent neuroimaging research where subjects who are administered psychedelic compounds seem to have archetypal religious experiences of "unity" and "ego dissolution" associated with reduced activity in the default mode network. This research has led to a re-evaluation of Jung's work, particularly the visions detailed in The Red Book, in the context of contemporary psychedelic, evolutionary, and developmental neuroscience. For example, in a chapter entitled "Integrating the Archaic and the Modern: The Red Book, Visual Cognitive Modalities and the Neuroscience of Altered States of Consciousness", in the 2020 volume Jung's Red Book for Our Time: Searching for Soul Under Postmodern Conditions, Volume 4, it is argued Jung was a pioneer who explored uncharted "cognitive domains" that are alien to Western modes of thought. While such domains of experience are not part of mainstream Western culture and thought, they are central to various Indigenous cultures that use psychedelics such as Iboga and Ayahuasca during rituals to alter consciousness. The author writes: "Jung seems to have been dealing with modes of consciousness alien to mainstream Western thought, exploring the terrain of uncharted cognitive domains.
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.
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.