The short version of peptide stability fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Route studied | Intranasal | Predominant route in published reports |
| Circulation stability | Short, minutes scale | Peptidases cleave it; the tail slows the process |
| Analytical method | RP-HPLC with mass spectrometry | Used for identity and purity assessment |
| Reported outcome domains | Anxiety and cognitive measures | Derived from small, mostly regional trials |
| Regulatory status | Marketed in Russia | Availability outside that market is limited |
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.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
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.
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.
=== Interaction proteomics and protein networks === Interaction proteomics is the analysis of protein interactions from scales of binary interactions to proteome- or network-wide. Most proteins function via protein–protein interactions, and one goal of interaction proteomics is to identify binary protein interactions, protein complexes, and interactomes. Several methods are available to probe protein–protein interactions. While the most traditional method is yeast two-hybrid analysis, a powerful emerging method is affinity purification followed by protein mass spectrometry using tagged protein baits. Other methods include surface plasmon resonance (SPR), protein microarrays, dual polarisation interferometry, microscale thermophoresis, kinetic exclusion assay, and experimental methods such as phage display and in silico computational methods. Knowledge of protein-protein interactions is especially useful in regard to biological networks and systems biology, for example in cell signaling cascades and gene regulatory networks (GRNs, where knowledge of protein-DNA interactions is also informative). Proteome-wide analysis of protein interactions, and integration of these interaction patterns into larger biological networks, is crucial towards understanding systems-level biology.
For example, mutations in SERPINF1 cause osteogenesis imperfecta type VI in humans. In the absence of a required serpin, the protease that it normally would regulate is over-active, leading to pathologies. Consequently, simple deficiency of a serpin (e.g. a null mutation) can result in disease. Gene knockouts, particularly in mice, are used experimentally to determine the normal functions of serpins by the effect of their absence.
== Further reading == Mulier, Jan P.; Hunter, Jennifer M.; de Boer, Hans D. (February 2021). "Seventy-five years since the birth of the Liverpool anaesthetic technique". Editorial. British Journal of Anaesthesia. 126 (2): 343–347. doi:10.1016/j.bja.2020.10.020. Donohue, Ciara; Hobson, Ben; Stephens, Robert C. M. (May 2013). "An introduction to anaesthesia" (PDF). British Journal of Hospital Medicine. 74 (5): C71-5. doi:10.12968/hmed.2013.74.Sup5.C71. PMID 23656984.
One month later, the Phillips group independently reported the wild-type GFP structure in Nature Biotechnology. These crystal structures provided vital background on chromophore formation and neighboring residue interactions. Researchers have modified these residues by directed and random mutagenesis to produce the wide variety of GFP derivatives in use since then. Further research into GFP has shown that it is resistant to detergents, proteases, guanidinium chloride (GdmCl) treatments, and drastic temperature changes.
=== PVAT AND ET-1 === ET-1 In addition to its direct vasoconstrictor effects, it causes changes in visceral and perivascular adipose tissue (PVAT), and may contribute to the pathogenesis of both insulin resistance and vascular dysfunction/damage. Perivascular adipose tissue seems to have anti contractile effect and this dilator effect was lost in obese patients. secondary to obesity, ET-1 high level changes on PVAT will lead to PVAT hypertrophy which will be associated with reduced partial oxygen pressure, an increase in the production of inflammatory cytokines such as TNF-α and IL-6, and elevation of reactive oxygen species. Thus, oxidative stress and hypoxia may promote imbalance in the production of vasoactive compounds and may affect vascular homeostasis by activating the ET-1 system.
Sources: en.wikipedia.org
=== EC 1.8.99 With other acceptors === EC 1.8.99.1: Now covered by EC 1.8.1.2, assimilatory sulfite reductase (NADPH) and EC 1.8.7.1, assimilatory sulfite reductase (ferredoxin) EC 1.8.99.2: adenylyl-sulfate reductase EC 1.8.99.3: an in vitro artifact of EC 1.8.1.22, dissimilatory sulfite reductase EC 1.8.99.4: Now EC 1.8.4.8, phosphoadenylyl-sulfate reductase (thioredoxin) EC 1.8.99.5: Now EC 1.8.1.22, dissimilatory sulfite reductase
the Extra-Terrestrial, Charles Nelson Reilly, characters from My Three Sons, and Kermit the Frog and Miss Piggy—in rapid succession. After completing his set, though getting the OK gesture from Carson, the impressionist comic was notably not waved over by the host to join him on the couch—a usual indication that while sufficiently pleased, the powerful host was probably not ecstatic about the performance. The end of 1983 saw Carrey go back home to Toronto once more for a publicized New Year's Eve performance at the Royal York Hotel's Imperial Room. Originally scheduled to start airing in January 1984, The Duck Factory sitcom debuted in April, airing Thursdays at 9:30pm between Cheers and Hill Street Blues. The same month, Carrey took a job hosting the 1984 U-Know Awards ceremony held in Toronto at the Royal York Hotel's Ballroom. By the time he made his debut appearance on NBC's Late Night with David Letterman in late July 1984, the network had already canceled The Duck Factory; Carrey went back to touring with his impressionist act, including often opening for Rodney Dangerfield. After being noticed doing stand-up by producer Samuel Goldwyn Jr. and contacted to audition for a teen horror sex comedy being developed by The Samuel Goldwyn Company, Carrey landed a starring role in Once Bitten shot in early 1985. Carrey would continue getting film roles; throughout late summer and early fall 1985, he shot a supporting part in Francis Ford Coppola's Peggy Sue Got Married which went into a long post-production process.
Sorenson, MD, from the Mayo Clinic in Rochester, Minnesota "While this is very disappointing, at least it was definitive and gives, I think, a pretty definitive answer, at least for this strategy for this drug," Dr. Sorenson said. However, he added, "there is still a great deal of evidence that the IGF-1 pathway can be beneficial to people who have ALS, but just not the way we administered it." Novel methods of delivering IGF-1 in a more selected fashion are now under way, including the use of viral mediators or stem cells. Two previous phase 3 trials of IGF-1 in ALS showed inconsistent results: 1 trial, carried out in North America, did find a benefit, whereas the other, a European trial, did not confirm the earlier findings. "The results of our study most resemble those of the previous European study, with no benefit in either survival or functional scales", De Sorenson concludes. "It is disappointing that we were unable to confirm the benefit that was noted in the previous North American study." Conclusive evidence points, what Iplex (and any form of IGF-1) can't slow progression in human ALS. Lot of sites that have published articles about the link between Lyme disease and ALS are sponsored by clinics specializing in the treatment of chronic Lyme disease, or by the sellers of products for treating this, or both.
"We are deeply distressed by this verdict and the harmful ramifications of criminalizing the honest reporting of mistakes. Health care delivery is highly complex. It is inevitable that mistakes will happen, and systems will fail. It is completely unrealistic to think otherwise. The criminalization of medical errors is unnerving, and this verdict sets into motion a dangerous precedent. There are more effective and just mechanisms to examine errors, establish system improvements and take corrective action. The non-intentional acts of Individual nurses like RaDonda Vaught should not be criminalized to ensure patient safety.
Sources: en.wikipedia.org
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.
Intranasal delivery is the route described in most published work. It is used because the peptide is degraded quickly once it reaches circulation. Direct evidence of brain penetration in humans is lacking.
Most trials are small, regionally concentrated, and often lack rigorous blinding or placebo control. Independent replication is limited. Reviews in English generally rate the evidence as preliminary.
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.