The short version of lyophilization fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-05-31 and is reviewed periodically as new material appears.
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.
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.
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.
| 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 |
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.
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.
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.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
== Dye colour == The suffix "R" in the name of Coomassie brilliant blue R-250 is an abbreviation for "red" as the blue colour of the dye has a slight reddish tint. For the "G" variant the blue colour has a more greenish tint. The "250" originally denoted the purity of the dye. The colour of the two dyes depends on the acidity of the solution. The "G" form of the dye has been studied in detail. At a pH of less than 0 the dye has a red colour with an absorption maximum at a wavelength of 465 nm. At a pH of around 1 the dye is green with an absorption maximum at 620 nm while above pH 2 the dye is bright blue with a maximum at 595 nm. At pH 7 the dye has an extinction coefficient of 43,000 M−1 cm−1. The different colours are a result of the different charged states of the dye molecule. In the red form, all three nitrogen atoms carry a positive charge. The two sulfonic acid groups have extremely low pKa and will normally be negatively charged, thus at a pH of around zero the dye will be a cation with an overall charge of +1. The green colour corresponds to a form of the dye with no net overall charge. In neutral media (pH 7), only the nitrogen atom of the diphenylamine moiety carries a positive charge and the blue dye molecule is an anion with an overall charge of −1. The pKa values for the losses of the two protons are 1.15 and 1.82, respectively. The final proton is lost under alkaline conditions and the dye becomes pink (pKa 12.4). The dye interacts electrostatically but noncovalently with the amino and carboxyl groups of proteins.
=== NNR === Research overview: This study involves creating a combination of model membranes which contain 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-distearoly-sn-glycero-3-phosphocholine (DSPC) referred to as the "host membranes", phospholipids labeled as 1,2,& 3 referred to as "exchanging molecules" or "reporting molecules" and varied cholesterol mole percentages in the presence of an aqueous solution containing 5% ethanol (v/v). The host membranes were chosen because their phase diagrams are well understood and have been extensively characterized by different analytical techniques.6 The nearest neighbor recognition technique is being applied to the formation of the modeled membranes to observe the association between cholesterol and phospholipids as well as the effects that the presence of ethanol has against this interaction. Researchers are observing whether or not ethanol enhances or disrupts the liquid-ordered phase by reorganizing this formation into a liquid-disordered phase. The liquid-ordered phase is similar to a lamellar phase and the liquid-disordered phase represents the non-lamellar phases but the exact type of each phase (hexagonal, cubic, etc.) is not described. As previously mentioned several different combinations of the host membranes, exchanging molecules, and cholesterol are created to form the model membranes. It is important to mention that the exchanging molecules selected have similar properties to the host membranes.
=== N-degrons === Proteolytic cleavage can lead to exposure of residues at the N-terminus of a protein. According to the N-end rule, different N-terminal amino acids (or N-degrons) are recognized to a different extent by their appropriate ubiquitin ligase (N-recognin), influencing the half-life of the protein. For instance, positively charged (Arg, Lys, His) and bulky hydrophobic amino acids (Phe, Trp, Tyr, Leu, Ile) are recognized preferentially and thus considered destabilizing degrons since they allow faster degradation of their proteins.
{\displaystyle \left(\mathbf {w} ,{\frac {\partial \mathbf {u} }{\partial t}}\right)=-{\bigl (}\mathbf {w} ,\left(\mathbf {u} \cdot \nabla \right)\mathbf {u} {\bigr )}-\nu \left(\nabla \mathbf {w} :\nabla \mathbf {u} \right)+\left(\mathbf {w} ,\mathbf {f} ^{S}\right)}
Sources: en.wikipedia.org
Antiseptics can be subdivided into about eight classes of materials. These classes can be subdivided according to their mechanism of action: small molecules that indiscriminately react with organic compounds and kill microorganisms (peroxides, iodine, phenols) and more complex molecules that disrupt the cell walls of the bacteria.
== History == Carbetocin was synthesized before 1971 at the Czechoslovak Institute of Organic Chemistry and Biochemistry and was first described by 1974. It was approved for medical use in Canada and the United Kingdom in 1997.
Black kōji produces citric acid during fermentation, which inhibits the growth of unwanted microorganisms. It is typically used for the production of awamori. There are three Aspergillus species that are used as black kōji:
Nutrition-related results A study reports results of the first longevity caloric restriction (CR) trial, CALERIE, finding that two years of nonintermittent CR slowed the pace of aging as measured by one of three aging clocks (modest DunedinPACE effects). Development and application of aging clocks and combination therapies A study reports the development of deep learning software using anatomic magnetic resonance images to estimate brain age with the highest accuracy for AI so far, including detecting early signs of Alzheimer's disease and varying neuroanatomical patterns of neurological aging. A study shows DNA methylation aging clocks could be useful indicators of health while social factors – such as health behaviors and poverty – are at least as good predictors and e.g. can better predict cognitive functioning. Around February, Bryan Johnson's Project Blueprint for one of the first comprehensive, possibly largely public, self-experimentations of a comprehensive combination therapy informed by the large scientific corpus on the topic and organ measurements to maximally reverse biological age and (epigenetic) aging markers achieves substantial media attention, with such activities previously largely reserved to biohackers without resources and means to evaluate effects. The pan-mammalian epigenetic clock is a molecular biomarker designed to measure the age of all mammalian tissues and species using cytosine methylation in highly conserved DNA regions. A study indicates chest radiographs evaluated using AI could be a performant biomarker for aging clocks.
== Evolution == Phylogenetic analyses suggest that DBP diverged from ancestral albumin through gene duplication events that occurred after the separation of jawless fish (cyclostomes) from jawed vertebrates approximately 450 million years ago. This timeline is supported by the apparent absence of DBP-like proteins in lampreys and hagfish, though these organisms retain vitamin D transport capability through alternative lipoprotein-mediated mechanisms. DBP is found throughout jawed vertebrates, from bony fish to mammals, suggesting its evolution coincided with the development of calcified skeletons and more sophisticated calcium homeostasis requirements.
Sources: en.wikipedia.org
Zverev's next breakthrough came during the grass court season at the Halle Open, where he upset world No. 3 Roger Federer in the semifinals, ending Federer's streak of ten consecutive appearances in the final while competing at the tournament. He was also the first teenager to defeat Federer since Murray nearly a decade earlier. Nonetheless, he finished runner-up at the event to veteran compatriot Florian Mayer. After this final, he entered the top 30 for the first time and stayed ranked in the 20s for the rest of the season. Despite being seeded at a major tournament for the first time, Zverev could then only match his best major singles result at Wimbledon, again falling to Berdych. During the US Open Series, he reached the semifinals of the Washington Open, but lost his opening round matches at both Masters events. He was then upset in the second round of the US Open by Dan Evans. After the US Open, Zverev returned to Europe and won his first career ATP title at the St. Petersburg Open. He recorded his first win over No. 9 Berdych in the semifinals, and No. 3 Stan Wawrinka in the final, coming back from 0–3 down in the third set. At his next event, he then defeated No. 10 Thiem in the first round of the 2016 China Open for the first time in four tries this year. In doing so, Zverev became the first teenager to record three consecutive victories against top ten opponents since Boris Becker in 1986. Zverev's third round appearance at the Shanghai Masters then helped him rise to No.
Although the Cossacks were sometimes portrayed by Bolsheviks, and later by émigré historians, as a monolithic counterrevolutionary group during the civil war, there were many Cossacks who fought with the Red Army throughout the conflict, known as Red Cossacks. Many poorer Cossack communities also remained receptive to the communist message. In late 1918 and early 1919, widespread desertion and defection among Don, Ural, and Orenburg Cossacks fighting with the Whites produced a military crisis that was exploited by the Red Army in those sectors. After the main White armies were defeated in early 1920, many Cossack soldiers switched their allegiance to the Bolsheviks, and fought with the Red Army against the Poles and in other operations. On 22 December 1917, the Council of People's Commissars effectively abolished the Cossack estate by ending their military service requirements and privileges. After the widespread anticommunist rebellions among Cossacks in 1918, the Soviet regime's approach hardened in early 1919, when the Red Army occupied Cossack districts in the Urals and northern Don. The Bolsheviks embarked on a policy of "de-Cossackization", intended to end the Cossack threat to the Soviet regime. This was pursued through resettlement, widespread executions of Cossack veterans from the White armies, and favoring the outlanders within the Cossack hosts. Ultimately, the de-Cossackization campaign led to a renewed rebellion among Cossacks in Soviet-occupied districts and produced a new round of setbacks for the Red Army in 1919.
The enzyme is bifunctional and in the reverse direction is equivalent to glutathionylspermidine amidase, which hydrolyses the product back to the starting materials. This enzyme is a ligase, specifically one forming carbon-nitrogen bonds as acid-D-ammonia (or amine) ligases (amide synthases). The systematic name of this enzyme class is gamma-L-glutamyl-L-cysteinyl-glycine:spermidine ligase (ADP-forming) [spermidine is numbered so that atom N-1 is in the amino group of the aminopropyl part of the molecule]. This enzyme is also called glutathione:spermidine ligase (ADP-forming). This enzyme participates in glutathione metabolism. It uses magnesium as a cofactor.
Female cannabis plants contain at least 113 cannabinoids, including cannabidiol (CBD), thought to be the major anticonvulsant that helps people with multiple sclerosis, and cannabichromene (CBC), an anti-inflammatory which may contribute to the pain-killing effect of cannabis.
Conventional vaccines contain either specific antigens from a pathogen, or attenuated viruses which stimulate an immune response in the vaccinated organism. DNA vaccines are members of the genetic vaccines, because they contain a genetic information (DNA or RNA) that codes for the cellular production (protein biosynthesis) of an antigen. DNA vaccines contain DNA that codes for specific antigens from a pathogen. The DNA is injected into the body and taken up by cells, whose normal metabolic processes synthesize proteins based on the genetic code in the plasmid that they have taken up. Because these proteins contain regions of amino acid sequences that are characteristic of bacteria or viruses, they are recognized as foreign and when they are processed by the host cells and displayed on their surface, the immune system is alerted, which then triggers immune responses. Alternatively, the DNA may be encapsulated in protein to facilitate cell entry. If this capsid protein is included in the DNA, the resulting vaccine can combine the potency of a live vaccine without reversion risks. In 1983, Enzo Paoletti and Dennis Panicali at the New York Department of Health devised a strategy to produce recombinant DNA vaccines by using genetic engineering to transform ordinary smallpox vaccine into vaccines that may be able to prevent other diseases. They altered the DNA of cowpox virus by inserting a gene from other viruses (namely Herpes simplex virus, hepatitis B and influenza).
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.