proteolysis is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-11-18. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
| 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 |
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.
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.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Non-depolarizing neuromuscular blockers: Non-depolarizing agents act as competitive inhibitors for acetylcholine. Upon the binding of non-depolarizing neuromuscular blockers, neurotransmission is reduced. Consequently, depolarizing and muscle-contracting effects are decreased. Non-depolarizing neuromuscular blockers are generally reversible, and hence have no permanent effects on acetylcholine receptors.
President Biden signs a series of executive orders regarding climate change, including halting new oil and gas leases on public lands, procuring an all-electric federal vehicle fleet, and doubling offshore wind power by 2030. One of the 14 men accused in the Gretchen Whitmer kidnapping plot pleads guilty and agrees to testify against his co-defendants, with sentencing set for July 8. Investment funds report major losses after video game retailer GameStop's stock prices rise 900 times their record low. The next day, January 28, some financial services companies restrict the trade of stocks of several companies, including GameStop, triggering outrage online. January 31–February 3 – A major winter storm strikes the Northeastern United States, bringing nearly 3 feet (0.91 m) of snow to some areas, causing over 575,000 power outages, and killing six people.
==== Iron recycling and loss ==== Most of the iron in the body is hoarded and recycled by the reticuloendothelial system, which breaks down aged red blood cells. In contrast to iron uptake and recycling, there is no physiologic regulatory mechanism for excreting iron. People lose a small but steady amount by gastrointestinal blood loss, sweating and by shedding cells of the skin and the mucosal lining of the gastrointestinal tract. The total amount of loss for healthy people in the developed world amounts to an estimated average of 1 mg a day for men, and 1.5–2 mg a day for women with regular menstrual periods. People with gastrointestinal parasitic infections, more commonly found in developing countries, often lose more. Those who cannot regulate absorption well enough get disorders of iron overload. In these diseases, the toxicity of iron starts overwhelming the body's ability to bind and store it.
Brown (1912–2004), American chemist known for work on organoboranes, 1979 Nobel Prize in Chemistry Jeannette Brown (born 1934), American organic medicinal chemist, historian, and author, known for research on drug development targeting tuberculosis and coccidiosis Jeanette Grasselli Brown (1928–2025), American analytical chemist and spectroscopist Rachel Fuller Brown (1898–1980), American chemist who co-developed the first useful antifungal antibiotic, nystatin
=== Genomic Architecture and Risk of Abdominal Obesity === In addition to the visible changes in adipose tissue associated with obesity, recent research indicates that the risk of developing abdominal obesity and cardiometabolic alterations also depends on the 3D organization of the genome in subcutaneous adipose tissue. Single‑cell epigenomic studies have shown that many genetic variants associated with abdominal fat distribution (measured as WHRadjBMI) are preferentially located in active genomic regions of adipocytes. These regions display low levels of DNA methylation and belong to the so‑called A compartment, which is characterized by higher gene activity. These findings suggest that adipocytes in subcutaneous adipose tissue play a key role in mediating the genetic risk associated with abdominal obesity.
Sources: en.wikipedia.org
=== Personalized cancer treatment === Personalized cancer treatment is a tuned method based on the patient's diagnosis and background. Microfluidic technology offers sensitive detection with higher throughput, as well as reduced time and costs. For personalized cancer treatment, tumor composition and drug sensitivities are very important. A patient's drug response can be predicted based on the status of biomarkers, or the severity and progression of the disease can be predicted based on the atypical presence of specific cells. Drop-qPCR is a droplet microfluidic technology in which droplets are transported in a reusable capillary and alternately flow through two areas maintained at different constant temperatures and fluorescence detection. It can be efficient with a low contamination risk to detect Her2. A digital droplet‐based PCR method can be used to detect the KRAS mutations with TaqMan probes, to enhance detection of the mutative gene ratio. In addition, accurate prediction of postoperative disease progression in breast or prostate cancer patients is essential for determining post-surgery treatment. A simple microfluidic chamber, coated with a carefully formulated extracellular matrix mixture is used for cells obtained from tumor biopsy after 72 hours of growth and a thorough evaluation of cells by imaging. Microfluidics is also suitable for circulating tumor cells (CTCs) and non-CTCs liquid biopsy analysis. Beads conjugate to anti‐epithelial cell adhesion molecule (EpCAM) antibodies for positive selection in the CTCs isolation chip (iCHIP).
Income inequality decreased during Xi's tenure. Since 2021, Xi has promoted the term common prosperity, which he defined as an "essential requirement of socialism", described as affluence for all and said entailed reasonable adjustments to excess incomes. Common prosperity has been used as the justification for large-scale crackdowns and regulations towards the perceived "excesses" of several sectors, most prominently tech and tutoring industries. Actions taken include fining large tech companies and passing laws such as the Data Security Law. China introduced severe restrictions on private tutoring in the name of promoting social equality, effectively eliminating the private education industry. Xi opened a new stock exchange in Beijing targeted for small and medium enterprises (SMEs). There have been other cultural regulations including restrictions on minors playing video games and crackdowns on celebrity culture. The push for common prosperity has also included salary and bonus cuts, especially across the financial sector, as well as crackdowns on wealth flaunting.
== References == Nordin G, Dybkaer R. Recommendation for term and measurement unit for "HbA1c". Clin Chem Lab Med 2007; 45(8):1081-2. Summary of NPU definition publications René Dybkær: "An Ontology on Property for Physical, Chemical and Biological Systems" Berzell M., "Electronic Healthcare Ontologies: Philosophy, the real world and IT structures"
1,1'-Carbonyldiimidazole (CDI) is an organic compound with the molecular formula (C3H3N2)2CO. It is a white crystalline solid. It is often used for the coupling of amino acids for peptide synthesis and as a reagent in organic synthesis.
Sources: en.wikipedia.org
It has been indicated that where there was a policy of providing IAP for GBS colonized mothers, the overall risk of EOGBS is 0.3%. Though maternal GBS colonization is the key determinant for EOD, other factors also increase the risk. These factors include onset of labor before 37 weeks of gestation (premature birth), prolonged rupture of membranes (> 18 h before delivery), intra-partum fever (>38 °C, >100.4 °F), amniotic infections (chorioamnionitis), young maternal age, and low levels of GBS anticapsular polysaccharide antibodies in the mother. Nevertheless, most babies who develop EOD are born to GBS colonized mothers without any additional risk factor. A previous sibling with EOD is also an important risk factor for the development of the infection in subsequent deliveries, probably reflecting a lack of GBS polysaccharides protective antibodies in the mother. Heavy GBS vaginal colonization is also associated with a higher risk for EOD. Overall, the case–fatality rates from EOD have declined, from 50% observed in studies from the 1970s to 2 to 10% in recent years, mainly as a consequence of improvements in therapy and management. Fatal neonatal infections by GBS are more frequent among premature infants. GBS LOD affects infants from 7 days to 3 months of age and is more likely to cause bacteremia or meningitis. LOD can be acquired from the mother or from environmental sources. Hearing loss and mental impairment can be long-term sequelae of GBS meningitis.
=== Impeachment of Sara Duterte === In December 2024, Duterte offered to join the defense team of his daughter, Vice President Sara Duterte, against her impeachment. On February 18, 2025, two weeks after the vice president was impeached by the House of Representatives, Duterte was listed as the legal counsel of his daughter in her Supreme Court petition to stop the impeachment from proceeding to trial.
Sulfur dioxide is sometimes used as a preservative for dried apricots, dried figs, and other dried fruits, owing to its antimicrobial properties and ability to prevent oxidation, and is called E220 when used in this way in Europe. As a preservative, it maintains the colorful appearance of the fruit and prevents rotting. Historically, molasses was "sulfured" as a preservative and also to lighten its color. Treatment of dried fruit was usually done outdoors, by igniting sublimed sulfur and burning in an enclosed space with the fruits. Fruits may be sulfured by dipping them into sodium bisulfite, sodium sulfite or sodium metabisulfite.
== Associations with national cuisines == In the United States, fried ice cream has been associated with Asian cuisine, appearing in reviews of Chinese, Japanese, and Polynesian restaurants in the "Dining Out" section of the New York Times in the 1970s.
Its historic outcome was an unprecedented call for a halt in research until it could be regulated in such a way that the public need not be anxious, and it led to a 16-month moratorium until National Institutes of Health (NIH) guidelines were established. Joshua Lederberg was the leading exception in emphasizing, as he had for years, the potential benefits. At Asilomar, in an atmosphere favoring control and regulation, he circulated a paper countering the pessimism and fears of misuses with the benefits conferred by successful use. He described "an early chance for a technology of untold importance for diagnostic and therapeutic medicine: the ready production of an unlimited variety of human proteins. Analogous applications may be foreseen in fermentation process for cheaply manufacturing essential nutrients, and in the improvement of microbes for the production of antibiotics and of special industrial chemicals." In June 1976, the 16-month moratorium on research expired with the Director's Advisory Committee (DAC) publication of the NIH guidelines of good practice. They defined the risks of certain kinds of experiments and the appropriate physical conditions for their pursuit, as well as a list of things too dangerous to perform at all. Moreover, modified organisms were not to be tested outside the confines of a laboratory or allowed into the environment.
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.
The most common approach combines reverse-phase liquid chromatography with mass spectrometry. Chromatography separates the components while mass spectrometry confirms the molecular mass. Peptide sequencing or tandem mass analysis can further verify the amino acid order.