proteolysis comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-04-23. Where a claim depends on a specific study, the study is described rather than over-claimed.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
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.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
| Property | Value | Notes |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
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.
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.
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.
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.
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, 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.
== Cause == There is a disc between each of the vertebrae in the spine. A healthy, well-hydrated disc will contain a great deal of water in its center, known as the nucleus pulposus, which provides cushioning and flexibility for the spine. Much of the mechanical stress that is caused by everyday movements is transferred to the discs within the spine and the water content within them allows them to effectively absorb the shock. At birth, a typical human nucleus pulposus will contain about 80% water. However natural daily stresses and minor injuries can cause these discs to gradually lose water as the annulus fibrosus, or the tough outer fibrous material of a disc, weakens. Because degenerative disc disease is largely due to natural daily stresses, the American Academy of Orthopaedic Manual Physical Therapists have suggested it is not truly a "disease" process. This water loss makes the discs more flexible and results in the gradual collapse and narrowing of the gap in the spinal column. As the space between vertebrae gets smaller, extra pressure can be placed on the discs causing tiny cracks or tears to appear in the annulus. If enough pressure is exerted, it is possible for the nucleus pulposus material to seep out through the tears in the annulus and can cause what is known as a herniated disc. As the two vertebrae above and below the affected disc begin to collapse upon each other, the facet joints at the back of the spine are forced to shift which can affect their function.
People stopping venlafaxine commonly experience SSRI withdrawal symptoms such as dysphoria, headaches, nausea, irritability, emotional lability, sensation of electric shocks (commonly called "brain zaps"), and sleep disturbance. Venlafaxine has a higher rate of moderate to severe withdrawal symptoms relative to other antidepressants (similar to the SSRI paroxetine). The higher risk and increased severity of withdrawal symptoms relative to other antidepressants may be related to the short half-life of venlafaxine and its active metabolite. After stopping venlafaxine, the levels of both serotonin and norepinephrine decrease, leading to the hypothesis that the withdrawal symptoms could result from an overly rapid reduction of neurotransmitter levels.
The Duterte administration has vowed to pursue what it describes as an "independent foreign policy" that would reject any meddling by foreign governments, reiterating Article II, Section 7 of the 1987 Constitution which states: "The State shall pursue an independent foreign policy. In its relations with other states the paramount consideration shall be national sovereignty, territorial integrity, national interest, and the right to self-determination." At a September 2016 press conference, Duterte stated: "We will observe and must insist on the time-honored principle of sovereignty, sovereign equality, non-interference and the commitment of peaceful settlements of dispute that will serve our people and protect the interests of our country." Duterte made his first international trips as president to Vientiane, Laos and Jakarta, Indonesia on September 5–9, 2016. Duterte pursued improved relations with China and Russia, and lessened the country's dependence on its traditional ally – the United States. He has adopted a cautious, pragmatic, and conciliatory stance towards China compared to his predecessor, and has set aside the previous administration's confrontational policy of asserting the Philippines' claims over the South China Sea and its islands. Militant groups decry the ties between President Duterte and China over the Chinese occupation of contested waters and the reported harassment of the fishermen amidst the territorial disputes in the South China Sea.
Kipa-Williams commented "Ari initially believes Tane robbed the Diner. But he also believes Colby is acting out of jealousy more than anything else." Ari and Tane realise they need to put some distance between themselves and the Bay when Nikau discovers Colby is planning on conducting a police line-up involving them all. Nikau later steals Tori's car in order to flee the Bay, but he accidentally kidnaps her young daughter Grace. Tane helps him return Grace to Tori anonymously, but Colby realises that the Paratas were involved in the car-jacking. Sarah Ellis of Inside Soap observed that with "the heat on their family", the brothers know they need to act fast. When they learn Gemma is planning a trip to New Zealand to scatter the ashes of her husband, they seize the chance to escape. A show spokesperson told Ellis: "It's not just about evading the law, Ari and Tane both want to pay their respects to their late brother Mikaere. So the family presses ahead with their plans, hoping that getting to New Zealand will give them time to consider their options. But things don't turn out how they'd planned..." When Colby hears the Paratas are leaving the country, he puts a block on their passports, so only Gemma is able to pass through security at the airport, while the men are detained. The storyline marked Gemma's departure from the serial. Despite a possible jail sentence hanging over them, the Parata men are keen to honour their late brother and father, so they go to the beach and perform a "deeply spiritual and moving" Haka ceremony to say their goodbyes to Mikaere.
Sources: en.wikipedia.org
It is characterized by mild summers with only 1 to 3 months above 10 °C or 50 °F and cold, snowy, extremely windy winters below −3 °C or 26.6 °F, although usually above −10 °C or 14 °F. The chain ranges from temperate to sub-Arctic climate types, and the vegetative cover consequently ranges from tundra in the north to dense spruce and larch forests on the larger southern islands. The highest elevations on the islands are Alaid Volcano (highest point: 2,339 m or 7,674 ft) on Atlasov Island at the northern end of the chain and Tyatya volcano (1,819 m or 5,968 ft) on Kunashir Island at the southern end. Landscape types and habitats on the islands include many kinds of beach and rocky shores, cliffs, wide rivers and fast gravelly streams, forests, grasslands, alpine tundra, crater lakes and peat bogs. The soils are generally productive, owing to the periodic influxes of volcanic ash and, in certain places, owing to significant enrichment by seabird guano. However, many of the steep, unconsolidated slopes are susceptible to landslides and newer volcanic activity can entirely denude a landscape. Only the southernmost island has large areas covered by trees, while more northerly islands have no trees, or spotty tree cover.
Source 2 is a video game engine developed by Valve. The engine was announced in 2015 as the successor to the original Source engine, with the first game to use it, Dota 2, being ported from Source that same year. Other Valve games such as Artifact, Dota Underlords, Half-Life: Alyx, Counter-Strike 2, and Deadlock have been produced with the engine.
2 HO–CH2CH2–Cl + Ca(OH)2 → 2 (CH2CH2)O + CaCl2 + 2H2O The produced ethylene oxide is purified by distillation. The chlorohydrin process allows to reach 95% conversion of ethylene chlorohydrin. The yield of ethylene oxide is about 80% of the theoretical value; for 1 tonne (0.98 long tons; 1.1 short tons) of ethylene oxide, about 200 kg (440 lb) of ethylene dichloride is produced. But, the major drawbacks of this process are high chlorine consumption and effluent load. This process is now obsolete.
Sources: en.wikipedia.org
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.