Semax 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 2026-06-12. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target 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.
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.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
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.
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.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Nevertheless, alpha-synuclein aggregates to form insoluble fibrils in pathological conditions characterized by Lewy bodies, such as Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. These disorders are known as synucleinopathies. In vitro models of synucleinopathies revealed that aggregation of alpha-synuclein may lead to various cellular disorders including microtubule impairment, synaptic and mitochondrial dysfunctions, oxidative stress as well as dysregulation of Calcium signaling, proteasomal and lysosomal pathway. Alpha-synuclein is the primary structural component of Lewy body fibrils. Occasionally, Lewy bodies contain tau protein; however, alpha-synuclein and tau constitute two distinctive subsets of filaments in the same inclusion bodies. Alpha-synuclein pathology is also found in both sporadic and familial cases with Alzheimer's disease. The alpha-synuclein seed amplification assay (SAA) using cerebrospinal fluid demonstrated high diagnostic performance in distinguishing synucleinopathies with Lewy bodies from control subjects. Additionally, SAA kinetics are associated with cognitive impairment and predict the development of dementia. The aggregation mechanism of alpha-synuclein is uncertain. There is evidence of a structured intermediate rich in beta structure that can be the precursor of aggregation and, ultimately, Lewy bodies. A single molecule study in 2008 suggests alpha-synuclein exists as a mix of unstructured, alpha-helix, and beta-sheet-rich conformers in equilibrium.
In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that catalyzes the chemical reactions that synthesize RNA from a DNA template strand. Along with the enzyme helicase, RNAP locally opens the double-stranded DNA so that one strand of the exposed nucleotides can be used as a template for the synthesis of RNA, a process called transcription. A transcription factor and its associated transcription mediator complex must be attached to a DNA binding site called a promoter region before RNAP can initiate the DNA unwinding at that position. RNAP not only initiates RNA transcription, it also guides the nucleotides into position, facilitates attachment and elongation, has intrinsic proofreading and replacement capabilities, and termination recognition capability. RNAP can produce different types of RNA, including: Messenger RNA (mRNA)
Phosphotungstic acid haematoxylin (PTAH) is a mix of haematoxylin with phosphotungstic acid, used in histology for staining. It stains some tissue in contrasting colors in a way similar to haematoxylin and eosin stain, as phosphotungstic acid binds to tissue proteins. It is used to show gliosis in the central nervous system, tumours of skeletal muscles, and fibrin deposits in lesions. Muscle is stained blue-black to dark brown, connective tissue is pale orange-pink to brownish red, fibrin and neuroglia stain deep blue, coarse elastic fibers show as purple, and bone and cartilage obtain yellowish to brownish red color. PTAH is ideal for demonstrating striated muscle fibers and mitochondria, often without a counterstain. As such, it is used to identify contraction bands, as seen in contraction band necrosis. PTAH can be helpful in diagnosing oncocytomas, infantile digital fibromas. PTAH stains ependymomas while it does not stain choroid plexus papillomas, providing one means of differentiating these tumors. This technique has been largely replaced by immunohistochemistry techniques.
Sources: en.wikipedia.org
Emperor Franz Joseph died of bronchitis and pneumonia at the age of 86 on 21 November 1916. "I remember the dear plump figure of Prince Lobkowitz going up to my husband," Zita later recounted, "and, with tears in his eyes, making the sign of the cross on Charles's forehead. As he did so he said, 'May God bless Your Majesty.' It was the first time we had heard the Imperial title used to us."
The hypothesis assumed that functional OR genes can be correlated to the olfactory capability of a given animal. In this view, a decrease in the fraction of functional OR genes would cause a reduction in the sense of smell; species with higher pseudogene count would also have a decreased olfactory ability. This assumption is flawed. Dogs, which are reputed to have good sense of smell, do not have the largest number of functional OR genes. Additionally, pseudogenes may be functional; 67% of human OR pseudogenes are expressed in the main olfactory epithelium, where they possibly have regulatory roles in gene expression. More importantly, the vision priority hypothesis assumed a drastic loss of functional OR genes at the branch of the OWMs, but this conclusion was based by low-resolution data from only 100 OR genes. High-resolution studies instead agree that primates have lost OR genes in every branch from the MRCA to humans, indicating that the degeneration of OR gene repertories in primates cannot simply be explained by the changing capabilities in vision. It has been shown that negative selection is still relaxed in modern human olfactory receptors, suggesting that no plateau of minimal function has yet been reached in modern humans and therefore the olfactory capability might still be decreasing. This is considered to provide a first clue to the future human genetic evolution.
Factors in this population may include inherited anatomical features, instability of ventilatory control, neuromuscular inefficiency of the dilator muscles of the upper airways, or a lower threshold for awakening in response to respiratory stimuli. Diagnosis of obstructive sleep apnea is significantly more common among people in relationships, who are alerted to their condition by being informed by their sleeping partner, since individuals with obstructive sleep apnea are often unaware of the condition. There is a stigma associated with loud snoring. It is not considered a feminine trait. Consequently, females are less likely to be told by their partners that they snore, or to admit it to themselves or doctors. Furthermore, CPAP (continuous positive airway pressure) machines are also perceived negatively by females. They are less likely to be utilized to their full extent in this group.
== Notable cases == Actor Robert Urich died from synovial sarcoma. Folksinger Kate McGarrigle died from clear-cell sarcoma. Actress Michelle Thomas died from desmoplastic small-round-cell tumor, a rare abdominal soft-tissue sarcoma. It Is Written evangelist Henry Feyerabend died from sarcoma in his leg. Video game concept artist Adam Adamowicz died from complications of a rare muscle sarcoma on February 9, 2012, at age 42. Professional wrestler Jake Roberts revealed he has muscle cancer. Professional wrestler Zack Ryder revealed he had synovial sarcoma as a teenager. India's ex-finance minister Arun Jaitley died from sarcoma on August 24, 2019. Writer Rachel Caine died from the disease on November 1, 2020. YouTuber Technoblade died from the disease in June, 2022.
Sources: en.wikipedia.org
In two weeks' fighting, Hoepner's forces advanced 60 km (37 mi) (4 km (2.5 mi) per day). Lacking strength and mobility to conduct battles of encirclement, the Group undertook frontal assaults which proved increasingly costly. A lack of tanks, insufficient motor transport and a precarious supply situation, along with tenacious Red Army resistance and the air superiority achieved by Soviet fighters hampered the attack. The 3rd Panzer Group further north saw slightly better progress, averaging 6 km (3.7 mi) a day. The attack by the 2nd Panzer Group on Tula and Kashira, 125 km (78 mi) south of Moscow, achieved only fleeting and precarious success, while Guderian vacillated between despair and optimism, depending on the situation at the front. Facing pressure from the German High Command, Kluge finally committed his weaker south flank to the attack on 1 December. In the aftermath of the battle, Hoepner and Guderian blamed slow commitment of the south flank of the 4th Army to the attack for the German failure to reach Moscow, grossly overestimating the capabilities of Kluge's remaining forces, according to Stahel. It also failed to appreciate the reality that Moscow was a fortified position which the Wehrmacht lacked the strength to either encircle nor take in a frontal assault, again according to Stahel. In contrast Forczyk lays the blame in part on Kluge's disingenuous lack of commitment to the Moscow operation. As late as 2 December, Hoepner urged his troops forward stating that "the goal [the encirclement of Moscow] can still be achieved".
==== Drugs ==== Many substances are potentially harmful to people with G6PD deficiency. Variation in response to these substances makes individual predictions difficult. Antimalarial drugs that can cause acute hemolysis in people with G6PD deficiency include primaquine and tafenoquine. Dapsone, methylene blue, pegloticase, rasburicase, and toluidine should also be avoided by people with G6PD deficiency.(CPIC guideline G6PD ) Henna has been linked to hemolytic crisis in G6PD-deficient infants. Rasburicase is contraindicated in G6PD deficiency. Over 40 medications, including ascorbic acid at high doses and sulfonamides, have been hypothesized to be linked to hemolysis in G6PD-deficient individuals, but the evidence supporting most of these medications is lacking.Clinical Pharmacogenetics Implementation Consortium;
=== Lysozyme === Lysozyme is a natural defense mechanism in humans that has the ability to break down peptidoglycan in bacterial cells. It degrades the peptidoglycan by targeting the β-1,4-glycosidic bonds that connect the alternating amino sugars in which it is composed of. This degradation of the glycosidic bonds within peptidoglycan cause the sugars to separate and inhibit the structural integrity of the peptidoglycan and the bacteria. Pseudopeptidoglycan, however, is composed of a different acidic amino sugar, which is N-acetyltalosaminuronic acid. This difference is the reason that it has β-1,3-glycosidic bonds (as opposed to the β-1,4-glycosidic bonds in bacteria). Lysozymes targets the linkage in peptidoglycan, and without that, becomes ineffective against pseudopeptidoglycan.
The oligonucleotides alternate between sense and antisense directions, and the overlapping segments determine the order of the PCR fragments, thereby selectively producing the final long DNA product. Asymmetric PCR: preferentially amplifies one DNA strand in a double-stranded DNA template. It is used in sequencing and hybridization probing where amplification of only one of the two complementary strands is required. PCR is carried out as usual, but with a great excess of the primer for the strand targeted for amplification. Because of the slow (arithmetic) amplification later in the reaction after the limiting primer has been used up, extra cycles of PCR are required. A recent modification on this process, known as Linear-After-The-Exponential-PCR (LATE-PCR), uses a limiting primer with a higher melting temperature (Tm) than the excess primer to maintain reaction efficiency as the limiting primer concentration decreases mid-reaction. Convective PCR: a pseudo-isothermal way of performing PCR. Instead of repeatedly heating and cooling the PCR mixture, the solution is subjected to a thermal gradient. The resulting thermal instability driven convective flow automatically shuffles the PCR reagents from the hot and cold regions repeatedly enabling PCR. Parameters such as thermal boundary conditions and geometry of the PCR enclosure can be optimized to yield robust and rapid PCR by harnessing the emergence of chaotic flow fields. Such convective flow PCR setup significantly reduces device power requirement and operation time.
Cuprate of Tl–Ba–Ca The first series of the Tl-based superconductor containing one Tl–O layer has the general formula TlBa2Can−1CunO2n+3, whereas the second series containing two Tl–O layers has a formula of Tl2Ba2Can−1CunO2n+4 with n =1, 2 and 3. In the structure of Tl2Ba2CuO6 (Tl-2201), there is one CuO2 layer with the stacking sequence (Tl–O) (Tl–O) (Ba–O) (Cu–O) (Ba–O) (Tl–O) (Tl–O). In Tl2Ba2CaCu2O8 (Tl-2212), there are two Cu–O layers with a Ca layer in between. Similar to the Tl2Ba2CuO6 structure, Tl–O layers are present outside the Ba–O layers. In Tl2Ba2Ca2Cu3O10 (Tl-2223), there are three CuO2 layers enclosing Ca layers between each of these. In Tl-based superconductors, Tc is found to increase with the increase in CuO2 layers. However, the value of Tc decreases after four CuO2 layers in TlBa2Can−1CunO2n+3, and in the Tl2Ba2Can−1CunO2n+4 compound, it decreases after three CuO2 layers. Cuprate of Hg–Ba–Ca The crystal structure of HgBa2CuO4 (Hg-1201), HgBa2CaCu2O6 (Hg-1212) and HgBa2Ca2Cu3O8 (Hg-1223) is similar to that of Tl-1201, Tl-1212 and Tl-1223, with Hg in place of Tl. It is noteworthy that the Tc of the Hg compound (Hg-1201) containing one CuO2 layer is much larger as compared to the one-CuO2-layer compound of thallium (Tl-1201). In the Hg-based superconductor, Tc is also found to increase as the CuO2 layer increases. For Hg-1201, Hg-1212 and Hg-1223, the values of Tc are 94, 128, and the record value at ambient pressure 134 K (−139 °C), respectively, as shown in table below.
Sources: en.wikipedia.org
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.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
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.