The short version of Pro-Gly-Pro tail fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-03-31. Anything still debated is marked as such rather than presented as settled.
The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
| Property | Value | Notes |
|---|---|---|
| Molecular weight | ~813.9 Da (free heptapeptide) | N-acetylated form is about 42 Da heavier |
| Residue count | 7 (heptapeptide) | Four residues from ACTH(4-10), three added |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility class | Freely soluble in water | Also dissolves in DMSO and polar organic solvents |
| Related parent fragment | ACTH(4-10) | Parent motif is Met-Glu-His-Phe |
Laboratory descriptions of the material are consistent across suppliers. It appears as a white to off-white lyophilized powder that dissolves readily in water and in polar organic solvents such as dimethyl sulfoxide. Aqueous solutions are clear and colorless at low concentrations. Because the peptide contains methionine, oxidation at the sulfur atom is a recognized degradation pathway, and handling notes usually call for protected, desiccated storage. Reported purity for research-grade lots is generally above 95 percent as measured by reversed-phase high-performance liquid chromatography.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
Identity and purity are commonly assessed by reversed-phase high-performance liquid chromatography, with ultraviolet detection near 214 nanometers for the peptide backbone. Mass spectrometry, either electrospray or matrix-assisted laser desorption, confirms molecular mass and detects truncation or modification products. Amino acid analysis can verify composition. Because the sequence contains no strongly absorbing aromatic residue apart from phenylalanine, detection wavelengths are chosen carefully. Purity values above 95 percent are typical for research-grade material.
Quality documentation for research-grade peptide usually includes a certificate of analysis stating purity, identity, and residual counterion content. Batch-to-batch variation in purity and salt form is a recognized issue, and comparisons across suppliers require attention to the exact counterion, for example acetate versus trifluoroacetate. Sequence verification by tandem mass spectrometry provides stronger evidence than a single mass measurement. For any study reporting biological results, the analytical method and the measured purity should be stated explicitly. Independent verification of supplier claims is considered good practice.
== Related legacy/cover bands featuring former King Crimson members == Since the early 2000s, several bands containing former, recent or current King Crimson members have toured and recorded, performing King Crimson music. Active between 2002 and 2005, the 21st Century Schizoid Band reunited several former King Crimson members who had played on the band's first four albums. The band featured Ian McDonald, Mel Collins, Peter Giles and Michael Giles (the latter subsequently replaced by Ian Wallace), and was fronted by Jakko Jakszyk, a decade prior to his own recruitment into King Crimson. The band engaged in several tours, played material from King Crimson's '60s and '70s catalogue, and recorded several live albums. The band disbanded upon Wallace's death in 2007. Since 2007, Tony Levin has led the trio Stick Men, which also features Pat Mastelotto. The band was initially completed by Chapman Stick player Michael Bernier, replaced in 2010 by touch guitarist and former Fripp student Markus Reuter. This band includes (and reinterprets) King Crimson compositions in their live sets. Reuter and Mastelotto also play together as a duo (previously called "Tuner"), within which they have been known to rework the mid-1980s King Crimson instrumental "Industry" live. Starting in 2023, Reuter, Mastelotto and Trey Gunn revived the moniker "Tuner" (re-styled as "Tu-ner") to perform music from the Double Duo era of King Crimson, plus material from each of their respective solo and combined careers.
Tea is mainly grown in Asia and Africa, with smaller areas in South America and around the Black and Caspian Seas. The four biggest tea-producing countries are China, India, Kenya and Sri Lanka, together representing 81% of world tea production. Smaller hubs of production include such places as São Miguel Island, Azores, in Portugal, and Guria, in Georgia. In 2022, global production of tea was 29.8 million tonnes, led by China with 49% and India with 20% of the world total. Kenya, Sri Lanka, and Turkey were secondary producers.
In this kind of united atom representation, one typically eliminates all explicit hydrogen atoms except those that have the capability to participate in hydrogen bonds (polar hydrogens). An example of this is the CHARMM 19 force-field. The polar hydrogens are usually retained in the model, because proper treatment of hydrogen bonds requires a reasonably accurate description of the directionality and the electrostatic interactions between the donor and acceptor groups. A hydroxyl group, for example, can be both a hydrogen bond donor, and a hydrogen bond acceptor, and it would be impossible to treat this with one OH pseudo-atom. About half the atoms in a protein or nucleic acid are non-polar hydrogens, so the use of united atoms can provide a substantial savings in computer time.
The new 23rd district covers southwestern Texas, including the Big Bend, and stretches eastward through Del Rio and Uvalde to the northern San Antonio suburbs including the west side of Stone Oak, Shavano Park and Camp Bullis with a small finger extending eastward to Lackland AFB in southwest San Antonio, and also westward to the eastern fringes of the El Paso suburbs. The incumbent is Republican Tony Gonzales, who was re-elected with 62.3% of the vote in 2024. Democrats are targeting the majority Hispanic district, which has a one-third White minority, and gave Donald Trump and Ted Cruz 56.8% and 52.9% of the vote, respectively, in 2024. Republican leaders called on Gonzales to end his re-election campaign after he admitted to having a sexual relationship with a former staff member who later died by suicide, following his earlier denial of the allegations. Gonzales ended his campaign on March 5, leading to the cancellation of the runoff and making challenger Brandon Herrera the Republican nominee. Gonzales later resigned on April 13 after he was expected to face an expulsion vote alongside Democratic representative Eric Swalwell, who was accused of sexual assault. Swalwell similarly had announced his resignation on April 13, hours before Gonzales' announcement. Despite multiple other vacancies which occurred around the same time having been filled by August, governor Greg Abbott never called an emergency special election to fill this seat, likely leaving it vacant until January 2027.
==== Australian plate ==== Lord Howe hotspot (22) 34°42′S 159°48′E, w= 0.8 az= 351° ±10° Tasmantid hotspot (39) 40°24′S 155°30′E, w= 0.8 az= 007° ±5° rate= 63 ±5 mm/yr East Australia hotspot (30) 40°48′S 146°00′E, w= 0.3 az= 000° ±15° rate= 65 ±3 mm/yr
Sources: en.wikipedia.org
==== Hodgkin-Huxley Model ==== The Hodgkin–Huxley model translates data about the current of a system at a specific voltage into time-dependent data describing the membrane potential. Experiments using this model typically rely on the same format and assumptions, but vary the differential equations to answer their particular questions. Much has been learned about vasopressin, GnRH, somatotrophs, corticotrophs, and lactotrophic hormones by employing this method.
Aminoacyl-tRNA (also aa-tRNA or charged tRNA) is tRNA to which its cognate amino acid is chemically bonded (charged). The aa-tRNA, along with particular elongation factors, deliver the amino acid to the ribosome for incorporation into the polypeptide chain that is being produced during translation. Alone, an amino acid is not the substrate necessary to allow for the formation of peptide bonds within a growing polypeptide chain. Instead, amino acids must be "charged" or aminoacylated with a tRNA to form their respective aa-tRNA. Every amino acid has its own specific aminoacyl-tRNA synthetase, which is utilized to chemically bind to the tRNA that it is specific to, or in other words, "cognate" to. The pairing of a tRNA with its cognate amino acid is crucial, as it ensures that only the particular amino acid matching the anticodon of the tRNA, and in turn matching the codon of the mRNA, is used during protein synthesis. In order to prevent translational errors, in which the wrong amino acid is incorporated into the polypeptide chain, evolution has provided for proofreading functionalities of aa-tRNA synthetases; these mechanisms ensure the proper pairing of an amino acid to its cognate tRNA. Amino acids that are misacylated with the proper tRNA substrate undergo hydrolysis through the deacylation mechanisms possessed by aa-tRNA synthetases. Due to the degeneracy of the genetic code, multiple tRNAs will have the same amino acid but different anticodons. These different tRNAs are called isoacceptors.
The leather manufacturing process is divided into three fundamental subprocesses: preparatory stages, tanning, and crusting. A further subprocess, finishing, can be added into the leather process sequence, but not all leathers receive finishing. The preparatory stages are when the hide is prepared for tanning. Preparatory stages may include soaking, hair removal, liming, deliming, bating, bleaching, and pickling. Tanning is a process that stabilizes the proteins, particularly collagen, of the raw hide to increase the thermal, chemical and microbiological stability of the hides and skins, making it suitable for a wide variety of end applications. The principal difference between raw and tanned hides is that raw hides dry out to form a hard, inflexible material that, when rewetted, will putrefy, while tanned material dries to a flexible form that does not become putrid when rewetted. Many tanning methods and materials exist. The typical process sees tanners load the hides into a drum and immerse them in a tank that contains the tanning "liquor". The hides soak while the drum slowly rotates about its axis, and the tanning liquor slowly penetrates through the full thickness of the hide. Once the process achieves even penetration, workers slowly raise the liquor's pH in a process called basification, which fixes the tanning material to the leather. The more tanning material fixed, the higher the leather's hydrothermal stability and shrinkage temperature resistance. Crusting is a process that thins and lubricates leather. It often includes a coloring operation.
== Clinical signs == Many signs are associated with PPID, but only a subset of these is displayed in any single horse. Some horses may present with chronic laminitis without other overt signs of the disease.
Sources: en.wikipedia.org
== Clinical trials == Phase I clinical trials evaluated the safety, tolerability, and pharmacokinetics of canfosfamide. Phase II trials evaluated clinical activity in various tumor types, especially ovarian cancer and non-small cell lung cancer. Phase III trials focused on its efficacy as part of combination therapy, particularly with standard chemotherapeutic agents. However, the trials did not demonstrate significant improvement in overall survival when compared to standard treatments alone.
It is possible for an entire large sand pile to reach a point where it is stable, but the addition of a single grain causes large parts of it to collapse. The avalanche is a well-known problem with large piles of snow and ice crystals on steep slopes. In dry conditions, snow slopes act similarly to sandpiles. An entire mountainside of snow can suddenly slide due to the presence of a skier, or even a loud noise or vibration.
The mammalian cell production process, as used for most biopharmaceuticals, is divided into the four main steps: (1) Cultivation, or the reproduction of the cells; (2) Fermentation, or the actual production of the protein, typically in 10,000 Liter bioreactors; (3) Purification, or the separation of the cells from the culture medium and purification, mostly by chromatography; (4) Formulation, or the conversion of the sensitive proteins to a stable form. All steps are fully automated. The low productivity of the animal culture makes the technology expensive and vulnerable to contamination, as a small amount of bacteria would soon outgrow a larger population of animal cells. Its main disadvantages are low volume productivity and the animal provenance. It is conceivable that other technologies, particularly plant cell production, will gain importance in future. Given the fundamental differences between the two process technologies, plants for mammalian cell culture technologies have to be built ex novo. The pros and cons of an involvement of a fine chemical company in cell culture technology are listed below: Pros:
== Spectroscopy == Spectroscopy is a category of characterization techniques which use a range of principles to reveal the chemical composition, composition variation, crystal structure and photoelectric properties of materials. Some common examples of spectroscopy techniques include:
== Bayesian inference of phylogeny background and bases == Bayesian inference refers to a probabilistic method developed by Reverend Thomas Bayes based on Bayes' theorem. Published posthumously in 1763 it was the first expression of inverse probability and the basis of Bayesian inference. Independently, unaware of Bayes' work, Pierre-Simon Laplace developed Bayes' theorem in 1774. Bayesian inference or the inverse probability method was the standard approach in statistical thinking until the early 1900s before RA Fisher developed what's now known as the classical/frequentist/Fisherian inference. Computational difficulties and philosophical objections had prevented the widespread adoption of the Bayesian approach until the 1990s, when Markov Chain Monte Carlo (MCMC) algorithms revolutionized Bayesian computation. The Bayesian approach to phylogenetic reconstruction combines the prior probability of a tree P(A) with the likelihood of the data (B) to produce a posterior probability distribution on trees P(A|B). The posterior probability of a tree will be the probability that the tree is correct, given the prior, the data, and the correctness of the likelihood model. MCMC methods can be described in three steps: first using a stochastic mechanism a new state for the Markov chain is proposed. Secondly, the probability of this new state to be correct is calculated. Thirdly, a new random variable (0,1) is proposed. If this new value is less than the acceptance probability the new state is accepted and the state of the chain is updated.
Sources: en.wikipedia.org
The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.
Semax is a synthetic analog of the ACTH(4-10) fragment rather than a copy of the full hormone. Truncation plus the added tail removes the steroidogenic portion of ACTH. That distinction explains why it is studied for nervous-system effects instead of adrenal stimulation.
It is registered as a prescription product in Russia and has been used there clinically, chiefly by the intranasal route. No approval exists in the United States or the European Union. Availability elsewhere typically falls under research-chemical distribution, with varying purity documentation.
Suppliers normally quote a percentage of total chromatographic peak area, most often from reversed-phase HPLC. That figure says nothing about what the remaining percentage contains, and it depends on the detection wavelength used. A mass spectrometry result is a separate and stronger check on identity.