A practical reference on Methionine oxidation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-05-30. Anything still debated is marked as such rather than presented as settled.
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.
Semax is supplied as a lyophilized powder that appears white to off-white. It dissolves readily in water, phosphate-buffered saline, and other aqueous media, which simplifies preparation of working solutions for laboratory use. The nasal products registered in Russia are dilute aqueous solutions, typically around 0.1 percent peptide by weight. Organic solvents are rarely necessary and can complicate handling. Because the peptide is hygroscopic, weighing should be performed quickly and with minimal exposure to ambient humidity.
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.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It corresponds to the ACTH(4-7) fragment extended at the C-terminus by a Pro-Gly-Pro tripeptide, an addition intended to slow enzymatic breakdown. The molecular formula is C37H51N9O10S and the molecular mass is approximately 814 daltons. In the literature it is often described as an ACTH(4-10) analog, although that label reflects a naming convention as much as a precise structural relationship. The compound was developed in Russia and remains most closely associated with that research tradition.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity | ≥95% by HPLC | Research-grade material |
| Detection wavelength | 214 nm | Peptide bond absorbance |
| Reconstitution medium | Sterile water or saline | Prepare fresh or aliquot immediately |
| Storage (solution) | -80 °C, single-use aliquots | Avoid repeated freeze-thaw cycles |
| Common salt form | Acetate or trifluoroacetate | Affects mass and solubility |
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.
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.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.
Solid semax is typically supplied as a lyophilised powder that is hygroscopic and sensitive to moisture, light, and repeated temperature cycling. Long-term storage of the dry peptide is generally recommended at approximately -20 degrees Celsius, while shorter working periods may use refrigeration at 2 to 8 degrees Celsius. Vials should remain tightly closed and desiccated when brought to room temperature, because condensation can damage the material before it is weighed. Dividing a batch into aliquots is preferable to thawing one container repeatedly.
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
Today, roughly one third of the city's residents are employed by the government, and tourism is also a major source of employment. On days when two or more large cruise ships dock in the town, tourists frequently outnumber the local residents. Peat was once a prominent heating/fuel source in Stanley, and stacks of drying peat under cover can still be seen by the occasional house.
=== Cytoplasmic condensates === Lewy bodies Stress granule P-body Germline P-granules – oskar Starch granules Glycogen granules Frodosomes (Dact1) Corneal lens formation and cataracts Other cytoplasmic inclusions such as pigment granules or cytoplasmic crystals Purinosomes Misfolded protein aggregation such as amyloid fibrils or mutant Haemoglobin S (HbS) fibres in sickle cell disease Signalosomes, such as the supramolecular assemblies in the Wnt signaling pathway. It can also be argued that cytoskeletal filaments form by a polymerisation process similar to phase separation, except ordered into filamentous networks instead of amorphous droplets or granules. Bacteria Ribonucleoprotein Bodies (BR-bodies)- In recent studies it has been shown that bacteria RNA degradosomes can assemble into phase-separated structures, termed bacterial ribonucleoprotein bodies (BR-bodies), with many analogous properties to eukaryotic processing bodies (P-bodies) and stress granules. FLOE1 granules: FLOE1 is a prion-like seed-specific protein that controls plant seed germination via phase separation into biomolecular condensates. Perinuclear compartment
== LCRs and the protopeptides of the early genetic code == The amino acids with the highest frequency in LCRs are glycine and alanine, with their respective codons GGC and GCC being the most frequent, as well as complementary. In eukaryotes and more specifically in chordates (such as human, mouse, chicken, zebrafish and sea squirt), alanine- and glycine-rich LCRs are over-represented in recently formed LCRs and probably are better tolerated by the cell. Intriguingly, it has also been suggested that they represent the very first two amino acids and codons of the early genetic code. Thus, these two codons and their respective amino acids must have been constituents of the earliest oligopeptides, with a length of 10–55 amino acids and very low complexity. Based on several different criteria and sources of data, Higgs and Pudritz suggest G, A, D, E, V, S, P, I, L, T as the early amino acids of the genetic code. Trifonov's work largely agrees with this categorization and proposes that the early amino acids in chronological order are G, A, D, V, S, P, E, L, T, R. An evolutionary analysis observed that many of the amino acids of the suggested very early genetic code (with the exception of the hydrophobic ones) are significantly enriched in bacterial LCRs. Most of the later additions to the genetic code are significantly under-represented in bacterial LCRs. They thus hypothesize and propose that, in a cell-free environment, the early genetic code may have also produced low complexity oligo-peptides from valine and leucine.
=== Quantification of proteins and biomolecules === There is an increasing trend of using ICP-MS as a tool in speciation analysis, which normally involves a front end chromatograph separation and an elemental selective detector, such as AAS and ICP-MS. For example, ICP-MS can be combined with size exclusion chromatography and preparative native PAGE for identifying and quantifying metalloproteins in biofluids. Also the phosphorylation status of proteins can be analyzed. In 2007, a new type of protein tagging reagents called metal-coded affinity tags (MeCAT) were introduced to label proteins quantitatively with metals, especially lanthanides. The MeCAT labelling allows relative and absolute quantification of all kind of proteins or other biomolecules like peptides. MeCAT comprises a site-specific biomolecule tagging group with at least a strong chelate group which binds metals. The MeCAT labelled proteins can be accurately quantified by ICP-MS down to low attomol amount of analyte which is at least 2–3 orders of magnitude more sensitive than other mass spectrometry based quantification methods. By introducing several MeCAT labels to a biomolecule and further optimization of LC-ICP-MS detection limits in the zeptomol range are within the realm of possibility. By using different lanthanides MeCAT multiplexing can be used for pharmacokinetics of proteins and peptides or the analysis of the differential expression of proteins (proteomics) e.g. in biological fluids.
He was a consistent performer in an inconsistent season for the Bombers, polling 16 Brownlow votes from a total of 43 received by Essendon players, including a three-vote game in his 100th AFL game, finishing equal-seventh in the 2010 Brownlow Medal count, and having the highest number of votes for a player from a team finishing outside the final eight. Watson was once again awarded the Crichton Medal, earning 291 points, which was 50 points clear of runner-up Heath Hocking. Watson had a relatively good season in 2011 despite missing six weeks with a hamstring injury, earning 15 Brownlow votes and finishing runner-up in the Crichton Medal, losing out to up-and-coming third-year midfielder David Zaharakis. Watson completed an outstanding 2012 season by winning the Brownlow Medal with 30 votes (though he was later ruled ineligible after being suspended during the Essendon Football Club supplements saga). Along with his third Crichton Medal, he also won a handful of other accolades, including the AFLPA best captain award, the Lou Richards Medal and selection in the 2012 All-Australian team as the centreman. Watson missed three weeks with a broken collarbone in 2013, but had another consistent season, earning 17 Brownlow votes, finishing runner-up in the Crichton Medal to former St Kilda utility (and later successor as captain) Brendon Goddard, and being named on the interchange in the 2013 All-Australian team. Between 2006 and 2013, Watson finished all but one season in the top two for votes for the Crichton Medal.
Sources: en.wikipedia.org
== tRNA-targeting antibiotics == Oxazolidines (e.g. linezolid) prevent the binding of the initiator tRNA at the P-site. Oxazolidines have been demonstrated to pleiotropically affect initiator-tRNA binding, EF-P (elongation factor P)-stimulated synthesis of peptide bonds, and EF-G-mediated translocation of initiator-tRNA into the P-site. Macrolide, lincosamide and streptogramin classes of antibiotics prevent peptide bond formation and/or the translocation of tRNA from the A-site to the P-site on the ribosome that eventually leads to interference with the elongation step and thus the inhibition of protein translation.
South Korea has been described as an anchor along the first island chain. In 2025, a United States Forces Korea commander stated that US forces on the Korean Peninsula will expand their scope of operations to prepare for a potential defense of Taiwan.
=== Where lefse is found === In Norway today, most families tend to purchase their lefse rather than making it. While today's Norwegian Americans consider making lefse at Christmas a tradition, more families are turning to purchase it from the store instead. Lefse can also be found in many grocery stores around Midwestern states and the Pacific Northwest states, including Minnesota, North Dakota, South Dakota, Iowa, Wisconsin, Oregon, Alaska, and Washington. Norsland Lefse, a factory in Rushford, Minnesota, produces about a half million rounds of lefse each year. The foodway of Scandinavian lefse stretches from the Midwest all the way through northeastern Montana. Small lefse factories dot the landscape throughout this area, mostly in Norwegian communities. In the larger of these communities, Lefse can be found in grocery stores year round. In the Red River Valley specifically, "restaurants, supermarkets, and clubs all serve fish, lefse, and other specialties." Many United States Scandinavian festivals have booths to sell lefse, and it can also be ordered online.
A keystone species is a singular species within an ecosystem that others within the same ecosystem, or the entire ecosystem itself, rely upon. Keystone species' are so vital for an ecosystem that without their presence, an ecosystem could transform or stop existing entirely. One way keystone species impact an ecosystem is through their presence in an ecosystem's food web and, by extension, a food chain within said ecosystem. Sea otters, a keystone species in Pacific coastal regions, prey on sea urchins. Without the presence of sea otters, sea urchins practice destructive grazing on kelp populations which contributes to declines in coastal ecosystems within the northern pacific regions. The presence of sea otters controls sea urchin populations and helps maintain kelp forests, which are vital for other species within the ecosystem.
Often, the patient consumes about 3–4 times the RDA's specification. Toxicity of vitamin A is believed to be associated with the methods of increasing vitamin A in the body, such as food modification, fortification, and supplementation, all of which are used to combat vitamin A deficiency. Toxicity is classified into two categories: acute and chronic. The former occurs a few hours or days after ingestion of a large amount of vitamin A. Chronic toxicity takes place when about 4,000 IU/kg or more of vitamin A is consumed for a long time. Symptoms of both include nausea, blurred vision, fatigue, weight loss, and menstrual abnormalities. Excess vitamin A is suspected to be a contributor to osteoporosis. This seems to happen at much lower doses than those required to induce acute intoxication. Only preformed vitamin A can cause these problems because the conversion of carotenoids or retinyl esters into vitamin A is downregulated when physiological requirements are met; but excessive uptake of carotenoids can cause carotenosis. Excess preformed vitamin A during early pregnancy is associated with a significant increase in birth defects. These defects may be severe, even life-threatening. Even twice the daily recommended amount can cause severe birth defects. The FDA recommends that pregnant women get their vitamin A from foods containing beta carotene and that they ensure that they consume no more than 5,000 IU of preformed vitamin A (if any) per day.
Sources: en.wikipedia.org
== Further reading == Price EJ, Rauz S, Tappuni AR, Sutcliffe N, Hackett KL, Barone F, Granata G, Ng WF, Fisher BA, Bombardieri M, Astorri E, Empson B, Larkin G, Crampton B, Bowman SJ, British Society for Rheumatology Standards, Guideline and Audit Working Group (1 October 2017). "The British Society for Rheumatology guideline for the management of adults with primary Sjögren's Syndrome". Rheumatology. 56 (10): e24–e48. doi:10.1093/rheumatology/kex166. PMID 28957550.
Alveolar crest fibers (I) run from the cervical part of the root to the alveolar bone crest. Horizontal fibers (J) attach to the cementum apical to the alveolar crest fibers and run perpendicularly from the root of the tooth to the alveolar bone. Oblique fibers (K) are the most numerous fibers in the periodontal ligament, running from cementum in an oblique direction to insert into bone coronally. These fibers resist vertical and intrusive forces. Apical fibers are found radiating from cementum around the apex of the root to the bone, forming base of the socket or alveolus. Interradicular fibers are only found between the roots of multirooted teeth, such as premolars and molars. They extend from radicular cementum to interradicular alveolar bone.
== External links == Lesch-Nyhan Syndrome at NIH's Office of Rare Diseases GeneReview/NIH/UW entry on Lesch–Nyhan syndrome National Institute of Child Health and Human Development (NICHD) Love Never Sinks • Lesch Nyhan• Patient Advocacy Group
Davidson, Alan (1979). North Atlantic Seafood. ISBN 0-670-51524-8. Kurlansky, Mark (1997). Cod: A Biography of the Fish That Changed the World. New York: Walker. ISBN 0-8027-1326-2. Sanjuán, Gloria (2009). La Cocina del Bacalao. Madrid: Libro Hobby. ISBN 978-84-9736-242-9.
Sources: en.wikipedia.org
Solid peptide is best kept frozen at about minus 20 degrees Celsius in a sealed container with desiccant. It should be allowed to reach room temperature before opening to prevent condensation. Repeated warming and cooling of the same vial is discouraged.
Reversed-phase liquid chromatography establishes purity, while mass spectrometry confirms molecular mass. The two techniques are normally used together. Retention time alone is not sufficient evidence of identity.
Different counterions change the mass per unit of peptide and can shift chromatographic behavior. Two samples of equal stated purity may therefore not be directly comparable. Reports should specify the counterion whenever quantitative comparisons are made.
It is registered as a pharmaceutical product in Russia, where it is typically supplied as a nasal solution. In most other countries it is not an approved drug and is traded as a research chemical instead. Approval status depends entirely on the jurisdiction involved.