This is a working overview of 甲硫氨酸氧化, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-02-15. Anything still debated is marked as such rather than presented as settled.
从分子层面看，Semax 是线性七肽，没有二硫键、糖基或脂链修饰，N 端为游离氨基，C 端为游离羧基。分子含组氨酸与谷氨酸侧链，因此在水和甲醇等极性溶剂中溶解良好，在非极性溶剂中溶解有限。计算分子量约为 814 Da，与其质子化离子的质荷比吻合，可用于质谱确认。
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
纯度评估以反相高效液相色谱为主，通过主峰面积百分比给出粗略结果，再配合电喷雾质谱核对分子量。氨基酸分析可验证组成比例，手性色谱或毛细管电泳用于检查残基构型。常见杂质包括缺失序列的短肽、氧化产物与二聚体。由于多数市售品不附带完整检验报告，独立第三方检测常被用来核实标称值。
Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.
Regulatory status differs sharply between jurisdictions. In Russia the peptide is registered as a prescription nasal preparation, while agencies such as the United States Food and Drug Administration have not approved it for any indication. Products sold elsewhere are typically labeled for laboratory research only, and such labels shift responsibility for safe handling to the purchaser. Because the same name covers pharmaceutical-grade nasal drops and bulk research powder, identity and purity documentation becomes the main practical concern when comparing sources.
| Property | Value | Notes |
|---|---|---|
| 分子式 | C37H51N9O10S | 游离碱形式 |
| 等电点 | 约 6.5 | 估算值，随缓冲体系变化 |
| 主要降解途径 | 水解与氧化 | 侧链氧化最为常见 |
| 溶液储存 | 2 至 8 摄氏度避光 | 避免反复冻融 |
| 常规分析手段 | 反相色谱与质谱联用 | 氨基酸分析辅助核对 |
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.
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.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
Lyophilized material is chemically stable for extended periods when kept dry, cold, and protected from light. The powder is hygroscopic, so vials should be warmed to room temperature before opening to reduce condensation on the contents. Once dissolved, the peptide is far less stable because peptide bonds are susceptible to hydrolysis and the methionine residue can oxidize. Solutions are typically aliquoted and held at 2-8 °C for short intervals or frozen for longer ones, and repeated freeze-thaw cycles should be avoided.
Routine characterization relies on reversed-phase high-performance liquid chromatography to establish purity and on mass spectrometry to confirm molecular identity. Electrospray ionization and matrix-assisted laser desorption ionization are both used for mass verification. Amino acid analysis and peptide mapping can detect sequence errors. Common impurities include truncated sequences, methionine sulfoxide formed by oxidation, and deamidated products. Chromatograms are usually recorded near 214 nm, where the peptide backbone absorbs, and purity is reported as the percentage area of the principal peak.
=== Brown adipose tissue === Brown adipose tissue stores free fatty acids rather than triglycerides, and is especially abundant in newborn and hibernating mammals. Brown adipose tissue is involved in thermogenesis, and has a considerably higher glyceroneogenesis activity. Brown adipose tissue contains more glyceroneogenesis-related enzymes, in particular PEPC-K and glycerol kinase. PEPC-K is around 10 times more active than in white adipose tissue, and is the key regulatory enzyme that controls the activity of the pathway. Glycerol kinase phosphorylates glycerol to generate glycerol 3-phosphate, which is used to build triglycerides. An increase in the activity of glycerol kinase will increase the production of glycerol 3-phosphate. Glyceroneogenesis in brown adipose tissue contributes to thermogenesis, a process that generates heat in warm-blooded animals by delivering free fatty acids to the mitochondria. In normal conditions, thermogenesis is down-regulated by the low concentration of free fatty acids in the cytosol, because glyceroneogenesis re-esterifies fatty acids to triglycerides. When exposed to cold, a neurotransmitter hormone called norepinephrine suppresses the activity of PEPC-K and thus the glyceroneogenesis re-esterification, increasing the availability of free fatty acids within the cell. Excess free fatty acids in the cytosol will consequently be delivered to the mitochondria for thermogenesis.
Enhanced mobility – components are described as "familiar, performance-enhancing, eat-out-of-hand" foods that require little or no preparation by the soldier. The beverages are reconstituted (CamelBak compatible) and consumed right out of the pouch. No water is needed for food preparation, only for the beverage mix. The food takes the form of pocket sandwiches to be eaten by hand. Lightweight – when compared to three Meals, Ready-to-Eat, the FSR reduces the weight and volume of one day's subsistence by approximately 50%. Characteristics – has a minimum two-year shelf life at 80 °F (27 °C) and provides an average of 2,900 calories per day. The FSR has nine meals per shipping container consisting of three each of three different menus up through 2010. Since 2011 there are 9 different meal combinations per shipping container. Meals – Each pouch contains items for a breakfast, lunch, and a dinner, although there is no requirement to consume the items in any specific order.
Venom in many snakes, such as pit vipers, affects virtually every organ system in the human body and can be a combination of many toxins, including cytotoxins, hemotoxins, neurotoxins, and myotoxins, allowing for an enormous variety of symptoms. Snake venom may cause cytotoxicity as various enzymes including hyaluronidases, collagenases, proteinases and phospholipases lead to breakdown (dermonecrosis) and injury of local tissue and inflammation which leads to pain, edema and blister formation. Metalloproteinases further lead to breakdown of the extracellular matrix (releasing inflammatory mediators) and cause microvascular damage, leading to hemorrhage, skeletal muscle damage (necrosis), blistering and further dermonecrosis. The metalloproteinase release of the inflammatory mediators leads to pain, swelling, and white blood cell (leukocyte) infiltration. The lymphatic system may be damaged by the various enzymes contained in the venom leading to edema; or the lymphatic system may also allow the venom to be carried systemically. Snake venom may cause muscle damage or myotoxicity via the enzyme phospholipase A2 which disrupts the plasma membrane of muscle cells. This damage to muscle cells may cause rhabdomyolysis, respiratory muscle compromise, or both. Other enzymes such as bradykinin potentiating peptides, natriuretic peptides, vascular endothelial growth factors, proteases can also cause hypotension or low blood pressure. Toxins in snake venom can also cause kidney damage (nephrotoxicity) via the same inflammatory cytokines.
=== Films and documentaries === In 2005, the Mendonça was adapted and released in the movie "Alice", directed by Marco Martins. It was the winner of the Regards Jeunes award in the Cannes Festival in 2005. In 2019, Mendonça was mentioned in the Netflix documentary, The Disappearance of Madeline McCann. In June 2019, the production of a movie inspired in Mendonça and other missing children was announced, Sombra - Uma Mãe Sabe (Shadow - A Mom Knows). It was also announced that the recording would start in September and would end in November 2019. The script was written by Bruno Gascon. The movie Patrick (2019), directed by Gonçalo Waddington was also compared with the Mendonça case.
Sources: en.wikipedia.org
The ÄKTA explorer was the first high end FPLC (Fast Protein Liquid Chromatography) system that was developed for Life Science research by the Swedish company Pharmacia in 1994. Its purpose was to simplify and automatize protein purification. It was followed by a line of similar devices (the "Äkta" line). The product line name was transferred together with the sale of Pharmacia first to Amersham and then to GE Healthcare. Although protein purification is possible with a large range of chromatographic devices, the Äkta line represents together with BioRad's NGC line the only devices that were specifically designed for this purpose both from the hardware and software perspective. Main users of these devices are the pharmaceutical industry and academic researchers.
Based on computational work by Bach, the strain energy for Z-cyclooctenes is 7.0 kcal/mol compared to 12.4 kcal/mol for cyclooctane due to a loss of two transannular interactions. E-cyclooctene has a highly twisted double bond resulting in a strain energy of 17.9 kcal/mol. As such, the highly strained trans-cyclooctene is used as a reactive dienophile. The diene is a 3,6-diaryl-s-tetrazine which has been substituted in order to resist immediate reaction with water. The reaction proceeds through an initial cycloaddition followed by a reverse Diels Alder to eliminate N2 and prevent reversibility of the reaction. Not only is the reaction tolerant of water, but it has been found that the rate increases in aqueous media. Reactions have also been performed using norbornenes as dienophiles at second order rates on the order of 1 M−1•s−1 in aqueous media. The reaction has been applied in labeling live cells and polymer coupling.
== Immuno-based analysers == Antibodies are used by some analysers to detect many substances by immunoassay and other reactions that employ the use of antibody-antigen reactions. When concentration of these compounds is too low to cause a measurable increase in turbidity when bound to antibody, more specialised methods must be used. Recent developments include automation for the immunohaematology lab, also known as transfusion medicine.
Sources: en.wikipedia.org
=== Acquisitions === In 1989, after a four-month legal dispute to avoid a takeover, Church's Chicken became the second-largest chicken restaurant chain when it was acquired by Popeyes for $330 million. The acquisition court documents stated that Church's Chicken would close 250 of its restaurants, "keep 92 with the Church's name, rename 303 others as Popeyes and sell 440 others for about $160 million over the next four years". Merrill Lynch and a group of banks led by Canadian Imperial financed the acquisition. In 1992, Popeyes' parent company, Al Copeland Enterprises, Inc., was forced to file chapter 11 bankruptcy for the more than $400 million debt it owed its creditors for the Church's Chicken buyout. In 1993, Al Copeland Enterprises, Inc. was renamed AFC Enterprises, Inc., or America's Favorite Chicken, and became the parent company of Church's Chicken and Popeyes. In 2004, Arcapita bought Church's Chicken from AFC Enterprises, Inc., and former Domino's Pizza and Little Caesars executive Harsha Agadi became president and CEO of Church's Chicken. In 2005, because Arcapita invests in companies that respect Shari'ah principles, it removed pork products from the Church's Chicken menu. In 2007, AFC Enterprises, Inc. filed a lawsuit against Church's Chicken and former franchise group CVI Company, for allegedly colluding to breach Popeyes' franchise, development and guaranty agreements with CVI, when "Church's [Chicken] bought all 10 of CVI's Popeyes' restaurants and converted most of them to the Church's Chicken brand".
The temperature at which dew forms on a clean surface is directly related to the vapor pressure of the air. Dew point hygrometers work by placing a mirror over a closed sample chamber. The mirror is cooled until the dew point temperature is measured by means of an optical sensor. This temperature is then used to find the relative humidity of the chamber using psychrometrics charts. This method is theoretically the most accurate (+/- 0.003 aw) and often the fastest. The sensor requires cleaning if debris accumulates on the mirror.
== Contributions == Notable organizations to which Eli Lilly and Company has provided funding include the Northern Ontario School of Medicine, Population Health Research Institute (PHRI) at McMaster University, University of Toronto, University of Washington, National Press Foundation, American Society of Hematology, Endocrine Society, European Society of Cardiology, HOPE Worldwide, AdvaMed, Centre for Addiction and Mental Health (CAMH), Hospital for Sick Children (SickKids), Princess Margaret Cancer Centre, Scarborough Health Network, Sinai Health System, Sunnybrook Health Sciences Centre, Arthritis Australia, Diabetes Canada, and Juvenile Diabetes Research Foundation. Notable lobbying organizations to which the company has contributed include Foundation for the National Institutes of Health, Innovative Medicines Canada, International Federation of Pharmaceutical Manufacturers & Associations, National Health Council, and Pharmaceutical Research and Manufacturers of America.
Sources: en.wikipedia.org
电喷雾或基质辅助激光解吸电离质谱是常用手段，测得的质子化离子质荷比可换算为分子量。结果与理论值落在合理误差内，才支持结构一致的判断。
甲硫氨酸侧链含硫醚，在氧气、光照或金属离子存在时容易被氧化。氧化产物极性略增，常在色谱图上表现为主峰之前的肩峰或前伸峰。
通常建议冷藏避光，并在较短时间内使用。不存在适用于所有配方的统一期限，具体取决于浓度、缓冲体系与容器材质。
It is a short synthetic peptide built from seven amino acids: methionine, glutamic acid, histidine, phenylalanine and three prolines. The sequence derives from the 4-10 fragment of adrenocorticotropic hormone with an added proline-glycine-proline tail. No plant or animal extract is involved; the material is produced by solid-phase peptide synthesis.