The short version of methionine sulfoxide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-12-03. Anything still debated is marked as such rather than presented as settled.
Purity assessment relies mainly on reversed-phase high-performance liquid chromatography, which separates the target heptapeptide from truncated sequences, deletion analogues, and oxidised forms. Mass spectrometry, usually coupled to liquid chromatography, confirms identity through the expected molecular ion and reveals modifications such as methionine sulfoxide formation. Amino acid analysis can verify composition, and tandem mass spectrometry supports sequence confirmation. Ultraviolet detection near 254 to 280 nanometres is convenient because the phenylalanine and histidine residues absorb in that region. Nuclear magnetic resonance is rarely used for routine release testing.
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
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。
| Property | Value | Notes |
|---|---|---|
| Typical analytical method | Reversed-phase HPLC with UV detection | Separates target peptide from truncated and oxidised forms |
| Identity confirmation | LC-MS or ESI-MS | Compares observed and calculated molecular ion |
| Primary degradation route | Methionine oxidation | Forms the sulfoxide; monitored as an early-eluting peak |
| Short-term storage | 2 to 8 degrees Celsius | Applies to working vials and reconstituted portions |
| Common synonyms | ACTH(4–10) analogue, MEHFPGP | Descriptive names used in laboratory catalogues |
== Education and early career == Tew earned a Bachelor of Science in Microbiology/Genetics from the University of Wales, Swansea in 1973 and a PhD in Biochemical Pharmacology from the University of London, where he also received postdoctoral training in 1976. He served as the Head of the Basic Pharmacology Program at the Lombardi Cancer Center from 1982 to 1985, when he became a member and later Chairman of Pharmacology at the Fox Chase Cancer Center. Concurrently, he worked as an Adjunct Associate Professor of Pharmacology at the University of Pennsylvania until 1990 and was awarded his DSc from the University of London in 1995.
Amphetamine is a central nervous system (CNS) stimulant that is used in the treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy; it is also used to treat binge eating disorder in the form of lisdexamfetamine. Historically, it has been used to treat nasal congestion and depression. Amphetamine is also used as an athletic performance enhancer and cognitive enhancer, and recreationally as an aphrodisiac and euphoriant. It is a prescription drug in many countries, and unauthorized possession and distribution of amphetamine are often tightly controlled due to the significant health risks associated with recreational use. Amphetamine was discovered as a chemical in 1887 by Lazăr Edeleanu, and then as a drug in the late 1920s. It exists as two enantiomers: levoamphetamine and dextroamphetamine. The first amphetamine pharmaceutical was Benzedrine. Pharmaceutical amphetamine is prescribed as racemic amphetamine, Adderall, dextroamphetamine, or lisdexamfetamine. Amphetamine increases monoamine and excitatory neurotransmission in the brain, with its most pronounced effects targeting the norepinephrine and dopamine neurotransmitter systems. At therapeutic doses, amphetamine causes emotional and cognitive effects such as euphoria, change in desire for sex, increased wakefulness, and improved cognitive control. It induces physical effects such as improved reaction time, fatigue resistance, decreased appetite, elevated heart rate, and increased muscle strength. Larger doses of amphetamine may impair cognitive function and induce rapid muscle breakdown.
==== Propagating homochirality from nucleic acids through a chemical network ==== Resolving homochiral RAO provides a path to homochiral RNA, which can function as both a hereditary and catalytic molecule in primitive life (see RNA world). This means that homochirality could be preserved during RNA replication, and that RNA-templated peptide synthesis could be stereoselective for amino acids. In modern cellular biology, aminoacyl-tRNA synthetases stereoselectively attach L-amino acids to D-tRNA molecule, an essential step in RNA-templated protein synthesis and a demonstration of chiral information transfer from nucleic acids to amino acids. Experimental work with prebiotic analogs of nonenzymatic aminoacyl-RNA reactions have shown that they also exhibit chiral selectivity for amino acids. For example, aminoacyl-RNA loop-closing ligation, a reaction important for increasing the stability of aminoacylated RNA and for formation of functional catalytic RNA, proceeds at up to a 200 times faster rate when D-RNA is aminoacylated with L-amino acids, and the inverse stereoselectivity is observed for L-RNA. Once homochiral peptides are produced from homochiral nucleic acids, stereoselectively could subsequently be imposed on other metabolites through the eventual development of enzyme-catalyzed reactions, just as in modern biology. Alternatively, homochiral ribozymes, thought to catalyze prebiotic chemical reactions prior to proteinaceous enzymes in the RNA world hypothesis, could have also propagated chirality to metabolic intermediates.
== Opioid equivalency table == Opioids are a class of compounds that elicit analgesic (pain killing) effects in humans and animals by binding to the μ-opioid receptor within the central nervous system. The following table lists opioid and non-opioid analgesic drugs and their relative potencies. Values for the potencies represent opioids taken orally unless another route of administration is provided. As such, their bioavailabilities differ, and they may be more potent when taken intravenously.
Sources: en.wikipedia.org
Fatty acids are also synthesized de novo within tissues with high metabolic demands, such as mammary glands (i.e., for milk fat production during lactation), immune cells (i.e., macrophages, B cells, T cells), and even within the brain (i.e., during neurogenesis). Notably, although saturated and monounsaturated fatty acids are considered non-essential, both saturated and monounsaturated fatty acids can be synthesized de novo alongside polyunsaturated fatty acids. De novo fatty acid synthesis is separated into two groups based on the compartment wherein fatty acid synthesis takes place: cytosolic fatty acid synthesis (FAS/FASI) and mitochondrial fatty acid synthesis (mtFAS/mtFASII).
=== Civil operations === An inaugural service from Moscow to Tashkent was flown on December 26, 1980, but services-proper commenced after February 1, 1981. Aeroflot first operated the Il-86 on peak domestic routes. Foreign services began in June 1981 to Eastern Europe. Services to larger West European cities began with the winter timetable starting in October that year. Charter flights to European points followed, with services on high-density medium/long-range routes within the Soviet Union coming last. Although the Il-86 was a medium-range airliner, from 1982 Aeroflot put it into scheduled service from Moscow to Havana via Shannon and Gander, "perhaps with limited payload or with additional tankerage." Other scheduled long-range services flown by the type were to Buenos Aires, Montevideo and Lima, Rio de Janeiro and São Paulo, all via Sal, Cape Verde. After the collapse of the Soviet Union in 1991, national airlines emerged in the 15 successor republics. Il-86s serving with Aeroflot administrations ("Directorates") in these nations accrued to their airlines and many were traded. From April 2002, the European Union, the US and much of the rest of the world banned noisier aircraft, including the Il-86. On October 23, 2006, Aeroflot Deputy Director General Igor Desyatnichenko said that the Il-86 was to be withdrawn from service starting November 15 that year as it operated for just two or three months in the summer."
=== Protease === OGT cleaves Host Cell Factor C1, at one or more of 6 repeating 26 amino acid sequences. The TPR domain of OGT binds to the carboxyl terminal portion of an HCF1 proteolytic repeat so that the cleavage region is in the glycosyltransferase active site above uridine-diphosphate-GlcNAc The large proportion of OGT complexed with HCF1 is necessary for HCF1 cleavage, and HCFC1 is required for OGT stabilization in the nucleus. HCF1 regulates OGT stability using a post-transcriptional mechanism, however the mechanism of the interaction with HCFC1 is still unknown.
Sources: en.wikipedia.org
Dry powder is usually kept at about -20 degrees Celsius for long-term storage and at 2 to 8 degrees Celsius for short working periods. Containers should stay sealed and protected from light and moisture to limit degradation.
Oxidation of the methionine residue to the sulfoxide is a frequently reported change, and it usually appears as an earlier-eluting peak in reversed-phase chromatography. Backbone hydrolysis products can also accumulate in aqueous solution.
Liquid chromatography coupled with mass spectrometry is the usual approach, because the observed molecular ion can be compared with a calculated mass of about 813.9 Da. Retention time alone does not establish identity.
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。