The short version of heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-09-30. Anything still debated is marked as such rather than presented as settled.
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.
Verification of a supplied batch generally combines a certificate of analysis with independent testing, because certificates are self-reported documents. A typical package includes a chromatographic trace, a mass spectrum, and a stated water or counter-ion content. Batch-to-batch consistency matters more than a single purity figure when results are compared across experiments. No single mandatory standard governs research-grade peptide release, so laboratories are expected to define their own acceptance criteria. Residual trifluoroacetate from purification is a frequently overlooked counter-ion.
各国监管态度分化明显。俄罗斯按处方药管理，部分东欧国家留有使用记录；欧盟与美国未批准其作为药物上市，市面流通品通常标注为研究用化学品。身份差异意味着标示含量、纯度与无菌性缺少统一核查。体育领域还牵涉反兴奋剂名录，跨境携带则受目的地药品法规约束。
Semax 是人工设计的七肽，序列为 Met-Glu-His-Phe-Pro-Gly-Pro，骨架取自促肾上腺皮质激素片段 ACTH(4-10)。它于二十世纪八十年代在苏联的分子遗传学研究机构内合成。设计目标是保留该片段与注意力和记忆相关的活性，同时剔除促皮质激素释放等内分泌作用。此后俄罗斯将其登记为药品并进入临床使用。
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
| Property | Value | Notes |
|---|---|---|
| Typical purity | 95% or higher | By reversed-phase HPLC area |
| Identity method | Electrospray mass spectrometry | Confirms molecular mass |
| Purity method | Reversed-phase HPLC | Detection near 214 nm |
| Primary degradation | Methionine oxidation | Sulfoxide product, +16 Da |
| Solution storage | 2-8 °C, short term | Aliquot to avoid freeze-thaw |
常规纯度与身份确认依赖反相高效液相色谱，并辅以质谱测定分子量。氨基酸组成分析可用于验证序列构成，肽图分析则能进一步定位修饰或降解产物。杂质谱通常关注缺失序列肽、截短片段和氧化产物。不同方法的检出限并不相同，因此各实验室报告的纯度数值不宜直接横向比较。
多数实验室与市售的 Semax 以冻干粉形式提供。冻干粉通常建议保存在 -20 °C 或更低温度下，同时避免光照与反复升温。短期运输有时采用冷藏条件，但长期保存仍以冷冻为主。分包操作应尽量减少开盖次数，以降低吸湿和微生物污染的风险。开封后若未一次用完，建议在干燥环境中密封并尽快放回低温储存。
The parent fragment ACTH(4-10) carries the sequence Met-Glu-His-Phe-Arg-Trp-Gly. Semax replaces the arginine and tryptophan positions with a proline-glycine-proline tail, giving Met-Glu-His-Phe-Pro-Gly-Pro. That change removes residues associated with adrenal stimulation, so the peptide does not drive cortisol release the way full ACTH does. This distinction shapes how the compound is grouped in the literature, where it sits with neuropeptides and peptide neuromodulators rather than with corticosteroids.
Regulatory status varies sharply by country. Semax is registered for medical use in Russia, where it appears in formularies as a nasal solution, and it also holds registration in a small number of neighbouring states. It has no approval from the United States Food and Drug Administration or the European Medicines Agency, and it is not a scheduled controlled substance in most jurisdictions. Elsewhere it circulates mainly as laboratory material, so purity documentation comes from suppliers rather than from a national pharmacopoeia.
Semax is a synthetic peptide created in the Soviet Union during the early 1980s by researchers working in Moscow. It was built from the short adrenocorticotropic hormone fragment known as ACTH(4-10), and the chain was then extended with three additional amino acids. The resulting molecule was named semax and entered clinical use in Russia in 1994. It is generally described as a nootropic and neuroprotective agent rather than as a hormone analogue.
N-methylimidazole is slightly more basic than imidazole but is otherwise similar, if more lipophilic. Many salts of [M(imidazole-1-R)6]2+ are known (R = alkyl, vinyl, etc.). 2-Methylimidazoles are somewhat bulky ligands owing to the steric clash between the 2-methyl group and other ligands in octahedral complexes. A modified benzimidazole ligand is found in all versions of vitamin B12.
Research published by the RAC indicates that the target set by the UK government for installing rapid or ultra-rapid chargers near motorways was missed during 2023. Provisional data released by the Met Office indicates 2023 was the second warmest year on record in the UK behind 2022, with Wales and Northern Ireland experiencing their warmest year on record during 2023. 16-year-old Luke Littler beats Rob Cross to reach the World Darts Championship final, making him the youngest person to reach the final; overtaking Kirk Shepherd who was 21 years and 88 days old when he reached the 2008 final. 3 January Luke Littler becomes the youngest finalist of the PDC World Darts Championship as he faces Luke Humphries in the 2024 final at the age of 16 years and 348 days. Humphries wins the final. Halifax, the UK's largest moneylender, cuts its mortgage rates by almost 1%, with other banks and lenders following. 4 January Prime Minister Rishi Sunak says his "working assumption" is that the general election will take place in the second half of this year. Sainsbury's announces that they will offer pay rises from March as supermarkets continue their battle to retain workers. The increase means that all their workers will be paid the voluntary Real Living Wage, which is higher than the compulsory National Living Wage. A man is arrested after firing shots at a cinema, newsagent, and a house in Croxteth, Liverpool.
=== Other === In addition to their function in respiration, the lungs have a number of other functions. They are involved in maintaining homeostasis, helping in the regulation of blood pressure as part of the renin–angiotensin system. The inner lining of the blood vessels secretes angiotensin-converting enzyme (ACE) an enzyme that catalyses the conversion of angiotensin I to angiotensin II. The lungs are involved in the blood's acid–base homeostasis by expelling carbon dioxide when breathing. The lungs also serve a protective role. Several blood-borne substances, such as a few types of prostaglandins, leukotrienes, serotonin and bradykinin, are excreted through the lungs. Drugs and other substances can be absorbed, modified or excreted in the lungs. The lungs filter out small blood clots from veins and prevent them from entering arteries and causing strokes. The lungs also play a pivotal role in speech by providing air and airflow for the creation of vocal sounds, and other paralanguage communications such as sighs and gasps. Research suggests a role of the lungs in the production of blood platelets.
A molecule is the smallest indivisible portion of a pure chemical substance that has its unique set of chemical properties, that is, its potential to undergo a certain set of chemical reactions with other substances. However, this definition only works well for substances that are composed of molecules, which is not true of many substances (see below). Molecules are typically a set of atoms bound together by covalent bonds, such that the structure is electrically neutral and all valence electrons are paired with other electrons either in bonds or in lone pairs. Thus, molecules exist as electrically neutral units, unlike ions. When this rule is broken, giving the "molecule" a charge, the result is sometimes named a molecular ion or a polyatomic ion. However, the discrete and separate nature of the molecular concept usually requires that molecular ions be present only in well-separated form, such as a directed beam in a vacuum in a mass spectrometer. Charged polyatomic collections residing in solids (for example, common sulfate or nitrate ions) are generally not considered "molecules" in chemistry. Some molecules contain one or more unpaired electrons, creating radicals. Most radicals are comparatively reactive, but some, such as nitric oxide (NO) can be stable.
Fibrinogen gamma chain, also known as the fibrinogen gamma gene (FGG), is a human gene found on chromosome 3. The protein encoded by this gene is the gamma component of fibrinogen, a blood-borne glycoprotein composed of three pairs of nonidentical polypeptide chains. Following vascular injury, fibrinogen is cleaved by thrombin to form fibrin which is the most abundant component of blood clots. In addition, various cleavage products of fibrinogen and fibrin regulate cell adhesion and spreading, display vasoconstrictor and chemotactic activities, and are mitogens for several cell types. Mutations in this gene lead to several disorders, including dysfibrinogenemia, hypofibrinogenemia and thrombophilia. Alternative splicing of the mRNA chain results in two transcript variants; the common γA chain and the alternatively spliced γ' chain. Approximately 10% of the total plasma fibrinogen consists of γA/γ' fibrinogen, with <1% consisting of γ'/γ' fibrinogen. Increased and decreased levels of γA/γ' fibrinogen have been associated with coronary artery disease and deep vein thrombosis respectively. In the lung parenchyma of smokers, upregulation of FGG transcript levels has been reported.
Sources: en.wikipedia.org
To do this, known controls are tested consecutively with unknown samples. By comparing the readouts of the controls with their known profiles the instrument can be confirmed to have been working properly at the time the unknowns were tested. Standards are also used to determine the instrument's limit of detection and limit of quantification for various common substances. Calculated quantities must be above the limit of detection to be confirmed as present and above the limit of quantification to be quantified. If the value is below the limit the value is not considered reliable.
According to Druze tradition, Jesus sought sanctuary on this summit and held a clandestine meeting with his disciples there. Druze believe that Hamza ibn Ali was a reincarnation of Jesus, and that Hamza ibn Ali is the true Messiah, who directed the deeds of the Messiah Jesus "the son of Joseph and Mary", but when Jesus "the son of Joseph and Mary" strayed from the path of the true Messiah, Hamza filled the hearts of the Jews with hatred for him – and for that reason, they crucified him, according to the Druze manuscripts. Despite this, Hamza ibn Ali took him down from the cross and allowed him to return to his family, to prepare men for the preaching of his religion. In an epistle ascribed to one of the founders of Druzism, Baha al-Din al-Muqtana, probably written sometime between AD 1027 and AD 1042, accused the Jews of crucifying Jesus. The Druze believe that each spokesmen or prophets (natiq) has a "foundation" or "guardian" who is responsible for the esoteric, interpretative law, while the spokesmen or prophets (natiq) himself presents the apparent, obligatory law. According to Druze belief, Jesus, son of Joseph and Mary, the first limit and fifth spokesman or prophet natiq, appeared and replaced Moses' law with his own, proclaiming his message and appointing Simon Peter (Sham'un al-Safa) as his foundation. He had twelve apostles who called people to worship and unify the God and to obey Jesus, considered the son of the God the Father. However, his followers did not fully understand his words and symbols.
The FDA's Office of Prescription Drug Promotion (OPDP) has responsibilities that revolve around the review and regulation of prescription drug advertising and promotion. This is achieved through surveillance activities and the issuance of enforcement letters to pharmaceutical manufacturers. Advertising and promotion for over-the-counter drugs is regulated by the Federal Trade Commission. The FDA also implements regulatory oversight through engagement with third-party enforcer firms. It expects pharmaceutical companies to ensure that third-party suppliers and labs comply with the agency's health and safety guidelines. The drug advertising regulation contains two broad requirements: (1) a company may advertise or promote a drug only for the specific indication or medical use for which it was approved by FDA. Also, an advertisement must contain a "fair balance" between the benefits and the risks (side effects) of a drug. The regulation of drug advertising in the U.S. is divided between the Food and Drug Administration (FDA) and the Federal Trade Commission (FTC), based on whether the drug in question is a prescription drug or an over-the-counter (OTC) drug. The FDA oversees the advertising of prescription drugs, while the FTC regulates the advertising of OTC drugs. The term off-label refers to the practice of prescribing a drug for a different purpose than what the FDA approved. Due to this approval requirement, manufacturers were prohibited from advertising COVID-19 vaccines during the period in which they had only been approved under Emergency Use Authorization.
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. By weight, it is considered a relatively cheap resin and a fairly poor barrier to oxygen and water vapor, with a relatively low melting point. Polystyrene is one of the most widely used plastics, with the scale of its production being several million tonnes per year. Polystyrene is naturally transparent to visible light, but can be colored with colorants. Uses include protective packaging (such as packing peanuts and optical disc jewel cases), containers, lids, bottles, trays, tumblers, disposable cutlery, models, and (as an alternative material to vinyl) phonograph records. As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C, its glass transition temperature. It becomes rigid again when cooled. This temperature behaviour, which can be controlled by photocrosslinking, is exploited for extrusion (as in Styrofoam) and also for molding and vacuum forming, since the material can cast in molds with fine detail. Under ASTM standards, polystyrene is regarded as not biodegradable. It is accumulating as a form of litter in the outside environment, particularly along shores and waterways, especially in its foam form, and in the oceans.
== Production == Natural menthol is obtained by freezing peppermint oil. The resultant crystals of menthol are then separated by filtration. Total world production of menthol in 1998 was 12,000 tonnes of which 2,500 tonnes was synthetic. In 2005, the annual production of synthetic menthol was almost double. Prices are in the $10–20/kg range with peaks in the $40/kg region but have reached as high as $100/kg. In 1985, it was estimated that China produced most of the world's supply of natural menthol, although it appears that India has pushed China into second place. Menthol is manufactured as a single enantiomer (94% e.e.) on the scale of 3,000 tonnes per year by Takasago International Corporation. The process involves an asymmetric synthesis developed by a team led by Ryōji Noyori, who won the 2001 Nobel Prize for Chemistry in recognition of his work on this process:
Sources: en.wikipedia.org
Dry powder is normally held at -20 °C or lower, away from light and moisture. Sealed vials can also be kept at 2-8 °C for shorter intervals. Warming to room temperature before opening prevents condensation.
In solution, hydrolysis of peptide bonds and oxidation of the methionine residue are the principal concerns. Oxidation converts methionine to its sulfoxide form, shifting the mass by sixteen daltons. Both processes are slowed by cold storage and by avoiding alkaline conditions.
A certificate documents what the supplier measured on a specific lot, not how a laboratory will use the material. Independent verification of identity and purity is common practice. Acceptance criteria should be defined before a batch is ordered.
不存在。它是依据 ACTH 的一段序列人工设计的分子，天然蛋白质中找不到与之完全相同的七肽。名称属于研究代号，而非天然物质名。