semax comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-01-15. Numbers and descriptions here follow the published literature rather than marketing material.
Semax 是一种人工合成的七肽，氨基酸序列为 Met-Glu-His-Phe-Pro-Gly-Pro，单字母缩写记作 MEHFPGP。它被归类为促肾上腺皮质激素片段 ACTH(4-10) 的结构类似物，但并不天然存在于生物体内。母体片段 ACTH(4-10) 的序列为 Met-Glu-His-Phe-Arg-Trp-Gly，Semax 替换了中间两个残基，并在羧基端延长了 Pro-Gly-Pro 三肽。这种延长被普遍认为能提升分子对肽酶的耐受性。
该化合物于二十世纪八十年代在俄罗斯被开发，相关工作由俄罗斯科学院分子遗传学研究所的研究团队主导。开发目标并非复制 ACTH 的完整激素活性，而是寻找保留其神经作用方向、同时去除促肾上腺皮质激素释放效应的短肽片段。研究记录显示，这一方向促成了多个相关短肽的合成与筛选，而 Semax 是其中被研究最广泛的一个。当地文献常以 Семакс 这一名称指代它。
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。
溶液状态的稳定性明显低于冻干粉。肽类在水溶液中可能经历水解、氧化与聚集，其中甲硫氨酸和天冬酰胺等残基常是敏感位点。Semax 含有甲硫氨酸，因此氧化风险相对突出。工作液一般主张现配现用，或冷藏并在数日内用尽。缓冲液种类、pH 和离子强度都会影响降解速率，而关于最佳条件的公开数据并不统一。
| Property | Value | Notes |
|---|---|---|
| 化学类别 | 合成七肽 | ACTH(4-10) 结构类似物 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | 单字母写作 MEHFPGP |
| 分子量 | 约 813.9 Da | 随确切形式和盐型略有变化 |
| 常见同义词 | ACTH(4-10) 类似物 | 俄语文献称 Семакс |
| 开发来源 | 俄罗斯 | 二十世纪八十年代 |
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It was derived from the ACTH(4-10) fragment, a short segment of adrenocorticotropic hormone that lacks the hormonal activity associated with the full-length peptide. Researchers at the Institute of Molecular Genetics in Moscow developed the compound during the 1980s. It has been registered as a pharmaceutical product in Russia and several neighbouring countries, where it is supplied as a nasal solution, and it is also sold internationally as a research chemical.
The proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
Material sold for laboratory use varies widely in stated purity and documentation. A certificate of analysis should list the analytical method, the column and detector used, and the observed purity value. Independent verification by an outside laboratory is the practical way to confirm identity when documentation is absent or internally inconsistent. Regulatory status differs by country, and a product legal in one jurisdiction may be unapproved or controlled in another.
=== Reactions with carbanion equivalents === Carboxylic acids react with Grignard reagents and organolithiums to form ketones. The first equivalent of nucleophile acts as a base and deprotonates the acid. A second equivalent will attack the carbonyl group to create a geminal alkoxide dianion, which is protonated upon workup to give the hydrate of a ketone. Because most ketone hydrates are unstable relative to their corresponding ketones, the equilibrium between the two is shifted heavily in favor of the ketone. For example, the equilibrium constant for the formation of acetone hydrate from acetone is only 0.002. The carboxylic group is the most acidic in organic compounds.
Once the allies had penetrated deep into Iraqi territory, they turned eastward, launching a flank attack against the elite Republican Guard before it could escape. The Iraqis resisted fiercely from dug-in positions and stationary vehicles, and even mounted armored charges. Unlike many previous engagements, the destruction of the first Iraqi tanks did not result in a mass surrender. The Iraqis suffered massive losses and lost dozens of tanks and vehicles, while US casualties were comparatively low, with a single Bradley knocked out. Coalition forces pressed another 10 km (6.2 mi) into Iraqi territory, and captured their objective within three hours. They took 500 prisoners and inflicted heavy losses, defeating Iraq's 26th Infantry Division. A US soldier was killed by an Iraqi land mine, another five by friendly fire, and 30 wounded during the battle. Meanwhile, British forces attacked Iraq's Medina Division and a major Republican Guard logistics base. In nearly two days of some of the war's most intense fighting, the British destroyed 40 enemy tanks and captured a division commander. Meanwhile, US forces attacked the village of Al Busayyah, meeting fierce resistance. The US force destroyed military hardware and took prisoners, while suffering no casualties. On 25 February 1991, Iraqi forces fired a Scud missile at an American barracks in Dhahran, Saudi Arabia. The missile attack killed 28 US military personnel. The coalition's advance was much swifter than US generals had expected.
=== GPR139 receptor === Big dynorphin is one of the activators of the GPR139, a G protein-coupled receptor (GPCR), recently deorphanized as a dynorphin receptor. In a wide neuropeptide library screen it exhibited one of the highest efficacies among prodynorphin-derived peptides. At low concentrations, dynorphins predominantly activate canonical opioid receptors (KOR, MOR, DOR), while at higher concentrations, they additionally recruit GPR139. This receptor couples to Gq/11 G protein-mediated signaling, which is mechanistically opposite to the Gi/o inhibitory signaling of classical opioid receptors. This permits GPR139 to function as a molecular homeostatic brake: when dynorphin reaches high concentrations during intense stress or pain, simultaneous GPR139 activation counteracts excessive opioid receptor signaling through excitatory signaling pathways, preventing pathological over-inhibition of neuronal activity.
Sources: en.wikipedia.org
== Function == Asparagine synthetase is required for normal development of the brain. Asparagine is also involved in protein synthesis during replication of poxviruses. The addition of N-acetylglucosamine to asparagine is performed by oligosaccharyltransferase enzymes in the endoplasmic reticulum. This glycosylation is involved in protein structure and function.
Bioanalysis is a sub-discipline of analytical chemistry covering the quantitative measurement of xenobiotics (drugs and their metabolites, and biological molecules in unnatural locations or concentrations) and biotics (macromolecules, proteins, DNA, large molecule drugs, metabolites) in biological systems.
The numerous added equipment and consumables for the day-long mission boosted the weight of Faith 7 considerably; it now weighed over 3,000 pounds (1,400 kg). On March 15, the Atlas was rolled out of the factory a second time and passed tests with flying colors; Convair engineers expressed confidence that this "was their best bird yet." The booster actuators were offset slightly to prevent a recurrence of the liftoff roll transient that occurred on Mercury-Atlas 8. Several minor modifications were made to 130D as a result of postflight findings from failed Atlas launches over the previous year. These included adding a plastic liner to the inside of the turbopumps to prevent the turbine blades from rubbing against the casing and triggering an explosion from a friction spark, improvements to the wiring of the programmer, and additional steps taken to prevent the possibility of a fire breaking out in or around the thrust section. The upgraded MA-2 engines featured baffled injector heads and a hypergolic igniter, eliminating any concerns of rough combustion or the need for hold-down time prior to liftoff. As such, the RCC (Rough Combustion Cutoff) sensors on 130D were operated open loop and for qualitative purposes only. The propellant conserved by not performing the three second hold-down time would allow a longer booster burn. On Mercury-Atlas 8, 112 gallons of fuel were removed prior to launch and so an extended burn was not possible even with eliminating the hold-down, but on this flight there would be enough propellant to extend burn time.
Sources: en.wikipedia.org
=== ThermoFluor of membrane proteins === Membrane proteins are often isolated in the presence of hydrophobic solubilizing agents that can partition hydrophobic-binding dyes like 1,8-ANS and SYPRO orange and generate a fluorescence background that obscures observation of a Thermofluor protein melting signal. Nevertheless, careful optimization of conditions (e.g., to avoid micelle formation of the solubilizing agent) can often produce satisfactory assay conditions
For example in the E1 transition, unless Δ l = ± 1, Δ ml = 0 or ± 1, Δ ms = 0, and Δ n = any integer, the equation above will yield a value equal to zero and the transition would be known as a “forbidden transition”. For example, this would occur for certain cases like when Δ l = 2. In this case, the transition would not be allowed and therefore would be much weaker than an allowed transition. These specific values for the changes in quantum numbers are known as the selection rules for the allowed transitions and are shown for common transitions in the table below:
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July 23, 2010: United Kingdom The ONS released preliminary figures showing that economic growth had accelerated from 0.3% in Q1 2010 to 1.1% in Q2. This is almost double the original forecast of 0.6% growth, and the news is a welcome surprise. In late August, this figure was revised up to 1.2% growth as a result of greater construction output. However, large budget cuts are being put into action by the new coalition government to tackle the £163bn budget deficit that the country faces.
Sources: en.wikipedia.org
不是。Semax 是完全人工合成的七肽，自然界中没有对应的已知肽段。它的设计灵感来自促肾上腺皮质激素片段 ACTH(4-10)，但序列经过了替换和延长。
Semax 被描述为 ACTH(4-10) 的结构类似物，两者共享部分序列特征。它保留了该片段的部分神经相关活性方向，但去除了完整片段带来的激素释放效应。二者并非同一物质，也不能互相替代。
加入的 Pro-Gly-Pro 三肽被普遍认为能提升分子对蛋白水解酶的稳定性。这种设计让短肽在体内维持时间更长。具体延长的程度以及不同组织中是否一致，文献中仍存在不同报告。
一般不建议常温长期保存。多数说明指向 -20 °C 冷冻避光。常温运输通常被视为短期可接受，但会加快降解风险。