This is a working overview of heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-06-17. Anything still debated is marked as such rather than presented as settled.
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。
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。
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.
| 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 |
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
Published studies examine a fairly narrow set of endpoints. Rodent experiments commonly measure maze learning, infarct volume after induced ischemia, and tissue levels of neurotrophic factors. Clinical reports from Russian centres describe attention, memory and recovery scores in patients after stroke or transient ischemic attack. Most of those human studies are small and few have been repeated by independent groups. Outcome measures differ between studies, which limits direct comparison.
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.
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.
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.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
probe Any reagent used to make a single measurement in a biochemical assay such as a gene expression experiment. Molecules which have a specific affinity for one or more other molecules may be used to probe for the presence of those other molecules in samples of unknown composition. Probes are often labelled or otherwise used as reporters to indicate whether or not a specific chemical reaction is taking place. See also hybridization probe.
3 (C6H5)2Hg + 2 Al → Al(C6H5)3 + 3 Hg Organomercury compounds react with halogens to give the corresponding organic halide, and palladium catalyzes cross-coupling between organomercurials and organic halides. This approach usually forms C−C bonds with low selectivity, but selectivity increases in the presence of halide salts. Carbonylation of lactones has been shown to employ Hg(II) reagents under palladium catalyzed conditions. (C−C bond formation and cis ester formation). Phenylmercuric chloride reversibly stores dichlorocarbene as phenyl(trichloromethyl)mercury. A convenient carbene source is sodium trichloroacetate:
== Related problems and reformulations == The hypercycle concept has been continuously studied since its origin. Shortly after Eigen and Schuster published their main work regarding hypercycles, John Maynard Smith raised an objection that the catalytic support for the replication given to other molecules is altruistic. Therefore, it cannot be selected and maintained in a system. He also underlined hypercycle vulnerability to parasites, as they are favoured by selection. Later on, Josef Hofbauer and Karl Sigmund indicated that in reality, a hypercycle can maintain only fewer than five members. In agreement with Eigen and Schuster's principal analysis, they argued that systems with five or more species exhibit limited and unstable cyclic behaviour, because some species can die out due to stochastic events and break the positive feedback loop that sustains the hypercycle. The extinction of the hypercycle then follows. It was also emphasized that a hypercycle size of up to four is too small to maintain the amount of information sufficient to cross the information threshold. Several researchers proposed a solution to these problems by introducing space into the initial model either explicitly or in the form of a spatial segregation within compartments. Bresch et al. proposed a package model as a solution for the parasite problem. Later on, Szathmáry and Demeter proposed a stochastic corrector machine model. Both compartmentalized systems proved to be robust against parasites.
=== Critiques and Limitations of the Agreement === The Algiers Peace Accords have been subject to substantial criticism from various stakeholders, including the Malian government, CMA, and international observers. One major critique centres on the lack of inclusivity in the agreement. The accord primarily focused on the interests of armed groups involved in the conflict, neglecting the concerns of sedentary populations. This exclusion has led to ongoing resentment and contributed to the formation of new militia groups, which further destabilised northern Mali. Another significant critique is that the accord inadvertently rewarded rebellion. By offering political and military concessions to groups that had taken up arms against the state, the peace process was seen by many in Mali as a capitulation. This perception fuelled the belief that future uprisings could extract similar concessions from the government. Additionally, the agreement's failure to address key economic drivers of the conflict, such as drug and arms trafficking, has been a notable shortcoming. Some signatories to the accord have been accused of continuing to engage in illicit trade, which undermines the peace process and fosters further instability.
Sources: en.wikipedia.org
==== Norway ==== In Norway, cider (sider) is a naturally fermented apple juice. Pear juice is sometimes mixed with the apple to get a better fermenting process started. Apples has been grown along the fjords of western Norway since the 13th century, and cider production has a long history along Hardangerfjorden and Sognefjorden. Production thrived between 1890 and 1920, but political regulations and the introduction of Vinmonopolet in 1921 reduced the commercial production. Today, more than a hundred domestic, and dozens of imported varieties are available through the state alcohol monopoly Vinmonopolet. Although they can hardly be marketed, in line with the law of 1975 prohibiting all advertising of alcoholic beverages of ABV above 2.5%, therefore the products receive little exposure despite a few favourable press reviews. In 2016 a new law opened for sale of beverages with ABV up to 22% directly from the producers, and by 2022, 130 different brands of Norwegian cider were commercially available. Ciders of low alcohol levels are widely available, mostly brands imported from Sweden; carbonated soft drinks with no alcoholic content may also be marketed as "cider".
Wenger's arrival at Arsenal was greeted with perplexity by some of the club's players, supporters and the local media. Although he was touted as a future technical director of The Football Association (FA), he was relatively unknown in English football. Glenn Moore's report in The Independent, dated 24 September 1996, highlighted the mood: "It is a measure of the insularity of the English game that when Arsène Wenger's name emerged as Arsenal's favoured candidate for their vacant manager's job many supporters were asking: 'Arsène who?'" Unlike his predecessors, Wenger was given control over transfers, contracts and training sessions, and the Arsenal board chose not to meddle in team affairs. One of his first acts as manager was to assure the experienced players they had a future at the club, but he noted the squad was "a bit tight," and needed competition for places. Wenger adopted a hands-on approach to training sessions which energised the squad, and made steps to change the drinking culture that afflicted Arsenal. Although he initially allowed players to have a pint of beer, they were forbidden to drink on days off and in the players' lounge. He later banned his players from casually drinking together. Wenger also promoted pasta as the pre-match dish, encouraged boiled chicken instead of red meat and discouraged junk food. Players received optional vitamin injections and Creatine, which reduced fatigue and improved their stamina.
The new 3rd district encompasses much of Collin County and Hunt County in the Dallas–Fort Worth Metroplex, including eastern Plano, McKinney, Allen, Wylie and Greenville, as well as much of the I-30 corridor to the east including Sulphur Springs and Mount Pleasant. The incumbent is Republican Keith Self, who was re-elected with 62.5% of the vote in 2024. Donald Trump and Ted Cruz each respectively won 60.3% and 57.7% of the vote here in 2024.
Sources: en.wikipedia.org
Stone-boiling and pit-baking were common techniques which involved heating large pebbles then transferring the hot stones into a perishable container to heat the water. This technology is typified in the Middle Palaeolithic example of the Abri Pataud hearths.
He helped to revive the Ginsberg crèche, a daycare for children of working mothers, and establish a Ginsberg education fund to raise bursaries for promising local students. He helped establish Njwaxa Home Industries, a leather goods company providing jobs for local women. In 1975, he co-founded the Zimele Trust, a fund for the families of political prisoners. Biko endorsed the unification of South Africa's black liberationist groups – among them the BCM, PAC, and African National Congress (ANC) – in order to concentrate their anti-apartheid efforts. To this end, he reached out to leading members of the ANC, PAC, and Unity Movement. His communications with the ANC were largely via Griffiths Mxenge, and plans were being made to smuggle him out of the country to meet Oliver Tambo, a leading ANC figure. Biko's negotiations with the PAC were primarily through intermediaries who exchanged messages between him and Sobukwe; those with the Unity Movement were largely via Fikile Bam.
Artificial chromosomes are manufactured chromosomes in the context of yeast artificial chromosomes (YACs), bacterial artificial chromosomes (BACs), or human artificial chromosomes (HACs). An artificial chromosome can carry a much larger DNA fragment than other vectors. YACs and BACs can carry a DNA fragment up to 300,000 nucleotides long. Three structural necessities of an artificial chromosome include an origin of replication, a centromere, and telomeric end sequences.
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。
The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.