This is a working overview of heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-25 and is reviewed periodically as new material appears.
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。
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 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.
| Property | Value | Notes |
|---|---|---|
| 结构类别 | 线性合成七肽 | 无环化结构，不含二硫键 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | N 端为甲硫氨酸 |
| 分子量 | 约 814 Da | 游离碱形式的计算值 |
| 外观 | 白色至类白色粉末 | 具吸湿性 |
| 溶解性 | 易溶于水 | 亦可溶于甲醇等极性溶剂 |
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.
Scientific literature on semax is unevenly distributed. A substantial share of published work originates from a small number of laboratories in Russia, while independent replication elsewhere is limited. Human data consist mostly of small trials with short follow-up, and several reported outcomes rely on subjective rating scales. Questions about how much intact peptide reaches the central nervous system after nasal administration, and how long it persists there, are still unresolved. The compound is best described as an active research subject rather than a settled pharmacological agent.
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。
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its chain combines the first seven residues of corticotropin with a C-terminal proline-glycine-proline extension, a modification intended to slow enzymatic breakdown. The free peptide has a molecular mass near 813.9 daltons. It belongs to the class of ACTH-derived fragments studied for central nervous system activity rather than for adrenal steroid stimulation. This structural relationship to a natural hormone fragment is the usual starting point for describing the compound in the literature.
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
=== Radial flow === Difficulties may arise when the problem becomes slightly more complicated. A seemingly modest twist on the parallel flow above would be the radial flow between parallel plates; this involves convection and thus non-linearity. The velocity field may be represented by a function
== Types of human remains in museums == Museum collections contain human remains in diverse forms, including entire preserved bodies, discrete parts of the anatomy, and even art and artifacts created out of human body parts.
== Causes == Elevated blood ketone levels are most often caused by accelerated ketone production but may also be caused by consumption of exogenous ketones or precursors. When glycogen and blood glucose reserves are low, a metabolic shift occurs in order to save glucose for the brain which is unable to use fatty acids for energy. This shift involves increasing fatty acid oxidation and production of ketones in the liver as an alternate energy source for the brain as well as the skeletal muscles, heart, and kidney. Low levels of ketones are always present in the blood and increase under circumstances of low glucose availability. For example, after an overnight fast, 2–6% of energy comes from ketones and this increases to 30–40% after a 3-day fast. The amount of carbohydrate restriction required to induce a state of ketosis is variable and depends on activity level, insulin sensitivity, genetics, age and other factors, but ketosis will usually occur when consuming less than 50 grams of carbohydrates per day for at least three days. Neonates, pregnant women and lactating women are populations that develop physiological ketosis especially rapidly in response to energetic challenges such as fasting or illness. This can progress to ketoacidosis in the setting of illness, although it occurs rarely. Propensity for ketone production in neonates is caused by their high-fat breast milk diet, disproportionately large central nervous system and limited liver glycogen.
Sources: en.wikipedia.org
3'-end Also three-prime end. One of two ends of a single linear strand of DNA or RNA, specifically the end at which the chain of nucleotides terminates at the third carbon atom in the furanose ring of deoxyribose or ribose (i.e. the terminus at which the 3' carbon is not attached to another nucleotide via a phosphodiester bond; in vivo, the 3' carbon is often still bonded to a hydroxyl group). By convention, sequences and structures positioned nearer to the 3'-end relative to others are referred to as downstream. Contrast 5'-end.
Low complexity regions (LCRs) in protein sequences, also defined in some contexts as compositionally biased regions (CBRs), are regions in protein sequences that differ from the composition and complexity of most proteins that is normally associated with globular structure. LCRs have different properties from normal regions regarding structure, function and evolution.
Although it remains uncertain as to who was involved in this incident, there has been immediate assertions that North Korea is connected, as it threatened to attack South Korea's government institutions, major national banks and traditional newspapers numerous times – in reaction to the sanctions it received from nuclear testing and to the continuation of Foal Eagle, South Korea's annual joint military exercise with the United States. North Korea's cyber warfare capabilities raise the alarm for South Korea, as North Korea is increasing its manpower through military academies specializing in hacking. Current figures state that South Korea only has 400 units of specialized personnel, while North Korea has more than 3,000 highly trained hackers; this portrays a huge gap in cyber warfare capabilities and sends a message to South Korea that it has to step up and strengthen its Cyber Warfare Command forces. Therefore, in order to be prepared from future attacks, South Korea and the United States will discuss further about deterrence plans at the Security Consultative Meeting (SCM). At SCM, they plan on developing strategies that focuses on accelerating the deployment of ballistic missiles as well as fostering its defense shield program, known as the Korean Air and Missile Defense.
Sources: en.wikipedia.org
Maximum continuous exertion is limited by the onset of burning sensation from lactate accumulation in muscles. Eventually, all glycogen is exhausted, and the muscle cell enters another semi-stable state. During this transition, up-regulation of the citric acid cycle due to abundance of pyruvate is reversed, and a substantial part of the ATP pool is necessarily discharged down to AMP, which allows the citric acid cycle to be sped up by some other mechanism (perhaps by the allosteric mechanism that reacts to the lower concentration of ATP, or by amplification of the residual AMPD activity by the bloated AMP pool), until ATP production is balanced with ATP consumption. AMP conversion to adenosine, excretion to the blood (as AMP and its various metabolites), further conversion to uric acid and excretion to urine becomes significant for some time, until all AMP is eliminated from the muscle cell. The muscle movements become noticeably less precise. Breathing slows down, and from this moment reacts very weakly to the load and not at all to the perceived effort. It becomes hard to rapidly increase the load on a muscle, as in McArdle's disease, and such a rapid load increase will dump even more purines into blood and urine (looking like translucent or rust-colored sharp shiny crystals and being highly irritating). The same situation would occur if blood flow to muscle cells becomes insufficient (except that somewhat less AMP is spilled over, and somewhat more of it is metabolized inside the muscle cell).
It sought, and got, the king's acceptance to have an Irish minister, to the complete exclusion of British ministers, formally advise the king in the exercise of his powers and functions as king in the Free State. This gave the President of the Executive Council the right to directly advise the king in his capacity as His Majesty's Irish Prime Minister. Two examples of this are the signing of a treaty between the Free State and the Portuguese Republic in 1931, and the act recognising the abdication of King Edward VIII in 1936 separately from the recognition by the British Parliament. The unprecedented replacement of the use of the Great Seal of the Realm and its replacement by the Great Seal of Saorstát Éireann, which the king awarded to the Free State in 1931. (The Irish Seal consisted of a picture of King George V enthroned on one side, with the Irish state harp and the words Saorstát Éireann on the reverse. It is now on display in the Irish National Museum, Collins Barracks, Dublin.) When Éamon de Valera became President of the Executive Council (prime minister) in 1932 he described Cosgrave's ministers' achievements simply. Having read the files, he told his son, Vivion, "they were magnificent, son". The Statute of Westminster allowed de Valera, on becoming President of the Executive Council (February 1932), to go even further.
=== Defense against pathogens === The exposure to these reactive species in the respiratory burst results in pathology. This is due to oxidative damage to the engulfed bacteria. Notably, peroxynitrite is a very strong oxidising agent that can lead to lipid peroxidation, protein oxidation, protein nitration, which are responsible for its bactericidal effects. It may react directly with proteins that contain transition metal centers, such as FeS, releasing Fe2+ for the Fenton reaction. Peroxynitrite may also react with various amino acids in the peptide chain, thereby altering protein structure and subsequently, protein function. It most commonly oxidises cysteine, and may indirectly induce tyrosine nitration through other generated RNS. Altered protein function includes changes in enzyme catalytic activity, cytoskeletal organisation and cell signal transduction. Hypochlorous acid reacts with a range of biomolecules, including DNA, lipids and proteins. HClO may oxidise cysteines and methionines via their sulfhydryl groups and sulfur groups respectively. The former leads to the formation of disulfide bonds, inducing protein crosslinking. Both oxidations result in protein aggregation, and ultimately, cell death. Sulfhydryl groups can be oxidised up to three times by three HClO molecules, forming sulfenic acids, sulfinic acids and R–SO3H, which are increasingly irreversible and bactericidal. Meanwhile, methionine oxidation is reversible. HOCl can also react with primary or secondary amines, producing chloroamines which are toxic to bacteria.
Sources: en.wikipedia.org
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。
Semax 对应 ACTH 第 4 至第 10 位的片段，并在两端做了替换与延长，使其不再具备促肾上腺皮质激素的典型内分泌活性。这一改动同时改变了它在体内的稳定性与分布特征。
俄罗斯将其列为处方药物，需要医生开具处方。多数其他国家把它当作研究化合物，不能作为药品销售或宣称疗效。具体合法性取决于当地法规。
It is registered as a pharmaceutical product in Russia, where it is typically supplied as a nasal solution. In most other countries it is not an approved drug and is traded as a research chemical instead. Approval status depends entirely on the jurisdiction involved.