Pro-Gly-Pro tail is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-12-01. 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。
研究兴趣主要集中在神经营养因子相关的路径上，包括脑源性神经营养因子与神经生长因子的表达变化。部分实验报告称在特定条件下观察到这些因子的水平上升，但具体信号通路和剂量依赖关系仍未完全厘清。多数公开数据来自细胞模型和动物实验，人体对照研究数量有限。因此，该化合物的作用机制在文献中属于活跃讨论，而非已经确立的定论。
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.
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 |
|---|---|---|
| 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 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.
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.
genetic information stored in the sequence of DNA molecules a "messenger" RNA molecule to carry the instructions for making one protein to the cytoplasm adaptor molecules ("they might contain nucleotides") to match short sequences of nucleotides in the RNA messenger molecules to specific amino acids ribonucleic-protein complexes that catalyse the assembly of amino acids into proteins according to the messenger RNA The adaptor molecules were eventually shown to be tRNAs and the catalytic "ribonucleic-protein complexes" became known as ribosomes. An important step was the realisation by Crick and Brenner on 15 April 1960 during a conversation with François Jacob that messenger RNA was not the same thing as ribosomal RNA. Later that summer, Brenner, Jacob, and Matthew Meselson conducted an experiment which was the first to prove the existence of messenger RNA. None of this, however, answered the fundamental theoretical question of the exact nature of the genetic code. In his 1958 article, Crick speculated, as had others, that a triplet of nucleotides could code for an amino acid. Such a code might be "degenerate", with 4×4×4=64 possible triplets of the four nucleotide subunits while there were only 20 amino acids. Some amino acids might have multiple triplet codes. Crick also explored other codes in which, for various reasons, only some of the triplets were used, "magically" producing just the 20 needed combinations. Experimental results were needed; theory alone could not decide the nature of the code.
Valve claimed consumers were not entitled to a refund for digitally downloaded games purchased from Valve via the Steam website or Steam Client (in any circumstances); Valve had excluded statutory guarantees or warranties that goods would be of acceptable quality; and Valve had restricted or modified statutory guarantees or warranties of acceptable quality. During the prosecution of this case, Valve implemented a refund policy for Steam purchases, but the case still reviewed Valve's actions prior to the onset of the lawsuit. The court overseeing the case sided with the ACCC in assigning a A$3 million (about US$2.1 million) fine against Valve in December 2016, as well as requiring Valve to inform Australian consumers of their rights when purchasing games from Steam. Valve appealed the court's determination that it "engaged in misleading or deceptive conduct and made false or misleading representations about consumer guarantees", as well as seeking to appeal the fine, but the Australian higher courts rejected the appeals in December 2017. In January 2018, Valve filed for a "special leave" of the court's decision, appealing to the High Court of Australia. The High Court dismissed this claim in April 2018, asserting that Valve still was liable under Australian law since it sold products directly to its citizens.
=== Indole butyrate disk === An indole butyrate disc is used to differentiate between Neisseria gonorrhoeae (negative result) and Moraxella catarrhalis (positive result). This test involves a butyrate disk, which when smeared with a culture, will change color for a positive result after 5 minutes of incubation. A blue color is the result of a positive test.
Sources: en.wikipedia.org
In organic chemistry, a carbodiimide (systematic IUPAC name: methanediimine) is a functional group with the formula RN=C=NR. On Earth they are exclusively synthetic, but in interstellar space the parent compound HN=C=NH has been detected by its maser emissions. A well known carbodiimide is dicyclohexylcarbodiimide, which is used in peptide synthesis. Dialkylcarbodiimides are stable. Some diaryl derivatives tend to convert to dimers and polymers upon standing at room temperature, though this mostly occurs with low melting point carbodiimides that are liquids at room temperature. Solid diaryl carbodiimides are more stable, but can slowly undergo hydrolysis in the presence of water over time.
Recent evidence has suggested that this macrophage activation may involve a phenomenon known as innate immune memory. Also known as trained immunity, innate immune memory is the innate immune system's ability, upon exposure to oxLDL or other atherogenic stimuli, to undergo epigenetic and metabolic reprogramming, leading to a hyperaugmented immune response following a secondary, non-specific restimulation. Under the microscope, the lesion now appears as a fatty streak. Foam cells eventually die and further propagate the inflammatory process. In addition to these cellular activities, there is also smooth muscle proliferation and migration from the tunica media into the intima in response to cytokines secreted by damaged endothelial cells. This leads to the formation of a fibrous capsule covering the fatty streak. Intact endothelium can prevent this smooth muscle proliferation by releasing nitric oxide.
Alan Hutchinson Fairlamb, CBE, FRSE, FLS, FMedSci, FRSB (born 30 April 1947, Newcastle upon Tyne, England) is a Wellcome Trust Principal Research Fellow and Professor of Biochemistry in the Division of Biological Chemistry and Drug Discovery at the School of Life Sciences, University of Dundee, Scotland. From 2006-2011 he was a member of the Scientific and Technical Advisory Committee of the Special Programme for Research and Training in Tropical Diseases (TDR) -- an independent global programme of scientific collaboration co-sponsored by UNICEF, UNDP, the World Bank and WHO. Currently he is a member of the governing board of the Tres Cantos Open Lab Foundation, whose aim is to accelerate the discovery and development of medicines to tackle diseases of the developing world in an open collaborative manner. Fairlamb and his team have studied the protozoan parasites causing three different diseases - sleeping sickness, Chagas disease and leishmaniasis. He was one of the 250 scientists involved in the genome sequencing of these parasites. In 1985, Fairlamb discovered a unique thiol compound present in these parasites, and named it trypanothione. This thiol metabolite is quite different from its human equivalent, glutathione. Trypanothione allows the parasites to fend off free radicals and other toxic oxidants produced by the immune system of the infected patient, and was shown to be vital for parasite survival and virulence. For instance, antimonials neutralize the Leishmania parasite's antioxidant defence system, allowing the patient to clear the infection.
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。
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.