If you have been reading about heptapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-06-02. Where a claim depends on a specific study, the study is described rather than over-claimed.
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 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.
| 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. 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.
Laboratory work points toward modulation of neurotrophic signaling, particularly expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal tissue. Studies also describe effects on monoamine turnover, inflammatory mediators, and oxidative markers. These observations come mainly from animal models and cultured cells, so the causal chain in humans is not firmly established. Whether the reported molecular changes translate into measurable clinical benefit is an open question. Reviews generally present the mechanism as plausible rather than demonstrated.
The presidency of Ronald Reagan (1981–89) saw a significant increase in federal focus on drug interdiction and prosecution. Shortly after his inauguration, Reagan announced, "We're taking down the surrender flag that has flown over so many drug efforts; we're running up a battle flag." From 1980 to 1984, the annual budget of the Federal Bureau of Investigation (FBI) drug enforcement units went from $8 million to $95 million. In 1982, Vice President George H. W. Bush and his aides began pushing for the involvement of the Central Intelligence Agency (CIA) and the US military in drug interdiction efforts. Early in the Reagan term, First Lady Nancy Reagan, with the help of an advertising agency, began her youth-oriented "Just Say No" anti-drug campaign. Propelled by the First Lady's tireless promotional efforts through the 1980s, "Just Say No" entered the American vernacular. Later research found that the campaign had little or no impact on youth drug use. One striking change attributed to the effort: public perception of drug abuse as America's most serious problem, in the 2–6% range in 1985, rose to 64% in 1989. In January 1982, Reagan established the South Florida Task Force, chaired by Bush, targeting a surge of cocaine and cannabis entering through the Miami region, and the sharp rise in related crime. The project involved the DEA, the Customs Service, the FBI and other agencies, and Armed Forces ships and planes. It was called the "most ambitious and expensive drug enforcement operation" in US history; critics called it an election year political stunt.
== Research and teaching == Strobel's research focuses on the biophysics and biochemistry of catalytic RNAs, including riboswitches and peptidyl transferase. His group developed the early methods of Nucleotide Analog Interference Mapping, used to determine the importance of particular functional groups in a structured RNA molecule. Strobel's group solved the x-ray crystal structure of the full length Azoarcus Group I catalytic intron, the glmS ribozyme, and the c-di-GMP riboswitch. He has also collaborated with the Thomas A. Steitz lab at Yale on structural studies toward better understanding the mechanism of ribosomal peptide synthesis. He was twice named a HHMI professor to promote undergraduate science education. With this award he instituted an undergraduate research course, the Rainforest Expedition and Laboratory, which explored microbial and chemical diversity in the world's rainforests as a means to inspire undergraduate students in the sciences. He has led groups of undergraduate students into the rainforest over spring break to hunt for novel endophytes that live inside plants. Following fieldwork, students then isolated microbes and tested them for interesting properties, discovering a variety of organisms including novel fungi with new biological and chemical properties, including Pestalotiopsis microspora, of which some strains degrade polyurethane.
=== Adhesion to dental metal === Tensile bond strengths to titanium plates treated with 3 experimental primers consisting of MDP in 3 concentrations were tested. The data obtained strongly suggest that MDP is effective to improve the adhesive performance of resin to titanium.
Sources: en.wikipedia.org
Growth factors (PDGF, TGF-β) and fibronectin encourage proliferation, migration to the wound bed, and production of ECM molecules by fibroblasts. Fibroblasts also secrete growth factors that attract epithelial cells to the wound site. Hypoxia also contributes to fibroblast proliferation and excretion of growth factors, though too little oxygen will inhibit their growth and deposition of ECM components, and can lead to excessive, fibrotic scarring.
== Alternative names == Type V collagen has a few alternative names alpha 1 These include: type V collagen preproprotein, CO5A1_HUMAN, and collagen type V alpha. Type V collagen can also be abbreviated to COLV or collagen V.
A collagen hybridizing peptide (CHP) is a synthetic peptide sequence with typically 6 to 10 repeating units of the Gly-Xaa-Yaa amino acid triplet, which mimics the hallmark sequence of natural collagens. A CHP peptide usually possesses a high content of proline and hydroxyproline in the Xaa and Yaa positions, which confers it a strong propensity to form the collagen's unique triple helix conformation. In the single-stranded (monomeric) status, the peptide can recognize denatured collagen strands in tissues by forming a hybridized triple helix with the collagen strands. This occurs via the triple helical chain assembly and inter-chain hydrogen bonding, in a manner similar to primers binding to melted DNA strands during PCR. The binding does not depend on a specific sequence or epitope on collagen, enabling CHPs to target denatured collagen chains of different types.
Sources: en.wikipedia.org
== Etymology and usage == The accepted etymology identifies the first component of the word crowbar with the bird-name "crow", perhaps due to the crowbar's resemblance to the feet or beak of a crow. The first use of the term is dated back to c. 1400. It was also called simply a crow, or iron crow; William Shakespeare used the latter, as in Romeo and Juliet, Act 5, Scene 2: "Get me an iron crow and bring it straight unto my cell." In Daniel Defoe's 1719 novel Robinson Crusoe, the protagonist lacks a pickaxe so uses a crowbar instead: "As for the pickaxe, I made use of the iron crows, which were proper enough, though heavy."
Unsupervised learning analyses a stream of data, finds patterns, and makes predictions without any other guidance. Supervised learning requires labelling the training data with the expected answers, and comes in two main varieties: classification (where the program must learn to predict what category the input belongs in) and regression (where the program must deduce a numeric function based on numeric input). Reinforcement learning is when the agent is rewarded for good responses and punished for bad ones. The agent learns to choose responses that are classified as "good". Transfer learning is when the knowledge gained from one problem is applied to a new problem. Deep learning is a type of machine learning that runs inputs through biologically inspired artificial neural networks for all of these types of learning. Computational learning theory can assess learners by computational complexity, sample complexity (how much data is required), or other notions of optimisation.
=== Peru === The travelers gradually descended into the cinchona forests and former Inca territories. In Riobamba, they stayed with Montufar’s brother, where Humboldt accessed rare sixteenth-century manuscripts written in an extinct dialect and later translated into Spanish. These documents described pre-conquest events and the major eruption of Nevado de Altar volcano, which affected nearby towns with ash for seven years. Traveling from Riobamba to Cuenca across the Paramo of Azuay, Humboldt studied the remains of the Inca road, notable for its precise porphyry paving and straightness, comparable to Roman roads, leading to Cuzco. He also visited the ruins of Inca Tapayupangi’s palace and its summer house carved from rock, which offered impressive views and prompted Humboldt to admire Inca public works. Southward, the group had to ford the Rio Guancabamba, a tributary of the Amazon, twenty-seven times. Although not wide, the river’s strong current endangered their mules, which carried important collections. Humboldt described the anxiety of watching their passage. Further along, he observed the local postal system known as “el correo que nada,” where a messenger swam downstream with mail secured in a cotton handkerchief, sometimes using a balsa log to rest and stopping at huts for food and shelter. Humboldt confirmed the reliability of this system, having received mail sent this way in Paris, and noted that groups of people also traveled the river in this manner.
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。
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.