This is a working overview of peptide degradation, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-08-28 and is reviewed periodically as new material appears.
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.
Solid semax is typically supplied as a lyophilised powder that is hygroscopic and sensitive to moisture, light, and repeated temperature cycling. Long-term storage of the dry peptide is generally recommended at approximately -20 degrees Celsius, while shorter working periods may use refrigeration at 2 to 8 degrees Celsius. Vials should remain tightly closed and desiccated when brought to room temperature, because condensation can damage the material before it is weighed. Dividing a batch into aliquots is preferable to thawing one container repeatedly.
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
| Property | Value | Notes |
|---|---|---|
| Molecular weight | ~813.9 Da (free heptapeptide) | N-acetylated form is about 42 Da heavier |
| Residue count | 7 (heptapeptide) | Four residues from ACTH(4-10), three added |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility class | Freely soluble in water | Also dissolves in DMSO and polar organic solvents |
| Related parent fragment | ACTH(4-10) | Parent motif is Met-Glu-His-Phe |
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。
Pharmacokinetic accounts emphasize rapid breakdown. After intravenous dosing the intact peptide disappears from blood within minutes, and nasal delivery produces low but measurable concentrations. Metabolites rather than the parent molecule may account for part of the observed activity, although the relative contribution is unresolved. Dosing in the literature varies widely and no optimal schedule has been agreed. These gaps are regularly cited as a reason the findings have not produced broad clinical adoption beyond the original research setting.
Proposed mechanisms center on neurotrophic signaling rather than on classical melanocortin receptor activation. Rodent experiments have reported shifts in the expression of brain-derived neurotrophic factor and nerve growth factor after administration, together with changes in the associated receptor systems. Several authors argue that the peptide acts largely through its degradation products and their interaction with peptidergic pathways, but this remains a hypothesis rather than a settled finding. No single molecular target has been identified in a way that the field broadly accepts.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
=== Mechanism of action === Labetalol is a beta blocker, or an antagonist of the β-adrenergic receptors. It is specifically a non-selective antagonist of the β1- and β2-adrenergic receptors. Labetalol has intrinsic sympathomimetic activity. It is also an antagonist of the α1-adrenergic receptor, and hence is additionally an alpha blocker. The antagonism of the adrenergic receptors by labetalol is competitive against other catecholamines and its actions on the receptors are potent and reversible. Labetalol acts by blocking α- and β-adrenergic receptors, resulting in decreased peripheral vascular resistance without significant alteration of heart rate or cardiac output. Labetalol is about equipotent in blocking β1- and β2-adrenergic receptors. The amount of α to β blockade depends on whether labetalol is administered orally or intravenously (IV). Orally, the ratio of α to β blockade is 1:3. Intravenously, α to β blockade ratio is 1:7. Thus, labetalol can be thought to be a beta blocker with some α-blocking effects. By comparison, labetalol is a weaker β-adrenergic receptor blocker than propranolol, and has a weaker affinity for α-adrenergic receptors compared to phentolamine. Labetalol's dual α- and β-adrenergic antagonism has different physiological effects in short- and long-term situations. In short-term, acute situations, labetalol decreases blood pressure by decreasing systemic vascular resistance with little effect on stroke volume, heart rate and cardiac output.
Equal treatment is a fundamental right in international law because it has been universally recognised that people should be judged by the content of their character, their skills and knowledge, and not irrelevant characteristics. An equal treatment claim under the Fair Work Act 2009 enables a complaint to the Fair Work Commission, similar to other labour rights. By contrast, claims under the Racial Discrimination Act 1975, the Sex Discrimination Act 1984, Disability Discrimination Act 1992 and Age Discrimination Act 2004 enable a separate path for claims to the Australian Human Rights Commission, created in 1986, which may resolve disputes by conciliation, or if that is unsuccessful claims can go to federal court. Within states, similar systems exist with a watchdog, and appeals to a Tribunal, for instance the Anti-Discrimination Board of NSW and then the NSW Civil and Administrative Tribunal, but claimants cannot bring proceedings at both federal and state level, and so must choose. The FWA 2009 section 27(1A) says that federal law does not exclude state anti-discrimination laws, meaning that greater protection can be provided by states where the federal government has not acted. Despite these rights to formal equality, structural problems (including unequal parental leave, and historic disadvantage) mean discrimination remains rife, so that the gender pay gap remains at 21.7% according to employer surveys, and the Indigenous pay gap is over 33%.
== Further reading == John Bankston, Francis Crick and James D. Watson; Francis Crick and James Watson: Pioneers in DNA Research (Mitchell Lane Publishers, Inc., 2002) ISBN 1-58415-122-6. Bill Bryson; A Short History of Nearly Everything (Broadway Books, 2003) ISBN 0-7679-0817-1. Soraya De Chadarevian; Designs For Life: Molecular Biology After World War II, CUP 2002, 444 pp; ISBN 0-521-57078-6. Roderick Braithwaite. Strikingly Alive: The History of the Mill Hill School Foundation 1807–2007; published Phillimore & Co. ISBN 978-1-86077-330-3 Edwin Chargaff; Heraclitean Fire, Rockefeller Press, 1978. S. Chomet (Ed.), D.N.A. Genesis of a Discovery, 1994, Newman- Hemisphere Press, London Dickerson, Richard E.; Present at the Flood: How Structural Molecular Biology Came About, Sinauer, 2005; ISBN 0-87893-168-6. Edward Edelson, Francis Crick And James Watson: And the Building Blocks of Life, Oxford University Press, 2000, ISBN 0-19-513971-2. John Finch; A Nobel Fellow On Every Floor, Medical Research Council 2008, 381 pp, ISBN 978-1-84046-940-0. Hager, Thomas; Force of Nature: The Life of Linus Pauling, Simon & Schuster 1995; ISBN 0-684-80909-5 Graeme Hunter; Light Is A Messenger, the life and science of William Lawrence Bragg (Oxford University Press, 2004) ISBN 0-19-852921-X. Horace Freeland Judson, The Eighth Day of Creation. Makers of the Revolution in Biology; Penguin Books 1995, first published by Jonathan Cape, 1977; ISBN 0-14-017800-7. Errol C. Friedberg; Sydney Brenner: A Biography, pub. CSHL Press October 2010, ISBN 0-87969-947-7.
=== Level design === Lost Coast was conceived as a part of the Highway 17 chapter in Half-Life 2 (Highway 17's development name was "Coast", hence the name "Lost Coast"), but was discarded during development. It features storyline details that were removed from Half-Life 2, such as the headcrab artillery launchers. Each area was designed with a specific purpose. An Eastern Orthodox architectural style was chosen for the monastery, as buildings of this type "are very colorful and have a large variety of materials" and are "often lit naturally, with extremes of darkness and brightness", providing an ideal showcase for the HDR lighting effects. Valve also thought a monastery would provide a starker contrast between old human architecture and futuristic Combine technology inside it. The cliffside that leads to the monastery had a gameplay-oriented purpose, and was meant to emulate a similar cliffside combat scene in the original Half-Life (1998). The cliffside also forces the player to be observant of threats from above and below, breaking from normal horizontal combat. The monastery's courtyard was designed as an area where the player recovers from the cliffside combat, while also presenting a contained combat arena later in the level in which the player must hold their ground while they are attacked from multiple directions.
=== Growth and proliferation === Intracrines such as fibroblast growth factor-2 (FGF2), vascular endothelial growth factor (VEGF), and insulin-like growth factor-1 (IGF-1) regulate cellular proliferation. In cancer, these factors often establish self-sustaining feed-forward loops, enhancing uncontrolled tumor growth. For example, VEGF's intracrine action is implicated in hematopoietic malignancies, while angiogenin has been identified in the nuclei of breast cancer cells, where it promotes proliferation.
Sources: en.wikipedia.org
Over the years National Semiconductor acquired several companies like Fairchild Semiconductor (1987), and Cyrix (1997). However, over time National Semiconductor spun off these acquisitions. Fairchild Semiconductor became a separate company again in 1997, and the Cyrix microprocessors division was sold to VIA Technologies of Taiwan in 1999. From 1997 to 2002, National enjoyed a large amount of publicity and awards with the development of the Cyrix Media Center, Cyrix WebPad, WebPad Metro and National Origami PDA concept devices created by National's Conceptual Products Group. Based largely on the success of the WebPad, National formed the Information Appliance Division (highly integrated processors & "internet gadgets") in 1998. The Information Appliance Division was sold to AMD in 2003. Other businesses dealing in such products as digital wireless chipsets, image sensors, and PC I/O chipsets have also been recently closed down or sold off as National has reincarnated itself as a high-performance analog semiconductor company.
Pyrite.Virtual Museum of Mineralogy. Universidad de Zaragoza, Spain Educational article about the famous pyrite crystals from the Navajun Mine How Minerals Form and Change "Pyrite oxidation under room conditions". Poliakoff, Martyn (2009). "Fool's Gold". The Periodic Table of Videos. University of Nottingham.
=== Expansion === The idea of expanding the tournament had been suggested as early as 2013 by then-UEFA president Michel Platini, as well as in 2016 by current FIFA president Gianni Infantino. Opponents of the proposal argued that the number of matches played was already at an unacceptable level, that the expansion would dilute the quality of the matches, and that the decision was driven by political rather than sporting concerns, specifically that Infantino was trying to win his election by promising to bring more countries to the World Cup. Starting with the 2026 edition, the World Cup expanded to 48 teams, an increase of 16 teams compared to the previous seven tournaments. As approved by the FIFA Council on March 14, 2023, the teams were split into 12 groups of 4 teams, with the top 2 teams in each group and the 8 best third-place teams progressing to a new round of 32. It was the first expansion and format change since 1998. The total number of matches played increased from 64 to 104, and the number of matches played by teams reaching the semifinals increased from 7 to 8. The tournament lasted 39 days, an increase from the 32 days of the 2014 and 2018 tournaments, and from the 29 days of the 2022 tournament, although each team still played three group matches. The final matchday at club level for players named in the final squads was May 24, 2026; clubs had to release their players by May 25, with exceptions granted to players participating in continental club competition finals up until May 30.
The two Δ formulas are frequently used to report the abundance of clumped isotopologues of methane. The reason for choosing stochastic distribution as the reference frame may be historical - in the process of developing CO2 clumped isotope measurement, the only material with known clumped isotope abundance was CO2 heated to 1000 °C. However, this reference frame is a good choice. Because the absolute abundance of each isotopologue primarily depends on the bulk carbon and hydrogen isotope compositions (δ13C and δD) of the molecules, i.e. very close to stochastic distribution. Therefore, the deviation from the stochastic distribution, which is the key information embedded in the methane clumped isotopologues, is denoted by Δ values.
Sources: en.wikipedia.org
== Name == The name açaí is a language variation of the Tupian word ïwasa’i, meaning “fruit that cries or expels water.” In the binomial nomenclature, the genus Euterpe refers to the tree’s growth habit. Its specific epithet oleracea means "vegetable" in Latin, referring to the fruit as edible.
=== Autoimmune disorders === People with type 1 diabetes are at an increased risk for developing several autoimmune disorders, particularly thyroid problems – around 20% of people with type 1 diabetes have hypothyroidism or hyperthyroidism, typically caused by Hashimoto thyroiditis or Graves' disease respectively. Celiac disease affects 2–8% of people with type 1 diabetes, and is more common in those who were younger at diabetes diagnosis, and in white people. Type 1 diabetics are also at increased risk of rheumatoid arthritis, lupus, autoimmune gastritis, pernicious anemia, vitiligo, and Addison's disease. Conversely, complex autoimmune syndromes caused by mutations in the immunity-related genes AIRE (causing autoimmune polyglandular syndrome), FoxP3 (causing IPEX syndrome), or STAT3 include type 1 diabetes in their effects.
The mechanism of melatonin biosynthesis initiates with the hydroxylation of L-tryptophan, a process that requires the cofactor tetrahydrobiopterin (THB) to react with oxygen and the active site iron of tryptophan hydroxylase. Although the complete mechanism is not entirely understood, two main mechanisms have been proposed: The first mechanism involves a slow transfer of one electron from THB to molecular oxygen (O2), potentially producing a superoxide (O−2). This superoxide could then recombine with the THB radical to form 4a-peroxypterin. 4a-peroxypterin may either react with the active site iron (II) to create an iron-peroxypterin intermediate or directly transfer an oxygen atom to the iron, facilitating the hydroxylation of L-tryptophan. Alternatively, the second mechanism proposes that oxygen interacts with the active site iron (II) first, forming iron (III) superoxide. This molecule could then react with THB to form an iron-peroxypterin intermediate. Following the formation of iron (IV) oxide from the iron-peroxypterin intermediate, this oxide selectively attacks a double bond to yield a carbocation at the C5 position of the indole ring. A subsequent 1,2-shift of the hydrogen and the loss of one of the two hydrogen atoms on C5 would restore aromaticity, producing 5-hydroxy-L-tryptophan. The decarboxylation of 5-hydroxy-L-tryptophan to produce 5-hydroxytryptamine is then facilitated by a decarboxylase enzyme with pyridoxal phosphate (PLP) as a cofactor.
=== Episil - oral mucositis pain === Oral mucositis is a severe side-effect of chemotherapy or radiotherapy during cancer treatment, and is often a dose-limiting factor in treatment. episil is administered as a lipid-based liquid that spreads on the intra-oral mucosal surfaces and transforms to a strongly bioadhesive FluidCrystal film that mechanically protects the sensitized and sore epithelium of the oral cavity. It has been demonstrated in several clinical trials that episil gives an immediate and significant reduction of pain. This analgesic effect was maintained over at least 8 hours following administration. The treatment was reported to be safe and well tolerated. The product is registered as a medical device in a wide range of countries, including the European Union and the United States.
Time-resolved mass spectrometry (TRMS) is a strategy in analytical chemistry that uses mass spectrometry platform to collect data with temporal resolution. Implementation of TRMS builds on the ability of mass spectrometers to process ions within sub-second duty cycles. It often requires the use of customized experimental setups. However, they can normally incorporate commercial mass spectrometers. As a concept in analytical chemistry, TRMS encompasses instrumental developments (e.g. interfaces, ion sources, mass analyzers), methodological developments, and applications.
Sources: en.wikipedia.org
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.
Semax is a synthetic analog of the ACTH(4-10) fragment rather than a copy of the full hormone. Truncation plus the added tail removes the steroidogenic portion of ACTH. That distinction explains why it is studied for nervous-system effects instead of adrenal stimulation.
It is registered as a prescription product in Russia and has been used there clinically, chiefly by the intranasal route. No approval exists in the United States or the European Union. Availability elsewhere typically falls under research-chemical distribution, with varying purity documentation.
Dry powder is usually kept at about -20 degrees Celsius for long-term storage and at 2 to 8 degrees Celsius for short working periods. Containers should stay sealed and protected from light and moisture to limit degradation.