This is a working overview of synthetic heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
溶液状态的稳定性明显低于冻干粉。肽类在水溶液中可能经历水解、氧化与聚集，其中甲硫氨酸和天冬酰胺等残基常是敏感位点。Semax 含有甲硫氨酸，因此氧化风险相对突出。工作液一般主张现配现用，或冷藏并在数日内用尽。缓冲液种类、pH 和离子强度都会影响降解速率，而关于最佳条件的公开数据并不统一。
常规纯度与身份确认依赖反相高效液相色谱，并辅以质谱测定分子量。氨基酸组成分析可用于验证序列构成，肽图分析则能进一步定位修饰或降解产物。杂质谱通常关注缺失序列肽、截短片段和氧化产物。不同方法的检出限并不相同，因此各实验室报告的纯度数值不宜直接横向比较。
多数实验室与市售的 Semax 以冻干粉形式提供。冻干粉通常建议保存在 -20 °C 或更低温度下，同时避免光照与反复升温。短期运输有时采用冷藏条件，但长期保存仍以冷冻为主。分包操作应尽量减少开盖次数，以降低吸湿和微生物污染的风险。开封后若未一次用完，建议在干燥环境中密封并尽快放回低温储存。
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | ACTH(4-7) analogue |
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Free N terminus, unmodified side chains |
| Molecular weight | 813.9 Da | Free base; salt forms differ |
| Appearance | White to off-white powder | Lyophilised solid |
| Solubility | Freely soluble in water | Hydrophilic; polar solvents preferred |
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.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
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.
Purity assessment relies mainly on reversed-phase high-performance liquid chromatography, which separates the target heptapeptide from truncated sequences, deletion analogues, and oxidised forms. Mass spectrometry, usually coupled to liquid chromatography, confirms identity through the expected molecular ion and reveals modifications such as methionine sulfoxide formation. Amino acid analysis can verify composition, and tandem mass spectrometry supports sequence confirmation. Ultraviolet detection near 254 to 280 nanometres is convenient because the phenylalanine and histidine residues absorb in that region. Nuclear magnetic resonance is rarely used for routine release testing.
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
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.
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.
Semax binds to melanocortin receptors and is thought to influence neuronal survival and plasticity rather than to act through the adrenal axis. Laboratory work has shown increased expression of brain-derived neurotrophic factor and nerve growth factor in treated tissue. Changes in c-Fos, a marker of neuronal activation, have also been reported. Because the peptide is rapidly degraded by peptidases, its effects are generally attributed to downstream signaling cascades rather than to sustained receptor occupancy.
Published studies are dominated by animal models of stroke, ischemia, and cognitive impairment, with a smaller number of human trials conducted in Russia. Many of the human reports are small, single-center, and published in Russian-language journals, which limits independent scrutiny. Outcome measures vary between studies and often rely on clinician-rated scales rather than objective biomarkers. Systematic reviews have noted the methodological weaknesses and called for larger, preregistered trials before firm conclusions can be drawn.
Quaternary structure the three-dimensional configuration of a protein molecule comprising several independent polypeptide chains. Secondary structure the interactions that occur between the C, O, and NH groups on amino acids in a polypeptide chain to form α-helices, β-sheets, turns, loops, and other forms, and that facilitate the folding into a three-dimensional structure. Superfamily a group of protein families of the same or different lengths that are related by distant yet detectable sequence similarity. Members of a given superfamily thus have a common evolutionary origin. Originally, Dayhoff defined the cutoff for superfamily status as being the chance that the sequences are not related of 10 6, on the basis of an alignment score (Dayhoff et al. 1978). Proteins with few identities in an alignment of the sequences but with a convincingly common number of structural and functional features are placed in the same superfamily. At the level of three-dimensional structure, superfamily proteins will share common structural features such as a common fold, but there may also be differences in the number and arrangement of secondary structures. The PIR resource uses the term homeomorphic superfamilies to refer to superfamilies that are composed of sequences that can be aligned from end to end, representing a sharing of single sequence homology domain, a region of similarity that extends throughout the alignment. This domain may also comprise smaller homology domains that are shared with other protein families and superfamilies.
Newtonian fluids: where stress is directly proportional to rate of strain Non-Newtonian fluids: where stress is not proportional to rate of strain, its higher powers and derivatives. Newtonian fluids follow Newton's law of viscosity and may be called viscous fluids. Fluids may be classified by their compressibility:
== Life == Bacterial life survives in the stratosphere, making it a part of the biosphere. In 2001, dust was collected at a height of 41 kilometres in a high-altitude balloon experiment and was found to contain bacterial material when examined later in the laboratory.
=== Other GLUT proteins === There are 14 total GLUT proteins separated into 3 classes based on sequence similarities. Class 1 consists of GLUT 1-4 and 14, class 2 contains GLUT 5, 7, 9 and 11, and class 3 has GLUT 6, 8, 10, 12 and 13. Although there are some sequence differences between all GLUT proteins, they all have some basic structural components. For example, both the N and C termini in GLUT proteins are exposed to the cytoplasm of the cell, and they all have 12 transmembrane segments.
Sources: en.wikipedia.org
Clashes in Dammaj spread to the Amran Governorate by January 2014. The Houthis achieved victory in Saada when the Yemeni government brokered a deal under which Salafi fighters and their families were evacuated to the neighboring Al Hudaydah Governorate. According to reports, the Houthis then blocked government troops from fully deploying throughout the territory, in spite of a signed agreement. Fighting in the Amran Governorate intensified during the year, with clashes between Houthis and supporters of the Islamist Islah Party eventually leading to a Houthi takeover of the entire governorate. The conflict spread to the Sanaa Governorate by July.
=== Global health research === Sarkar led a team of international scientists investigating naturally occurring arsenic and other toxic metals throughout South- and Southeast Asia. In his early research in Bangladesh, Sarkar identified a small child with advanced signs of arsenic poisoning, an observation that motivated extensive research in this region. Discovery Canada Television produced an hour-long documentary focusing on Sarkar's work on this devastating health crisis in Bangladesh. Sarkar's team discovered that arsenic is not the only toxic metal contaminating the groundwater; other toxic metals such as manganese, lead, chromium, and uranium are also present in groundwater. They produced heat maps of arsenic and other toxic metals in Bangladesh and West Bengal (India) groundwater, identifying areas where contamination is of special concern. Their investigation was further extended to the neighboring country of Myanmar (Burma), which has a similar geology, and where they found high concentrations of many of the same toxic metals in groundwater. Sarkar's team also carried out field work in Kathmandu, Nepal, in 2015. In addition, the team called for the WHO to re-evaluate its guidelines for many toxic substances in drinking water based on their health hazards. Sarkar's team stressed that multiple metal contamination of groundwater is an issue of global concern, and the risks may be further magnified by climate change.
=== Ion implantation === Ion implantation may be used to treat the surfaces of dielectric materials such as sapphire and silica to make composites with near-surface dispersions of metal or oxide nanoparticles.
== Structure == Prokaryotic riboflavin biosynthesis proteins are also known as the prokaryotic type-I FAD synthetases, which consist of a C-terminal riboflavin kinase (RFK) and an N-terminal FMN-adenylyltransferase (FMNAT). The globular RFK consists of six antiparallel β-sheets that form a β-barrel, and an α-helix adjacent to this structure. The barrel and helix are held together by 7 independent loops. The FMNAT module contains an α/β dinucleotide binding domain within the active site, which it uses to bind to the substrate. The overall structure is held together by 5 parallel β-sheets that are adjacent to 4 α-helices, with 2 being long and 2 being short. A subdomain, containing 2 smaller α-helices, encompasses the area that connects to the C-terminal RFK module.
One appraiser had called the mansion "uninhabitable" since 2012, five years before Pritzker bought it. Federal authorities later opened an investigation into the matter. According to Forbes, as of August 2025, Pritzker's estimated net worth is $3.9 billion. A 2018 Chicago Tribune investigation uncovered several overseas trusts and shell companies connected to Pritzker and his siblings. Pritzker has said that the trusts his grandfather established yield no personal benefit to him and are used only for charitable contributions. According to The Wall Street Journal, Pritzker is the second-richest U.S. politician as of 2025. On September 21, 2026, Pritzker said he had been taking a GLP-1 drug for about two years to lose weight and control his blood sugar level. Pritzker talked about his use despite his previous refusal to discuss it because he "came to the conclusion that it would be helpful to others to hear why I went on a GLP-1 and what the effect has been for me". Pritzker began taking the drug after being diagnosed with type 2 diabetes told that he would have to take insulin for the rest of his life. He said that since starting the drug he has been able to stop taking insulin and has lost about 80 pounds. Pritzker's use of GLP-1 is covered by the State of Illinois's health insurance plan, which was expanded in July 2023 to cover the drug for state employees with physician approval. The expansion was put in place before Pritzker began using a GLP-1 drug.
Sources: en.wikipedia.org
==== Chronic disease ==== Many kidney failure patients experience a hormonal imbalance due to the suppression of testosterone production and testicular damage from high levels of urea also known as uremia-associated hypogonadism. Additionally, gynecomastia has been observed in 50% of patients with chronic kidney disease undergoing dialysis. Similar to the mechanism behind refeeding gynecomastia, dialysis allows patients with renal failure who were previously malnourished to expand their diets and regain weight. Dialysis-associated gynecomastia resolves spontaneously within 1–2 years. In individuals with liver failure or cirrhosis, the liver's ability to properly metabolize hormones such as estrogen may be impaired. Additionally, those with alcoholic liver disease are further put at risk for the development of gynecomastia; ethanol may directly disrupt the synthesis of testosterone, and the presence of phytoestrogens in alcoholic drinks may also contribute to a higher estrogen to testosterone ratio. Conditions that can cause malabsorption such as cystic fibrosis or ulcerative colitis may also produce gynecomastia. A small proportion of male gynecomastia cases may be seen with rare inherited disorders such as spinal and bulbar muscular atrophy and the very rare aromatase excess syndrome.
=== Semen displacement === The shape of the human penis is thought to have evolved as a result of sperm competition. Semen displacement is an adaptation of the shape of the penis to draw foreign semen away from the cervix. This means that a male can displace a rival male's sperm from the female reproductive tract before replacing it with his own. Semen displacement has two main benefits for a male. Firstly, by displacing a rival male's sperm, the risk of the rival sperm fertilising the egg is reduced. Secondly, the male replaces the rival's sperm with his own, thereby increasing the probability of his fertilising the egg and successfully reproducing with the female. However, males have to ensure they do not displace their own sperm. It is thought that the relatively quick loss of erection after ejaculation, penile hypersensitivity following ejaculation, and the shallower, slower thrusting of the male after ejaculation prevent this from occurring. The coronal ridge is the part of the human penis thought to have evolved to allow for semen displacement. Research has studied how much semen is displaced by differently shaped artificial genitals. This research showed that, when combined with thrusting, the coronal ridge of the penis is able to remove the seminal fluid of a rival male from within the female reproductive tract. It does this by forcing the semen under the frenulum of the coronal ridge, causing it to collect behind the coronal ridge shaft.
Conservative leader Kemi Badenoch outlines her party's immigration policy, which reaffirms its commitment to a "strict migration cap"; she also says that her party got it "wrong" on immigration while in government. MPs will debate an online petition calling for a re-run of the 2024 general election in Westminster Hall, a secondary debating chamber, on 6 January 2025 after the petition attracted 2.8 million signatures. 28 November – Former prime minister David Cameron announces his support for an assisted dying law in the UK. Transport Secretary Louise Haigh reveals that she pleaded guilty to falsely saying a mobile phone had been stolen during a mugging before she became an MP and was given an absolute discharge by magistrates. Unite the Union announces plans to proceed with a legal challenge to overturn the UK government's cuts to Winter Fuel Payments. The Scottish Government announces that all pensioner households will receive a Winter Fuel Payment from Winter 2025–26, with those on Pension Credit receiving £200 or £300 dependent on age and the rest receiving £100. Former Conservative MP Andrea Jenkyns defects to Reform UK, and announces plans to run as Mayor of Greater Lincolnshire in May 2025. BBC News Wales reports that Senedd Conservatives will hold a vote of confidence in Welsh Conservative leader Andrew RT Davies on 3 December following a series of criticisms about his leadership. Mauritian prime minister Navin Ramgoolam asks for an independent review of the UK's deal with his country over sovereignty of the Chagos Islands.
The protein encoded by the DLD gene comes together with another protein to form a dimer in the central metabolic pathway. Several amino acids within the catalytic pocket have been identified as important to DLD function, including R281 and N473. Although the overall fold of the human enzyme is similar to that of yeast, the human structure is different in that it has two loops that extend from the general protein structure and into the FAD binding sites when bound the NAD+ molecule, required for catalysis, is not close to the FAD moiety. However, when NADH is bound instead, it is stacked directly op top of the FAD central structure. The current hE3 structures show directly that the disease-causing mutations occur at three locations in the human enzyme: the dimer interface, the active site, and the FAD and NAD(+)-binding sites.
Most tests employ a monoclonal antibody, which is specific to the β-subunit of hCG (β-hCG). This procedure is employed to ensure that tests do not make false positives by confusing hCG with LH and FSH. (The latter two are always present at varying levels in the body, whereas the presence of hCG almost always indicates pregnancy.) Many hCG immunoassays are based on the sandwich principle, which uses antibodies to hCG labeled with an enzyme or a conventional or luminescent dye. Pregnancy urine dipstick tests are based on the lateral flow technique.
Sources: en.wikipedia.org
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.
It contains the 4-7 fragment of adrenocorticotropic hormone extended at the C terminus. That truncation removes the region associated with steroidogenic activity. The design intent was to keep neurotrophic properties while avoiding full hormonal effects.
No natural source of the intact heptapeptide is known. It is produced by solid-phase peptide synthesis. Some related ACTH fragments arise as hormone processing products, but the Pro-Gly-Pro extension is a designed addition rather than a natural sequence.
一般不建议常温长期保存。多数说明指向 -20 °C 冷冻避光。常温运输通常被视为短期可接受，但会加快降解风险。