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.
Last reviewed on 2025-09-27. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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。
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。
| 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 |
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
Semax is supplied as a lyophilized powder that appears white to off-white. It dissolves readily in water, phosphate-buffered saline, and other aqueous media, which simplifies preparation of working solutions for laboratory use. The nasal products registered in Russia are dilute aqueous solutions, typically around 0.1 percent peptide by weight. Organic solvents are rarely necessary and can complicate handling. Because the peptide is hygroscopic, weighing should be performed quickly and with minimal exposure to ambient humidity.
Solid material is normally kept at minus 20 degrees Celsius in a sealed, desiccated container. Reconstituted solutions are less stable and are usually divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and loss of activity. Light exposure is minimized by using amber glassware or foil wrapping. Published stability data for this peptide are sparse, so recommended storage conditions rest mainly on general practice for short synthetic peptides rather than on dedicated study.
== Further reading == Valera, Maria José; Torija, Maria Jesús; Mas, Albert; Mateo, Estibaliz (2013). "Acetobacter malorum and Acetobacter cerevisiae identification and quantification by Real-Time PCR with TaqMan-MGB probes". Food Microbiology. 36 (1): 30–39. doi:10.1016/j.fm.2013.03.008. ISSN 0740-0020. PMID 23764217. Sagarzazu, Noelia Isabel, et al. "Optimization of denaturing high performance liquid chromatography technique for rapid detection and identification of acetic acid bacteria of interest in vinegar production." Acetic Acid Bacteria 2.1s (2013): e5. Ogawa S, Tachimoto H, Kaga T (January 2010). "Elevation of ceramide in Acetobacter malorum S24 by low pH stress and high temperature stress". Journal of Bioscience and Bioengineering. 109 (1): 32–6. doi:10.1016/j.jbiosc.2009.07.007. PMID 20129078.
=== Bernot et al. (2023) === In recent study, Bernot et al. placed Copepoda as a sister group to Branchiopoda in Allotriocarida, which result in the recovery of clade Communostraca. Multicrustacea was not found. There are some major changes within class Malacostraca.
Nature magazine criticised the over-reliance on JIF, pointing not just to its statistical flaws but to negative effects on science: "The resulting pressures and disappointments are nothing but demoralizing, and in badly run labs can encourage sloppy research that, for example, fails to test assumptions thoroughly or to take all the data into account before submitting big claims." Various publishers now use a mixture of metrics on their website; the PLOS series of journals does not display the impact factor. Microsoft Academic took a similar view, stating that h-index, EI/SCI and journal impact factors are not shown because "the research literature has provided abundant evidence that these metrics are at best a rough approximation of research impact and scholarly influence." In 2021, Utrecht University promised to abandon all quantitative bibliometrics, including the impact factor. The university stated that "it has become a very sick model that goes beyond what is really relevant for science and putting science forward". This followed a 2018 decision by the main Dutch funding body for research, NWO, to remove all references to journal impact factors and the h-index in all call texts and application forms. Utrecht's decision met with some resistance. An open letter signed by over 150 Dutch academics argued that, while imperfect, the JIF is still useful, and that omitting it "will lead to randomness and a compromising of scientific quality".
A study found comparable absorption of transdermal estradiol patches (within ±25% of reference) for a number of skin sites including the abdomen, upper arm, upper thigh, lower back, and side. However, absorption was 15% lower for the upper thigh compared to the abdomen and the difference was significant. Another study found that transdermal estradiol patches had 20 to 25% higher bioavailability when applied to the buttocks than when applied to the abdomen. Studies of topical steroids have found that the scrotum is especially permeable among skin sites. Studies of transdermal testosterone cream, gel, and patches applied to the scrotum in men have observed 5- to 8-fold higher levels of testosterone than with application to conventional skin sites. In a study of topical application of hydrocortisone solution in men, skin permeability (defined as total radiolabeled urinary excretion) relative to the forearm (1.0) was 42.0 for the scrotum, 13.0 for the jaw angle, 6.0 for the forehead, 3.6 for the underarm, 3.5 for the scalp, 1.7 for the back, 0.8 for the palm of the hand, 0.4 for the ankle, and 0.1 for the sole of the foot. In accordance with findings with other topical steroids, a study in men with prostate cancer treated with transdermal estradiol patches applied to the scrotum observed about 5-fold higher estradiol levels relative to application to conventional skin sites such as the forearm. Penile skin may have similarly enhanced absorption characteristics relative to scrotal skin.
After considering the different sources, it can be concluded that the half-life of vitamin B6 is typically measured in several weeks. The end-product of vitamin B6 catabolism is 4-pyridoxic acid, which makes up about half of the B6 compounds in urine. 4-Pyridoxic acid is formed by the action of aldehyde oxidase in the liver. Amounts excreted increase within 1–2 weeks with vitamin supplementation and decrease as rapidly after supplementation ceases. Other vitamin forms excreted in the urine include pyridoxal, pyridoxamine and pyridoxine, and their phosphates. When large doses of pyridoxine are given orally, the proportion of these other forms increases. A small amount of vitamin B6 is also excreted in the feces. This may be a combination of unabsorbed vitamin and what was synthesized by large intestine microbiota.
Sources: en.wikipedia.org
=== Military legacy === The war was the harbinger of a new type of combat: guerrilla warfare. The counterinsurgency techniques and lessons learned (restriction of movement, containment of space, targeting of anything that could give sustenance to guerrillas, harassment through sweeper groups coupled with rapid reaction forces, sourcing and co-ordination of intelligence, and nurturing of native allies) were used by the British, and other forces, in future guerrilla campaigns including to counter Malayan communist rebels during the Malayan Emergency. In World War II the British adopted concepts of raiding from the Boer commandos when they set up special raiding forces, and in acknowledgement chose the name British Commandos.
Fast growing microorganisms such as bacteria and yeast have a high concentration of nucleic acid, notably RNA. Levels must be limited in the diets of monogastric animals to <50 g per day. Ingestion of purine compounds arising from RNA breakdown leads to increased plasma levels of uric acid, which can cause gout and kidney stones. Uric acid can be converted to allantoin, which is excreted in urine. Nucleic acid removal is not necessary from animal feeds but is from human foods (humans have lost parts of the uric acid catabolic pathway during their evolution). This problem can be remediated, however. One common method consists in a heat treatment which kills the cells, inactivates proteases and allows endogenous RNases to hydrolyse RNA with release of nucleotides from cell to culture broth.
=== Anti-aging === mTOR inhibitors may be useful for treating/preventing several age-associated conditions, including neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. After a short-term treatment with the mTOR inhibitors dactolisib and everolimus, in elderly (65 and older), treated subjects had a reduced number of infections over the course of a year. Various natural compounds, including epigallocatechin gallate (EGCG), caffeine, curcumin, berberine, quercetin, resveratrol and pterostilbene, have been reported to inhibit mTOR when applied to isolated cells in culture. As yet no high quality evidence exists that these substances inhibit mTOR signaling or extend lifespan when taken as dietary supplements by humans, despite encouraging results in animals such as fruit flies and mice. Various trials are ongoing.
The use of adsorbent chemicals, such as zeolites, and other hemostatic agents are also used for sealing severe injuries quickly (such as in traumatic bleeding secondary to gunshot wounds). Thrombin and fibrin glue are used surgically to treat bleeding and to thrombose aneurysms. Hemostatic Powder Spray TC-325 is used to treated gastrointestinal bleeding. Desmopressin is used to improve platelet function by activating arginine vasopressin receptor 1A. Coagulation factor concentrates are used to treat hemophilia, to reverse the effects of anticoagulants, and to treat bleeding in people with impaired coagulation factor synthesis or increased consumption. Prothrombin complex concentrate, cryoprecipitate and fresh frozen plasma are commonly used coagulation factor products. Recombinant activated human factor VII is sometimes used in the treatment of major bleeding. Tranexamic acid and aminocaproic acid inhibit fibrinolysis and lead to a de facto reduced bleeding rate. Before its withdrawal, aprotinin was used in some forms of major surgery to decrease bleeding risk and the need for blood products.
Sources: en.wikipedia.org
== Genetics == AGAT deficiency is caused by deficient activity of arginine:glycine amidinotransferase, which is coded for by GATM, located on the long arm of chromosome 15. AGAT deficiency is inherited in an autosomal recessive manner, which means pathogenic variants must be inherited from each parent. This enzyme catalyzes the first step in creatine biosynthesis, the combination of arginine and glycine to form guanidinoacetate, which also results in the formation or ornithine as a by product. These reactions take place primarily in the kidney and pancreas. The clinical manifestations of AGAT deficiency are caused by the decreased amounts of creatine produced.
21,000, 5 November 2010 - The SENSEX closed at 21,004.96, for its first close above the 21,000 mark. It would take nearly three years for the index to make its next close above this level. 22,000, 24 March 2014 - The SENSEX closed at 22,055.48, for its first close above the 22,000 mark. For the first time, the SENSEX zoomed ahead of the Hang Seng Index. 23,000, 12 May 2014 - The SENSEX closed at 23,551.00, for its first close above the 23,000 mark, 24,000, 16 May 2014 - The SENSEX closed at 24,121.74, for its first close above the 24,000 mark, Breaking all previous records and above all other indexes in the world. 25,000, 5 June 2014 - The SENSEX closed at 25,019.51, for its first close above the 25,000 mark, 26,000, 7 July 2014 - The SENSEX closed at 26,123.55, for its first close above the 26,000 mark, 27,000, 2 September 2014 - The SENSEX closed at 27019.39, for its first close above the 27,000 mark, 28,000, 5 November 2014 - The SENSEX crossed 28,000 mark, on 5 November 2014. This is the seventh 1000-point milestone the index has crossed in 2014, breaking the six 1000-point record set in 2007.
=== Patent ductus arteriosus === Paracetamol helps ductal closure in patent ductus arteriosus. It is as effective for this purpose as ibuprofen or indomethacin, but results in less frequent gastrointestinal bleeding than ibuprofen. Its use for extremely low birth weight and gestational age infants, however, requires further study.
== Artificial ribozymes == Since the discovery of ribozymes that exist in living organisms, there has been interest in the study of new synthetic ribozymes made in the laboratory. For example, artificially produced self-cleaving RNAs with good enzymatic activity have been produced. Tang and Breaker isolated self-cleaving RNAs by in vitro selection of RNAs originating from random-sequence RNAs. Some of the synthetic ribozymes that were produced had novel structures, while some were similar to the naturally occurring hammerhead ribozyme. In 2015, researchers at Northwestern University and the University of Illinois Chicago engineered a tethered ribosome that works nearly as well as the authentic cellular component that produces all the proteins and enzymes within the cell. Called Ribosome-T, or Ribo-T, the artificial ribosome was created by Michael Jewett and Alexander Mankin. The techniques used to create artificial ribozymes involve directed evolution. This approach takes advantage of RNA's dual nature as both a catalyst and an informational polymer, making it easy for an investigator to produce vast populations of RNA catalysts using polymerase enzymes. The ribozymes are mutated by reverse transcribing them with reverse transcriptase into various cDNA and amplified with error-prone PCR. The selection parameters in these experiments often differ. One approach for selecting a ligase ribozyme involves using biotin tags, which are covalently linked to the substrate.
=== Professional history and early years in Vermont === After graduating from college, Sanders returned to New York City, where he worked various jobs, including as a Head Start teacher, a psychiatric aide, and a carpenter. In 1968, he moved to Stannard, Vermont, a town small in both area and population (88 residents at the 1970 census) within Vermont's rural Northeast Kingdom region, because he had been "captivated by rural life". While there, he worked as a carpenter, filmmaker, and writer who created and sold "radical film strips" and other educational materials to schools. Sanders wrote articles for The Vermont Freeman. One article later received media attention during his national political career after its contents were rediscovered and reported in the press. He lived in the area for several years before moving to the more populous Chittenden County in the mid-1970s. During his 2018 reelection campaign, he returned to the town to hold an event with voters and other candidates.
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.
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。