肽纯度 comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-12-19. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
Clinical evidence consists largely of small trials with modest sample sizes, often without independent replication. Reported endpoints include cognitive scores, recovery after stroke, and visual function, but study designs vary widely and few trials meet contemporary reporting standards. Systematic reviewers have noted a high risk of bias in several of these reports. No large multicenter trial conducted outside Russia has been published. The compound is therefore best described as investigational in most jurisdictions, with its clinical role still unresolved.
| Property | Value | Notes |
|---|---|---|
| Typical analytical method | Reversed-phase HPLC with UV detection | Separates target peptide from truncated and oxidised forms |
| Identity confirmation | LC-MS or ESI-MS | Compares observed and calculated molecular ion |
| Primary degradation route | Methionine oxidation | Forms the sulfoxide; monitored as an early-eluting peak |
| Short-term storage | 2 to 8 degrees Celsius | Applies to working vials and reconstituted portions |
| Common synonyms | ACTH(4–10) analogue, MEHFPGP | Descriptive names used in laboratory catalogues |
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。
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。
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.
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.
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
纯度评估以反相高效液相色谱为主，通过主峰面积百分比给出粗略结果，再配合电喷雾质谱核对分子量。氨基酸分析可验证组成比例，手性色谱或毛细管电泳用于检查残基构型。常见杂质包括缺失序列的短肽、氧化产物与二聚体。由于多数市售品不附带完整检验报告，独立第三方检测常被用来核实标称值。
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.
==== Budding ==== Sendai virus, as all other envelope viruses, uses host cellular membrane lipid bilayer for viral capsid membrane formation. Binding to a host cell membrane of viral proteins (M, HN and F) promotes their interaction with RNP complex, which is composed of the viral genomic RNA bound to SeV proteins (NP, P and L). Thus, all viral structural components, including viral glycoproteins and genomic RNP complex, are getting assembled together. After such assembling the infectious viral particles are budding out from individually or collectively infected cells (syncytia). It has been suggested that recirculating endosomes are involved in viral RNP complex translocation. C-protein facilitates budding by interacting with AIP1/Alix, which is a host protein that is involved in apoptosis and endosomal membrane trafficking. The infectious virus particles usually released by 24 hours post infection (hpi), and peak titers appeared between 48 and 72 hpi.
== Prevention == Hyperpigmentation can generally be prevented by inhibition of melanogenesis, with agents such as 4-Butylresorcinol, while the wound is healing. Notice that such agents might interfere with wound healing.
=== Inhibition === NADPH oxidase can be inhibited by apocynin, nitric oxide (NO), and diphenylene iodonium. Apocynin acts by preventing the assembly of the NADPH oxidase subunits. Apocynin decreases influenza-induced lung inflammation in mice in vivo and so may have clinical benefits in the treatment of influenza. Inhibition of NADPH oxidase by NO blocks the source of oxidative stress in the vasculature. NO donor drugs (nitrovasodilators) have therefore been used for more than a century to treat coronary artery disease, hypertension, and heart failure by preventing excess superoxide from deteriorating healthy vascular cells. More advanced NADPH oxidase inhibitors include GKT-831 (Formerly GKT137831), a dual Inhibitor of isoforms NOX4 and NOX1 which was patented in 2007. The compound was initially developed for Idiopathic pulmonary fibrosis and obtained orphan drug designation by the FDA and EMA at end of 2010.
This tag is used for protein purification of peptides, fragments of mAbs, recombinant proteins and its fragments. It can be used in research labs and it is intended for large-scale purification during downstream manufacturing process as well. The iCapTag™-target protein complex can be expressed in a wide range of expression hosts (e.g. CHO and E.coli cells) polyglutamate tag, a peptide binding efficiently to anion-exchange resin such as Mono-Q (EEEEEE) polyarginine tag, a peptide binding efficiently to cation-exchange resin (from 5 to 9 consecutive R) E-tag, a peptide recognized by an antibody (GAPVPYPDPLEPR) FLAG-tag, a peptide recognized by an antibody (DYKDDDDK) HA-tag, a peptide from hemagglutinin recognized by an antibody (YPYDVPDYA) His-tag, 5-10 histidines bound by a nickel or cobalt chelate (HHHHHH) Gly-His-tags are N-terminal His-Tag variants (e.g. GHHHH, or GHHHHHH, or GSSHHHHHH) that still bind to immobilised metal cations but can also be activated via azidogluconoylation to enable click-chemistry applications Myc-tag, a peptide derived from c-myc recognized by an antibody (EQKLISEEDL) NE-tag, an 18-amino-acid synthetic peptide (TKENPRSNQEESYDDNES) recognized by a monoclonal IgG1 antibody, which is useful in a wide spectrum of applications including Western blotting, ELISA, flow cytometry, immunocytochemistry, immunoprecipitation, and affinity purification of recombinant proteins Rho1D4-tag, refers to the last 9 amino acids of the intracellular C-terminus of bovine rhodopsin (TETSQVAPA).
Sources: en.wikipedia.org
The kinase AKT indirectly promotes synthesis of rRNA as RNA polymerase I is AKT-dependent. Certain angiogenic ribonucleases, such as angiogenin (ANG), can translocate and accumulate in the nucleolus. When the concentration of ANG becomes too high, some studies have found that ANG can bind to the promoter region of rDNA and unnecessarily increase rRNA transcription. This can be damaging to the nucleolus and can even lead to unchecked transcription and cancer. During times of cellular glucose restriction, AMP-activated protein kinase (AMPK) discourages metabolic processes that consume energy but are non-essential. As a result, it is capable of phosphorylating RNA polymerase I (at the Ser-635 site) in order to down-regulate rRNA synthesis by disrupting transcription initiation. Impairment or removal of more than one pseudouridine or 29-O-methylation regions from the ribosome decoding center significantly reduces rate of rRNA transcription by reducing the rate of incorporation of new amino acids. Formation of heterochromatin is essential to silencing rRNA transcription, without which ribosomal RNA is synthesized unchecked and greatly decreases the lifespan of the organism.
An evaporative light scattering detector (ELSD) is a destructive chromatography detector, used in conjunction with high-performance liquid chromatography (HPLC), ultra high-performance liquid chromatography (UHPLC), purification liquid chromatography such as flash or preparative chromatography (using a splitter), countercurrent or centrifugal partition chromatography and supercritical fluid chromatography (SFC). It is commonly used for analysis of compounds that do not absorb UV-VIS radiation significantly, such as sugars, antiviral drugs, antibiotics, fatty acids, lipids, oils, phospholipids, polymers, surfactants, terpenoids and triglycerides. ELSDs works by nebulizing the column's effluents into a fine aerosol mist, which then passes through a heated drift tube, where the solvent evaporates. Thus, it can be easily used in gradient method of LC and SFC. The remaining non-volatile analyte particles are carried further by a carrier gas to a light scattering cell, where a beam of light illuminates them and they scatter it. The scattered light proceeds to a photodiode which converts it to a signal, which is proportional to the mass of the analyte particles. This is why it is considered as a sort of "universal detector" as it is able to detect all compound which are less volatile than the mobile phase, i.e. non volatile and semi-volatile compounds. ELSD is related to the charged aerosol detector (CAD), in which the aerosol is charged. Like the CAD, it falls under the category of destructive detectors.
When I woke up just after dawn on September 28, 1928, I certainly didn't plan to revolutionize all medicine by discovering the world's first antibiotic, or bacteria killer. But I suppose that was exactly what I did. He concluded that the mould was releasing a substance that was inhibiting bacterial growth, and he produced culture broth of the mould and subsequently concentrated the antibacterial component. After testing against different bacteria, he found that the mould could kill only specific, Gram-positive bacteria. For example, staphylococcus, streptococcus, and diphtheria bacillus (Corynebacterium diphtheriae) were easily killed; but there was no effect on typhoid bacterium (Salmonella typhimurium) and a bacterium once thought to cause influenza (Haemophilus influenzae). He prepared a large-culture method from which he could obtain large amounts of the mould juice. He called this juice "penicillin", explaining the reason as "to avoid the repetition of the rather cumbersome phrase 'Mould broth filtrate'." He invented the name on 7 March 1929. In his Nobel lecture he gave a further explanation, saying:
Sources: en.wikipedia.org
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.
Oxidation of the methionine residue to the sulfoxide is a frequently reported change, and it usually appears as an earlier-eluting peak in reversed-phase chromatography. Backbone hydrolysis products can also accumulate in aqueous solution.
Liquid chromatography coupled with mass spectrometry is the usual approach, because the observed molecular ion can be compared with a calculated mass of about 813.9 Da. Retention time alone does not establish identity.
Semax is a synthetic seven-amino-acid peptide derived from a fragment of corticotropin. It is used in Russia as a nasal preparation, while elsewhere it is studied as a research compound. It is not approved as a medicine in most countries.