This is a working overview of single-use aliquot, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-07-29 and is reviewed periodically as new material appears.
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
Identity and purity are established with standard peptide methods. Reversed-phase HPLC with ultraviolet detection near 214 nm resolves the parent peak from deletion and truncation byproducts, and reports typically quote a main-peak percentage. Mass spectrometry by electrospray or MALDI-TOF confirms the expected molecular mass, while amino acid analysis or peptide mapping can verify composition when the sequence itself is in question. A certificate of analysis that pairs a chromatogram with a mass spectrum is more informative than a purity figure alone. Counter-ion content and residual solvents are separate specifications and are frequently omitted.
从分子层面看，Semax 是线性七肽，没有二硫键、糖基或脂链修饰，N 端为游离氨基，C 端为游离羧基。分子含组氨酸与谷氨酸侧链，因此在水和甲醇等极性溶剂中溶解良好，在非极性溶剂中溶解有限。计算分子量约为 814 Da，与其质子化离子的质荷比吻合，可用于质谱确认。
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。
| Property | Value | Notes |
|---|---|---|
| Solid storage temperature | -20 °C or below | Desiccated and protected from light |
| Solution storage temperature | -80 °C as single-use aliquots | Avoid repeated freeze-thaw cycles |
| Purity assessment method | RP-HPLC, around 214 nm | Reported as main-peak area percent |
| Identity confirmation method | ESI-MS or MALDI-TOF | Measured mass compared with calculated mass |
| Common synonyms | ACTH(4-10) analog; Met-Glu-His-Phe-Pro-Gly-Pro | Also written as Semaxum in some sources |
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.
== Use in agriculture == Plant regulators (PRs) or plant growth regulators (PGRs) are compounds, both naturally occurring and synthetic, used in agriculture to modify the behaviour of plants. They can be used to increase or inhibit growth, influence flowering and/or fruit growth, alter the maturation, or reduce abiotic stress. The compendium of pesticide common names lists 103 plant growth regulators, many of which have been removed from the market. When used in field conditions, plant hormones or mixtures that include them can be applied as biostimulants.
=== Distribution === Ceftriaxone penetrates tissues and body fluids well, including cerebrospinal fluid to treat central nervous system infections. Ceftriaxone is reversibly bound to human plasma proteins and the binding of ceftriaxone decreases with increasing concentration from a value of 95% at plasma concentrations less than 25 mcg/mL to 85% at plasma concentration of 300 mcg/mL. Over a 0.15 to 3 g dose range in healthy adult subjects, the apparent volume of distribution ranged from 5.8 to 13.5 L.
KefB/KefC K+ efflux proteins of E. coli (i.e., TC# 2.A.37.1.3 and TC# 2.A.37.1.1, respectively), which may be capable of catalyzing both K+/H+ antiport and K+ uniport, depending on conditions Na+/H+ antiporter of Enterococcus hirae (i.e., NapA, TC# 2.A.37.2.1) K+/H+ antiporter of S. cerevisiae (i.e., Kha1, TC# 2.A.37.4.1). It has been proposed that under normal physiological conditions, these proteins may function by essentially the same mechanism. KefC and KefB of E. coli are responsible for glutathione-gated K+ efflux. Each of these proteins consists of a transmembrane hydrophobic N-terminal domain, and a lesser conserved C-terminal hydrophilic domain. Each protein interacts with a second protein encoded by genes that overlap the gene encoding the primary transporter. The KefC ancillary protein is YabF while the KefB ancillary protein is YheR. These ancillary proteins stimulate transport activity about 10-fold. These proteins are important for cell survival during exposure to toxic metabolites, possibly because they can release K+, allowing H+ uptake. Activation of the KefB or KefC K+ efflux system only occurs in the presence of glutathione and a reactive electrophile such as methylglyoxal or N-ethylmaleimide. Formation of the methylglyoxal-glutathione conjugate, S-lactoylglutathione, is catalyzed by glyoxalase I, and S-lactoylglutathione activates KefB and KefC. H+ uptake (acidification of the cytoplasm) accompanying or following K+ efflux may serve as a further protective mechanism against electrophile toxicity.
Sources: en.wikipedia.org
Epimysium (plural epimysia) (Greek epi- for on, upon, or above + Greek mys for muscle) is the fibrous tissue envelope that surrounds skeletal muscle. It is a layer of dense irregular connective tissue which ensheaths the entire muscle and protects muscles from friction against other muscles and bones. It also allows a muscle to contract and move powerfully while maintaining its structural integrity. It is continuous with fascia and other connective tissue wrappings of muscle including the endomysium and perimysium. It is also continuous with tendons, where it becomes thicker and collagenous. While the epimysium is irregular on muscles, it is regular on tendons.
=== As a biochemical tool === Concanavalin A and other commercially available lectins have been used widely in affinity chromatography for purifying glycoproteins. In general, proteins may be characterized with respect to glycoforms and carbohydrate structure by means of affinity chromatography, blotting, affinity electrophoresis, and affinity immunoelectrophoreis with lectins, as well as in microarrays, as in evanescent-field fluorescence-assisted lectin microarray.
Anabolic steroids are synthetically derived from testosterone and modified to have greater anabolic effects. They work by increasing the concentration of nitrogen in the muscle which inhibits catabolic glucocorticoid binding to muscle. This ultimately prohibits the breakdown of muscle and preserves muscle mass. Examples of anabolic steroids include: oxandrolone, stanozolol and nandrolone. Anabolic steroids can be taken through a transdermal method, orally, or through injection. Injectable forms of the steroid are the most potent and long-lasting. In general, potential side effects include: muscle hypertrophy, acne, hypertension, elevated cholesterol, thrombosis, decreased high-density lipoproteins, altered libido, hepatic carcinoma, cholestasis, peliosis hepatitis, septic arthritis, Wilm's tumor, psychosis, aggression, addiction, and depression. Potential side effects specifically in males include: male pattern baldness, oligospermia, prostate hypertrophy, testicular atrophy, and prostate cancer. Potential side effects specifically in females include: hirsutism, uterine atrophy, amenorrhea, breast atrophy, and thickening of vocal cords (voice deepening). Urine samples are tested to determine the ratio of testosterone glucuronide to epitestosterone glucuronide, which should be 3:1. Any ratio of 4:1 or greater is considered a positive test. The Anti-Drug Abuse Act of 1988 and the Anabolic Steroid Act of 1990 both deemed anabolic steroids as an illegal substance when not used for disease treatment.
=== March 2008 === The free fall of the SENSEX accelerated in March 2008. The month started out with the Sensex losing 900.84 points on 3 March 2008, on concerns emanating from growing credit losses in US. This would be the first of four one-day falls of greater than 700 points during the month. On 13 March 2008, the SENSEX plummeted another 770.63 points on global economic jitters.
Sources: en.wikipedia.org
Each freeze-thaw cycle can degrade a fraction of the peptide and promote aggregation. Dividing a stock solution into single-use volumes removes repeated cycling as a variable. It also limits the time a thawed solution spends at room temperature.
A high main-peak percentage says little about identity, counter-ion content, or residual solvents. It also does not distinguish an isomer or a closely eluting analog. Mass confirmation and the accompanying documentation cover those gaps.
Salt form changes mass, solubility, and hygroscopicity, and acetate and trifluoroacetate salts behave differently in solution. Storage guidance still centers on -20 °C for powder and lower temperatures for solutions. The certificate should state which salt is present.
电喷雾或基质辅助激光解吸电离质谱是常用手段，测得的质子化离子质荷比可换算为分子量。结果与理论值落在合理误差内，才支持结构一致的判断。