lyophilized powder 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.
Updated 2026-04-01. Numbers and descriptions here follow the published literature rather than marketing material.
Semax 是人工设计的七肽，序列为 Met-Glu-His-Phe-Pro-Gly-Pro，骨架取自促肾上腺皮质激素片段 ACTH(4-10)。它于二十世纪八十年代在苏联的分子遗传学研究机构内合成。设计目标是保留该片段与注意力和记忆相关的活性，同时剔除促皮质激素释放等内分泌作用。此后俄罗斯将其登记为药品并进入临床使用。
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
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.
| Property | Value | Notes |
|---|---|---|
| 结构类别 | 线性合成七肽 | 无环化结构，不含二硫键 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | N 端为甲硫氨酸 |
| 分子量 | 约 814 Da | 游离碱形式的计算值 |
| 外观 | 白色至类白色粉末 | 具吸湿性 |
| 溶解性 | 易溶于水 | 亦可溶于甲醇等极性溶剂 |
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.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
Operation Protea had exposed a glaring lack of professionalism on the part of FAPLA units, which had relied too heavily on their Soviet advisers and were almost immediately routed once they had to leave their fortified bases. In terms of training, morale, organisation, and professional competence—including the ability to operate its own equipment with effectiveness—the Angolan army had proved decidedly vulnerable. Protea indicated that it was in no condition to repel or even inflict serious losses on the South African expeditionary troops, resulting in a ratio of casualties almost overwhelmingly in the SADF's favour. That debacle led to a greater FAPLA dependency on augmented Cuban forces and another large arms deal, valued in excess of one billion dollars, being signed with the Soviet Union. Defence expenditures increased to consume 50% of Angola's state budget by the end of 1982. FAPLA embarked on a massive recruiting drive, purchased new T-54/55 and T-62 tanks from the Soviet Union, and took delivery of about thirty new combat aircraft, including twelve Sukhoi Su-20 strike fighters. It also ordered more air search radars and surface-to-air missiles to replace those destroyed in Protea. While Namibianisation altered the tactical realities of the war on the Cutline, the SADF was planning a fourth operation modelled after Sceptic, Protea, and Daisy. In April 1982, PLAN insurgents killed 9 South African soldiers near Tsumeb, over 200 kilometres south of the border.
Morpholino Also phosphorodiamidate Morpholino oligomer. A synthetic nucleic acid analogue connecting a short sequence of nucleobases into an artificial antisense oligomer, used in genetic engineering to knockdown gene expression by pairing with complementary sequences in naturally occurring RNA or DNA molecules, especially mRNA transcripts, thereby inhibiting interactions with other biomolecules such as proteins and ribosomes. Morpholino oligomers are not themselves translated, and neither they nor their hybrid duplexes with RNA are attacked by nucleases; also, unlike the negatively charged phosphates of normal nucleic acids, the synthetic backbones of Morpholinos are electrically neutral, making them less likely to interact non-selectively with a host cell's charged proteins. These properties make them useful and reliable tools for artificially generating mutant phenotypes in living cells.
== Etymology == The name derives from the Ancient Greek word πολύς (polus, meaning "many, much") and the word 'phenol' which refers to a chemical structure formed by attachment of an aromatic benzenoid (phenyl) ring to a hydroxyl (-OH) group (hence the -ol suffix). The term "polyphenol" has been in use at least since 1894.
Sources: en.wikipedia.org
==== Clipper alcohol douse ==== If more than one animal is being branded the clippers must also be washed with alcohol between shaving each animal. This prevents hair particles from building up in the blades of the clippers, whose residue on the animal's skin can cause uneven or failed branding.
The hormone is synthesized and secreted from alpha cells (α-cells) of the islets of Langerhans, which are located in the endocrine portion of the pancreas. Glucagon is produced from the preproglucagon gene Gcg. Preproglucagon first has its signal peptide removed by signal peptidase, forming the 160-amino acid protein proglucagon. Proglucagon is then cleaved by proprotein convertase 2 to glucagon (amino acids 33-61) in pancreatic islet α cells. In intestinal L cells, proglucagon is cleaved to the alternate products glicentin (1–69), glicentin-related pancreatic polypeptide (1–30), oxyntomodulin (33–69), glucagon-like peptide 1 (72–107 or 108), and glucagon-like peptide 2 (126–158). In rodents, the alpha cells are located in the outer rim of the islet. Human islet structure is much less segregated, and alpha cells are distributed throughout the islet in close proximity to beta cells. Glucagon is also produced by alpha cells in the stomach. Recent research has demonstrated that glucagon production may also take place outside the pancreas, with the gut being the most likely site of extrapancreatic glucagon synthesis.
Progesterone is the most important progestogen in the body. As a potent agonist of the nuclear progesterone receptor (nPR) (with an affinity of KD = 1 nM), the resulting effects on ribosomal transcription play a major role in regulation of female reproduction. In addition, progesterone is an agonist of the more recently discovered membrane progesterone receptors (mPRs), of which the expression has regulation effects in reproduction function (oocyte maturation, labor, and sperm motility) and cancer, although the roles are not yet well defined. Progesterone is also a ligand of the PGRMC1 (progesterone receptor membrane component 1) which impacts tumor progression, metabolic regulation, and viability control of nerve cells. Moreover, progesterone is also known to be an antagonist of the sigma σ1 receptor, a negative allosteric modulator of nicotinic acetylcholine receptors, and a potent antagonist of the mineralocorticoid receptor (MR). Progesterone prevents MR activation by binding to this receptor with an affinity exceeding even those of aldosterone, and glucocorticoids such as cortisol and corticosterone, and it produces antimineralocorticoid effects, such as natriuresis, at physiological concentrations. Progesterone also binds to, and behaves as a partial agonist of, the glucocorticoid receptor (GR), albeit with very low potency (EC50 >100-fold less relative to cortisol). Through its neurosteroid active metabolites, such as 5α-dihydroprogesterone and allopregnanolone, progesterone acts indirectly as a positive allosteric modulator of the GABAA receptor.
Sources: en.wikipedia.org
不存在。它是依据 ACTH 的一段序列人工设计的分子，天然蛋白质中找不到与之完全相同的七肽。名称属于研究代号，而非天然物质名。
Semax 对应 ACTH 第 4 至第 10 位的片段，并在两端做了替换与延长，使其不再具备促肾上腺皮质激素的典型内分泌活性。这一改动同时改变了它在体内的稳定性与分布特征。
俄罗斯将其列为处方药物，需要医生开具处方。多数其他国家把它当作研究化合物，不能作为药品销售或宣称疗效。具体合法性取决于当地法规。
Solid peptide is best kept frozen at about minus 20 degrees Celsius in a sealed container with desiccant. It should be allowed to reach room temperature before opening to prevent condensation. Repeated warming and cooling of the same vial is discouraged.