deamidation 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.
Last reviewed on 2026-04-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
20世纪70年代，研究者从胸腺提取物中纯化出多种小肽，Tα1是其中被较早表征的一种。最初的制备依赖组织匀浆和层析步骤，产量低且成分复杂。随着固相肽合成技术成熟，实验室和工业界能够生产与天然序列一致的合成版本。合成肽的纯度可达95%以上，并可通过反相高效液相色谱和质谱进行鉴定。这一转变使研究不再依赖动物胸腺来源。
市售的胸腺素α1通常以冻干粉形式提供，溶解后用于注射。其氨基酸组成包括多个酸性残基，因此在中性pH下带负电荷。该肽可溶于水和生理盐水，但在有机溶剂中溶解度有限。储存条件通常为冻干状态下负20摄氏度，溶解后需冷藏并避免反复冻融。常见的同义词包括胸腺肽α1、thymalfasin和Tα1。
Practical handling focuses on limiting adsorption and contamination. The peptide dissolves readily in water, and dilute solutions tend to adhere to plastic and glass surfaces, so an inert carrier protein or a defined buffer can reduce losses in laboratory work. Workers also record the counter-ion form, since an acetate or trifluoroacetate salt changes the mass balance of the weighed powder. Documentation of lot number, purity value, and storage history supports reproducibility when results from different laboratories are compared.
Lyophilized material is generally held at reduced temperature to slow degradation, and storage at minus twenty degrees Celsius or lower is common practice for long-term retention. Short-term working portions are often kept between two and eight degrees Celsius. Once dissolved, the peptide is less stable than the dry powder, and repeated freeze-thaw cycles are associated with loss of material and with aggregate formation. Vials are usually allowed to reach room temperature before opening so that condensation does not introduce moisture, and solutions are protected from light where practical.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography, which separates the peptide from closely related impurities and from truncated or oxidized variants. Mass spectrometry supplies the molecular mass and confirms the expected sequence length, while amino acid analysis can be used to check composition. Because the molecule has no chromophore beyond the peptide backbone, ultraviolet detection is typically performed at a low wavelength, where baseline interference from solvents and buffers is a practical concern. Water content and counter-ion content are often reported alongside purity.
| Property | Value | Notes |
|---|---|---|
| 化学分类 | 线性肽 | 由28个氨基酸组成 |
| 分子量 | 约3108 Da | 合成版本一致 |
| 外观 | 白色至类白色粉末 | 冻干品 |
| 溶解度 | 易溶于水 | 微溶于有机溶剂 |
| 储存温度 | -20°C（冻干） | 溶解后2-8°C |
Immune signaling studies link thymosin alpha 1 to Toll-like receptor pathways, particularly TLR2 and TLR9, on dendritic cells and other antigen-presenting cells. Activation of these receptors promotes maturation of T cells and increases natural killer cell activity. The peptide shifts cytokine output toward a T helper 1 profile, raising interferon gamma and interleukin 2 while modulating interleukin 10. Whether these effects translate into clinical benefit for any specific disease remains a subject of debate. Reported outcomes vary across trials and populations.
Thymosin alpha 1 is approved as a medicine in several countries, including Italy and China, for indications such as chronic hepatitis B and as an immune adjuvant. It is not approved by the United States Food and Drug Administration as a therapeutic product. In research settings the peptide appears in studies of sepsis, vaccine response, and oncology support, often with mixed or inconclusive results. The evidence base is uneven, and reviews note that many trials were small. Regulatory status therefore differs widely between jurisdictions.
Lyophilized thymosin alpha-1 is generally stored at or below minus twenty degrees Celsius, protected from moisture and light. Short-term handling at ambient temperature is possible for dry powder, but reconstituted solutions degrade faster and are usually kept at two to eight degrees Celsius with a defined expiry of days rather than weeks. Repeated freeze-thaw cycles should be avoided because they promote aggregation and loss of potency. Exact limits depend on the formulation and should follow the supplier's documentation.
Identity and purity are normally assessed by reversed-phase high-performance liquid chromatography, which separates the peptide from related impurities and truncation products. Mass spectrometry confirms molecular mass and detects modifications such as deamidation or oxidation. Amino acid analysis and peptide mapping provide additional sequence-level confirmation. For research material, a certificate of analysis typically reports these results together with water content and counter-ion identity, since the lyophilized powder is often supplied as an acetate or trifluoroacetate salt.
=== Regulation of fatty acid synthesis === Acetyl-CoA is formed into malonyl-CoA by acetyl-CoA carboxylase, at which point malonyl-CoA is destined to feed into the fatty acid synthesis pathway. Acetyl-CoA carboxylase is the point of regulation in saturated straight-chain fatty acid synthesis, and is subject to both phosphorylation and allosteric regulation. Regulation by phosphorylation occurs mostly in mammals, while allosteric regulation occurs in most organisms. Allosteric control occurs as feedback inhibition by palmitoyl-CoA and activation by citrate. When there are high levels of palmitoyl-CoA, the final product of saturated fatty acid synthesis, it allosterically inactivates acetyl-CoA carboxylase to prevent a build-up of fatty acids in cells. Citrate acts to activate acetyl-CoA carboxylase under high levels, because high levels indicate that there is enough acetyl-CoA to feed into the Krebs cycle and produce energy. High plasma levels of insulin in the blood plasma (e.g. after meals) cause the dephosphorylation and activation of acetyl-CoA carboxylase, thus promoting the formation of malonyl-CoA from acetyl-CoA, and consequently the conversion of carbohydrates into fatty acids, while epinephrine and glucagon (released into the blood during starvation and exercise) cause the phosphorylation of this enzyme, inhibiting lipogenesis in favor of fatty acid oxidation via beta-oxidation.
=== National politics === For elections to the National Assembly, Le Havre is divided between Seine-Maritime's 7th and 8th constituency. They are currently represented by Agnès Firmin-Le Bodo and Jean-Paul Lecoq.
=== Stem cells === Levels of p53 play an important role in the maintenance of stem cells throughout development and the rest of human life. In human embryonic stem cells (hESCs)s, p53 is maintained at low inactive levels. This is because activation of p53 leads to rapid differentiation of hESCs. Studies have shown that knocking out p53 delays differentiation and that adding p53 causes spontaneous differentiation, showing how p53 promotes differentiation of hESCs and plays a key role in cell cycle as a differentiation regulator. When p53 becomes stabilized and activated in hESCs, it increases p21 to establish a longer G1. This typically leads to abolition of S-phase entry, which stops the cell cycle in G1, leading to differentiation. Work in mouse embryonic stem cells has recently shown however that the expression of P53 does not necessarily lead to differentiation. p53 also activates miR-34a and miR-145, which then repress the hESCs pluripotency factors, further instigating differentiation. In adult stem cells, p53 regulation is important for maintenance of stemness in adult stem cell niches. Mechanical signals such as hypoxia affect levels of p53 in these niche cells through the hypoxia inducible factors, HIF-1α and HIF-2α. While HIF-1α stabilizes p53, HIF-2α suppresses it. Suppression of p53 plays important roles in cancer stem cell phenotype, induced pluripotent stem cells and other stem cell roles and behaviors, such as blastema formation. Cells with decreased levels of p53 have been shown to reprogram into stem cells with a much greater efficiency than normal cells.
This increase is comparable to the increase which was found in mouse myotubes. In contrast to the mouse myotubes calciseptine did not change the reversal potential of the Ca2+ current. In rat muscle fibers after applying calciseptine there were very slight changes found in twitch tension, which shows us that the peptide had very little effect on muscle contraction. Calciseptine also had little effect on frog muscle fibers. There is a small effect of calciseptine during a series of repetitive stimuli which generate a tetanus; calciseptine increased tetanic tension. The average tetanic tension after applying calciseptine was slightly higher than the control value. Though calciseptine gives an increase in charge movement and increase in influx of Ca2+ through L-type channels this has no major effects on contraction of the muscle, even in tetanus. Research on rats and guinea pigs revealed that synthetic calciseptine and FS2 as well, have the same effect as their natural counterparts.
Eight people, including two children, were killed while 29 others were injured in Russian missile attacks on Dnipropetrovsk Oblast, particularly in Dnipro and Synelnykove. A total of 22 missiles and 14 Shahed drones were fired, including six Kh-22 missiles and two Iskander-K missiles; according to Ukraine, 29 were intercepted including two Kh-22s, which were intercepted by the Patriot air defense system, the first time these missiles were intercepted since the start of the invasion. Two people were killed in separate attacks in Mykolaiv Oblast and Kherson. A Russian Tupolev Tu-22M3 long range strategic bomber crashed in Stavropol Krai while returning to base, killing one crew member, with another missing. Ukraine claimed to have shot it down, at a range of 308 km, using an S-200 missile, according to an interview with Lt. Gen. Kyrylo Budanov, head of the HUR. Russian authorities claimed the aircraft crashed due to a technical malfunction. Russian media reported that Russell Bentley, an American citizen and a resident of Donetsk Oblast who fought for pro-Russian separatists during the Donbas War was killed in unspecified circumstances after going missing following a Ukrainian attack on 8 April. His wife claimed that he had been abducted by Russian soldiers. Russian media outlets claimed that Izvestia war correspondent Semyon Eremin was killed by a Ukrainian drone strike after visiting a Russian unit in Zaporizhzhia Oblast.
Sources: en.wikipedia.org
== Further reading == Virtual Textbook of Organic Chemistry Visualizations of the low-temperature crystal structures of alkanes (methane to nonane) Redwood, Boverton (1911). "Paraffin" . Encyclopædia Britannica. Vol. 20 (11th ed.). pp. 752–756.
== Usage during original Cold War == The phrase "new Cold War" was first used in 1955 by US secretary of state John Foster Dulles, and in a 1956 New York Times article warning of Soviet propaganda promoting the Cold War's resurgence. Other analysts, such as academics Fred Halliday, Alan M. Wald, David S. Painter, and Noam Chomsky, used the interchangeable terms to refer to the 1979–1985 or 1985–1991 phases of the Cold War. Some other analysts used similar terms to refer to the Cold War of the mid-1970s. Columnist William Safire argued in a 1975 New York Times editorial that the Nixon administration's policy of détente with the Soviet Union had failed and that "Cold War II" was then underway. Academic Gordon H. Chang used the term "Cold War II" to refer to the Cold War period after the 1972 meeting in China between US president Richard Nixon and Chinese Communist Party chairman Mao Zedong.
Logan Roy is a fictional character and one of the main characters of the American HBO satirical dark comedy-drama television series Succession. He is portrayed by Brian Cox and was created by showrunner Jesse Armstrong. Armstrong initially conceived the series as a feature film about the Murdoch family. He later decided to create a new script centered on original characters, with Logan being loosely based on Rupert Murdoch and Sumner Redstone. Logan Roy is the self-made billionaire founder of media and entertainment conglomerate Waystar RoyCo and the patriarch of the Roy family. He is a harsh leader who primarily focuses on his company rather than his four children Connor, Kendall, Roman and Siobhan. He is distrustful of his children and his subordinates, refusing to step down as CEO at the start of the series despite his advanced age as well as health. His conflicts with his family, his employees at Waystar, other businesses, and the United States Department of Justice form the central story-line of the series. The character and Brian Cox's performance has been critically acclaimed, and has been cited as one of the best villains and characters in television. For his performance, Cox won the Golden Globe Award for Best Actor in a Drama Series and was nominated for three Primetime Emmy Awards for Outstanding Lead Actor in a Drama Series.
==== Overall genital system structure ==== The genital system of an adult male P. phalangioides is located in the ventral portion of the opisthosoma and can be characterized by a large pair of testes and thin, twisted vasa deferentia which become thicker upon nearing the genital opening of the male pedipalp. These vasa deferentia distally fuse creating the ductus ejaculatorius of the spider. The ductus ejaculatorius is composed of lumen which contains large quantities of spermatozoa and other secretions. This variety of secretions is not seen in subadult males whose lumen only contains dense secretion matrix. Ventrally surrounding specific portions of the genital tract are apullate silk glands, and overall, the genital system is bordered by parts of the midgut gland. All stages of spermatogenesis are apparent in the adult testes, and the spermatozoa are coiled. In order to reach this stage with a fully formed male genital system, P. phalangioides must first go through two subadult phases.
Sources: en.wikipedia.org
它不是经典的内分泌激素，而是一种免疫调节肽。其作用主要通过局部免疫细胞间的信号传递实现，而非经血液循环作用于远隔器官。
天然胸腺素α1主要从胸腺组织提取，也可在脾脏和淋巴结中检出。目前研究和临床使用的多为化学合成版本，不再依赖动物组织。
胸腺素组分5是牛胸腺提取物的粗组分，包含多种肽。胸腺素α1是其中一种被纯化和表征的单一肽，具有明确的28个氨基酸序列。
Cool storage below freezing is usual for long-term retention, with a desiccant and protection from light. Portions are often split before first use to avoid repeated handling.