This is a working overview of thymosin beta-4, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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。
Lyophilized material is typically treated as a hygroscopic solid that should be brought to room temperature before the container is opened, which limits condensation on the powder. Reconstitution is commonly done with sterile water or a buffered diluent, and gentle mixing is preferred over vigorous agitation to reduce foaming and surface adsorption. Because peptides can bind to plastic and glass, diluents containing a small amount of carrier protein are sometimes used in laboratory work. Working solutions are generally aliquoted and prepared fresh rather than subjected to repeated freezing and thawing.
Stability depends on temperature, pH, and the number of freeze-thaw events the sample has experienced. Freeze-dried material is commonly held at -20 °C or colder, while reconstituted liquid is kept cold and used within a short window. Extreme pH and prolonged light exposure can promote deamidation, oxidation, or aggregation, particularly at asparagine and methionine positions. Adsorption to container walls can lower the measured concentration of a dilute solution even when the peptide molecules themselves remain intact.
| 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 |
Thymosin alpha-1 is a synthetic peptide of 28 amino acids whose sequence matches the amino-terminal region of prothymosin alpha. The chain is acetylated at its first residue and contains one disulfide bridge between two cysteine residues, which folds the molecule into a compact loop. Its molecular formula, C129H215N33O55, corresponds to a monoisotopic mass of roughly 3,106 daltons. Material used in laboratories is made by solid-phase synthesis rather than isolated from animal tissue.
Early work on thymic extracts in the 1960s described a heat-stable acidic fraction containing many polypeptides. Separation of that mixture yielded individual components, and thymosin alpha-1 was named as one of them on the basis of assays for T-cell activity. The first preparations came from calf thymus, while subsequent research and clinical material has been chemically synthesized. Nomenclature in older papers is inconsistent, and the same peptide sometimes appears under different designations, which complicates literature searches.
Most published studies on thymosin alpha-1 report changes in immune measurements rather than clinical outcomes, and findings differ across designs and populations. Whether the peptide signals through one defined receptor or through several less specific interactions remains an open question. Its reported circulation half-life of a few hours complicates comparison of dosing schedules across trials. Mechanistic claims are frequently drawn from isolated cell cultures, and how far those results extend to whole organisms is unresolved.
Whether the free 28-residue peptide circulates in human tissue remains debated. The best-documented human source is prothymosin alpha, a larger acidic protein that carries the sequence at its N-terminus. Reports of measurable peptide levels in serum and lymphoid tissue exist, yet some of that signal may come from cross-reacting fragments or from the parent protein. Most reviews therefore treat prothymosin alpha as the established human molecule and describe independent circulation of the small peptide as an unresolved question.
Immunological studies connect the peptide to multiple parts of the immune response. It has been reported to engage Toll-like receptor signaling, to promote dendritic cell maturation, and to influence the balance of T helper cell subsets. Changes in natural killer cell activity and in cytokine release appear in cell culture and animal models. These observations describe broad immunomodulatory behavior rather than a single defined receptor target, and the primary molecular interaction has not been settled.
Thymosin alpha-1 is a 28-residue peptide first isolated from thymus tissue in the 1970s. It corresponds to the N-terminal portion of thymosin beta-4, from which it is cleaved in vivo. The peptide carries an acetyl group at its N-terminus, a modification that affects its charge and stability. Synthetic material produced by solid-phase peptide synthesis is chemically identical to the natural fragment and is the form used in research and clinical studies.
Laboratory work indicates that the peptide acts on cells of both the innate and adaptive immune systems. Reported effects include signalling through Toll-like receptors on dendritic cells, enhanced T-cell maturation, and increased natural killer cell activity. These actions are described largely from cell-culture and animal experiments, and the precise receptor-level events remain incompletely defined. Studies in humans have generally measured immune markers rather than a single defined molecular target. The resulting picture remains partly descriptive.
Clinical research has examined the peptide in chronic hepatitis B and C, as a vaccine adjuvant, and in sepsis and oncology settings. Results across trials have been mixed, and several studies were small or conducted under differing protocols. Regulatory status varies by country, and the compound is not approved in every jurisdiction where it is studied. Evidence for any single indication should be read with attention to sample size and endpoint choice.
== Carbon-11 == Carbon-11 or 11C is a radioactive isotope of carbon that decays to boron-11 with a half-life to 20.34 minutes. This decay mainly occurs due to positron emission, with around 0.19–0.23% of decays instead occurring by electron capture.
=== No development reported === Atomoxetine/orexin antagonist (AD-182) – combination of atomoxetine (norepinephrine reuptake inhibitor) and an orexin receptor antagonist [24] Daridorexant (ACT-541468; nemorexant; Quviviq) – orexin OX1 and OX2 receptor antagonist [25] Lemborexant (Dayvigo; E-2006; LEM) – orexin OX1 and OX2 receptor antagonist [26] Research programme: AMPA receptor agonists - RespireRx (ampakines; CX compounds) – ampakines (AMPA receptor positive allosteric modulators) and brain-derived neurotrophic factor (BDNF) stimulants [27] Research programme: sleep apnoea therapeutics - Apnimed – undefined mechanism of action [28] Seltorexant (JNJ-42847922; JNJ-7922; MIN-202) – orexin OX2 receptor antagonist [29] Vornorexant (ORN-0829; TS-142) – orexin OX1 and OX2 receptor antagonist [30]
In July 2009, Mohammad Sajjadur Rahman noted that Russia's role in the Caucasus region in the 1990s "transformed the separatist conflicts into a dispute between Georgia and Russia" and that "Realism, the most dominant theory of International Relations, can be applied in analyzing Russian behavior" in the conflict which was the first Russian military action since the Soviet–Afghan War. Rahman denied the claim that Russia was defending itself, explaining that "long before the war broke out, Russia had established the infrastructure and logistical support for a military invasion" and decision to go to war was "guided by a number of geopolitical interests that Russia sought to advance through a decisive victory", such as "Putins’ evident desire to elevate Russia's Great Power image". However, "the war exposed Russia's failure to accomplish political objectives without recourse to violence." Rahman summarized that "the causes of the August war were indeed complex and multifaceted" and the failure of the West "in deescalating the tension also contributed to the outbreak of this limited war."
Sources: en.wikipedia.org
=== Legal status === Oxycodone is subject to international conventions on narcotic drugs. In addition, oxycodone is subject to national laws that differ by country. The 1931 Convention for Limiting the Manufacture and Regulating the Distribution of Narcotic Drugs of the League of Nations included oxycodone. The 1961 Single Convention on Narcotic Drugs of the United Nations, which replaced the 1931 convention, categorized oxycodone in Schedule I. Global restrictions on Schedule I drugs include "limit[ing] exclusively to medical and scientific purposes the production, manufacture, export, import, distribution of, trade in, use and possession of" these drugs; "requir[ing] medical prescriptions for the supply or dispensation of [these] drugs to individuals"; and "prevent[ing] the accumulation" of quantities of these drugs "in excess of those required for the normal conduct of business".
=== Mechanism of action === The alkylation mechanism of melphalan is shared by all nitrogen mustards, proceeding through the formation of an aziridinium cation. This highly reactive intermediate interacts with nitrogen atoms in nucleotide bases, generating positively charged adducts. Melphalan chemically modifies DNA nucleotides through alkylation, primarily targeting guanine at the N7 position within the major groove, and to a lesser extent adenine at the N3 position within the minor groove.
Once glucose enters the cell, the first step is phosphorylation of glucose by a family of enzymes called hexokinases to form glucose 6-phosphate (G6P). This reaction consumes ATP, but it acts to keep the glucose concentration inside the cell low, promoting continuous transport of blood glucose into the cell through the plasma membrane transporters. In addition, phosphorylation blocks the glucose from leaking out – the cell lacks transporters for G6P, and free diffusion out of the cell is prevented due to the charged nature of G6P. Glucose may alternatively be formed from the phosphorolysis or hydrolysis of intracellular starch or glycogen. In animals, an isozyme of hexokinase called glucokinase is also used in the liver, which has a much lower affinity for glucose (Km in the vicinity of normal glycemia), and differs in regulatory properties. The various substrate affinities and regulation of this enzyme reflect the role of the liver in maintaining blood sugar levels. Cofactors: Mg2+
Sources: en.wikipedia.org
=== Reference ranges === The European Food Safety Authority (EFSA) recommends a dietary allowance of 70 μg per day selenium intake for adults. In the US, the Dietary Reference Intake for adults is 55 μg/day. In the UK it is 75 μg/day for adult males and 60 μg/day for adult females. The 55 μg/day recommendation is based on the full expression of plasma glutathione peroxidase. Selenoprotein P is a better indicator of selenium nutritional status, and full expression of it would require more than 66 μg/day.
=== Chemical precursor === Castor oil can react with other materials to produce other chemical compounds that have numerous applications. Transesterification followed by steam cracking gives undecylenic acid, a precursor to specialized polymer nylon 11, and heptanal, a component in fragrances. Breakdown of castor oil in strong base gives 2-octanol, both a fragrance component and a specialized solvent, and the dicarboxylic acid sebacic acid. Hydrogenation of castor oil saturates the alkenes, giving a waxy lubricant. Castor oil may be epoxidized by reacting the OH groups with epichlorohydrin to make the triglycidyl ether of castor oil which is useful in epoxy technology. This is available commercially as Heloxy 505. The production of lithium grease consumes a significant amount of castor oil. Hydrogenation of castor oil yields 12-hydroxystearic acid, a precursor to lithium 12-hydroxystearate, a thickener in lubricating greases. Since it has a relatively high dielectric constant (4.7), highly refined and dried castor oil is sometimes used as a dielectric fluid within high-performance, high-voltage capacitors.
However, building on the same experiment, they discovered that a mixture sodium citrate and glucose (dextrose) solution was a perfect preservative; as they reported in February issue of the Journal of Experimental Medicine, the preserved bloods were just like fresh bloods and that they "function excellently when reintroduced into the body." Blood could be preserved for up to four weeks. An accompanying experiment using citrate-saccharose (sucrose) mixture was also a success which could maintain blood cells for two weeks. This use of citrate and sugars, sometimes known as Rous-Turner solution, was the foundation for the development of blood banks and improvement of transfusion method. Another discovery of Rous and Turner was the most critical step in the safety of blood transfusion. Rous was well aware that Landsteiner's concept of blood types had not yet found practical value, as he remarked: "The fate of Landsteiner's effort to call attention to the practical bearing of the group differences in human bloods provides an exquisite instance of knowledge marking time on technique. Transfusion was still not done because (until at least 1915), the risk of clotting was too great." In June 1915, they made a crucial report in the Journal of the American Medical Association that agglutination could be avoided if the blood samples of the donor and recipient were tested before.
coding strand Also sense strand, positive (+) sense strand, and nontemplate strand. The strand of a double-stranded DNA molecule whose nucleotide sequence corresponds directly to that of the RNA transcript produced during transcription (except that thymine bases are substituted with uracil bases in the RNA molecule). Though it is not itself transcribed, the coding strand is by convention the strand used when displaying a DNA sequence because of the direct analogy between its sequence and the codons of the RNA product. Contrast template strand; see also sense.
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。
Cold storage slows the chemical degradation reactions that occur in solution. Lyophilized powder is more stable than reconstituted liquid and tolerates longer storage periods. Repeated temperature cycling should still be avoided because it can drive aggregation and loss of material.