If you have been reading about thymalfasin and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-11-10. 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。
胸腺素α1（thymosin alpha 1，Tα1）是一种由28个氨基酸组成的酸性肽，N端被乙酰化，分子量约为3108道尔顿。该肽最早从牛胸腺组织提取物中分离，属于胸腺素组分5的一个成分。其序列在不同哺乳动物中高度保守，提示其具有基本的生物学功能。名称中的“α1”指其在电泳中的迁移位置，并非表示亚型编号。它既存在于胸腺，也存在于脾脏和淋巴结等免疫组织。
Reverse-phase high-performance liquid chromatography is the standard technique for assessing purity and concentration, because the peptide's hydrophobicity allows clean separation from related impurities. Mass spectrometry confirms molecular identity and detects sequence errors or truncations. Amino acid analysis and peptide mapping supply additional structural confirmation when required. Chromatographic purity values reported on certificates of analysis describe the proportion of the main peak and do not by themselves establish biological activity.
Like most short peptides, thymosin alpha-1 is susceptible to hydrolysis under strongly acidic or basic conditions and to oxidation when exposed to air over long periods. The acetylated amino terminus blocks one common degradation route, which contributes to the molecule's relative robustness in solution. Lyophilized material generally retains potency for extended periods when kept cold and dry. Once reconstituted, aqueous solutions are less stable and are typically used within a defined window rather than held indefinitely at ambient temperature.
| 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 |
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.
The peptide occurs naturally in thymic tissue and has been detected in serum and other biological fluids. Reported concentrations are low, and reliable measurement generally requires immunoassay or mass spectrometry with an enrichment step. It is released from a larger precursor, prothymosin alpha, by proteolytic cleavage, although the enzymes involved are not fully characterized. Whether circulating levels reflect thymic output specifically remains an open question.
Thymosin alpha 1 is a 28-amino-acid peptide first isolated from thymosin fraction 5, a bovine thymic extract. Its sequence begins with an acetylated serine residue and carries a high proportion of acidic residues, so the molecule has a net negative charge near neutral pH. Despite the shared name, it is unrelated in sequence to the thymosin beta family. Synthetic material prepared by solid-phase peptide synthesis is identical in sequence to the natural peptide.
Within the immune system, the peptide acts on several cell types rather than a single target. Reported activities include promotion of T-cell maturation, enhancement of natural killer cell activity, and modulation of cytokine production by dendritic cells and macrophages. Some of these effects appear to operate through toll-like receptor signaling, though the precise receptor-level mechanism remains debated. Whether the observed immune changes translate into clinical benefit is a separate question and depends on the indication studied.
The peptide was described in the 1970s as a component of thymic extracts, and early research focused on restoring immune function in immunodeficiency states. A synthetic version entered clinical development in the 1980s and is approved as a drug in several countries for conditions such as chronic hepatitis B and certain immunodeficiencies. Approval status varies widely by jurisdiction, and in the United States it is not an approved therapeutic. Regulatory and clinical positions differ, so statements about efficacy should be tied to specific indications and studies.
Thymosin alpha-1 is supplied as a lyophilized powder in most research settings. The solid dissolves readily in water and in common aqueous buffers, and it is typically reconstituted shortly before use. Solutions are clear and colourless at ordinary working concentrations. Because the peptide is hygroscopic, weighing and reconstitution are usually performed with minimal exposure to ambient air. Aliquots are prepared to avoid repeated freeze-thaw cycles, and working solutions are kept cold.
Long-term storage is generally at minus twenty degrees Celsius or colder, preferably desiccated and protected from light. Lyophilized material is more stable than reconstituted solution, which degrades faster at room temperature. Stability depends on pH, ionic strength, and the presence of oxidising agents. Published stability data for the peptide are limited, so storage claims in catalogues should be treated as general guidance rather than measured guarantees. Freeze-thaw cycles are kept to a minimum.
== Mechanism of action == Apixaban is a highly selective, orally bioavailable, and reversible direct inhibitor of free and clot-bound factor Xa. Factor Xa catalyzes the conversion of prothrombin to thrombin, the final enzyme in the coagulation cascade that is responsible for fibrin clot formation. Apixaban has no direct effect on platelet aggregation, but by inhibiting factor Xa, it indirectly decreases clot formation induced by thrombin.
Lys arylation Similar to cysteine, lysine N-arylation could be achieved through Pd OACs with different dialkylbiaryl phosphine ligands. Due to weaker nucleophilicity and slower reductive elimination rate compared to cysteine, the selection of supporting ligands is shown to be critical. The bulky BrettPhos and t-BuBrettPhos ligands in conjunction with mildly basic sodium phenoxide have been used as the strategy to functionalize lysines on peptide substrates. The reaction happens in mild conditions and is selective over most other nucleophilic amino acid residues.
=== Municipal administration === The number of inhabitants in Le Havre is between 150,000 and 199,999 so the number of councillors is 59 members. The mayor, 41 aldermen and 17 deputies form the council of Le Havre elected in 2008. It meets on average once a month at the town hall. The debates are generally public except for certain proceedings. Le Havre has experienced many territorial extensions by annexing neighbouring communes:
=== Stress-responsive kinases === Kinases that regulate p53 phosphorylation can be divided into two broad groups. One group includes members of the MAPK pathways, including JNK1–3, ERK1/2 and p38 MAPK, which are activated by diverse cellular stresses such as oxidative stress and heat shock. A second group comprises DNA damage response kinases, including ATM, ATR and DNA-PK, together with downstream checkpoint kinases such as CHK1 and CHK2, which are activated by DNA damage and replication stress and contribute to p53 regulation through phosphorylation-dependent signalling. Additional kinases implicated in p53 phosphorylation include the CDK-activating kinase (CAK; CDK7–cyclin H–MAT1), which has been shown to phosphorylate p53 (for example at Ser33) in vitro and in vivo, and TP53RK (PRPK), which has been reported to phosphorylate p53 at Ser15. Oncogene-induced activation of p53 can also occur via p14ARF (ARF), which inhibits the p53 antagonist MDM2 and thereby stabilizes p53.
Bradycardia, junctional rhythms and QRS widening are particularly associated with increased risk of adverse outcomes The serum potassium concentration at which electrocardiographic changes develop is somewhat variable. Although the factors influencing the effect of serum potassium levels on cardiac electrophysiology are not entirely understood, the concentrations of other electrolytes, as well as levels of catecholamines, play a major role. ECG findings are not a reliable finding in hyperkalemia. In a retrospective review, blinded cardiologists documented peaked T-waves in only 3 of 90 ECGs with hyperkalemia. Sensitivity of peaked-Ts for hyperkalemia ranged from 0.18 to 0.52, depending on the criteria for peak-T waves.
Sources: en.wikipedia.org
=== Founding === The Convention on the Organisation for Economic Co-operation and Development was signed on 14 December 1960, and the OECD officially superseded the OEEC in September 1961, consisting of the European founder countries of the OEEC, with the additions of the United States and Canada. Three countries, (the Netherlands, Luxembourg, and Italy)—all OEEC members—ratified the OECD Convention after September 1961, but are nevertheless considered founding members. The official founding members were Austria, Belgium, Canada, Denmark, France, Greece, Iceland, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, Turkey, the United Kingdom, the United States, and West Germany. Japan became a member in 1964, and over the following decade, Finland, Australia, and New Zealand also joined the organisation. Yugoslavia had observer status in the organisation, starting with the establishment of the OECD, until its dissolution as a country. The OECD also created agencies such as the OECD Development Centre (1961), International Energy Agency (IEA, 1974), and Financial Action Task Force on Money Laundering (FATF). The aims of the OECD are stated in Article 1 of the Convention as:
== Characterization == The glutathione peroxidase family consists of 8 known human isoforms. Glutathione peroxidases use glutathione as an electron donor and are active with both hydrogen peroxide and organic hydroperoxide substrates. Gpx1, Gpx2, Gpx3, and Gpx4 have been shown to be selenium-containing enzymes, whereas Gpx6 is a selenoprotein in humans with cysteine-containing homologues in rodents. Amyloid beta, when bound to heme, has been shown to have peroxidase activity. A typical group of peroxidases are the haloperoxidases. This group is able to form reactive halogen species and, as a result, natural organohalogen substances. A majority of peroxidase protein sequences can be found in the PeroxiBase database.
=== Hyperthermia therapy === Hyperthermia therapy is heat treatment for cancer that can be a powerful tool when used in combination with chemotherapy (thermochemotherapy) or radiation for the control of a variety of cancers. The heat can be applied locally to the tumor site, which will dilate blood vessels to the tumor, allowing more chemotherapeutic medication to enter the tumor. Additionally, the tumor cell membrane will become more porous, further allowing more of the chemotherapeutic medicine to enter the tumor cell. Hyperthermia has also been shown to help prevent or reverse "chemo-resistance." Chemotherapy resistance sometimes develops over time as the tumors adapt and can overcome the toxicity of the chemo medication. "Overcoming chemoresistance has been extensively studied within the past, especially using CDDP-resistant cells. In regard to the potential benefit that drug-resistant cells can be recruited for effective therapy by combining chemotherapy with hyperthermia, it was important to show that chemoresistance against several anticancer drugs (e.g. mitomycin C, anthracyclines, BCNU, melphalan) including CDDP could be reversed at least partially by the addition of heat.
The most important drugs with a dipeptide (L-alanyl-L-proline) moiety are the "-pril" cardiovascular drugs, such as Alapril (lisinopril), Captoril (captopril), Novolac (imidapril) and Renitec (enalapril). The artificial sweetener Aspartame (N-L-α-Aspartyl-L-phenylalanine 1-methyl ester) is also a dipeptide. At the high end, there is the anticoagulant hirudin, MW ≈ 7000, which is composed of 65 amino acids. Apart from pharmaceuticals, peptides are also used for diagnostics and vaccines. The total production volume (excluding Aspartame) of chemically synthesized, pure peptides is about 1,500 kg (3,300 lb) and sales approach $500 million on the active pharmaceutical (API) level and $10 billion on the finished drug level, respectively. The bulk of the production of peptide drugs, which also include the first generation anti-AIDS drugs, the "...navirs", is outsourced to a few specialized contract manufacturers, such as Bachem, Switzerland; Chengu GT Biochem, China; Chinese Peptide Company, China; Lonza, Switzerland, and Polypeptide, Denmark. Proteins are "very high-molecular-weight" (MW > 100,000) organic compounds, consisting of amino acid sequences linked by peptide bonds. They are essential to the structure and function of all living cells and viruses and are among the most actively studied molecules in biochemistry. They can be made only by advanced biotechnological processes; primarily mammalian cell cultures. Monoclonal antibodies (mAb) prevail among human-made proteins. About a dozen of them are approved as pharmaceuticals.
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。
The lyophilized solid is normally held at 2 to 8 °C in a sealed, light-protected container. Dry storage limits both hydrolysis and microbial growth. Material kept this way remains stable for the shelf life stated by the supplier.