The short version of Thymosin fraction 5 fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-30 and is reviewed periodically as new material appears.
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.
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。
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。
| Property | Value | Notes |
|---|---|---|
| Class | Synthetic peptide | 28 residues; not a small-molecule compound |
| Molecular mass | About 3,106 Da | Monoisotopic mass of the unmodified chain |
| N-terminal group | Acetylated serine | Present in both native and synthetic forms |
| Secondary structure | Disulfide-constrained loop | One bridge between two cysteine residues |
| Typical source | Solid-phase synthesis | Early isolates came from bovine thymus extracts |
Thymosin alpha-1 is a synthetic peptide of 28 amino acid residues that corresponds to a naturally occurring fragment first isolated from thymus tissue. Its chain is acetylated at the amino terminus, a modification that shields the peptide from rapid cleavage by aminopeptidases. The molecule carries a net negative charge at physiological pH and dissolves freely in water. Researchers classify it as an immune-modulating agent rather than a classical hormone, because it acts on several cell types of both the innate and the adaptive immune system.
The peptide was identified during work in the 1970s on thymosin fraction 5, a partially purified extract of calf thymus. Investigators separated that mixture and characterized individual components, one of which they named thymosin alpha-1. The same compound later received the international nonproprietary name thymalfasin. Commercial material is produced by solid-phase peptide synthesis rather than by extraction, so synthetic and natural forms share an identical sequence. Naming conventions vary across the literature, and readers should distinguish the alpha-1 peptide from other thymosins that have unrelated sequences and functions.
Biologically, the peptide is studied mainly in the context of immune cell development and regulation. It is produced in the thymus and in several other tissues, and it appears to influence the maturation and activity of T cells and other immune populations. Laboratory work describes effects on cytokine production, on the balance between T cell subsets, and on the function of dendritic cells. Much of this evidence comes from cell culture and animal models, so the extent to which the same pathways operate in humans remains an open question.
Clinical interest has centered on chronic viral hepatitis, on immune restoration in various conditions, and on use as an adjuvant intended to improve responses to vaccines. Trials have reported mixed results, and regulatory status differs sharply between countries; in some places it is a prescription product, while elsewhere it is sold without an approved therapeutic indication. Because published studies vary widely in design, population, and endpoints, comparisons across them are difficult and no single conclusion covers the whole literature.
The peptide is generated in cells by cleavage of prothymosin alpha, a larger acidic protein encoded by the PTMA gene. Prothymosin alpha is expressed in many tissues, not only in the thymus, and its functions include nuclear roles in chromatin-related processes. The 28-residue fragment corresponds to the N-terminal portion of that precursor. How the cleavage occurs and how the fragment's concentration is regulated remain open questions; circulating amounts are small and difficult to measure reliably with routine assays.
Thymosin alpha 1 is a short peptide first isolated from bovine thymus tissue in the early 1970s during fractionation work aimed at identifying factors that influence T cell development. It belongs to a family of acidic thymic peptides, and the original preparations contained several components that were later separated by chromatography. The compound is now produced synthetically rather than extracted from tissue, which removes batch variability tied to animal sourcing. Researchers describe it as an immunomodulatory peptide because laboratory studies show effects on several cell types of the innate and adaptive immune systems.
The molecule consists of 28 amino acid residues with an acetyl group attached to the N-terminal serine. Its sequence is acidic overall, with several glutamic and aspartic acid residues distributed along the chain and no cysteine, so disulfide bridges do not form. The peptide carries a net negative charge at physiological pH. Because the N-terminus is blocked, the intact molecule resists degradation by many aminopeptidases, which contributes to its stability in biological fluids.
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 synthetic 28-amino-acid peptide whose sequence was first identified in extracts of bovine thymus tissue during the 1970s. The chain carries an acetyl group on its N-terminal serine. Its acidic residue content is high, which produces strong water solubility and an isoelectric point well below neutrality. Material supplied for laboratory and clinical use is manufactured by solid-phase peptide synthesis rather than purified from animal tissue. Different salt forms, such as the acetate, alter the counter-ion content without changing the peptide backbone.
== Distribution and habitat == N. christyi has a small geographic range. It occurs in western Democratic Republic of Congo, the southern half of the Republic of Congo, a very small portion of southeastern Gabon, and in the province of Cabinda in far northern Angola. N. christyi is found most commonly in or near water, in lowland bushy or wooded areas along banks of lakes, rivers, and streams. It is limited to the lower Congo River and nearby wet forested areas.
===== Domestic electrical installation ===== Ground fault interrupters are available to reduce electric fields and (in the case of current flow) magnetic fields from residential electrical installations. In plaster installations, only a small part of the electric field can escape from the wall. However, a mains disconnect switch automatically disconnects the relevant line as long as no electrical load is switched on; as soon as a load is switched on, the mains voltage is also switched on. Ground fault interrupters were introduced in 1973 and have been continuously improved over the decades. In 1990, for example, it became possible to disconnect the PEN conductor (formerly known as the neutral conductor). Circuit breakers can be installed in several different circuits, preferably in those that supply bedrooms. However, they only turn off when no continuous current consumers such as air conditioners, fans, humidifiers, electric alarm clocks, night lights, standby devices, alarm systems, chargers, and similar devices are turned on. Instead of the mains voltage, a low voltage (2-12 volts) is applied, which can be used to detect when a consumer is switched on. Rooms can also be shielded with copper wallpaper or special wall paints containing metal, thus applying the Faraday cage principle.
Peptidoglycan, murein or mucopeptide is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like layer (sacculus) that surrounds the bacterial cytoplasmic membrane. The sugar component consists of alternating residues of β-(1,4) linked N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). Attached to the N-acetylmuramic acid is an oligopeptide chain made of three to five amino acids. The peptide chain can be cross-linked to the peptide chain of another strand forming the 3D mesh-like layer. Peptidoglycan serves a structural role in the bacterial cell wall, giving structural strength, as well as counteracting the osmotic pressure of the cytoplasm. This repetitive linking results in a dense peptidoglycan layer which is critical for maintaining cell form and withstanding high osmotic pressures, and it is regularly replaced by peptidoglycan production. Peptidoglycan hydrolysis and synthesis are two processes that must occur in order for cells to grow and multiply, a technique carried out in three stages: clipping of current material, insertion of new material, and re-crosslinking of existing material to new material. The peptidoglycan layer is substantially thicker in gram-positive bacteria (20 to 80 nanometers) than in gram-negative bacteria (7 to 8 nanometers). Depending on pH growth conditions, the peptidoglycan forms around 40 to 90% of the cell wall's dry weight of gram-positive bacteria but only around 10% of gram-negative strains.
Sources: en.wikipedia.org
== Selected publications == Addona, T. A.; et al. (2009). "Multi-site assessment of the precision and reproducibility of multiple reaction monitoring–based measurements of proteins in plasma". Nature Biotechnology. 27 (7): 633–641. doi:10.1038/nbt.1546. Petrotchenko, E. V.; Borchers, C. H. (2022). "Protein Chemistry Combined with Mass Spectrometry for Protein Structure Determination". Chemical Reviews. 122 (8): 7488–7499. doi:10.1021/acs.chemrev.1c00302. Mohammed, Y.; et al. (2025). "SysQuan: Repurposing SILAC Mice for the Cost-Effective Absolute Quantitation of the Human Proteome". Molecular & Cellular Proteomics. 24 (6): 100974. doi:10.1016/j.mcpro.2025.100974.
== Chromosome and gene abnormalities == Most cases of MFS have tumor cells that contain complex chromosome and/or gene abnormalities including ring chromosomes (i.e. chromosome whose ends are fused together to form a ring), double minutes (i.e. small fragments of extrachromosomal DNA), chromosomes with deletions of part of their genetic material, and chromosome translocations (i.e. abnormal switches in genetic material between different chromosomes). There were no apparent differences in these abnormalities between lower grade and higher grade tumors but their numbers were higher and more prevalent in recurrent tumors. These forms of chromosome/gene cytogenetic alterations are commonly found in various tumor types regardless of their grade or severity. Tumor cell mutations or deletions in the NF1 gene occur ~10% of MFS cases while mutations in the CDKN2A/CDKN2B and amplifications in the CDK6, CCND1, and MDM2 genes occur in rare MFS cases. While the cells in many tumor types express specific chromosome/gene abnormalities that help in determining their diagnoses, the cited chromosome and gene abnormalities discovered in TBS tumor cells have not yet been found specific enough to be of help in diagnosing MFS. The chromosome/gene abnormalities have not yet been defined in the epithelioid variant of MFS.
The U.S. Department of Energy (DOE) has published a list of yearly technical system targets for on-board hydrogen storage for light-duty fuel cell vehicles which guide researchers in the field (5.5 wt %/40 g L−1 by 2017; 7.5 wt %/70 g L−1 ultimate). Materials with high porosity and high surface area such as MOFs have been designed and synthesized in an effort to meet these targets. These adsorptive materials generally work via physical adsorption rather than chemisorption due to the large HOMO–LUMO gap and low HOMO energy level of molecular hydrogen. A benchmark material to this end is MOF-177 which was found to store hydrogen at 7.5 wt % with a volumetric capacity of 32 g L−1 at 77 K and 70 bar. MOF-177 consists of [Zn4O]6+ clusters interconnected by 1,3,5-benzenetribenzoate organic linkers and has a measured BET surface area of 4630 m2 g−1. Another exemplary material is PCN-61 which exhibits a hydrogen uptake of 6.24 wt % and 42.5 g L−1 at 35 bar and 77 K and 2.25 wt % at atmospheric pressure. PCN-61 consists of [Cu2]4+ paddle-wheel units connected through 5,5′,5′′-benzene-1,3,5-triyltris(1-ethynyl-2-isophthalate) organic linkers and has a measured BET surface area of 3000 m2 g−1. Despite these promising MOF examples, the classes of synthetic porous materials with the highest performance for practical hydrogen storage are activated carbon and covalent organic frameworks (COFs).
Sources: en.wikipedia.org
Canada's media is highly autonomous, diverse, and very regionalized. The Broadcasting Act declares "the system should serve to safeguard, enrich, and strengthen the cultural, political, social, and economic fabric of Canada". Canada has a well-developed media sector, but its cultural output—particularly in English films, television shows, and magazines—is often overshadowed by imports from the United States. As a result, the preservation of a distinctly Canadian culture is supported by federal government programs, laws, and institutions such as the Canadian Broadcasting Corporation (CBC), the National Film Board of Canada (NFB), and the Canadian Radio-television and Telecommunications Commission (CRTC). Canadian mass media, both print and digital, and in both official languages, is largely dominated by a "handful of corporations". The largest of these corporations is the country's national public broadcaster, the Canadian Broadcasting Corporation, which also plays a significant role in producing domestic cultural content, operating its own radio and TV networks in both English and French. In addition to the CBC, some provincial governments offer their own public educational TV broadcast services as well, such as TVOntario and Télé-Québec. Non-news media content in Canada, including film and television, is influenced both by local creators as well as by imports from the United States, the United Kingdom, Australia, and France.
Chloroform Ethyl chloride Diethyl ether Ethane and ethylene Laughing gas (nitrous oxide) Poppers (alkyl nitrites) Solvents and propellants (including propane, butane, freon, gasoline, kerosene, toluene) along with the fumes of glues containing them
=== "Ötzi the Iceman" and reconstructing Neolithic lifeways === Ötzi is a Neolithic man who, in 1991, was found in an Alpine glacier between Austria and Italy. Ötzi is exceptionally well preserved since his body was dehydrated and encapsulated in glacial ice. Radiocarbon dating gave an age of approximately 5,200 years old. TIMS, ICP-MS and gas mass spectrometry have all been applied to the strontium, lead, and oxygen isotopes in Ötzi's bones and teeth. His teeth indicated a likely birth and early childhood near to where the Eisack and Rienz rivers confluence. In his adulthood, however, Ötzi's bones suggest that he moved to the lower Vinschgau and Etsch valley. More recent isotopic data, gathered from his gut contents, provides yet another timescale and hint that Ötzi's movement could be attributable to seasonal migration.
=== Adverse drug reactions === Ritonavir exhibits hepatic activity. It induces CYP1A2 and inhibits CYP3A4 and CYP2D6. Concomitant therapy of ritonavir with a variety of medications may result in serious and sometimes fatal drug interactions. Due to it being a strong inhibitor (that causes at least a five-fold increase in the plasma AUC values, or more than 80% decrease in clearance) of both cytochrome P450 enzymes CYP2D6 and CYP3A4, ritonavir can severely potentiate and prolong the half-life and/or increase the blood concentration of phenobarbital, primidone, carbamazepine, phenytoin, PDE5 inhibitors like sildenafil, opioids such as hydrocodone, oxycodone, pethidine and fentanyl, antiarrhythmic agents such as amiodarone, propafenone and disopyramide, immunosuppressants such as tacrolimus, voclosporin and sirolimus, neuroleptics like lurasidone and pimozide, as well as some chemotherapeutic agents, benzodiazepines and some ergot derivatives. The FDA has issued a boxed warning for this type of drug interaction. CYP3A4 inducers can counteract the inhibiting effects of ritonavir and lead to drastically reduced levels of "boosted" drugs, increasing the risk of developing drug resistance. Other CYP3A4 inhibitors may have an additive effect with ritonavir, causing increased drug levels.
Sources: en.wikipedia.org
Its sequence corresponds to the amino-terminal portion of prothymosin alpha, a larger protein present in many cell types. The isolated 28-residue peptide is a fragment of that protein rather than a separately encoded molecule, and laboratory material is produced by synthesis.
The single bridge between two cysteine residues holds the chain in a folded loop that influences its shape and its behavior in solution. Loss of the bridge through reduction or oxidation shifts chromatographic retention and is tracked during stability work.
It is a defined 28-residue sequence derived from a larger precursor, whereas many other thymic preparations are mixtures of several polypeptides. Its acetylated amino terminus and single disulfide bridge distinguish it chemically from unrelated thymic extracts.
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。