This is a working overview of thymalfasin, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-01 and is reviewed periodically as new material appears.
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.
Identity and purity testing for thymosin alpha 1 relies mainly on reversed-phase high-performance liquid chromatography and mass spectrometry. Chromatography separates the parent peptide from truncated or modified variants, while mass spectrometry confirms the expected molecular mass. Amino acid analysis and peptide mapping provide additional sequence confirmation. Counterion content, water content, and residual solvents are measured separately as part of specification testing. No single method captures every attribute, so laboratories combine several techniques.
The peptide lacks cysteine, methionine, and tryptophan, so disulfide scrambling and sulfur oxidation are not major degradation routes. Instead, aspartate residues can undergo isomerization or cyclization to succinimide intermediates, generating isoaspartate variants. Hydrolysis of peptide bonds also occurs slowly in solution. These changes may reduce biological activity even when the main peak remains detectable. Stability studies therefore track both potency and the appearance of related substances.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Acetylated peptide | N-terminal acetyl group blocks aminopeptidase attack |
| Residue count | 28 amino acids | Matches the N-terminus of prothymosin alpha |
| Molecular mass | About 3,108 Da | Value for the free, unmodified peptide |
| Isoelectric point | Approximately 4.2 | Acidic; net negative charge at neutral pH |
| Encoding gene | PTMA | Human gene for the precursor protein |
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。
Thymosin alpha-1 is a short peptide of 28 amino acid residues first described in the 1970s as a component of thymic extracts. Its N-terminal residue carries an acetyl group, and the sequence is highly conserved across mammalian species. The peptide is not encoded as a standalone gene product; it is released by proteolytic cleavage from the N-terminus of prothymosin alpha, a larger acidic nuclear protein. That precursor relationship places it within a broader family of thymic and immune-associated peptides that have been studied for decades.
The activity of this peptide is generally described as immunomodulatory rather than directly antimicrobial. Experimental work links it to signaling through certain Toll-like receptors on dendritic cells and to downstream maturation of antigen-presenting cells. Reported effects include expansion of T cell subsets, shifts in cytokine profiles, and increased natural killer cell activity. These observations come largely from cell culture and animal models, and the precise receptor-level events in humans remain incompletely characterized.
This could be due to the branch point at the intermediate α-ketoisovalerate, which can be transaminated to produce valine or further acetylated to generate leucine. There may be different isotope effects associated with the addition of an amino or acetyl group at position C-2 in α-ketoisovalerate. As discussed above, the isotopic consequences of this branch point would depend on the relative rates of leucine vs valine production. One would also expect relative depletion of 13C in leucine because its synthesis requires the addition of another isotopically light acetyl group. In Escherichia coli, the carboxyl carbon in leucine (derived from acetyl-CoA) has a δ13C value roughly 13‰ lower than that of the entire molecule. Curiously, the same depletion is not observed in photoautotrophs. Further, there is little consistency in the δ13C of most amino acids between cyanobacteria and eukaryotic photoautotrophs. These discrepancies demonstrate the limits of our understanding of the mechanisms that set amino acid isotopic compositions. Regardless, isotopic variations between different taxa have been used to great effect in ecology.
The Bowery Theatre was a 19th-century playhouse at 46 Bowery. It was founded in the 1820s by rich families to compete with the upscale Park Theatre. By the 1850s, the theatre came to cater to immigrant groups such as the Irish, Germans, and Chinese. It burned down four times in 17 years, and a fire in 1929 destroyed it for good.
This shocks Minerva, who states that it leads to a world the Combine are sieging. Minerva betrays the protagonist after he sabotages the Combine's defenses, activating an orbital laser and attempting to destroy the base as she declares him a "redeemed traitor". He survives, however, and Minerva becomes apologetic, later admitting she has grown "attached" to him. She explains that the portal, wherever it may lead, could mean the difference between life and death for billions of people, hence her desperation to destroy it. She urges him to escape as she recharges the satellite's laser, as the Combine have become aware of her location and she fears retribution. With the aid of Minerva and a stolen helicopter, the protagonist fights to the surface and escapes the island just as it is annihilated by a second orbital blast. Minerva's communications are unusual in that each is prefixed by a time/date stamp in International Date Format (ISO 8601), giving an explicit timescale to the plot. These timestamps extend to several written pieces on the series's website that give background to the story. From these and the in-game messages it is possible to construct a partial timeline of events covered in the Minerva series.
==== Desiccation stress ==== Desiccation (drought) stress is defined as conditions where water becomes the growth limiting factor. MAAs have been reportedly found in high concentrations in many microorganisms exposed to drought stress. Particularly cyanobacteria species that are exposed to desiccation, UV radiation and oxidation stress have been shown to possess MAA's in an extracellular matrix. However it has been shown that MAAs do not provide sufficient protection against high doses of UV radiation.
Sources: en.wikipedia.org
=== Protein-protein interactions === Phosphorylation of the cytosolic components of NADPH oxidase, a large membrane-bound, multi-protein enzyme present in phagocytic cells, plays an important role in the regulation of protein-protein interactions in the enzyme. Important in protein degradation. In the late 1990s, it was recognized that phosphorylation of some proteins causes them to be degraded by the ATP-dependent ubiquitin/proteasome pathway. These target proteins become substrates for particular E3 ubiquitin ligases only when they are phosphorylated.
=== Non-volatile chlorogenic acids === Chlorogenic acids belong to a group of compounds known as phenolic acids. The content of chlorogenic acids in dried arabica green coffee beans is 65 mg/g, and in robusta 140 mg/g, depending on the time of harvest. At roasting temperature, more than 70% of chlorogenic acids are destroyed. Chlorogenic acids are homologous compounds comprising caffeic acid, ferulic acid and 3,4-dimethoxycinnamic acid, which are connected by an ester bond to the hydroxyl groups of quinic acid. Chlorogenic acids have a bitter taste in low concentrations such as 50 mg/L water. At higher concentrations of 1 g/L water, they have a sour taste. Chlorogenic acids increase the solubility of caffeine, and are important modulators of taste.
Silver salts have antiseptic properties. In 1881 Credé introduced a method known as Credé's prophylaxis, which used of dilute (2%) solutions of silver nitrate in newborn babies' eyes at birth to prevent contraction of gonorrhea from the mother, which could cause blindness via ophthalmia neonatorum. (Modern antibiotics are now used instead). Fused silver nitrate, shaped into sticks, was traditionally called "lunar caustic". It is used as a cauterizing agent, for example to remove granulation tissue around a stoma. General Sir James Abbott noted in his journals that in India in 1827 it was infused by a British surgeon into wounds in his arm resulting from the bite of a mad dog to cauterize the wounds and prevent the onset of rabies. Silver nitrate is used to cauterize superficial blood vessels in the nose to help prevent nosebleeds. Dentists sometimes use silver nitrate-infused swabs to heal oral ulcers. Silver nitrate is used by some podiatrists to kill cells located in the nail bed. The Canadian physician C. A. Douglas Ringrose researched the use of silver nitrate for sterilization procedures, believing that silver nitrate could be used to block and corrode the fallopian tubes. The technique was ineffective.
A natriuretic peptide is a hormone molecule that plays a crucial role in the regulation of the cardiovascular system. These hormones were first discovered in the 1980s and were found to have very strong diuretic, natriuretic, and vasodilatory effects. There are three main types of natriuretic peptides: atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). Two minor hormones include urodilatin (URO) which is processed in the kidney and encoded by the same gene as ANP, and dendroaspis NP (DNP) that was discovered through isolation of the venom from the green mamba snake. Since they are activated during heart failure, they are important for the protection of the heart and its tissues. Additionally, there are three natriuretic peptide receptors: natriuretic peptide receptor A (NPR-A), Natriuretic Peptide Receptor-B (NPR-B), and Natriuretic Peptide Receptor-C (NPR-C). NPR-A and NPR-B use cyclic guanosine monophosphate (cGMP) as its intracellular messenger. NPR-A binds selectively to ANP and BNP while NPR-B binds selectively to CNP. Although initially thought to have no signaling activity, NPR-C is now believed to inhibit cyclic adenosine monophosphate (cAMP) using the Giα subunit along with activating phospholipase C-β using the Giβγ subunit. The three natriuretic peptides ANP, BNP, and CNP can bind to NPR-C however it has a higher affinity towards ANP and CNP. Natriuretic peptides will lose their activity when degraded by the enzyme neprilysin which is found on the plasma membrane.
On February 9, 1909, the Smoking Opium Exclusion Act, "to prohibit the importation and use of opium for other than medicinal purposes", became the first US federal law to ban the non-medical use of a substance. This was soon followed by the Harrison Narcotics Tax Act of 1914, that regulated and taxed the production, importation, and distribution of opiates and coca products. Amending the Smoking Opium Exclusion Act, the Anti-Heroin Act of 1924 specifically outlawed the manufacture, importation and sale of heroin. During World War I (1914–1918), soldiers were commonly treated with morphine, giving rise to addiction among veterans. An international wartime focus on military use of opiates and cocaine for medical treatment and performance enhancement, and concern over potential abuse, led to the global adoption of the International Opium Convention, through its incorporation into the Treaty of Versailles in 1919, with administration by the newly established League of Nations. The treaty, originally formulated in 1912 but not widely implemented, became the basis of current international drug control policy. It was initially concerned with regulating the free trade of drugs, without affecting production or use, and in 1920, it established the Opium Advisory Committee (OAC). The US, one of the most prohibitionist countries, felt these provisions did not go far enough in restricting drugs. In 1919, the 18th Amendment to the US Constitution was ratified, prohibiting the manufacture, sale and transportation of "intoxicating liquors", with exceptions for religious and medical use.
Sources: en.wikipedia.org
Thymosin fraction 5 is a mixture of many peptides obtained from thymus tissue, while thymosin alpha 1 is a single defined 28-residue molecule. The two names appear together in older literature because the purified peptide was first obtained from that mixture.
The precursor, prothymosin alpha, is encoded by the PTMA gene in humans. The 28-residue peptide corresponds to the N-terminal segment released from that larger protein.
It is produced as a fragment of prothymosin alpha and is present in many tissues. Circulating concentrations are low, which makes routine measurement difficult.
The lyophilized powder is kept refrigerated at 2 to 8 degrees Celsius and protected from light. Reconstituted solutions should be used promptly. Freezing and thawing repeatedly is avoided.