The short version of immunomodulatory peptide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-09-22. Anything still debated is marked as such rather than presented as settled.
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.
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 of 28 amino acid residues that derives from the amino terminal region of a larger precursor protein known as prothymosin alpha. The peptide carries an acetyl group on its first residue and contains no disulfide bonds or carbohydrate chains. Its sequence is highly conserved across mammalian species, which is one reason laboratories treat it as a molecule with a defined and reproducible structure rather than a variable tissue extract. The name follows an early naming convention for thymus-derived fractions and does not imply that the peptide acts as a hormone in the classical endocrine sense.
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.
| 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 |
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.
Thymosin beta-4 is a separate 43-residue peptide that binds actin and participates in cell migration; it shares no sequence similarity with thymosin alpha-1 despite the common family name. Other preparative materials, such as thymosin fraction 5 and thymopoietin, contain distinct mixtures or peptides. The shared thymosin label reflects the tissue of origin used in early purification, not a common structural core. Treating these molecules as interchangeable is a frequent source of confusion in laboratory reports and in popular summaries alike.
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。
== Chemistry == Sodium hyaluronate is the sodium salt of hyaluronic acid. It is a glycosaminoglycan and long-chain polymer of disaccharide units of Na-glucuronate-N-acetylglucosamine. It can bind to specific receptors for which it has a high affinity. The polyanionic form, commonly referred to as hyaluronan, is a visco-elastic polymer found in the aqueous and vitreous humour of the eye and in the fluid of articulating joints.
Annual per capita consumption of cheese was 4 pounds (1.8 kg) in 1909; 32 pounds (15 kg) in 2000; the average person consumed 389 grams (13.7 oz) of carbohydrates daily in 1970; 490 grams (17 oz) in 2000; 41 pounds (19 kg) of fats and oils in 1909; 79 pounds (36 kg) in 2000. In 1977, 18% of an average person's food was consumed outside the home; in 1996, this had risen to 32%. Obesity is a major public health problem in the United States owing to its rapidly increasing prevalence, substantial mortality and morbidity, and growing healthcare costs. Several studies have inquired about the relationship between community food environment and obesity, which are often inversely related. The large-scale study demonstrated a substantial and inverse relationship between the local food environment and adult obesity in the US using local spatially weighted regression. Approximately 23.5 million American live in food deserts, areas in geolocations with minimal healthy food retailers. More importantly, there were considerable regional differences in the strength and direction of this connection. The findings of the study also show the need for geographically specific public health policies and interventions to address issues with food environments that are specific to particular regions.
== Examples == Two-dimensional separations can be carried out in gas chromatography or liquid chromatography. Various different coupling strategies have been developed to "resample" from the first column into the second. Some important hardware for two-dimensional separations are Deans' switch and Modulator, which selectively transfer the first dimension eluent to second dimension column. The chief advantage of two-dimensional techniques is that they offer a large increase in peak capacity, without requiring extremely efficient separations in either column. (For instance, if the first column offers a peak capacity (k1)of 100 for a 10-minute separation, and the second column offers a peak capacity of 5 (k2) in a 5-second separation, then the combined peak capacity may approach k1 × k2=500, with the total separation time still ~ 10 minutes). 2D separations have been applied to the analysis of gasoline and other petroleum mixtures, and more recently to protein mixtures.
Sources: en.wikipedia.org
== Distribution and applications == A mixture of monophenol oxidase and catechol oxidase enzymes is present in nearly all plant tissues, and can also be found in bacteria, animals, and fungi. In insects, cuticular polyphenol oxidases are present and their products are responsible for desiccation tolerance. Grape reaction product (2-S glutathionyl caftaric acid) is an oxidation compound produced by action of PPO on caftaric acid and found in wine. This compound production is responsible for the lower level of browning in certain white wines. Plants make use of polyphenol oxidase as one in a suite of chemical defences against parasites.
To a first approximation, the non-polar phase in such experiments is usually dominated by the un-ionized form of the solute, which is electrically neutral, though this may not be true for the aqueous phase. To measure the partition coefficient of ionizable solutes, the pH of the aqueous phase is adjusted such that the predominant form of the compound in solution is the un-ionized, or its measurement at another pH of interest requires consideration of all species, un-ionized and ionized (see following). A corresponding partition coefficient for ionizable compounds, abbreviated log P I, is derived for cases where there are dominant ionized forms of the molecule, such that one must consider partition of all forms, ionized and un-ionized, between the two phases (as well as the interaction of the two equilibria, partition and ionization). M is used to indicate the number of ionized forms; for the I-th form (I = 1, 2, ... , M) the logarithm of the corresponding partition coefficient,
== Features == SENP1 (Sentrin-specific protease 1) is a human protease of 643 amino acids with a molecular weight of 73 kDa, EC number in humans 3.4.22.B70. It adopts a conformation that identifies it as a member of the superfamily of cysteine proteases, which contain a catalytic triad with three characterized amino acids: a cysteine at position 603, a histidine at position 533 and aspartic acid at position 550. The primary nucleophile is cysteine located at the N-terminal alpha helix of the protein core. The other two amino acids, aspartate and histidine, are located in the end of a beta sheet.
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 name reflects an early convention for naming thymus-derived fractions. The peptide is characterized and measured as a defined molecule, and it does not operate through a single classical endocrine axis.