Thymalfasin comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-06-02. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Laboratory supplies of the peptide usually arrive as a lyophilized powder in sealed vials. The powder is hygroscopic, so a vial should be allowed to reach room temperature before it is opened to prevent condensation on the contents. Weighing and transfer are best performed in a low-humidity environment with clean tools. Once dissolved, the solution should be mixed gently rather than vortexed, because foaming and shear can reduce recovery of the peptide.
Storage recommendations center on low temperature, dryness, and protection from repeated freezing and thawing. The intact powder is commonly held at 20 degrees below zero Celsius or colder, while a working solution is divided into single-use aliquots to limit freeze-thaw cycles. Buffered saline or phosphate-buffered saline at neutral pH is frequently used as a diluent. Light sensitivity is not well documented, yet amber vials or foil wrapping are common practice for long-term storage of peptide stocks.
| Property | Value | Notes |
|---|---|---|
| Molecular mass | About 3.1 kDa | 28 residues, N-terminally acetylated |
| Appearance | White to off-white powder | Lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in aqueous buffers |
| Storage temperature | 2 to 8 °C | Protect from light and moisture |
| Common synonyms | Thymalfasin; Tα1 | Same peptide sequence |
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.
Routine handling calls for storage of the lyophilized powder at refrigerated temperatures, away from light, in a sealed container. Working solutions are often prepared in sterile water or buffer and kept cold between uses. Repeated freeze-thaw cycles are generally avoided because they can promote aggregation and loss of material. Laboratories usually record lot number, reconstitution date, and storage conditions so that any change in behavior can be traced to a specific preparation.
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.
The 2012 Essendon Football Club season is the club's 114th season in the Australian Football League (AFL). After a promising start to the season Essendon found themselves second on the ladder with a record of 8 wins and 1 loss (which was by a single point). The season then took an unexpected turn which saw Essendon lose 10 out of the last 13 games and miss the finals. They became the first club to have an 8–1 record and miss finals since Melbourne in the 1971 season. Prior to the final round vice-captain Mark McVeigh announced his retirement from football after 14 season and 232 games at the club. After the Home and Away season completed Essendon captain Jobe Watson was awarded the Brownlow Medal. The highest individual accolade in the AFL. This was later handed back following the drug scandal. The season became notorious for the illegal supplements program that was operated by the club prior to and into the 2012 season. After a three-year investigation, thirty-four players on the 2012 squad were suspected to have been administered the banned peptide Thymosin beta-4 and were suspended for the 2016 season.
==== Solubility ==== One of the issues faced by drug delivery is the solubility of the drug in the body; around 40% of newly detected chemicals found in drug discovery are poorly soluble in water. This low solubility affects the bioavailability of the drug, meaning the rate at which the drug reaches the circulatory system and thus the target site. Low bioavailability is most commonly seen in oral administration, which is the preferred choice for drug administration due to its convenience, low costs, and good patient practice. A measure to improve poor bioavailability is to inject the drugs in a solvent mixture with a solubilizing agent. However, results show this solution is ineffective, with the solubilizing agent demonstrating side-effects and/or toxicity. Nanocrystals used for drug delivery can increase saturation solubility and dispersion velocity. Generally, saturation solubility is thought to be a function of temperature, but it is also based on other factors, such as crystalline structure and particle size, in regards to nanocrystals. The Ostwald-Freundlich equation below shows this relationship:
=== Fractional base units and referenced KMD plots === Kendrick mass defect plots created by using fractional base units exhibit enhanced resolution. Referenced Kendrick mass defect plots (KMD plots referenced to the terminal group and adduct composition) with fractional base units can be used to obtain an overview of copolymer composition.
Sources: en.wikipedia.org
Mister Donut is an international chain of doughnut stores. Though founded in the United States in 1956 by Harry Winokur, it now primarily operates in Asia. The chain's offerings include doughnuts, coffee, muffins, and pastries. After being acquired by Allied Domecq in 1990, most of Mister Donut's North American stores became Dunkin' Donuts. Although it maintains a small presence in the United States, Mister Donut's main markets are Hong Kong, Japan, El Salvador, the Philippines, Thailand, Indonesia, Taiwan, and Singapore.
=== Interactions === ERp44 Hisatsune et al. demonstrated, by co-immunoprecipitation, an interaction between ERAP1 and the disulfide-shuffling chaperone ERp44, facilitated by disulfide bonds formed with cysteine residues in the exon 10 loop of ERAP1. This interaction was proposed to be the main mechanism for ER retention.
== Further reading == Stanislao Cannizzaro (1858). Sketch of a Course of Chemical Philosophy. The Alembic Club. John Dalton (1808). A New System of Chemical Philosophy vol. 1. John Dalton (1817). A New System of Chemical Philosophy vol. 2. J. P. Millington (1906). John Dalton. J. M. Dent & Co. (London); E. P. Dutton & Co. (New York). Jaume Navarro (2012). A History of the Electron: J. J. and G. P. Thomson. Cambridge University Press. ISBN 978-1-107-00522-8. Trusted, Jennifer (1999). The Mystery of Matter. MacMillan. ISBN 0-333-76002-6. Charles Adolphe Wurtz (1881) The Atomic Theory, D. Appleton and Company, New York. Rocke, Alan J. (1984). Chemical Atomism in the Nineteenth Century: From Dalton to Cannizzaro. Columbus: Ohio State University Press. ISBN 978-0-8142-0360-6. Thomas Thomson (1807). A System of Chemistry: In Five Volumes, Volume 3. John Brown. Thomas Thomson (1831). The History of Chemistry, Volume 2. H. Colburn, and R. Bentley.
Sources: en.wikipedia.org
It is a 28-residue synthetic peptide studied as an immune-modulating agent and approved as a drug in some countries. The sequence matches a naturally occurring fragment isolated from thymus tissue. It is not a hormone in the endocrine sense.
The name traces back to thymosin fraction 5, a crude thymus extract examined in the 1970s. Individual peptides in that mixture were labeled with Greek letters, and alpha-1 was one of them. The international nonproprietary name thymalfasin was assigned later.
No. Thymosin beta-4 contains 43 residues and binds actin, while thymosin alpha-1 contains 28 residues and acts on immune cells. The two sit in a historical naming group but share no sequence similarity, and they are not substitutes for one another.
Aliquots are typically frozen well below zero Celsius and thawed only once, since repeated cycles promote aggregation and loss. Dilution into a neutral buffer limits degradation during short working periods, and prolonged storage at room temperature is avoided.