If you have been reading about freeze-thaw cycling 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 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or chemically modified byproducts. Mass spectrometry confirms the expected molecular mass and can indicate acetylation state or sequence errors. Amino acid analysis and peptide mapping supply complementary sequence-level information, while endotoxin testing is relevant for preparations intended for cell or animal work. Purity figures reported by suppliers refer to the method used and are not directly comparable across laboratories unless conditions are stated.
Lyophilized material is typically treated as a hygroscopic solid that should be brought to room temperature before the container is opened, which limits condensation on the powder. Reconstitution is commonly done with sterile water or a buffered diluent, and gentle mixing is preferred over vigorous agitation to reduce foaming and surface adsorption. Because peptides can bind to plastic and glass, diluents containing a small amount of carrier protein are sometimes used in laboratory work. Working solutions are generally aliquoted and prepared fresh rather than subjected to repeated freezing and thawing.
Stability depends on temperature, pH, and the number of freeze-thaw events the sample has experienced. Freeze-dried material is commonly held at -20 °C or colder, while reconstituted liquid is kept cold and used within a short window. Extreme pH and prolonged light exposure can promote deamidation, oxidation, or aggregation, particularly at asparagine and methionine positions. Adsorption to container walls can lower the measured concentration of a dilute solution even when the peptide molecules themselves remain intact.
| 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 |
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.
Clinical research has examined the peptide in chronic hepatitis B and C, as a vaccine adjuvant, and in sepsis and oncology settings. Results across trials have been mixed, and several studies were small or conducted under differing protocols. Regulatory status varies by country, and the compound is not approved in every jurisdiction where it is studied. Evidence for any single indication should be read with attention to sample size and endpoint choice.
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.
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.
Thymosin alpha 1 is a synthetic 28-amino-acid peptide first isolated in 1966 from thymosin fraction 5, a bovine thymus extract. Its chain begins with an acetylated serine residue and ends with asparagine. The native peptide carries a molecular mass near 3,108 daltons. Researchers classify it as an immunomodulatory agent rather than a hormone with a single endocrine target. Early work framed it as a thymus-derived factor that supports T-cell maturation. The synthetic form used in research and clinical products matches the natural sequence.
Immune signaling studies link thymosin alpha 1 to Toll-like receptor pathways, particularly TLR2 and TLR9, on dendritic cells and other antigen-presenting cells. Activation of these receptors promotes maturation of T cells and increases natural killer cell activity. The peptide shifts cytokine output toward a T helper 1 profile, raising interferon gamma and interleukin 2 while modulating interleukin 10. Whether these effects translate into clinical benefit for any specific disease remains a subject of debate. Reported outcomes vary across trials and populations.
Thymosin alpha 1 is approved as a medicine in several countries, including Italy and China, for indications such as chronic hepatitis B and as an immune adjuvant. It is not approved by the United States Food and Drug Administration as a therapeutic product. In research settings the peptide appears in studies of sepsis, vaccine response, and oncology support, often with mixed or inconclusive results. The evidence base is uneven, and reviews note that many trials were small. Regulatory status therefore differs widely between jurisdictions.
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.
Recognition of its prevalence and consequences has led to governments and non-government organizations promoting vitamin A fortification of foods and creating programs that administer large bolus-size oral doses of vitamin A to young children every four to six months. In 2008, the World Health Organization estimated that vitamin A supplementation over a decade in 40 countries averted 1.25 million deaths due to vitamin A deficiency. A Cochrane review reported that vitamin A supplementation is associated with a clinically meaningful reduction in morbidity and mortality in children ages six month to five years of age. All-cause mortality was reduced by 14%, and incidence of diarrhea by 12%. However, a Cochrane review by the same group concluded there was insufficient evidence to recommend blanket vitamin A supplementation for infants one to six months of age, as it did not reduce infant mortality or morbidity.
== External links == SIPG, Shanghai International Port (Group) Co., Ltd Entry in MarineTraffic PortFinder – database of information about the port CNSHG – its United Nations location code VesselFinder – database of ships currently in the port Entry in the World Port Index database
=== 20th and 21st centuries === In 1994, Nobel-Prize winning novelist Saul Bellow nearly died from ciguatera after eating red snapper on vacation in St. Martin, fictionalized in his last novel Ravelstein.
== Pathogenicity mechanisms and virulence factors == Burkholderia pseudomallei is an opportunistic pathogen and, since its an environmental organism, has no requirement to pass through an animal host to replicate. From the point of view of the bacterium, human infection is a developmental "dead end". Strains which cause disease in humans differ from those causing disease in other animals, by possessing certain genomic islands. It may have the ability to cause disease in humans via DNA acquired from other microorganisms. Its mutation rate is also high, and the organism continues to evolve even after infecting a host. Burkholderia pseudomallei is able to invade cells - being an intracellular pathogen. It is able to polymerise actin, and to spread from cell to cell, causing cell fusion and the formation of multinucleated giant cells. It possesses a uniquely fusogenic type VI secretion system that is required for cell-cell spread and virulence in mammalian hosts. The bacterium also expresses a toxin called lethal factor 1. B. pseudomallei is one of the first Proteobacteria to be identified as containing an active type VI secretion system. It is also the only organism identified that contains up to six different type VI secretion systems. B. pseudomallei is intrinsically resistant to many antimicrobial agents by virtue of its efflux pump mechanism. This mediates resistance to aminoglycosides (AmrAB-OprA), tetracyclines, fluoroquinolones, and macrolides (BpeAB-OprB).
== Match-fixing scandals == Ten of the twelve members of the gold medal-winning Spanish basketball team at the 2000 Summer Paralympics were revealed to have no disability. Fresno Case scandal (2004) – an attempt to rig a vote to prevent the Catalan rink hockey team from being accepted into international competition. Melbourne Football Club tanking scandal (2009) – allegations arose that the club deliberately lost matches in 2009 so that it would put itself into a position whereby they would secure a priority draft pick at that year's draft. In 2011, snooker player John Higgins was accused of accepting bribery in order to lose frames purposefully. Higgins denied any accusations of match-fixing and bribery, however, he was found guilty of accepting bribery while there was no evidence for him match-fixing. "World number one John Higgins has been suspended from all future tournaments after reportedly agreeing to take a £261,000 bribe to lose frames." Match fixing in tennis 1964 British football match-fixing scandal 1971 Bundesliga scandal Match-fixing investigations of Norwegian Second Division Match fixing in English football Match fixing in Romanian football
Sources: en.wikipedia.org
For the record robbery, he was sentenced to eight years in prison, but three weeks after the verdict, in July 1976, he fled again, this time by driving a Scania truck through three prison gates at Norrköping Prison. Together with a number of fellow prisoners, they fled to a waiting getaway car. On 31 July 1976, he was arrested in Halmstad. On 12 August 1976, Olofsson married Belgian national Marijke Demuynck in Kumla Prison. In 1979, while still in prison, Olofsson began studies in journalism at Stockholm University. He did an internship at the newspaper Arbetaren. During a leave on Midsummer's Eve in 1980, Olofsson got into a fight with fisherman Leif Sundin on Möja. The sentence was two and a half years for assault. His studies were interrupted by the verdict, but he eventually graduated in 1983. Olofsson was released in 1983; he then left Sweden with his wife and settled in her home country of Belgium. In November 1984, he was arrested in the port city of Blankenberge in Belgium, suspected of having tried to smuggle 25 kilograms of amphetamine into Sweden with the so-called Televerksligan ("Televerket Gang"). He was sentenced to ten years in prison for complicity in an aggravated felony drug offense.
In 2002, they developed an unnatural base pair between 2-amino-8-(2-thienyl)purine (s) and pyridine-2-one (y) that functions in vitro in transcription and translation, for the site-specific incorporation of non-standard amino acids into proteins. In 2006, they created 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds) and pyrrole-2-carbaldehyde (Pa) as a third base pair for replication and transcription. Afterward, Ds and 4-[3-(6-aminohexanamido)-1-propynyl]-2-nitropyrrole (Px) was discovered as a high fidelity pair in PCR amplification. In 2013, they applied the Ds-Px pair to DNA aptamer generation by in vitro selection (SELEX) and demonstrated the genetic alphabet expansion significantly augment DNA aptamer affinities to target proteins.
== Chemistry == Oxymorphone is commercially produced from thebaine, which is a minor constituent of the opium poppy (Papaver somniferum) but thebaine is found in greater abundance (3%) in the roots of the oriental poppy (Papaver orientale). German patents from the mid-1930s indicate that oxymorphone as well as hydromorphone, hydrocodone, oxycodone, and acetylmorphone can be prepared—without the need for hydrogen gas—from solutions of codeine, morphine, and dionine by refluxing an acidic aqueous solution, or the precursor drug dissolved in ethanol, in the presence of certain metals, namely palladium and platinum in fine powder or colloidal form or platinum black. Oxymorphone hydrochloride occurs as odourless white crystals or white to off-white powder. It darkens in colour with prolonged exposure to light. One gram of oxymorphone hydrochloride is soluble in 4 ml of water and it is sparingly soluble in alcohol and ether. It degrades upon contact with light. Oxymorphone can be acetylated like morphine, hydromorphone, and some other opioids. Mono-, di-, tri-, and tetra- esters of oxymorphone were developed in the 1930s but are not used in medicine at this time. Presumably other esters such as nicotinyl, benzoyl, formyl, or cinnamyl can be produced. The 2013 US DEA annual manufacturing quotas were 18 375 kilogrammes for conversion (a number of drugs can be made from oxymorphone, both painkillers and opioid antagonists like naloxone) and 6875 kg for direct manufacture of end-products.
== Further reading == Smart, P.L., and Frances, P.D. (1991), Quaternary dating methods - a user's guide. Quaternary Research Association Technical Guide No.4 ISBN 0-907780-08-3 Lowe, J.J., and Walker, M.J.C. (1997), Reconstructing Quaternary Environments (2nd edition). Longman publishing ISBN 0-582-10166-2 Mattinson, J. M. (2013), Revolution and evolution: 100 years of U-Pb geochronology. Elements 9, 53–57. Geochronology bibliography Talk:Origins Archive
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.
Cold storage slows the chemical degradation reactions that occur in solution. Lyophilized powder is more stable than reconstituted liquid and tolerates longer storage periods. Repeated temperature cycling should still be avoided because it can drive aggregation and loss of material.