This is a working overview of Thymosin fraction 5, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-09-05. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
Most published studies on thymosin alpha-1 report changes in immune measurements rather than clinical outcomes, and findings differ across designs and populations. Whether the peptide signals through one defined receptor or through several less specific interactions remains an open question. Its reported circulation half-life of a few hours complicates comparison of dosing schedules across trials. Mechanistic claims are frequently drawn from isolated cell cultures, and how far those results extend to whole organisms is unresolved.
| 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 synthetic peptide of 28 amino acids, corresponding to the N-terminal fragment of prothymosin alpha. Its sequence begins with acetylation at the N-terminus, a modification that affects stability and receptor interaction. The peptide is acidic, with a calculated isoelectric point near 4.2, and carries no disulfide bonds, so its secondary structure is largely flexible in solution. Molecular mass is approximately 3108 daltons. The native form was first isolated from bovine thymus tissue, while pharmaceutical material is produced by solid-phase peptide synthesis.
Within the immune system, the peptide acts on several cell types rather than a single target. Reported activities include promotion of T-cell maturation, enhancement of natural killer cell activity, and modulation of cytokine production by dendritic cells and macrophages. Some of these effects appear to operate through toll-like receptor signaling, though the precise receptor-level mechanism remains debated. Whether the observed immune changes translate into clinical benefit is a separate question and depends on the indication studied.
The peptide was described in the 1970s as a component of thymic extracts, and early research focused on restoring immune function in immunodeficiency states. A synthetic version entered clinical development in the 1980s and is approved as a drug in several countries for conditions such as chronic hepatitis B and certain immunodeficiencies. Approval status varies widely by jurisdiction, and in the United States it is not an approved therapeutic. Regulatory and clinical positions differ, so statements about efficacy should be tied to specific indications and studies.
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.
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.
Whether the free 28-residue peptide circulates in human tissue remains debated. The best-documented human source is prothymosin alpha, a larger acidic protein that carries the sequence at its N-terminus. Reports of measurable peptide levels in serum and lymphoid tissue exist, yet some of that signal may come from cross-reacting fragments or from the parent protein. Most reviews therefore treat prothymosin alpha as the established human molecule and describe independent circulation of the small peptide as an unresolved question.
Human Genome Project (HGP) A collaborative international scientific research project with the goal of sequencing all of the chromosomal DNA and identifying and mapping all of the genes within human cells, and ultimately of assembling a complete reference genome for the human species. The project was launched in 1990 by a consortium of federal agencies, universities, and research institutions and was declared complete in 2003. Because each individual human being has a unique genome, the finished reference genome is a mosaic of sequences obtained by sampling DNA from thousands of individuals across the world and does not represent any one individual.
Hypochlorous acid is an inorganic compound with the chemical formula ClOH, also written as HClO, HOCl, or ClHO. Its structure is H−O−Cl. It is an acid that forms when chlorine dissolves in water, and itself partially dissociates, forming a hypochlorite anion, ClO−. HClO and ClO− are oxidizers, and the primary disinfection agents of chlorine solutions. HClO cannot be isolated from these solutions due to rapid equilibration with its precursor, chlorine, and its anhydride, dichlorine monoxide. Because of its strong antimicrobial properties, the related compounds sodium hypochlorite (NaOCl) and calcium hypochlorite (Ca(OCl)2) are ingredients in many commercial bleaches, deodorants, and disinfectants. The white blood cells of mammals, such as humans, also contain hypochlorous acid as a tool against foreign bodies. In living organisms, HOCl is generated by the reaction of hydrogen peroxide with chloride ions under the catalysis of the heme enzyme myeloperoxidase (MPO). Like many other disinfectants, hypochlorous acid solutions will destroy pathogens, such as COVID-19, adsorbed on surfaces.
If there are to be multiple ICP-MS instruments running for long periods of time, then it will most likely be beneficial for the laboratory to install a bulk or micro bulk argon tank which will be maintained by a gas supply company, thus eliminating the need to change out tanks frequently as well as minimizing loss of argon that is left over in each used tank as well as down time for tank changeover. Helium can be used either in place of, or mixed with, argon for plasma generation. Helium's higher first ionisation energy allows greater ionisation and therefore higher sensitivity for hard-to-ionise elements. The use of pure helium also avoids argon-based interferences such as ArO. However, many of the interferences can be mitigated by use of a collision cell, and the greater cost of helium has prevented its use in commercial ICP-MS.
Sources: en.wikipedia.org
Each individual reaction is stereospecific so that when the substrate of the enzyme is (R)-propane-1,2-diol it produces (R)-lactaldehyde but the enantiomeric substrate (S)-propane-1,2-diol gives only (S)-lactaldehyde. The enzyme's cofactor is nicotinamide adenine dinucleotide (NAD+), which is converted to NADH, and also releases a proton. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (R)[or (S)]-propane-1,2-diol:NAD+ oxidoreductase. Other names in common use include propanediol:nicotinamide adenine dinucleotide (NAD+) oxidoreductase, and L-lactaldehyde:propanediol oxidoreductase. This enzyme participates in pyruvate metabolism and glyoxylate and dicarboxylate metabolism.
Ethnically Polish settlement spread over a large area further to the east, including its greatest concentration in the Vilnius Region, amounted to only over 20% of that number. Polish paramilitary organizations oriented toward independence, such as the Union of Active Struggle, were formed in 1908–1914, mainly in Galicia. The Poles were divided and their political parties fragmented on the eve of World War I, with Dmowski's National Democracy (pro-Entente) and Piłsudski's faction assuming opposing positions.
=== Founding and early activity === White Castle was founded 1921 in Wichita, Kansas. Anderson partnered with Ingram to make White Castle into a chain of restaurants and market the brand and its distinctive product. The two men incorporated the business in 1924 and named it White Castle System of Eating Houses Corporation. Anderson and Ingram started with only $700 for the original White Castle in Wichita, Kansas. The original location was the northwest corner of First and Main; the building is no longer standing. After the novel The Jungle by Upton Sinclair had been published in 1906 and exposed the poor sanitation practices of the meat-packing industry, many Americans became wary of eating ground beef. The founders set out to change the public's perception of the cleanliness of the industry they were creating. To invoke a feeling of cleanliness, their restaurants were small buildings with stainless steel interiors, and employees outfitted with spotless uniforms. Their first restaurants in Wichita were a success, and the company branched out into other Midwestern markets, starting in 1922 with El Dorado, Kansas.
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.
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.