This is a working overview of prothymosin alpha, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-07-16. Anything still debated is marked as such rather than presented as settled.
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.
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.
Quantifying thymosin alpha-1 in a sample usually relies on reverse-phase high-performance liquid chromatography. The peptide lacks strong chromophores, so detection often occurs at 214 nm, where the peptide backbone absorbs. Mass spectrometry provides confirmatory identification and can detect sequence variants or truncations. Immunoassays have been used in biological matrices, but they may cross-react with related fragments. For purity assessment, chromatographic peak area gives the main component percentage, while mass accuracy verifies molecular identity.
The lyophilized peptide is generally stable for extended periods when kept cold and dry. Once dissolved, aqueous solutions are less stable; hydrolysis, oxidation, and aggregation can degrade the material. Storage at -20 °C or lower slows these processes. Repeated freeze-thaw cycles are best avoided because they can promote aggregation. The exact shelf life depends on formulation, pH, and concentration, so stability studies are typically performed for each specific product.
| 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 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.
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.
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.
As with other ratites, emus have a relatively low basal metabolic rate compared to other types of birds. At −5 °C (23 °F), the metabolic rate of an emu sitting down is about 60% of that when standing, partly because the lack of feathers under the stomach leads to a higher rate of heat loss when standing from the exposed underbelly.
=== Timeline === Mixue Ice Cream & Tea began in 1997 when Zhang Hongchao opened the first location under the Mixue name. After six relocations, the first successful Mixue Ice Cream & Tea store opened in 2003. Around 2005 or 2006, the company introduced soft serve ice cream at the price of just CN¥1, this quickly became a best-seller and its first signature product. In 2007, Mixue began franchising after opening a new ice cream shop. The following year, it established Mixue Ice Cream & Tea Trading Co., Ltd. to manage its growing network of franchises. Mixue took its first step outside of China on September 5, 2018, with a store opening in Hanoi, Vietnam. Later that year, in November, it launched a new brand mascot, Snow King. Between May 24 and 26, 2019, the company hosted an "ice cream music festival" at Opalala Water Park in Zhengzhou, drawing over 30,000 visitors. On June 24, 2020, Mixue celebrated the opening of its 10,000th store in Yuanyang County, Henan, Xinxiang. The same year, it expanded into Indonesia with a branch in Cihampelas Walk, Bandung. In 2022, Mixue made significant purchases of over 9,000 tonnes (8,900 long tons; 9,900 short tons) of tea, benefiting around 50,000 tea farmers, while also supporting over 11,000 franchisees and generating more than 500,000 jobs. It launched a CN¥6.5 million scholarship program across five universities in Henan and expanded into additional Southeast Asian markets, opening stores in Singapore, Thailand, Cambodia, Philippines, Laos, and Myanmar. By the end of 2022, Mixue had also entered South Korea and Japan.
National Fireproofing Contractors Association https://www.nfca-online.org/ Structural Fire Protection - American Institute of Steel Construction https://www.aisc.org/globalassets/modern-steel/archives/2002/12/2002v12_fire.pdf NFPA Standards Archived 2011-07-28 at the Wayback Machine
Sources: en.wikipedia.org
Phthalates have been banned from use in feeding bottles in the EU. In the US, there have been repeated calls for the removal of phthalates by the U.S. Consumer Product Safety Commission (CPSC) and others. Their use in children's toys and products was somewhat restricted by the Consumer Product Safety Improvement Act of 2008. Plastics labeled #3 may leach phthalates. Latex rubber nipples may contain phthalates, so silicone nipples may be recommended instead. Packaging may indicate whether a product is "BPA-free" or "phthalate-free". Plastics may degrade over time in other ways, There are concerns that small beads of plastic may be released into fluids from some types of plastic bottles. In 2020 researchers reported that infant feeding bottles made out of polypropylene caused microplastics exposure to infants ranging from 14,600 to 4,550,000 particles per capita per day in 48 regions with contemporary preparation procedures. Microplastics release is higher with warmer liquids and similar with other polypropylene products such as lunchboxes. In 2022, the first study to examine the presence of plastic polymers in human blood found plastics of multiple types in the blood samples of 17 out of 22 healthy adults tested (nearly 80%). Medical experts have suggested reducing exposure to microplastics by not shaking plastic bottles or exposing them to high temperatures. Some recommend using alternative materials such as glass, silicone, or stainless steel.
A regular working electrode has a radius within an order of magnitude of 1 mm. Having a controlled surface area with a well-defined shape is necessary for being able to interpret cyclic voltammetry results. To run cyclic voltammetry experiments at very high scan rates a regular working electrode is insufficient. High scan rates create peaks with large currents and increased resistances, which result in distortions. Ultramicroelectrodes can be used to minimize the current and resistance. The counter electrode, also known as the auxiliary or second electrode, can be any material that conducts current easily, will not react with the bulk solution, and has a surface area much larger than the working electrode. Common choices are platinum and graphite. Reactions occurring at the counter electrode surface are unimportant as long as it continues to conduct current well. To maintain the observed current the counter electrode will often oxidize or reduce the solvent or bulk electrolyte.
=== Evolutionary mechanism of compensation === Compensatory mutations can be explained by the genetic phenomenon epistasis whereby the phenotypic effect of one mutation is dependent upon mutation(s) at other loci. While epistasis was originally conceived in the context of interaction between different genes, intragenic epistasis has also been studied recently. Existence of compensated pathogenic deviations can be explained by 'sign epistasis', in which the effects of a deleterious mutation can be compensated by the presence of an epistatic mutation in another loci. For a given protein, a deleterious mutation (D) and a compensatory mutation (C) can be considered, where C can be in the same protein as D or in a different interacting protein depending on the context. The fitness effect of C itself could be neutral or somewhat deleterious such that it can still exist in the population, and the effect of D is deleterious to the extent that it cannot exist in the population. However, when C and D co-occur together, the combined fitness effect becomes neutral or positive. Thus, compensatory mutations can bring novelty to proteins by forging new pathways of protein evolution : it allows individuals to travel from one fitness peak to another through the valleys of lower fitness. DePristo et al. 2005 outlined two models to explain the dynamics of compensatory pathogenic deviations (CPD). In the first hypothesis P is a pathogenic amino acid mutation that and C is a neutral compensatory mutation.
Sources: en.wikipedia.org
Control is a standard against which experimental observations may be evaluated. In clinical trials, one group of participants is given an experimental drug, while another group (i.e., the control group) is given either a standard treatment for the disease or a placebo. (NLM) Coordinating Committee
=== Versions === The same scale has been validated in Spanish, Brazilian Portuguese, and Polish versions. A version has also been designed and validated for children. More recently, in September 2011, a modified version of the scale was validated using a criterion of self-assessment for ages six–eight years of age. A version of the scale was developed into a chart suitable for use on US television by Gary Kahan of NewYork–Presbyterian Hospital.
==== Submergent ==== Submerged macrophytes completely grow under water with roots attached to the substrate (rooted submerged) (e.g. Myriophyllum spicatum) or without any root system (unrooted submerged) (e.g. Ceratophyllum demersum). They can also grow up to the water's surface. Helophytes are plants that grow partly submerged in marshes and regrow from buds below the water surface. Fringing stands of tall vegetation by water basins and rivers may include helophytes. Examples include stands of Equisetum fluviatile, Glyceria maxima, Hippuris vulgaris, Sagittaria, Carex, Schoenoplectus, Sparganium, Acorus, yellow flag (Iris pseudacorus), Typha and Phragmites australis. Although seaweeds, which are large multicellular marine algae, have similar ecological functions to aquatic plants such as seagrass, they lack the specialized root/rhizoid system of plants. Instead, seaweeds have holdfasts that only serve as anchors and have no absorptive functions.
centriole A cylindrical organelle composed of microtubules, present only in certain eukaryotes. A pair of centrioles migrate to and define the two opposite poles of a dividing cell where, as part of a centrosome, they initiate the growth of the spindle apparatus.
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.
Reverse-phase HPLC with ultraviolet detection at 214 nm is common. Mass spectrometry is used to confirm molecular identity and detect modifications. Immunoassays exist but may not distinguish the intact peptide from fragments.