acetylated peptide 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 2026-02-09. Numbers and descriptions here follow the published literature rather than marketing material.
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.
胸腺素α1（thymosin alpha 1，Tα1）是一种由28个氨基酸组成的酸性肽，N端被乙酰化，分子量约为3108道尔顿。该肽最早从牛胸腺组织提取物中分离，属于胸腺素组分5的一个成分。其序列在不同哺乳动物中高度保守，提示其具有基本的生物学功能。名称中的“α1”指其在电泳中的迁移位置，并非表示亚型编号。它既存在于胸腺，也存在于脾脏和淋巴结等免疫组织。
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。
| Property | Value | Notes |
|---|---|---|
| Class | Synthetic peptide | 28 residues; not a small-molecule compound |
| Molecular mass | About 3,106 Da | Monoisotopic mass of the unmodified chain |
| N-terminal group | Acetylated serine | Present in both native and synthetic forms |
| Secondary structure | Disulfide-constrained loop | One bridge between two cysteine residues |
| Typical source | Solid-phase synthesis | Early isolates came from bovine thymus extracts |
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.
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.
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 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.
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.
=== PDMS hydrogel === This method uses a hydrogel that is contained within a porous, silicone-based polymer called polydimethylsiloxane (PDMS). The polymer allows the hydrogel to withstand 14-19 times more force than it could on its own.
As of 2024, only one study has directly examined ancient Israelite genetic material. The analysis examined First Temple-era skeletal remains excavated in Abu Ghosh, and showed one male individual belonging to the J2 Y-DNA haplogroup, a set of closely related DNA sequences thought to have originated in the Caucasus or Eastern Anatolia, as well as the T1a and H87 mitochondrial DNA haplogroups, the former of which has also been detected among Canaanites, and the latter in Basques, Tunisian Arabs, and Iraqis, suggesting a Mediterranean, Near Eastern, or perhaps Arabian origin. A 2004 study (by Shen et al.) comparing Samaritans to several Jewish populations (including Ashkenazi Jews, Iraqi Jews, Libyan Jews, Moroccan Jews, and Yemenite Jews) found that "the principal components analysis suggested a common ancestry of Samaritan and Jewish patrilineages. Most of the former may be traced back to a common ancestor in what is today identified as the paternally inherited Israelite high priesthood (Cohanim), with a common ancestor projected to the time of the Assyrian conquest of the kingdom of Israel." A 2020 study (by Agranat-Tamr et al.) stated that there was genetic continuity between the Bronze Age and Iron Age southern Levantines, which included the Israelites and Judahites. They could be "modeled as a mixture of local earlier Neolithic populations and populations from the northeastern part of the Near East (e.g. Zagros Mountains, Caucasians/Armenians and possibly, Hurrians)".
== Other rhEGFs == Several other products containing recombinant human EGF have been marketed. The potencies of these products can differ by the expression system used, despite all intending to match the structure of human EGF. Instead of measuring by mass, the international unit system from the World Health Organization provides a way to describe the potency-adjusted amount of rhEGF. However, the WHO does not prescribe a specific way of measuring the potency. rhEGF bioassay remains a field in active development.
Sources: en.wikipedia.org
=== Light === Herbarium specimens are sensitive to visible light and ultraviolet radiation, which can cause fading of biological pigments (fading or shifts in color) and/or damage to chemical bonds (weakened or embrittled).
=== Satiety === L cells are enteroendocrine cells, i.e., specialized cells that secrete hormones directly into the circulation. L cells reside in the epithelium of the gastrointestinal tract, particularly the terminal ileum and colon. They are stimulated to secrete PYY (also termed peptide YY) and GLP-1 (also termed glucagon-like peptide-1) by the SC-FAs that accumulate inside the intestines after feeding. L cells express FFAR3 and/or FFAR2. Ffar3 and Ffar2 gene knock out mice show reduced secretions of GLP-1 and PYY. Leptin is a peptide hormone released by adipose tissue that triggers satiety and thereby tends to reduce or stop further food intake and the development of obesity. It also plays a role in female reproductive function, lipolysis (e.g., the breakdown of triglycerides into their component free fatty acids and glycerol), the growth of fetuses, inflammation, and angiogenesis (i.e., the formation of new blood vessels from pre-existing blood vessels). While studies have suggested that the SC-FA-induced activation of FFAR3 leads to the secretion of leptin from the white adipose tissue of intact animals and the fat tissue isolated from human tissues, other studies have suggested that FFAR2 rather than FFAR3 is responsible for the SC-FA-induced release of leptin from fat tissue. A systematic review of the published studies on this issue concluded that SC-FA-induced activation of FFAR3 is likely responsible for the SC-FA-induced release of leptin from cultured fat tissue taken from animals.
=== Systems biology === Advances in quantitative proteomics would clearly enable more in-depth analysis of cellular systems. Another research frontier is the analysis of single cells, and protein covariation across single cells which reflects biological processes such as protein complex formation, immune functions, as well as cell cycle and priming of cancer cells for drug resistance Biological systems are subject to a variety of perturbations (cell cycle, cellular differentiation, carcinogenesis, environment (biophysical), etc.). Transcriptional and translational responses to these perturbations results in functional changes to the proteome implicated in response to the stimulus. Therefore, describing and quantifying proteome-wide changes in protein abundance is crucial towards understanding biological phenomenon more holistically, on the level of the entire system. In this way, proteomics can be seen as complementary to genomics, transcriptomics, epigenomics, metabolomics, and other -omics approaches in integrative analyses attempting to define biological phenotypes more comprehensively. As an example, The Cancer Proteome Atlas provides quantitative protein expression data for ~200 proteins in over 4,000 tumor samples with matched transcriptomic and genomic data from The Cancer Genome Atlas. Similar datasets in other cell types, tissue types, and species, particularly using deep shotgun mass spectrometry, will be an immensely important resource for research in fields like cancer biology, developmental and stem cell biology, medicine, and evolutionary biology.
Sources: en.wikipedia.org
=== Destruction and preservation === Because of its waterlogged condition the Flag Fen Basin was an area where peat deposits developed around 2000 BC, and they survive there today. The anaerobic conditions generated by silt deposits from the fens protected the wooden posts and rafters of the collapsed structures from rotting away under the influence of air and bacteria. In the 10th century BC the ground level was much lower than today, increasing around 1 mm (0.039 inches) per year as autumnal debris was added to the surface of the fens. By the early Roman period most of the structure was covered and preserved.
His administration outlined key indicators for altering his stay-at-home mandate, including the ability to closely monitor and track potential cases, prevent infection of high-risk people, increase surge capacity at hospitals, develop therapeutics, ensure physical distancing at schools, businesses, and child-care facilities, and develop guidelines for restoring isolation orders if the virus surges. The plan to end the shutdown had four phases. Newsom emphasized that easing restrictions would be based on data, not dates, saying, "We will base reopening plans on facts and data, not on ideology. Not what we want. Not what we hope." Of a return of Major League Baseball and the NFL, he said, "I would move very cautiously in that expectation." In early May, Newsom announced that certain retailers could reopen for pickup. Most Californians approved of Newsom's handling of the crisis and were more concerned about reopening too early than too late, but there were demonstrations and protests against these policies. Under pressure, Newsom delegated more decision-making on reopening to the local level. That same month, he announced a plan for registered voters to have the option to vote by mail in the November election. California was the first state in the country to commit to sending mail-in ballots to all registered voters for the November general election. On May 25, 2020, Newsom announced the state had approved 43 counties' applications to accelerate their reopening plans.
During the period he was Labour MP for Glasgow Kelvin, from 1997 to 2003, he voted against the whip 32 times, five votes out of 665 (0.8%) in the 1997–2001 parliament and the majority (27 votes out of 209 or 12.9%) in the period from the 2001 election until his expulsion from the Labour Party. He was one of several politicians arrested in February 2001 during a protest at the Faslane nuclear base in Scotland, which led to him being convicted of a breach of the peace and fined £180. In May 2002, he was among the 72 MPs who signed The Guardian's campaign to repeal the Act of Settlement 1701, alongside the Archbishop of York David Hope and several non-Anglican religious leaders.
==== Acetylcholine synthesis ==== Acetyl-CoA is also an important component in the biogenic synthesis of the neurotransmitter acetylcholine. Choline, in combination with acetyl-CoA, is catalyzed by the enzyme choline acetyltransferase to produce acetylcholine and coenzyme A as a byproduct.
Sources: en.wikipedia.org
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.
The single bridge between two cysteine residues holds the chain in a folded loop that influences its shape and its behavior in solution. Loss of the bridge through reduction or oxidation shifts chromatographic retention and is tracked during stability work.
It is a defined 28-residue sequence derived from a larger precursor, whereas many other thymic preparations are mixtures of several polypeptides. Its acetylated amino terminus and single disulfide bridge distinguish it chemically from unrelated thymic extracts.
它不是经典的内分泌激素，而是一种免疫调节肽。其作用主要通过局部免疫细胞间的信号传递实现，而非经血液循环作用于远隔器官。