thymalfasin is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-08-19. Numbers and descriptions here follow the published literature rather than marketing material.
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。
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。
Several names appear in the literature for this peptide, including thymalfasin and the abbreviation T-alpha-1. Naming conventions differ among research articles, regulatory documents, and supplier catalogs, which complicates literature searches. Both synthetic and recombinant production routes yield a peptide with the same 28-residue sequence as the thymic isolate. Because the thymosin label also covers unrelated peptides, sources should be compared by sequence rather than by name alone.
The peptide occurs naturally in thymic tissue and has been detected in serum and other biological fluids. Reported concentrations are low, and reliable measurement generally requires immunoassay or mass spectrometry with an enrichment step. It is released from a larger precursor, prothymosin alpha, by proteolytic cleavage, although the enzymes involved are not fully characterized. Whether circulating levels reflect thymic output specifically remains an open question.
Thymosin alpha 1 is a 28-amino-acid peptide first isolated from thymosin fraction 5, a bovine thymic extract. Its sequence begins with an acetylated serine residue and carries a high proportion of acidic residues, so the molecule has a net negative charge near neutral pH. Despite the shared name, it is unrelated in sequence to the thymosin beta family. Synthetic material prepared by solid-phase peptide synthesis is identical in sequence to the natural peptide.
| Property | Value | Notes |
|---|---|---|
| 化学分类 | 线性肽 | 由28个氨基酸组成 |
| 分子量 | 约3108 Da | 合成版本一致 |
| 外观 | 白色至类白色粉末 | 冻干品 |
| 溶解度 | 易溶于水 | 微溶于有机溶剂 |
| 储存温度 | -20°C（冻干） | 溶解后2-8°C |
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.
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.
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.
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.
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.
Quality control for thymosin alpha-1 focuses on identity, purity, and potency. Identity is confirmed by mass spectrometry and amino acid analysis, while purity is assessed by chromatography with limits on related substances and residual solvents. Potency assays may use cell-based immune readouts, but these are not standardized across laboratories. Regulatory status differs by jurisdiction; no product is approved in the United States for clinical use, whereas some other countries register injectable forms for specific indications.
The two medial giant axons connect with each other and send signals from the front to the rear. Stimulation of these causes the earthworm to very quickly retreat, contracting into its burrow and flattening its tail, thus anchoring it in its burrow to escape a surface predator. The presence of a nervous system is essential for an animal to be able to experience nociception or pain. However, other physiological capacities are also required such as opioid sensitivity and central modulation of responses by analgesics. Enkephalin and α-endorphin-like substances have been found in earthworms. Injections of naloxone (an opioid antagonist) inhibit the withdrawal responses of earthworms. This indicates that opioid substances play a role in sensory modulation, similar to that found in many vertebrates.
Porcine All three previously mentioned types of retinol-binding proteins (RBP, CRBP, CRABP) have been identified within the porcine placenta during pregnancy via immunohistochemistry. As previously mentioned, retinol and retinoic acid are modulators of gene expression and are necessary for the proper development and growth of a conceptus. Porcine exhibit a diffuse type placenta that has areolar-gland subunits which allows for transport of larger molecules between dam and fetus. RBP and CRBP have been identified in the endometrial glands and areolar trophoblasts, suggesting that RBP is crucial in transport of retinol from the gland to the trophectoderm of the conceptus. RBP expression has also been identified within the yolk sac, myometrium, oviduct, and numerous other fetal tissues.
=== San Antonio Nathan Shock Center === The San Antonio Nathan Shock Center (NSC) is one of only eight National Institute on Aging (NIA)-funded Nathan Shock Centers of Excellence in the Basic Biology of Aging in the United States. Since its establishment in 1995, the Center has served as an internationally recognized resource dedicated to advancing the fundamental biology of aging and accelerating the development of interventions that promote healthy aging and extend healthspan. The overarching mission of the Center is to identify the molecular, cellular, and physiological mechanisms that drive the aging process and translate these discoveries into strategies that delay or prevent age-associated diseases and functional decline. The San Antonio Nathan Shock Center provides investigators with an integrated, "one-stop-shop" research infrastructure that supports every stage of aging research—from experimental design and animal model development to functional phenotyping, pathology, metabolism, pharmacology, and data interpretation. This comprehensive approach enables investigators to conduct rigorous, multidisciplinary studies that examine lifespan, healthspan, and the biological mechanisms underlying aging. By integrating specialized expertise and state-of-the-art technologies within a single research environment, the Center accelerates scientific discovery while promoting collaboration among investigators locally, nationally, and internationally. The Center is organized around six highly integrated research cores that provide specialized services and scientific expertise.
=== Gas chromatography === GC is a method involving the separation of different analytes within a sample of mixed gases. The separated gases can be detected multiple ways, but one of the most powerful detection methods for gas chromatography is mass spectrometry. After the gases separate, they enter the mass spectrometer and are analyzed. This combination not only separates the analytes, but gives structural information about each one. The GC sample must be volatile, or able to enter the gas phase, while also being thermally stable so that it does not break down as it is heated to enter the gas phase. Mass spectrometry ionization techniques requiring the sample to be in the gas phase have similar concerns. Electron ionization (EI) in mass spectrometry requires samples that are small molecules, volatile, and thermally stable, similar to that of gas chromatography. This ensures that as long as GC is performed on the sample before entering the mass spectrometer, the sample will be prepared for ionization by EI. Chemical ionization (CI) is another method that requires samples to be in the gas phase. This is so that the sample can react with a reagent gas to form an ion that can be analyzed by the mass spectrometer. CI has many of the same requirements in sample preparation as EI, such as volatility and thermal stability of the sample. GC is useful for sample preparation for this technique as well. One advantage of CI is that larger molecules separated by GC can be analyzed by this ionization method.
Sources: en.wikipedia.org
=== Photobiont === The photobiont partner of Parmotrema perlatum is from Trebouxia, a green algal genus belonging to the order Trebouxiales (order Chlorophyta). It has been identified as an undescribed species within a clade containing Trebouxia arboricola. A study compared the desiccation tolerance and physiological responses of lichenised Trebouxia to isolated cultures of the same alga. Both forms can survive extended desiccation, but with differing responses to photo-oxidative stress. Lichenisation enhances the photoprotective mechanisms of Trebouxia, improving quenching of excess light energy, particularly under high relative humidity, and controlling reactive oxygen species production under light exposure. However, isolated cultures showed better photosynthetic performance after desiccation recovery. This research demonstrates the mutual benefits of the lichen-photobiont partnership, where the alga gains a sheltered environment boosting its resilience to environmental stressors. Further studies on Parmotrema perlatum revealed specific antioxidant mechanisms supporting its photobiont under stress. The lichen shows high levels of reactive oxygen species scavenging enzymes such as superoxide dismutase and ascorbate peroxidase, protecting the photobiont from oxidative damage during dehydration and rehydration cycles. This enhanced antioxidant system provides not only physical shelter but also biochemical protection, increasing the photobiont's resilience to environmental fluctuations.
== Tolerance and physical dependence == Chronic use of ketazolam as with other benzodiazepines can lead to physical dependence and the appearance of the benzodiazepine withdrawal syndrome upon cessation of use or decrease in dose. Tolerance to ketazolam's therapeutic effects occurs over a period of 15 days.
In 1775, the Continental Congress determined a ration that included either one pound (450 g) of beef, three-quarters pound (340 g) of pork, or one pound (450 g) of salted fish per day, as well as one pound (450 g) of flour or bread per day, one pint of milk per day, one quart of spruce beer or cider per day, three pounds (1.4 kg) of peas or beans per week, one pint of rice per week, and a small amount of molasses. However, in reality, the Continental Army had difficulties supplying its units. Congress lacked the authority to raise sufficient taxes and transportation and other supply issues compounded the problem. In reality, soldiers might receive some flour and perhaps a small amount of meat or fish. In order to preserve the food, meat was often salted and the flour would often be baked into hard biscuits. As these rations had hardly any nutrients, a weekly ration of vinegar or sauerkraut was eventually added to try to prevent scurvy, but this was insufficient. Sometimes days would pass between rations. Soldiers had to resort to foraging, with those who understood the local vegetation being able to find food in woods around the camps. At Valley Forge, watercress and sorrel were sometimes foraged to provide the troops with some vegetables. Soldiers at times had to hunt whatever animals they could find and beg civilians for food. They also bought food when possible, but this proved difficult as the Continental Army mostly paid in promissory notes which were widely distrusted and many soldiers had little goods or money to trade.
While some of the neutrons released from the fission of 238U are fast enough to induce another fission in 238U, most are not, meaning it can never achieve criticality. While there is a very small (albeit nonzero) chance of a thermal neutron inducing fission in 238U, neutron absorption is orders of magnitude more likely.
== Education == Bewley completed a Ph.D. from University of California, San Diego in 1995. Her dissertation was titled New antifungal and cytotoxic cyclic peptides and studies of the bacterial symbionts of lithistid sponges. Bewley's doctoral advisor was D. John Faulkner.
Sources: en.wikipedia.org
In 1937, the administration of BST was shown to increase the milk yield in lactating cows by preventing mammary cell death in dairy cattle. Until the 1980s, use of the compound was very limited in agriculture as the sole source of the hormone was from bovine carcasses. During this time, the knowledge of the structure and function of the hormone increased. With the advent of biotechnology, one of the pioneering biotech companies, Genentech, in 1981 succeeded in cloning and patenting the gene for BST. Monsanto had been working along the same lines and struck a deal with Genentech in 1979 to license Genentech's patents and collaborate on development of a recombinant version of BST – a process on which Monsanto would invest $300 million. The two companies used genetic engineering to clone the BST gene into E. coli. The bacteria are grown in bioreactors, then broken up and separated from the rBST, which is purified to produce the injectable hormone. They published their first field trial results in 1981. Lilly, American Cyanamid, Upjohn, and Monsanto all submitted applications to market rBST to the FDA, and the FDA completed its review of the human safety component of these applications in 1986 and found food from rBST-treated cows to be safe; however, strong public concern led to calls for more studies, investigations, and public discussions, which included an unprecedented conference on the safety of rBST in 1990 organized by the National Institutes of Health at the request of Senator Patrick Leahy. FDA approved Monsanto's application in 1993.
A major proponent of representative government was Itagaki Taisuke (1837–1919), a powerful Tosa leader who had resigned from the Council of State over the Korean affair in 1873. Itagaki sought peaceful, rather than rebellious, means to gain a voice in government. He started a school and a movement aimed at establishing a constitutional monarchy and a legislative assembly. Such movements were called The Freedom and People's Rights Movement. Itagaki and others wrote the Tosa Memorial in 1874, criticizing the unbridled power of the oligarchy and calling for the immediate establishment of representative government. Between 1871 and 1873, a series of land and tax laws were enacted as the basis for modern fiscal policy. Private ownership was legalized, deeds were issued, and lands were assessed at fair market value with taxes paid in cash rather than in kind as in pre-Meiji days and at slightly lower rates. Dissatisfied with the pace of reform after having rejoined the Council of State in 1875, Itagaki organized his followers and other democratic proponents into the nationwide Aikokusha (Society of Patriots) to push for representative government in 1878. In 1881, in an action for which he is best known, Itagaki helped found the Jiyūtō (Liberal Party), which favored French political doctrines. In 1882, Ōkuma Shigenobu established the Rikken Kaishintō (Constitutional Progressive Party), which called for a British-style constitutional democracy.
==== Flight ==== Flies fly via straight sequences of movement interspersed by rapid turns called saccades. During these turns, a fly is able to rotate 90 degrees in less than 50 milliseconds. Characteristics of Drosophila flight may be dominated by the viscosity of the air, rather than the inertia of the fly body, but the opposite case with inertia as the dominant force may occur. However, subsequent work showed that while the viscous effects on the insect body during flight may be negligible, the aerodynamic forces on the wings themselves actually cause fruit flies' turns to be damped viscously.
== SARS-CoV-2 proofreading enzyme == Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the COVID-19 pandemic. The SARS-CoV-2 RNA virus genome encodes a replication-and transcription complex, a multisubunit protein machine that carries out viral genome replication and transcription, processes essential to the virus life cycle. One of the proteins specified by the coronavirus genome is a non-structural protein, nsp14, that is a 3'-to-5' exoribonuclease (ExoN). This protein resides in the protein complex nsp10-nsp14 that enhances replication fidelity by proofreading RNA synthesis, an activity critical for the virus life cycle. Furthermore, the coronavirus proofreading exoribonuclease nsp14-ExoN is required for maintaining genetic recombination generated during infection.
Sources: en.wikipedia.org
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。
天然胸腺素α1主要从胸腺组织提取，也可在脾脏和淋巴结中检出。目前研究和临床使用的多为化学合成版本，不再依赖动物组织。
胸腺素组分5是牛胸腺提取物的粗组分，包含多种肽。胸腺素α1是其中一种被纯化和表征的单一肽，具有明确的28个氨基酸序列。
It is a 28-amino-acid peptide originally purified from a bovine thymic extract and later produced synthetically. It is studied mainly for its effects on immune cell function.