Everything below concerns solid-phase synthesis. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-06. Where a claim depends on a specific study, the study is described rather than over-claimed.
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。
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.
| 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 |
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.
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.
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.
In the US, medical residencies traditionally require lengthy hours of their trainees. Early residents literally resided at the hospitals, often working in unpaid positions during their education. During this time, a resident might always be "on call" or share that duty with just one other physician. The American public, and the medical education establishment, recognized that such long hours were counter-productive, since sleep deprivation increases rates of medical errors. This was noted in a landmark study on the effects of sleep deprivation and error rate in an intensive-care unit. The Accreditation Council for Graduate Medical Education (ACGME) has limited the number of work-hours to 80 hours weekly (averaged over 4 weeks), overnight call frequency to no more than one overnight every third day, and 10 hours off between shifts. Still, a review committee may grant exceptions for up to 10%, or a maximum of 88 hours, to individual programs. Until early 2017, duty periods for postgraduate year 1 could not exceed 16 hours per day, while postgraduate year 2 residents and those in subsequent years can have up to a maximum of 24 hours of continuous duty. After early 2017, all years of residents may work up to 24-hour shifts. While these limits are voluntary, adherence has been mandated for the purposes of accreditation, though lack of adherence to hour restrictions is not uncommon.
== Early life and education == Phil S. Baran was born in Denville, New Jersey, on August 10, 1977, and grew up in Coral Springs, Florida. He was not a strong academic student in high school, but developed early interests in creative pursuits like role-playing games, computer programming, and Lego building. Encouraged by his chemistry teacher to experiment after school, Baran quickly channeled his creativity into crafting molecules. In 1995 he began a chemistry degree at New York University, and enthusiastically accepted David Schuster's offer to work in his lab, synthesizing compounds that linked C60 with porphyrins to make artificial photosynthetic systems. He received his BS in chemistry from New York University in 1997. He went on to earn his PhD from The Scripps Research Institute in 2001, under the supervision of K. C. Nicolaou, an experience he recalls was 'like hardcore Navy Seal training' and where he co-authored 30 papers in less than four years. He then pursued a postdoctoral fellowship in the laboratory of Nobel Laureate Elias James Corey at Harvard University who reflected on Baran's time in his lab, saying, "He had a phenomenal grasp of synthetic chemistry," and "felt that he could be a leader in his generation." Baran is married to Mariana Baran and has four children.
=== Coated microneedles === Coated MNs are fabricated by coating drug solution over solid MNs and the thickness of the drug layer can be adjusted depending on the amount of drug to be administered. A benefit of coated MNs is that less of the drug is needed as compared to other drug administration routes. This is because the layer of drug will quickly dissolve and delivered into the systemic circulation directly across the skin. The solid MNs which are removed afterwards may be contaminated by left-over drugs and the reuse of those MNs raise the concern of cross-infection between patients. Coated microneedles are often covered in other surfactants or thickening agents to assure that the drug is delivered properly. Some of the chemicals used on coated microneedles are known irritants. While there is risk of local inflammation to the area where the array was, the array can be removed immediately with no harm to the patient.
Sources: en.wikipedia.org
In biology, a substitution model, also called models of sequence evolution, are Markov models that describe changes over evolutionary time. These models describe evolutionary changes in macromolecules, such as DNA sequences or protein sequences, that can be represented as a sequence of symbols (e.g., A, C, G, and T in the case of DNA or the 20 "standard" proteinogenic amino acids in the case of proteins). Substitution models are used to calculate the likelihood of phylogenetic trees using multiple sequence alignment data. Thus, substitution models are central to maximum likelihood estimation of phylogeny as well as Bayesian inference in phylogeny. Estimates of evolutionary distances (numbers of substitutions that have occurred since a pair of sequences diverged from a common ancestor) are typically calculated using substitution models (evolutionary distances are used as input for distance methods such as neighbor joining). Substitution models are also central to phylogenetic invariants because they are necessary to predict site pattern frequencies given a tree topology. Substitution models are also necessary to simulate sequence data for a group of organisms related by a specific tree.
By the time Sir John Cradock was appointed governor of the Cape Colony in 1811, the Zuurveld region had lapsed into disorder, and many white farmers had begun abandoning their farms. Early during 1812, on the instructions of the governor, Lieutenant-Colonel John Graham forced 20,000 Xhosa to cross the Fish River. Subsequently, 27 military posts were erected across this border, which resulted in the establishment of the garrison towns of Grahamstown and Cradock. At the end of the 19th century, the area known as British Kaffraria between the Fish and Kei rivers had been set aside for the "Bantu", and was known as the Ciskei from then on. Europeans gave the name Ciskei to the area to distinguish it from the Transkei, the area north of the Kei. After the Union of South Africa formed in 1910, the "Bantu" rights of occupation remained unclear, and differed from colony to colony within South Africa. The Native Lands Act of 1913 demarcated the reserves in the Union, and made it illegal to sell or lease these lands to Europeans (except in the Cape Colony). General Hertzog pursued his segregation policy, and subsequently passed the Native Trust and Land Act in 1936. This act effectively abolished the right of the Cape "Bantu" to buy land outside of the existing reserves. The boundaries of the Ciskei region changed as land was added and excised.
=== Binding site === Advances in the field of recombinant protein engineering and expression, protein purification, NMR, X-ray crystallography and computational chemistry have improved the skills of drug designers to use data that have been gathered on the three-dimensional structures of protein ligand complexes. Most bacterial species have various types of PBP which differ in various ways such as enzymatic function, molecular weight and the affinity for β-lactam antibiotics. There are two types of enzymes that are particularly interesting with regard to the binding site of β-lactams: PBP and β-lactamases. Target alterations in the binding site of PBP have led to high-level resistance of β-lactams among bacteria like staphylococci, enterococci and pneumococci. For example, the binding site of PBP2 in Neisseria gonorrhoeae has been structurally determined and has three sequence motifs that can be seen in nearly all β-lactam interacting enzymes:
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 corresponds to a fragment of the larger protein prothymosin alpha, which is present in many tissues. The isolated 28-amino-acid peptide was originally obtained from thymus preparations, and the pharmaceutical product is synthesized rather than extracted. The term therefore describes both a natural fragment and a manufactured drug substance.