胸腺素α1 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 2026-02-26. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Lyophilized thymosin alpha 1 is typically stored refrigerated at 2 to 8 degrees Celsius and kept away from light. Reconstituted solutions are less stable and are usually used promptly after preparation. Repeated freeze-thaw cycles are avoided because they can promote aggregation and loss of activity. The peptide adsorbs to some plastic and glass surfaces, so a carrier protein is often added to dilute working solutions. Manufacturer instructions and published protocols both govern handling.
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。
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。
| Property | Value | Notes |
|---|---|---|
| Physical form | Lyophilized powder | Reconstituted before use |
| Typical storage | 2-8 °C, protected from light | Applies to the powder |
| Reconstitution solvent | Sterile water or saline | Follow product labeling |
| Solution stability | Shorter than the powder | Refrigerate and use promptly |
| Primary purity method | Reversed-phase HPLC | Detects related substances |
The compound has been investigated as an adjunct in chronic viral hepatitis and as a vaccine adjuvant, with results that vary by study design and population. Regulators in some countries have approved a synthetic form for specific indications, while other agencies have not. Whether the peptide produces consistent clinical benefit across diverse patient groups is still an open question, and many trials have been small. Its status is therefore best described as investigational in many contexts and established only narrowly.
The name itself causes confusion, because several unrelated thymic peptides share the thymosin label. Thymosin beta-4, for example, is a different molecule with different functions. Naming conventions in the literature also mix descriptive research terms with assigned nonproprietary names, so a reader should confirm which entity a given paper addresses. Clarifying that point is usually the first step in interpreting any claim about this peptide.
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.
在信号层面，Tα1可能通过Toll样受体等模式识别受体发挥作用。部分实验显示，它能激活髓样分化因子88依赖的通路，进而促进核因子κB进入细胞核。这导致白细胞介素2、干扰素γ和白细胞介素12等细胞因子的转录增加。这些细胞因子偏向辅助性T细胞1型应答，有助于细胞免疫。然而，具体受体和结合位点尚未完全确定，不同实验模型的结果存在差异。
临床研究将Tα1用于慢性病毒感染、肿瘤辅助治疗和疫苗佐剂等场景。部分试验报告了免疫学指标改善，但临床终点获益在不同研究中并不一致。系统综述指出，研究间在人群、剂量和联合方案上差异较大，难以汇总结论。因此，Tα1的确切临床地位仍属开放问题，需要更多高质量随机对照试验来澄清。其机制研究也需从体外实验向体内模型推进。
The hot filament reaches a temperature of less than 2,500 °C (2,770 K; 4,530 °F), leading to the inability to create atomic ions of species with a high ionization energy, such as osmium and tungsten. Although the TIMS method can create molecular ions instead in this case, species with high ionization energy can be analyzed more effectively with MC-ICP-MS.
=== Pharmacodynamics === Methylestradiol is an estrogen, or an agonist of the estrogen receptor. It shows somewhat lower affinity for the estrogen receptor than estradiol or ethinylestradiol. Methylestradiol is an active metabolite of the androgens/anabolic steroids methyltestosterone (17α-methyltestosterone), metandienone (17α-methyl-δ1-testosterone), and normethandrone (17α-methyl-19-nortestosterone), and is responsible for their estrogenic side effects, such as gynecomastia and fluid retention.
== Chemical properties == myo-Inositol is a meso compound, meaning it is optically inactive because it has a plane of symmetry. It is a white crystalline powder, relatively stable in the air. It is highly soluble in water, slightly soluble in glacial acetic acid, ethanol, glycol, and glycerin, but insoluble in chloroform and ether. In its most stable conformation, the myo-inositol isomer assumes the chair conformation, which moves the maximum number of hydroxyls to the equatorial position, where they are farthest apart from each other. In this conformation, the natural myo isomer has a structure in which five of the six hydroxyls (the first, third, fourth, fifth, and sixth) are equatorial, whereas the second hydroxyl group is axial.
In 1964, the first franchise was purchased by former police officer Kermit Bekke. This location, located at 1654 West Carson Street in Torrance, California, had its grand opening on May 28, 1965. Bekke sold his franchise a year and a half later. This location closed in 1975 when it moved across the street to store #1130 at 1619 West Carson Street, which itself would close in the late 1990s and subsequently be repurposed. On January 20, 1967, the 100th Taco Bell grand opening took place in Anaheim, located at 400 South Brookhurst (store #63); this location would later be replaced by a new location at 324 South Brookhurst in 1993. The first Taco Bell restaurant east of the Mississippi River (the 270th to open, store #258) opened at 2050 East Main Street in Springfield, Ohio, on September 20, 1968. Original Taco Bells featured only walk-up window service without indoor seating or drive-thru service. Inside seating was added sporadically in 1968 and drive-thru service was not generally available until 1980. As of 2025, seven original mission-style operating Taco Bell restaurants still remain, located in California and Colorado. A mission-style location (opened in April 1976) that operated in Honolulu, Hawaii (store #1281) remodeled in 2024, and another Mission-style location in Scottsdale, Arizona (store #31, opened circa July 3, 1966) closed on April 12, 2025.
Sources: en.wikipedia.org
Outer membrane proteins are membrane proteins with key roles associated with bacterial cell structure and morphology; cell membrane homeostasis; the uptake of nutrients; protection of the cell from toxins including antibiotics; and virulence factors including adhesins, exotoxins, and biofilm formation. There are a number of outer membrane proteins that are specifically virulence-related. Outer membrane proteins consist of two major classes of protein - transmembrane proteins and lipoproteins. The transmembrane proteins form channels or pores in the membrane called porins, and actively pumping efflux channels. The outer membranes of a bacterium can contain a huge number of proteins. In E. Coli for example there are around 500,000 in the membrane. Bacterial outer membrane proteins typically have a unique beta barrel structure that spans the membrane. The beta barrels fold to expose a hydrophobic surface before their insertion into the outer membrane. Beta barrels vary in sequence and size that ranges from 8 to 36 beta strands. A subset of OMPs have a perisplasmic or an extracellular link to their beta barrel structure. An outer membrane protein is translocated across the inner membrane through Sec machinery, and finally inserted to the outer membrane by the barrel assembly machinery complex.
In evolutionary biology, sequence space is a way of representing all possible sequences (for a protein, gene or genome). The sequence space has one dimension per amino acid or nucleotide in the sequence leading to highly dimensional spaces. Most sequences in sequence space have no function, leaving relatively small regions that are populated by naturally occurring genes. Each protein sequence is adjacent to all other sequences that can be reached through a single mutation. It has been estimated that the whole functional protein sequence space has been explored by life on the Earth. Evolution by natural selection can be visualised as the process of sampling nearby sequences in sequence space and moving to any with improved fitness over the current one.
Each fission of a parent atom produces a different set of fission product atoms. However, while an individual fission is not predictable, the fission products are statistically predictable. The amount of any particular isotope produced per fission is called its yield, typically expressed as percent per parent fission; therefore, yields total to 200%, not 100%. (The true total is in fact slightly greater than 200%, owing to rare cases of ternary fission.) While fission products include every element from zinc through the lanthanides, the majority of the fission products occur in two peaks. One peak occurs at about (expressed by atomic masses 85 through 105) strontium to ruthenium while the other peak is at about tellurium to neodymium (expressed by atomic masses 130 through 145). The yield is somewhat dependent on the parent atom and also on the energy of the initiating neutron. In general the higher the energy of the state that undergoes nuclear fission, the more likely that the two fission products have similar mass. Hence, as the neutron energy increases and/or the energy of the fissile atom increases, the valley between the two peaks becomes more shallow. For instance, the curve of yield against mass for 239Pu has a more shallow valley than that observed for 235U when the neutrons are thermal neutrons. The curves for the fission of the later actinides tend to make even more shallow valleys. In extreme cases such as 259Fm, only one peak is seen; this is a consequence of symmetric fission becoming dominant due to shell effects.
Sources: en.wikipedia.org
Olfactory receptors (ORs), also known as odorant receptors, are chemoreceptors expressed in the cell membranes of olfactory receptor neurons and are responsible for the detection of odorants (for example, compounds that have an odor) which give rise to the sense of smell. Activated olfactory receptors trigger nerve impulses which transmit information about odor to the brain. Vertebrates have a total of four olfactory receptor families: OR, TAAR, V1R/ORA, and V2R/OlfC. This article focuses on the OR family. This consists of members of the rhodopsin-like (class A) G protein-coupled receptors (GPCRs). OR forms the largest multigene family in vertebrates consisting of around 400 genes in humans and 1400 genes in mice. In insects, olfactory receptors are members of an unrelated group of ligand-gated ion channels.
=== Prehistory === The site of modern-day Moscow has been inhabited since prehistoric times. Among the earliest archaeological discoveries were relics of the Lyalovo culture, which experts assign to the Neolithic period. These relics confirm that the area's first inhabitants were hunters and gatherers. Around 950 AD, two Slavic tribes—Vyatichi and Krivichi—settled in the area. The Vyatichi may have formed the majority of Moscow's indigenous population.
The most common mechanism of stimulation of acupuncture points employs penetration of the skin by thin metal needles, which are manipulated manually or the needle may be further stimulated by electrical stimulation (electroacupuncture). Acupuncture needles are typically made of stainless steel, making them flexible and preventing them from rusting or breaking. Needles are usually disposed of after each use to prevent contamination. Reusable needles when used should be sterilized between applications. In many areas, only sterile, single-use acupuncture needles are allowed, including the State of California. Needles vary in length between 13 and 130 millimetres (0.51 and 5.12 in), with shorter needles used near the face and eyes, and longer needles in areas with thicker tissues; needle diameters vary from 0.16 mm (0.006 in) to 0.46 mm (0.018 in), with thicker needles used on more robust patients. Thinner needles may be flexible and require tubes for insertion. The tip of the needle should not be made too sharp to prevent breakage, although blunt needles cause more pain. Apart from the usual filiform needle, other needle types include three-edged needles and the Nine Ancient Needles. Japanese acupuncturists use extremely thin needles that are used superficially, sometimes without penetrating the skin, and surrounded by a guide tube (a 17th-century invention adopted in China and the West). Korean acupuncture uses copper needles and has a greater focus on the hand.
Sources: en.wikipedia.org
The lyophilized powder is kept refrigerated at 2 to 8 degrees Celsius and protected from light. Reconstituted solutions should be used promptly. Freezing and thawing repeatedly is avoided.
Reversed-phase HPLC is the primary tool for purity, paired with mass spectrometry for identity. Amino acid analysis and peptide mapping add sequence confirmation. Several techniques are combined because no single test covers every attribute.
It lacks sulfur-containing residues, so oxidation is limited. Aspartate isomerization and slow hydrolysis are the main concerns. Solution stability is shorter than that of the lyophilized powder.
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。