If you have been reading about deamidation and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-04-23. Numbers and descriptions here follow the published literature rather than marketing material.
Whether the free 28-residue peptide circulates in human tissue remains debated. The best-documented human source is prothymosin alpha, a larger acidic protein that carries the sequence at its N-terminus. Reports of measurable peptide levels in serum and lymphoid tissue exist, yet some of that signal may come from cross-reacting fragments or from the parent protein. Most reviews therefore treat prothymosin alpha as the established human molecule and describe independent circulation of the small peptide as an unresolved question.
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.
Like most short peptides, thymosin alpha-1 is susceptible to hydrolysis under strongly acidic or basic conditions and to oxidation when exposed to air over long periods. The acetylated amino terminus blocks one common degradation route, which contributes to the molecule's relative robustness in solution. Lyophilized material generally retains potency for extended periods when kept cold and dry. Once reconstituted, aqueous solutions are less stable and are typically used within a defined window rather than held indefinitely at ambient temperature.
Routine handling calls for storage of the lyophilized powder at refrigerated temperatures, away from light, in a sealed container. Working solutions are often prepared in sterile water or buffer and kept cold between uses. Repeated freeze-thaw cycles are generally avoided because they can promote aggregation and loss of material. Laboratories usually record lot number, reconstitution date, and storage conditions so that any change in behavior can be traced to a specific preparation.
Reverse-phase high-performance liquid chromatography is the standard technique for assessing purity and concentration, because the peptide's hydrophobicity allows clean separation from related impurities. Mass spectrometry confirms molecular identity and detects sequence errors or truncations. Amino acid analysis and peptide mapping supply additional structural confirmation when required. Chromatographic purity values reported on certificates of analysis describe the proportion of the main peak and do not by themselves establish biological activity.
| Property | Value | Notes |
|---|---|---|
| Amino acid length | 28 residues | Single chain with an acetylated N-terminus |
| Molecular mass | Approximately 3,108 Da | Small shifts occur with counter-ion and water content |
| Isoelectric point | Around 3.5 | Low value follows from the many acidic residues |
| Parent molecule | N-terminal region of prothymosin alpha | Free circulating form in humans is not firmly established |
| Common synonyms | Thymalfasin; T alpha 1 | Older literature also uses the full spelled-out form |
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。
Lyophilized thymosin alpha-1 is generally stored at or below minus twenty degrees Celsius, protected from moisture and light. Short-term handling at ambient temperature is possible for dry powder, but reconstituted solutions degrade faster and are usually kept at two to eight degrees Celsius with a defined expiry of days rather than weeks. Repeated freeze-thaw cycles should be avoided because they promote aggregation and loss of potency. Exact limits depend on the formulation and should follow the supplier's documentation.
Identity and purity are normally assessed by reversed-phase high-performance liquid chromatography, which separates the peptide from related impurities and truncation products. Mass spectrometry confirms molecular mass and detects modifications such as deamidation or oxidation. Amino acid analysis and peptide mapping provide additional sequence-level confirmation. For research material, a certificate of analysis typically reports these results together with water content and counter-ion identity, since the lyophilized powder is often supplied as an acetate or trifluoroacetate salt.
== General Principles in Infants/Children Immunization == Because measles kills, every infant needs to be vaccinated against measles at the age of 9 months or as soon as possible after 9 months as part of the routine infant vaccination schedule. It is safe to vaccinate a sick child who is suffering from a minor illness (cough, cold, diarrhea, fever or malnutrition) or who has already been vaccinated against measles. If the vaccination schedule is interrupted, it is not necessary to restart. Instead, the schedule should be resumed using minimal intervals between doses to catch up as quickly as possible. Vaccine combinations (few exceptions), antibiotics, low-dose steroids (less than 20 mg per day), minor infections with low fever (below 38.5º Celsius), diarrhea, malnutrition, kidney or liver disease, heart or lung disease, non-progressive encephalopathy, well controlled epilepsy or advanced age, are not contraindications to vaccination. Contrary to what the majority of doctors may think, vaccines against hepatitis B and tetanus can be applied in any period of the pregnancy. There are very few true contraindication and precaution conditions. Only two of these conditions are generally considered to be permanent: severe (anaphylactic) allergic reaction to a vaccine component or following a prior dose of a vaccine, and encephalopathy not due to another identifiable cause occurring within 7 days of pertussis vaccination. Only the diluent supplied by the manufacturer should be used to reconstitute a freeze-dried vaccine.
=== June === June 2, 2009: Switzerland Switzerland officially entered a recession in the first quarter of 2009 when its economy shrank by 0.8%, after contracting 0.3% in the last quarter of 2008. The contraction was caused mainly by weakness in exports, which fell 5.4% in the quarter. Meanwhile, the Swiss watch industry had been reporting double-digit declines in watch exports for the past four months.
== History of human tissue == In humans with non-injured tissues, the tissue naturally regenerates over time; by default, new available cells replace expended cells. For example, the body regenerates a full bone within ten years, while non-injured skin tissue is regenerated within two weeks. With injured tissue, the body usually has a different response. This emergency response usually involves building a degree of scar tissue over a time period longer than a regenerative response, as has been proven clinically and via observation. There are many more historical and nuanced understandings about regeneration processes. In full thickness wounds that are under 2 mm, regeneration generally occurs before scarring. In 2008, in full thickness wounds over 3 mm, it was found that a wound needed a material inserted in order to induce full tissue regeneration. Whereas third degree burns heal slowly by scarring, in 2016 it was known that full thickness fractional photothermolysis holes heal without scarring. Up to 40% of full thickness skin can be removed without scarring in an area, in a fractional pattern via coring of tissue. Some human organs and tissues regenerate rather than simply scar, as a result of injury. These include the liver, fingertips, and endometrium. More information is now known regarding the passive replacement of tissues in the human body, as well as the mechanics of stem cells. Advances in research have enabled the induced regeneration of many more tissues and organs than previously thought possible.
Sources: en.wikipedia.org
Naja christyi (formerly Boulengerina christyi), commonly known as the Congo water cobra or Christy's water cobra, is a species of venomous snakes belonging to the family Elapidae. The species is native to Sub-Saharan Africa. This species was formerly in the genus Boulengerina, but more recent research by Wallach et al. has shown that Boulengerina is actually a subgenus and Boulengerina christyi is a synonym of Naja christyi. This species has no known subspecies.
The Arabidopsis serpin, AtSerpin1 (At1g47710; 3LE2), mediates set-point control over programmed cell death by targeting the 'Responsive to Desiccation-21' (RD21) papain-like cysteine protease. AtSerpin1 also inhibits metacaspase-like proteases in vitro. Two other Arabidopsis serpins, AtSRP2 (At2g14540) and AtSRP3 (At1g64030) appear to be involved in responses to DNA damage.
In addition, if the medicine has distributed fully at equilibrium in the body, which is called the volume of distribution at a stable state. In case the loading dose was administered after the CRI, the time period of which will keep the concentration at a stable state equals 3 time constants or 5 terminal half-lives of the specific medicine. The bolus dose can full with the volume of the medicine in an efficient and effective way so that the medicine can be cleared and delivered. This also can promote to achieve the stable state in a prompter approach. Administering a CRI has two important methods: targeting a specific infusion rate, and making the infusion rate constant.
Sources: en.wikipedia.org
=== EC 1.6.2 With a heme protein as acceptor === EC 1.6.2.1: now EC 1.6.99.3 NADH dehydrogenase EC 1.6.2.2: cytochrome-b5 reductase EC 1.6.2.3: deleted EC 1.6.2.4: NADPH—hemoprotein reductase EC 1.6.2.5: NADPH—cytochrome-c2 reductase EC 1.6.2.6: leghemoglobin reductase
==== Intermolecular forces ==== Nanoparticles can self-assemble as a result of their intermolecular forces. As systems look to minimize their free energy, self-assembly is one option for the system to achieve its lowest free energy thermodynamically. Nanoparticles can be programmed to self-assemble by changing the functionality of their side groups, taking advantage of weak and specific intermolecular forces to spontaneously order the particles. These direct interparticle interactions can be typical intermolecular forces such as hydrogen bonding or Van der Waals forces, but can also be internal characteristics, such as hydrophobicity or hydrophilicity. For example, lipophilic nanoparticles have the tendency to self-assemble and form crystals as solvents are evaporated. While these aggregations are based on intermolecular forces, external factors such as temperature and pH also play a role in spontaneous self-assembly.
== Enzyme mechanism == Cystathionase uses pyridoxal phosphate to facilitate the cleavage of the sulfur-gamma carbon bond of cystathionine, resulting in the release of cysteine. The lysine residue reforms the internal aldimine by kicking off α-iminobutyric acid. Afterwards the external ketimine is hydrolyzed, causing the formation of α-ketobutyrate. The amino group on cystathionine is deprotonated and undergoes a nucleophilic attack of the internal aldimine. An additional deprotonation by a general base results in the formation of the external aldimine and removal of the lysine residue. The basic lysine residue is then able to deprotonate the alpha carbon, pushing electron density into the nitrogen of the pyridine ring. Pyridoxal phosphate is necessary to stabilize this carbanionic intermediate; otherwise the proton's pKa would be too high. The beta carbon is then deprotonated, creating an alpha-beta unsaturation and pushing a lone pair onto the aldimine nitrogen. To reform the aldimine, this lone pair pushes back down, cleaving the sulfur-gamma carbon bond, resulting in the release of cysteine. A pyridoxamine derivative of vinyl glyoxylate remains after the gamma elimination. The lone pair from the pyridine nitrogen pushes electron density to the gamma carbon, which is protonated by lysine. Lysine then attacks the external aldimine, pushing electron density to the beta carbon, which is protonated by a general acid. The imine is then hydrolyzed to release α-ketobutyrate. Deprotonation of the lysine residue causes ammonia to leave, thus completing the catalytic cycle.
Sources: en.wikipedia.org
It is usually described as an immunomodulatory peptide rather than a classic circulating hormone. No endocrine gland is known to release it as a primary secretory product, and its measured presence in blood is not firmly established.
Prothymosin alpha is a much larger acidic protein, roughly 111 to 113 residues long, and the thymosin alpha-1 sequence matches its N-terminal region. The small peptide is therefore best understood as a fragment of that parent protein rather than a separate gene product.
Trials and clinical reports have examined chronic hepatitis B and C, use as a vaccine adjuvant, and supportive treatment in some immunodeficiency and oncology settings. Results vary by indication, and regulatory approval differs between countries.
The lyophilized solid is normally held at 2 to 8 °C in a sealed, light-protected container. Dry storage limits both hydrolysis and microbial growth. Material kept this way remains stable for the shelf life stated by the supplier.