This is a working overview of thymalfasin, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-01-11 and is reviewed periodically as new material appears.
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.
Most published studies on thymosin alpha-1 report changes in immune measurements rather than clinical outcomes, and findings differ across designs and populations. Whether the peptide signals through one defined receptor or through several less specific interactions remains an open question. Its reported circulation half-life of a few hours complicates comparison of dosing schedules across trials. Mechanistic claims are frequently drawn from isolated cell cultures, and how far those results extend to whole organisms is unresolved.
Storage recommendations center on low temperature, dryness, and protection from repeated freezing and thawing. The intact powder is commonly held at 20 degrees below zero Celsius or colder, while a working solution is divided into single-use aliquots to limit freeze-thaw cycles. Buffered saline or phosphate-buffered saline at neutral pH is frequently used as a diluent. Light sensitivity is not well documented, yet amber vials or foil wrapping are common practice for long-term storage of peptide stocks.
Identity and purity are assessed with a small set of standard peptide methods. Reversed-phase high-performance liquid chromatography separates the main peak from truncated or oxidized species, and its area percentage is the usual purity measure. Mass spectrometry confirms the observed molecular mass against the expected value, while amino acid analysis or peptide mapping checks composition and sequence. Specifications for research-grade material are often stated as 95 percent or higher, though the exact limit depends on the supplier and the intended use.
Laboratory supplies of the peptide usually arrive as a lyophilized powder in sealed vials. The powder is hygroscopic, so a vial should be allowed to reach room temperature before it is opened to prevent condensation on the contents. Weighing and transfer are best performed in a low-humidity environment with clean tools. Once dissolved, the solution should be mixed gently rather than vortexed, because foaming and shear can reduce recovery of the peptide.
| 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 |
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.
The proportions [given by Webb] indicate that this might have been a squid-like form, and not an Octopus. The "breadth" is evidently that of the softened and collapsed body, and would represent an actual maximum diameter in life of at least 7 feet and a probable weight of 4 or 5 tons for the body and head. These dimensions are decidedly larger than those of any of the well-authenticated Newfoundland specimens. It is perhaps a species of Architeuthis. Verrill soon changed his mind about the identity of the creature. In the January 3 issue of the New York Herald, he wrote that the carcass was indeed that of a giant octopus. However, the paper did not state that Verrill was the author of the article. The article read:
== Selected-ion monitoring chromatogram (SIM) == A selected-ion monitoring (SIM) chromatogram is similar to an EIC/XIC, with the exception that the mass spectrometer is operated in SIM mode, such that only preselected m/z values are detected in the analysis. SIM experiments can be performed using mass spectrometry (MS) or tandem mass spectrometry (MS/MS) instruments. They are more common on MS instruments. This differs significantly from the extracted-ion chromatogram mentioned above in that only data for the ion(s) of interest are collected in a SIM experiment; for extracted-ion chromatograms (EIC or XIC), data for an entire mass range are collected during the run and then examined for analytes of interest after the completion of the run.
Ryder, along with 33 other past and present Essendon players, was found guilty of using a banned performance enhancing substance, thymosin beta-4, as part of Essendon's sports supplements program during the 2012 season. He and his team-mates were initially found not guilty in March 2015 by the AFL Anti-Doping Tribunal, but a guilty verdict was returned in January 2016 after an appeal by the World Anti-Doping Agency. He was suspended for two years which, with backdating, ended in November 2016; as a result, he served approximately 14 months of his suspension and missed the entire 2016 AFL season. In the 2017 season, Ryder returned from suspension and became one of the best ruckmen in the league. He played his 200th AFL game in round 14, in which Port Adelaide defeated Collingwood by 31 points at the MCG. Eventually, he was named an All Australian ruckman and John Cahill Medalist as a best and fairest player for the club.
Since the establishment of psychoanalytic theory, the notion and meaning of individuals having an unconscious, popularised by Freud, has come to be commonly accepted. An individual's personal unconscious is made up of thoughts and emotions that have, at some time, been experienced or held in mind but which have been repressed or forgotten. By contrast, the collective unconscious is neither acquired by activities within an individual's life nor is it a container of things that are thoughts, memories or ideas which are capable of being conscious during one's life. In this sense, the contents of it were never naturally "known" through physical or cognitive experience and then forgotten. The collective unconscious consists of universal heritable elements common to all humans, distinct from other species. However, this does not necessarily imply a genetic cause, but rather encapsulates influences of evolutionary biology, the history of civilization, ethnology, brain and nervous system development, and general psychological development.
Sources: en.wikipedia.org
== Properties of the interface == The study of the molecular structure can give fine details about the interface that enables the interaction between proteins. When characterizing PPI interfaces it is important to take into account the type of complex. Parameters evaluated include size (measured in absolute dimensions Å2 or in solvent-accessible surface area (SASA)), shape, complementarity between surfaces, residue interface propensities, hydrophobicity, segmentation and secondary structure, and conformational changes on complex formation. The great majority of PPI interfaces reflects the composition of protein surfaces, rather than the protein cores, in spite of being frequently enriched in hydrophobic residues, particularly in aromatic residues. PPI interfaces are dynamic and frequently planar, although they can be globular and protruding as well. Based on three structures – insulin dimer, trypsin-pancreatic trypsin inhibitor complex, and oxyhaemoglobin – Cyrus Chothia and Joel Janin found that between 1,130 and 1,720 Å2 of surface area was removed from contact with water indicating that hydrophobicity is a major factor of stabilization of PPIs. Later studies refined the buried surface area of the majority of interactions to 1,600±350 Å2. However, much larger interaction interfaces were also observed and were associated with significant changes in conformation of one of the interaction partners. PPIs interfaces exhibit both shape and electrostatic complementarity.
In classical molecular dynamics, one potential energy surface (usually the ground state) is represented in the force field. This is a consequence of the Born–Oppenheimer approximation. In excited states, chemical reactions or when a more accurate representation is needed, electronic behavior can be obtained from first principles using a quantum mechanical method, such as density functional theory. This is named Ab Initio Molecular Dynamics (AIMD). Due to the cost of treating the electronic degrees of freedom, the computational burden of these simulations is far higher than classical molecular dynamics. For this reason, AIMD is typically limited to smaller systems and shorter times. Ab initio quantum mechanical and chemical methods may be used to calculate the potential energy of a system on the fly, as needed for conformations in a trajectory. This calculation is usually made in the close neighborhood of the reaction coordinate. Although various approximations may be used, these are based on theoretical considerations, not on empirical fitting. Ab initio calculations produce a vast amount of information that is not available from empirical methods, such as density of electronic states or other electronic properties. A significant advantage of using ab initio methods is the ability to study reactions that involve breaking or formation of covalent bonds, which correspond to multiple electronic states. Moreover, ab initio methods also allow recovering effects beyond the Born–Oppenheimer approximation using approaches like mixed quantum-classical dynamics.
== History == RNAP was discovered independently by Sam Weiss, Audrey Stevens, and Jerard Hurwitz in 1960. By this time, one half of the 1959 Nobel Prize in Medicine had been awarded to Severo Ochoa for the discovery of what was believed to be RNAP, but instead turned out to be polynucleotide phosphorylase.
Vasodilators—calcium channel blockers, such as the dihydropyridines nifedipine or amlodipine, preferably slow-release preparations—are often first-line treatment. They have the common side effects of headache, flushing, and ankle edema, but these are not typically of sufficient severity to require cessation of treatment. The limited evidence available shows that calcium-channel blockers are only slightly effective in reducing how often attacks happen, but some studies have found that CCBs may decrease the severity of attacks, pain, and disability associated with Raynaud's phenomenon. People whose disease is secondary to erythromelalgia often cannot use vasodilators for therapy, as they trigger "flares", causing the extremities to become burning red due to too much blood supply. People with severe disease prone to ulceration or large artery thrombotic events may be prescribed aspirin. Sympatholytic agents, such as the alpha-adrenergic blocker prazosin, may provide temporary relief to secondary Raynaud's phenomenon. Angiotensin receptor blockers, such as Losartan, or ACE inhibitors may aid blood flow to the fingers, and there is some evidence that angiotensin receptor blockers (often losartan) reduce frequency and severity of attacks, and possibly better than nifedipine. The prostaglandin iloprost is used to manage critical ischemia and pulmonary hypertension in Raynaud's phenomenon, and the endothelin receptor antagonist bosentan is used to manage severe pulmonary hypertension and prevent finger ulcers in scleroderma.
Depolarization opens both the sodium and potassium channels in the membrane, allowing the ions to flow into and out of the axon, respectively. If the depolarization is small (say, increasing Vm from −70 mV to −60 mV), the outward potassium current overwhelms the inward sodium current and the membrane repolarizes back to its normal resting potential around −70 mV. However, if the depolarization is large enough, the inward sodium current increases more than the outward potassium current and a runaway condition (positive feedback) results: the more inward current there is, the more Vm increases, which in turn further increases the inward current. A sufficiently strong depolarization (increase in Vm) causes the voltage-sensitive sodium channels to open; the increasing permeability to sodium drives Vm closer to the sodium equilibrium voltage ENa≈ +55 mV. The increasing voltage in turn causes even more sodium channels to open, which pushes Vm still further towards ENa. This positive feedback continues until the sodium channels are fully open and Vm is close to ENa. The sharp rise in Vm and sodium permeability correspond to the rising phase of the action potential. The critical threshold voltage for this runaway condition is usually around −45 mV, but it depends on the recent activity of the axon. A cell that has just fired an action potential cannot fire another one immediately, since the Na+ channels have not recovered from the inactivated state. The period during which no new action potential can be fired is called the absolute refractory period.
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.
Aliquots are typically frozen well below zero Celsius and thawed only once, since repeated cycles promote aggregation and loss. Dilution into a neutral buffer limits degradation during short working periods, and prolonged storage at room temperature is avoided.