If you have been reading about thymosin alpha 1 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.
Last reviewed on 2026-06-04. Where a claim depends on a specific study, the study is described rather than over-claimed.
Thymosin alpha 1 is a short peptide first isolated from bovine thymus tissue in the early 1970s during fractionation work aimed at identifying factors that influence T cell development. It belongs to a family of acidic thymic peptides, and the original preparations contained several components that were later separated by chromatography. The compound is now produced synthetically rather than extracted from tissue, which removes batch variability tied to animal sourcing. Researchers describe it as an immunomodulatory peptide because laboratory studies show effects on several cell types of the innate and adaptive immune systems.
The molecule consists of 28 amino acid residues with an acetyl group attached to the N-terminal serine. Its sequence is acidic overall, with several glutamic and aspartic acid residues distributed along the chain and no cysteine, so disulfide bridges do not form. The peptide carries a net negative charge at physiological pH. Because the N-terminus is blocked, the intact molecule resists degradation by many aminopeptidases, which contributes to its stability in biological fluids.
Lyophilized material is generally held at reduced temperature to slow degradation, and storage at minus twenty degrees Celsius or lower is common practice for long-term retention. Short-term working portions are often kept between two and eight degrees Celsius. Once dissolved, the peptide is less stable than the dry powder, and repeated freeze-thaw cycles are associated with loss of material and with aggregate formation. Vials are usually allowed to reach room temperature before opening so that condensation does not introduce moisture, and solutions are protected from light where practical.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography, which separates the peptide from closely related impurities and from truncated or oxidized variants. Mass spectrometry supplies the molecular mass and confirms the expected sequence length, while amino acid analysis can be used to check composition. Because the molecule has no chromophore beyond the peptide backbone, ultraviolet detection is typically performed at a low wavelength, where baseline interference from solvents and buffers is a practical concern. Water content and counter-ion content are often reported alongside purity.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Acetylated peptide | N-terminal acetyl group blocks aminopeptidase attack |
| Residue count | 28 amino acids | Matches the N-terminus of prothymosin alpha |
| Molecular mass | About 3,108 Da | Value for the free, unmodified peptide |
| Isoelectric point | Approximately 4.2 | Acidic; net negative charge at neutral pH |
| Encoding gene | PTMA | Human gene for the precursor protein |
The most stable and dense form of selenium is gray and has a chiral hexagonal crystal lattice (space group 152 or 154 depending on the chirality) consisting of helical polymeric chains, where the Se–Se distance is 237.3 pm and Se–Se–Se angle is 103.1°. The minimum distance between chains is 343.6 pm. Gray selenium is formed by mild heating of other allotropes, by slow cooling of molten selenium, or by condensing selenium vapor just below the melting point. Whereas other selenium forms are insulators, gray selenium is a semiconductor showing appreciable photoconductivity. Unlike the other allotropes, it is insoluble in CSs. It resists oxidation by air and is not attacked by nonoxidizing acids. With strong reducing agents, it forms polyselenides. Selenium does not exhibit the changes in viscosity that sulfur undergoes when gradually heated.
== Applications == Spontaneous isopeptide bond formation has been exploited in the development a peptide tag called SpyTag. SpyTag can spontaneously and irreversibly react with its binding partner (a protein termed SpyCatcher) through a covalent isopeptide bond. This molecular tool may have applications for in vivo protein targeting, fluorescent microscopy, and irreversible attachment for a protein microarray. Following this, other Tag/Catcher systems were developed such as SnoopTag/SnoopCatcher and SdyTag/SdyCatcher that complement SpyTag/SpyCatcher.
Extraperitoneal fascia (also: endoabdominal fascia or subperitoneal fascia) is a fascial plane – consisting mostly of loose areolar connective tissue – situated between the fascial linings of the walls of the abdominal and pelvic cavities (transversalis fascia, anterior layer of thoracolumbar fascia, iliac fascia, and psoas fascia) externally, and the parietal peritoneum internally. Its quality and quantity varies considerably. It occupies the extraperitoneal space.
Sources: en.wikipedia.org
2C-B has been reported to be an allosteric or non-competitive serotonin transporter (SERT) inhibitor or serotonin reuptake inhibitor, albeit of very low potency. Although 2C-B itself was not evaluated, other closely related members of the 2C series, including 2C-C, 2C-D, 2C-E, 2C-I, and 2C-T-2, all showed no activity as monoamine releasing agents of serotonin, norepinephrine, or dopamine (EC50 = >100,000 nM or "inactive"). 2C-B shows dopaminergic actions mediated by the dopamine transporter (DAT) in monkeys but not in rodents. 2C-B produces the head-twitch response, a behavioral proxy of psychedelic effects, in rodents. It shows reinforcing effects in monkeys but not in rodents. The drug also shows potent and efficacious anti-inflammatory effects in preclinical research. In contrast to MDMA, which robustly increases oxytocin levels and produces associated entactogenic effects, 2C-B minimally affects oxytocin levels in humans.
== Appearances == The Headcrab debuted in Half-Life (1998) as an enemy that attacks protagonist Gordon Freeman and other surviving humans by leaping at them and biting them. Headcrabs first appear when a portal is opened, sending various interdimensional beings into the game's world and sending the Black Mesa lab into chaos. Throughout the game, the player encounters bodies with Headcrabs on their head, some of which becoming animated and attacking living people. In the sequel, Half-Life 2, the Headcrab and Headcrab Zombies return in a similar capacity. Headcrabs can be found in various environments, and the main antagonists, the Combine, who have taken control of the world post-invasion, have been attacking civilian and resistance groups by shooting rockets with Headcrabs in them to infect the population. Other Headcrabs appear, including a fast one and a poison one, the latter of which can put Gordon in serious danger if bitten. The character Isaac Kleiner manages to debeak a Headcrab, keeping it as a pet called Lamarr. Headcrabs also appear in Half-Life: Alyx, a virtual reality game. Fast-moving Headcrabs and Zombies were originally considered for inclusion, but were removed due to tests finding that they moved too fast for players to properly react. Outside of the Half-Life series, the Headcrab makes multiple cameo appearances. Multiple games, such as Vindictus and the Steam releases of Phantasy Star Online 2, Death Stranding, and Fall Guys featured accessories based on the Headcrab.
Amphetamine is a potent psychostimulant of the phenethylamine class that is approved for the treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy. Amphetamine is also used off-label as a performance and cognitive enhancer, and recreationally as an aphrodisiac and euphoriant. Although it is a prescription medication in many countries, unauthorized possession and distribution of amphetamine is often tightly controlled due to the significant health risks associated with uncontrolled or heavy use. As a consequence, amphetamine is illegally manufactured in clandestine labs to be trafficked and sold to users. Based upon drug and drug precursor seizures worldwide, illicit amphetamine production and trafficking is much less prevalent than that of methamphetamine. The first pharmaceutical amphetamine was Benzedrine, a brand of inhalers used to treat a variety of conditions. Because the dextrorotary isomer has greater stimulant properties, Benzedrine was gradually discontinued in favor of formulations containing all or mostly dextroamphetamine. Presently, it is typically prescribed as mixed amphetamine salts, dextroamphetamine, and lisdexamfetamine. Amphetamine is a norepinephrine–dopamine releasing agent (NDRA). It enters neurons through dopamine and norepinephrine transporters and facilitates neurotransmitter efflux by activating TAAR1 and inhibiting VMAT2. At therapeutic doses, this causes emotional and cognitive effects such as euphoria, change in libido, increased arousal, and improved cognitive control.
Sources: en.wikipedia.org
Hydrophobins have been found to be structurally and functionally similar to cerato-platanins, another group of small cysteine-rich proteins, which also contain a high percentage of hydrophobic amino acids, and are also associated with hyphal growth. This family of proteins includes the rodlet proteins of Neurospora crassa (gene eas) and Emericella nidulans (gene rodA), these proteins are the main component of the hydrophobic sheath covering the surface of many fungal spores. Genomic sequencing of two fungi from dry or salty environments (Wallemia sebi and W. ichthyophaga) revealed that these species contain predicted hydrophobins with unusually high proportion of acidic amino acids and therefore with potentially novel characteristics. High proportion of acidic amino acids is thought to be an adaptation of proteins to high concentrations of salt.
=== Subsequent history === The discovery of TOR and mTOR stemmed from independent studies of the natural product rapamycin by Joseph Heitman, Rao Movva, and Michael N. Hall in 1991; by David M. Sabatini, Hediye Erdjument-Bromage, Mary Lui, Paul Tempst, and Solomon H. Snyder in 1994; and by Candace J. Sabers, Mary M. Martin, Gregory J. Brunn, Josie M. Williams, Francis J. Dumont, Gregory Wiederrecht, and Robert T. Abraham in 1995. In 1991, working in yeast, Hall and colleagues identified the TOR1 and TOR2 genes. In 1993, Robert Cafferkey, George Livi, and colleagues, and Jeannette Kunz, Michael N. Hall, and colleagues independently cloned genes that mediate the toxicity of rapamycin in fungi, known as the TOR/DRR genes. Rapamycin arrests fungal activity at the G1 phase of the cell cycle. In mammals, it suppresses the immune system by blocking the G1 to S phase transition in T-lymphocytes. Thus, it is used as an immunosuppressant following organ transplantation. Interest in rapamycin was renewed following the discovery of the structurally related immunosuppressive natural product FK506 (later called Tacrolimus) in 1987. In 1989–90, FK506 and rapamycin were determined to inhibit T-cell receptor (TCR) and IL-2 receptor signaling pathways, respectively. The two natural products were used to discover the FK506- and rapamycin-binding proteins, including FKBP12, and to provide evidence that FKBP12–FK506 and FKBP12–rapamycin might act through gain-of-function mechanisms that target distinct cellular functions.
Quercetin: Quercetin (a flavonoid found in vegan food) supplements, has been suggested to treat baldness. A 2012 study demonstrated that alopecia areata could be used to prevent ant treated with quercetin in mice. Quercetin is found in onions primarily in the peel and the first scaly leaf but not in the flesh. Onion bulb size or weight does not appear to be affected by quercetin concentration. A 2020 study demonstrated that quercitrin stimulated hair shaft growth in cultured human hair follicles. Volatile compounds responsible for pungency and tearing in onions when they are cut (e.g. syn-propanethial S-oxide gas). However, no formal studies have been conducted to evaluate if these compounds promote hair growth or if they help other compounds to penetrate the skin to form hair follicles. To use the volatile compounds: Onions must be extracted and applied topically quickly before the volatile compounds evaporate. The extract will cause tearing eyes, but it can be prevented with a shower cap, or a pair of swimming goggles. To discard the volatile compounds: The onion juice is extracted and stored for a short while to evaporate the volatile compounds. The extract will not cause tearing eyes. Also, both genetically modified, and plant breed onions have been produced with significantly reduced levels of tear-inducing lachrymatory factor.
Sources: en.wikipedia.org
Thymosin fraction 5 is a mixture of many peptides obtained from thymus tissue, while thymosin alpha 1 is a single defined 28-residue molecule. The two names appear together in older literature because the purified peptide was first obtained from that mixture.
The precursor, prothymosin alpha, is encoded by the PTMA gene in humans. The 28-residue peptide corresponds to the N-terminal segment released from that larger protein.
It is produced as a fragment of prothymosin alpha and is present in many tissues. Circulating concentrations are low, which makes routine measurement difficult.
Cool storage below freezing is usual for long-term retention, with a desiccant and protection from light. Portions are often split before first use to avoid repeated handling.