Everything below concerns Thymosin beta-4. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-07-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
Once in solution, short peptides are generally less stable than the dry powder, and repeated freeze-thaw cycles are a common cause of loss. Laboratory guidance usually calls for aliquoting on first dissolution and storing aliquots at -20 °C or below, away from light. Adsorption to plastic and glass surfaces can lower measured concentration, particularly at low concentrations, so container material and buffer choice can affect results. Visible cloudiness, colour change or unexpected precipitate is a signal to re-check the material.
Purity is normally assessed by reversed-phase HPLC, with the main peak reported as a percentage of total peak area, while identity is confirmed by mass spectrometry. Electrospray and MALDI-TOF instruments are both used, and the observed mass is compared with the value calculated from the stated sequence. Ion-exchange or size-exclusion methods appear where aggregation or charge variants are of interest. Water content, counter-ion content and residual trifluoroacetate from purification are separate variables that can shift the measured mass and should be weighed when reading a certificate of analysis.
Regulatory status differs by country, but TB-500 is not an approved pharmaceutical in major jurisdictions. It is commonly sold as a research chemical for laboratory use, which places responsibility for identity and purity on the supplier and the laboratory. Published human data are limited, and most reports involve preclinical models or cell culture. Questions about whether the fragment mimics all actions of thymosin beta-4, and under which conditions, remain open. Independent verification of any material is therefore a practical requirement in research settings.
TB-500 is a synthetic heptapeptide with the sequence Ac-LKKTETQ. It corresponds to a short N-terminal region of thymosin beta-4, a 43-amino-acid protein found in many cell types. The fragment contains an actin-binding motif, which is one reason it appears in laboratory studies of cell migration and cytoskeletal dynamics. TB-500 is not the full-length protein and is produced as a research chemical rather than an approved therapeutic agent. Its molecular weight is approximately 889 Da.
| Property | Value | Notes |
|---|---|---|
| Typical form | Lyophilised powder | Reconstituted before use |
| Storage temperature, dry | -20 °C or below | Desiccated, protected from light |
| Purity determination | Reversed-phase HPLC | Reported as percentage of total peak area |
| Identity confirmation | Mass spectrometry | ESI or MALDI-TOF versus calculated mass |
| Common synonyms | Tβ4 fragment; thymosin beta-4 fragment | Naming varies between suppliers |
Full-length thymosin beta-4 consists of roughly forty-three amino acids and ranks among the more abundant small proteins in the cytoplasm. The fragment is much shorter, so it cannot reproduce every function attributed to the intact molecule. In cell culture, short actin-binding motifs can interfere with filament dynamics and cell movement, but such observations come from controlled experiments rather than from whole-animal work. Whether a truncated fragment produces the same effects as the parent protein remains an open question.
Interest in the peptide grew during the 2000s and 2010s, when studies of tendon and ligament injuries in horses reported changes in lesion size after treatment. Those reports circulated widely outside the scientific literature and shaped much of the current online discussion. Subsequent reviews noted inconsistent study design, small groups, and a shortage of independent replication. Popular descriptions often blur the line between the fragment, the complete protein, and unrelated growth factors, which complicates comparisons across sources.
Lyophilized TB-500 is hygroscopic and should be kept dry before use. The usual storage recommendation for the solid is -20 °C, protected from light and moisture. Once dissolved, the peptide is less stable, and repeated freeze-thaw cycles can promote aggregation or degradation. Laboratories often divide a reconstituted solution into single-use aliquots and store them at -80 °C. Exact stability limits depend on buffer, pH, and concentration, so published data do not define a single universal condition.
Identity and purity are checked with chromatographic and mass spectrometric methods. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities, while mass spectrometry confirms the expected molecular mass. A certificate of analysis may report a purity percentage, but the laboratory should still verify the material independently. Common quality concerns include truncated sequences, deamidation, oxidation, and residual solvents from synthesis. Because TB-500 is short, some impurities can differ from the target by only a few mass units.
Detection in biological matrices generally relies on liquid chromatography coupled with tandem mass spectrometry, because the peptide lacks a convenient ultraviolet chromophore beyond the amide backbone. Immunoassays have been described, but antibodies raised against the fragment can cross-react with the full-length protein or with unrelated peptides, so findings usually require confirmation by a second technique. Sample preparation typically involves protein precipitation followed by solid-phase extraction. Reported detection windows depend on dose, route, matrix, and instrument sensitivity.
Lyophilised material is stable for extended periods when kept dry and cold, and suppliers typically recommend storage well below freezing. Once dissolved, the peptide is handled at refrigeration temperatures and used within a short period, because peptide bonds and the acetylated terminus can be affected by repeated freeze-thaw cycles, proteases, or extreme pH. Bacteriostatic water and saline are both described as solvents, although preservatives can interfere with some analytical workflows. Reconstituted solutions are inspected for particulates before use.
Sports authorities classify the peptide as a prohibited substance, and it appears on the World Anti-Doping Agency list under peptide hormones, growth factors, and related substances. Racing jurisdictions for horses and dogs have issued separate restrictions, and several national bodies treat it as a controlled or prescription-only item. As a research chemical it is sold without a therapeutic indication, and labels usually state that the product is not for human or veterinary use. Regulatory treatment therefore varies by country.
== Occurrence == Trace amounts of plutonium-238, plutonium-239, plutonium-240, and plutonium-244 can be found in nature. Small traces of plutonium-239, a few parts per trillion, and its decay products are naturally found in some concentrated ores of uranium, such as the natural nuclear fission reactor in Oklo, Gabon. The ratio of plutonium-239 to uranium at the Cigar Lake Mine uranium deposit ranges from 2.4×10−12 to 44×10−12. These trace amounts of 239Pu originate in the following fashion: on rare occasions, 238U undergoes spontaneous fission, and in the process, the nucleus emits one or two free neutrons with some kinetic energy. When one of these neutrons strikes the nucleus of another 238U atom, it is absorbed by the atom, which becomes 239U. With a relatively short half-life, 239U decays to 239Np, which decays into 239Pu. Finally, exceedingly small amounts of plutonium-238, attributed to the extremely rare double beta decay of uranium-238, have been found in natural uranium samples. Due to its relatively long half-life of about 80 million years, it was suggested that plutonium-244 occurs naturally as a primordial nuclide, but early reports of its detection could not be confirmed. Based on its likely initial abundance in the Solar System, present experiments as of 2022 are likely about an order of magnitude away from detecting live primordial 244Pu. However, its long half-life ensured its circulation across the Solar System before its extinction, and indeed, evidence of the spontaneous fission of extinct 244Pu has been found in meteorites.
=== Distribution === Estradiol is rapidly distributed throughout the body, with a distribution phase of about 6 minutes following intravenous injection. Estradiol is taken up into cells via passive diffusion due to its lipophilicity. Due to binding to the ERs, estradiol is preferentially concentrated in tissues with the highest ER content. In animals, these tissues have included the uterus, vagina, mammary glands, pituitary gland, hypothalamus, other brain regions, adipose tissue, liver, and adrenal glands, among other tissues. In contrast to estradiol, due to its low affinities for the ERs, estrone is not accumulated in target tissues. Estradiol has been found to cross the blood–brain barrier in rhesus monkeys. The volume of distribution of estradiol has been found to be 0.85 to 1.17 L/kg. In another study however, its volume of distribution was only 0.082 ± 0.015 L/kg (4.8 L in women of average weight 58.4 kg). In terms of plasma protein binding, estradiol is bound loosely to albumin and tightly to SHBG, with approximately 97 to 98% of estradiol bound to plasma proteins. In the circulation, approximately 38% of estradiol is bound to SHBG and 60% is bound to albumin, with 2 to 3% free or unbound. However, with oral estradiol, there is an increase in hepatic SHBG production and hence SHBG levels (e.g., +50%), and this results in a relatively reduced fraction of free estradiol. As only free estradiol that is not bound to plasma proteins or SHBG is biologically active, this may reduce the potency of oral estradiol by some degree.
=== Fermented dry sausage === Adding sake kasu when mixing the ingredients for fermented dry sausage can increase the speed of decomposition in both sarcoplasmic and myofibrillar proteins. It also can increase the amount of peptides and free amino acids, causing the fermented dry sausage to increase in hardness and acidity.
=== Antidotes === Andexxa (Andexanet alfa) from Portola Pharmaceuticals is a recombinant protein that is given intravenously. It works as an antidote to all direct and indirect FXa inhibitors. Andexxa acts as a decoy receptor for Xa inhibitors.
== Chemical reaction == The two substrates of this enzyme are the luciferin, coelenterazine and oxygen. Its products are the oxyluciferin, coelenteramide, carbon dioxide, and a photon. It belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and initial incorporation of two atoms of oxygen into the substrate. Although the enzyme is part of the group of enzymes that act on coelenterazine, such as Renilla and Gaussia luciferases, it does not share base pair sequences with these enzymes. OpLuc catalyzes the ATP independent chemical reaction:
Sources: en.wikipedia.org
== Signs and symptoms == To properly diagnose catatonia, both the ICD-11 and DSM-5 require three or more of the symptoms defined in the table below. However, each person can have a different set of symptoms that may worsen, improve, and change in appearance throughout a single episode. Symptoms may develop in varying amounts of time, presenting in hours, days, or even weeks.
=== Television === Scénarios sur la drogue (2000) – directed by Guillaume Canet and Jean-Christophe Pagnac (episode "Avalanche") Nana (2001) – directed by Édouard Molinaro The Private Life of Samuel Pepys (2003) – directed by Oliver Parker Gossip Girl (2010) – directed by Mark Piznarski and starring Doillon as herself
Based on a precautionary approach, WHO recommends focusing control of exposure on preventing inhalation exposure with the aim of reducing it as much as possible (strong recommendation, moderate-quality evidence). WHO recommends reduction of exposures to a range of MNMs that have been consistently measured in workplaces especially during cleaning and maintenance, collecting material from reaction vessels and feeding MNMs into the production process. In the absence of toxicological information, WHO recommends implementing the highest level of controls to prevent workers from any exposure. When more information is available, WHO recommends taking a more tailored approach (strong recommendation, moderate-quality evidence). WHO recommends taking control measures based on the principle of hierarchy of controls, meaning that the first control measure should be to eliminate the source of exposure before implementing control measures that are more dependent on worker involvement, with PPE being used only as a last resort. According to this principle, engineering controls should be used when there is a high level of inhalation exposure or when there is no, or very little, toxicological information available. In the absence of appropriate engineering controls PPE should be used, especially respiratory protection, as part of a respiratory protection programme that includes fit-testing (strong recommendation, moderate-quality evidence).
A typical Indian meal is built on a plain cereal, complemented by savoury dishes. The cooked cereal could be steamed rice; chapati, a thin unleavened bread; idli, a steamed breakfast cake; or dosa, a griddled pancake. The savoury dishes might include lentils, pulses, vegetables, meat, poultry and fish commonly spiced with ginger and garlic, but also coriander, cumin, turmeric, cinnamon, cardamom and others. In some instances, the ingredients may be mixed during the cooking process. India has distinctive vegetarian cuisines, each a feature of the geographical and cultural histories of its communities. About 20% to 39% of India's population consists of vegetarians. Although meat is eaten widely, the proportional consumption of meat is low. The most significant import of cooking techniques into India during the last millennium occurred during the Mughal Empire, spreading into northern India from regions to its northwest, along with dishes such as pilaf. Onions, garlic, almonds, and spices were added to the simple yogurt marinade of Persia. Rice was partially cooked and layered alternately with sauteed meat, the pot sealed tightly, and slow cooked according to another Persian cooking technique, to produce biryani, a feature of festive dining in many parts of India. The diversity of Indian food served worldwide has been partially concealed by the dominance of Punjabi cuisine.
Sources: en.wikipedia.org
=== Lactose fermentation === In one study that sought to prove that some fermentation produced by L. lactis can hinder motility in pathogenic bacteria, the motilities of Pseudomonas, Vibrio, and Leptospira strains were severely disrupted by lactose utilization on the part of L. lactis. Using flagellar Salmonella as the experimental group, the research team found that a product of lactose fermentation is the cause of motility impairment in Salmonella. It is suggested that the L. lactis supernatant mainly affects Salmonella motility through disruption of flagellar rotation rather than through irreversible damage to morphology and physiology. Lactose fermentation by L. lactis produces acetate that reduces the intracellular pH of Salmonella, which in turn slows the rotation of their flagella. These results highlight the potential use of L. lactis for preventing infections by multiple bacterial species.
Around 1500 BCE a tribe called the Oenotri ("vine-cultivators"), settled in the region. Ancient sources state they were Greeks who were led to the region by their king, Oenotrus. However it is more likely they were an ancient Italic people who spoke an Italic language. During the eighth and seventh centuries BCE, Greeks founded many settlements on the coast of southern Italy. In Calabria they founded Chone (Pallagorio), Cosentia (Cosenza), Clampetia (Amantea), Scyllaeum (Scilla), Sybaris (Sibari), Hipponion (Vibo Valentia), Epizephyrian Locris (Locri), Kaulon (Monasterace), Krimisa (Cirò Marina), Kroton (Crotone), Laüs (comune of Santa Maria del Cedro), Medma (Rosarno), Metauros (Gioia Tauro), Petelia (Strongoli), Rhégion (Reggio Calabria), Scylletium (Borgia), Temesa (Campora San Giovanni), Terina (Nocera Terinese), Pandosia (Acri) and Thurii, (Thurio, comune of Corigliano Calabro). In the year 744 BCE a group of Chalcidian settlers founded Rhegion (today Reggio Calabria) at the southern end of the peninsula. Soon after, other Chalcidans founded Zancle (current Messina) on the other side of the strait, securing their dominion over that arm of the sea. Later Chalcidian settlers from Rhegion and Zancle founded Metauros (Gioia Tauro) and divided the river of the same name (today Petrace) from the Italic city of the Tauri. In 710 BCE Ionian colonists founded Sybaris on the fertile plain of the same name at the mouth of the Crati.
The Dervish movement successfully repulsed the British Empire four times and forced it to retreat to the coastal region. The Darawiish defeated the Italian, British, Abyssinian colonial powers on numerous occasions, most notably, the 1903 victory at Cagaarweyne commanded by Suleiman Aden Galaydh, forcing the British Empire to retreat to the coastal region in the early 1900s. The Dervishes were finally defeated in 1920 by British airpower.
Sources: en.wikipedia.org
Sealed, desiccated and protected from light, at -20 °C or lower for long-term storage. Short-term storage at refrigerator temperature is common in working laboratories.
Synthesis routes, purification steps and the analytical method used all affect the reported figure. A purity number is only comparable when the chromatographic conditions and detection wavelength are stated.
It reports what the supplier measured on a sample, which is useful but not absolute. Independent mass confirmation on the received lot is the more reliable check.
TB-500 is a synthetic heptapeptide corresponding to a fragment of thymosin beta-4. It is used in laboratory research and is not an approved drug.