Everything below concerns reconstitution. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-03-19. Numbers and descriptions here follow the published literature rather than marketing material.
Literature and online discussion often conflate TB-500 with full-length thymosin beta-4, even though the two differ in size and are not interchangeable in analytical terms. The fragment is produced by solid-phase peptide synthesis, and the product is a defined seven-residue chain rather than a biological extract. Because the term is a trade-style label, two vendors may supply materials of the same nominal sequence but different counter-ion content, purity, or water content. Comparisons across studies are therefore difficult unless the exact sequence and purity are reported.
TB-500 is a research peptide whose sequence matches residues 17 to 23 of thymosin beta-4, a 43-residue protein present in most mammalian cells. The chain is seven amino acids long, written as LKKTETQ, and is normally supplied with an acetyl group on the N-terminus. Suppliers list it as a lyophilised powder under the code name TB-500, and the same sequence appears elsewhere in catalogues as the thymosin beta-4 actin-binding fragment. The label is commercial rather than systematic, so no single authority fixes exactly what TB-500 denotes.
Thymosin beta-4 was isolated from calf thymus in the early 1980s and later characterised as an abundant intracellular actin-sequestering protein. Interest in short synthetic fragments grew once the actin-binding motif had been mapped to the middle of the sequence. TB-500 came out of that line of work as a truncated analogue rather than a natural isolate, and it is now sold mainly to laboratories. Published studies on the fragment have been largely in vitro or in animal models, and controlled human trials remain sparse, so claims about effects in people rest on extrapolation.
The seven-residue chain carries several polar and charged side chains, so it dissolves readily in water and in aqueous buffers near neutral pH. No cysteine is present, so disulphide formation is not a concern and reducing agents are unnecessary. Dilute ammonium hydroxide or acetonitrile-water mixtures are sometimes used for stock solutions when initial dissolution is slow. Strongly alkaline conditions and prolonged contact with oxidising agents are avoided because they can modify lysine-containing stretches, and haze in solution usually signals incomplete dissolution or aggregated material.
Identity and purity are checked with reversed-phase high-performance liquid chromatography, which separates the target sequence from truncated or deletion analogues, and with mass spectrometry, which confirms the expected molecular mass. Amino acid analysis and peptide mapping give orthogonal confirmation but are used less often outside specialist laboratories. Counter-ion content varies: material purified on trifluoroacetic acid gradients retains trifluoroacetate, and ion exchange can convert the salt form. Residual water and solvent are measured by Karl Fischer titration or thermogravimetric analysis, and any purity figure should be read together with the method used to obtain it.
Lyophilised peptide powders are hygroscopic, and the fragment absorbs atmospheric moisture when a vial is opened at room temperature. Weighing and aliquoting are normally done quickly in a dry environment, and stock solutions are divided into single-use portions before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and can shift the measured content of a vial. These practices are general to synthetic peptides rather than unique to this sequence, but they matter more for short chains kept for long periods.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Supplied as a lyophilised cake in sealed vials |
| Solubility class | Freely soluble in water | Polar and charged side chains dominate the sequence |
| Typical storage temperature | -20 °C or below | Dry and dark; a desiccant is often recommended |
| Identity confirmation | Mass spectrometry | Observed mass compared with the theoretical value |
| Common synonyms | Thymosin beta-4 fragment | Also written as T beta 4 fragment 17-23 |
Discussion of the compound frequently appears alongside other short peptides described as fragments of larger proteins. That grouping is convenient but can be misleading, because fragment length, charge, and modification state determine how a peptide behaves in solution and in any experimental system. A seven-residue acetylated peptide and a full-length protein differ in mass by roughly an order of magnitude, and they cannot be assumed to share distribution or binding properties. Precision about which molecule is under discussion is the single most useful step when reading such material.
TB-500 is a shorthand label used in supplier catalogs and online discussion for a short synthetic peptide described as a fragment of thymosin beta-4. Most product listings present it as the N-terminally acetylated heptapeptide Ac-LKKTETQ, a sequence corresponding to the actin-binding region of the parent protein. The name is not a formal chemical designation and does not appear in standard nomenclature systems. Because labeling practices vary between vendors, two products sold under the same name may not contain the same molecule, and the stated sequence should be treated as a claim rather than a fixed definition.
Laboratory work on thymosin beta-4 describes binding to monomeric actin and effects on cell migration, angiogenesis, and inflammatory signaling in cultured cells. Animal models have examined skin, corneal, and cardiac repair after injury, with outcomes reported mainly in preclinical literature. Most of that evidence concerns the parent protein rather than preparations labelled TB-500, so extrapolation from animal findings to a specific commercial product remains uncertain. Whether the two behave identically in living systems has not been established in controlled human studies.
No major regulatory agency has approved TB-500 for therapeutic use, and it holds no pharmacopoeial monograph. The name appears on the World Anti-Doping Agency prohibited list within the class covering peptide hormones, growth factors, and related substances. Detection in doping control relies on mass spectrometric methods applied to urine, often after preparation steps that concentrate the analyte. Discussion of TB-500 therefore clusters in biochemistry, sports medicine, and anti-doping literature rather than in registered clinical trials.
TB-500 is a synthetic peptide preparation marketed under a name derived from thymosin beta-4, a 43-residue actin-binding protein first isolated from thymus tissue. The full-length protein has a reported molecular mass near 4963 Da, while material sold as TB-500 is often described as a fragment containing the actin-binding motif LKKTETQ. Because suppliers use the name inconsistently, published sources sometimes refer to the same label as a fragment, a synthetic copy, or a related analog. This naming ambiguity complicates direct comparison of reports across studies.
Reconstitution of a lyophilized peptide is normally done with sterile water or a suitable buffer under aseptic conditions. Adding solvent down the vial wall and allowing gentle dissolution instead of vigorous vortexing reduces the chance of aggregation, which can lower the effective concentration of the resulting solution. Concentrated stocks are usually diluted into working buffer shortly before use. Because no standard preparation protocol exists for TB-500 specifically, laboratories adapt general peptide handling practice, and reported results may reflect differing preparation choices.
Dry peptide powder is commonly kept at −20 °C in a desiccated container away from light, a practice that limits moisture uptake and oxidation. Once dissolved, solutions are generally held at 2–8 °C for short periods or frozen at −20 °C or lower for longer storage, with repeated freeze-thaw cycles avoided. Hydrolysis and oxidation are the main degradation routes for peptides in solution, and both accelerate at higher temperature or extreme pH. Published stability data specific to TB-500 are limited, so shelf life should be treated as uncertain.
Identity and purity checks for peptide material typically combine reversed-phase high-performance liquid chromatography with mass measurement, since retention time alone cannot confirm a sequence. Mass measurement verifies the expected molecular mass within instrument tolerance, while chromatographic peak area provides a purity estimate. Anti-doping analysis of urine uses related but more sensitive workflows, sometimes after solid-phase extraction. For research material, batch documentation, certificate content, and independent testing are common points of scrutiny, because supply chains outside pharmaceutical regulation vary widely in the paperwork they provide.
The most frequently cited identity is a seven-residue fragment with the sequence LKKTETQ, taken from the actin-binding domain of the parent protein. A separate molecule, N-acetyl-seryl-aspartyl-lysyl-proline, often shortened to Ac-SDKP, derives from the same protein's N-terminal region and appears in overlapping literature. Reported molecular masses therefore differ between sources, and a mass value on its own does not establish which fragment is present. Confirmation requires a defined sequence rather than a single number.
Research interest in thymosin beta-4 fragments centres on actin sequestration, cell migration and tissue repair models. Most published work uses cultured cells or animal wound and cardiac preparations, and findings are generally described as preliminary. No fragment of this protein has been approved as a therapeutic product by major regulators. Reviews of the field note inconsistent dosing, delivery routes and outcome measures across studies, which complicates direct comparison. The material is best understood as a laboratory reagent with an active but unresolved research literature.
TB-500 is a catalogue name applied to a synthetic peptide related to thymosin beta-4, an actin-binding protein found in most mammalian cells. Suppliers do not use the label consistently: some describe it as the full 43-residue protein, others as a short fragment from the actin-binding region, and others as a related tetrapeptide. Because the name is commercial rather than chemical, two products sold under it may not contain the same molecule. This naming ambiguity is the first point to check in any description of the material.
The French tried to reach Kaluga and swing through southern Russia, where they could find food and forage supplies. In the Battle of Maloyaroslavets, the replenished Russian army blocked the road to Kaluga. While an indecisive engagement, it nevertheless doomed the Grande Armée; with the Russians refusing to be dislodged, Napoleon was forced to retreat back down the Smolensk road along which he had already advanced, and which had already been denuded of supplies—most crucially, food. The French supply chain, already in tatters from the attrition of wagons and horses, began to collapse completely. The lack of horses also rendered Napoleon's cavalry ineffective, leaving the Grande Armée vulnerable to sustained guerrilla warfare by Russian peasants and irregular troops. The Grande Armée was dealt a further catastrophic blow by the onset of the Russian Winter, which the underfed and undersupplied Grande Armée was unprepared to cope with. When the remnants of Napoleon's army struggled across the Berezina River in November with the Russian army in pursuit, only 27,000 fit soldiers survived, with 380,000 men dead or missing and 100,000 captured. Napoleon then left his men and returned to Paris to prepare the defence against the advancing Russians. The campaign had effectively ended on 14 December 1812, when the last enemy troops left Russia. The Russians had lost around 210,000 men, but with their shorter supply lines, they soon replenished their armies. For every six soldiers of the Grande Armée that entered Russia, only one would make it out in fighting condition.
There is no disease-modifying treatments proven to cure Alzheimer's disease, and because of this, AD research has focused on interventions to prevent the onset and progression. There is no evidence that supports any particular measure in preventing AD, and studies of measures to prevent the onset or progression have produced inconsistent results. Epidemiological studies have proposed relationships between an individual's likelihood of developing AD and modifiable factors, such as medications, lifestyle, and diet. There are some challenges in determining whether interventions for AD act as a primary prevention method, preventing the disease itself, or a secondary prevention method, identifying the early stages of the disease. These challenges include duration of intervention, different stages of disease at which intervention begins, and lack of standardization of inclusion criteria regarding biomarkers specific for AD. Further research is needed to determine factors that can help prevent AD.
== Differential diagnosis == Other disorders that may be accompanied by chorea include benign hereditary chorea, bilateral striatal necrosis, abetalipoproteinemia, ataxia–telangiectasia, biotin-thiamine-responsive basal ganglia disease (BTBGD), Fahr disease, familial dyskinesia–facial myokymia (Bird–Raskind syndrome) due to an ADCY5 gene mutation, glutaric aciduria, Lesch–Nyhan syndrome, mitochondrial disorders, Huntington's disease, Wilson disease, hyperthyroidism, lupus erythematosus, pregnancy (chorea gravidarum), drug intoxication and side effects of certain anticonvulsants (e.g. phenytoin) or psychotropic agents. Although some of these can similarly present in an acute way, there will typically be other neurological signs (such as ataxia or cognitive impairment), or other disease manifestations, or positive family history, which will help distinguish between them.
Eventually, because no one could play against Neftchi in the half-final, Neftchi were right away promoted to the final, where they defeated the Lithuanian club Kaunas 4–2. 2009 European football match-fixing scandal 2011 Turkish sports corruption scandal – in July 2011, as part of a major match-fixing investigation by authorities in Turkey, nearly 60 people suspected to be involved with fixing games were detained by Istanbul Police Department Organized Crime Control Bureau and then arrested by the court. In June 2014, retrial process has started for all the convicted people. 2011–12 Italian football match-fixing scandal 2013 Lebanese match fixing scandal – in 2013, Lebanese footballers, Ramez Dayoub (playing for Selangor FA) and Mahmoud El Ali (playing for Persiba Balikpapan), were banned for life by the Lebanese Football Association for participating in match-fixing scandals. 22 players were investigated for this. 2013 English football match-fixing scandal 2015 Greek football scandal – it emerged on 6 April 2015, when prosecutor Aristidis Korreas' 173-page work was revealed. Telephone tapping operated by the National Intelligence Service of Greece has played a significant role in the case. According to the prosecutor's conclusion, Olympiakos. owner Evangelos Marinakis along with Greek Football Federation members Theodoros Kouridis, Aristidis Stathopoulos and Georgios Sarris were suspected of directing a criminal organization since 2011. The goal behind their scheme was to "absolutely control Greek football's fate by the methods of blackmailing and fraud".
Sources: en.wikipedia.org
=== 1974 === February 7: Grenada becomes independent from the UK. April 25: Portuguese Armed Forces revolt against the authoritarian regime of Estado Novo. Fascism in Portugal officially ended, and Spain became the last and only fascist country that still stood at the time. June 26: NATO holds a summit in Brussels, the first one since 1957 to be held. June 28: The Moscow Summit begins. July 20: Turkey invaded Cyprus after a coup d'état conducted by the Greek junta. July 24: The Greek Junta gives up its power after the Cypriot Junta government of the 1974 Cypriot coup d'état fell on July 23. This initiated a new period of Greek history known as Metapolitefsi, which led to the restoration of democracy in Greece. August 9: Gerald Ford becomes President of the United States upon the resignation of Nixon. September 4: The United States and East Germany begin diplomatic relations. September 12: The pro-Western monarch of Ethiopia, Haile Selassie, is ousted by a Marxist military junta known as the Derg. November 24: The SALT II Agreement is drafted at the Vladivostok Summit Meeting on Arms Control. December 8: Following a referendum, Greece voted to confirm their abolition of their monarchy the previous year.
==== Unemployment ==== According to the U.S. Department of Labor Bureau of Labor Statistics, the unemployment rate is 8.3% as of October 2017. In the 20th century, the unemployment rate was around 5%, according to the U.S. Department of Labor's archives.
==== Gangrene and gallbladder rupture ==== Cholecystitis causes the gallbladder to become distended and firm. Distension can lead to decreased blood flow to the gallbladder, causing tissue death and eventually gangrene. Once tissue has died, the gallbladder is at greatly increased risk of rupture (perforation), which can cause sharp pain. Rupture can also occur in cases of chronic cholecystitis. Rupture is a rare but serious complication that leads to abscess formation or peritonitis. Massive rupture of the gallbladder has a mortality rate of 30%.
Sources: en.wikipedia.org
No. Thymosin beta-4 is a 43-residue protein, while TB-500 matches only residues 17 to 23 of that chain. The two are related but differ in size, and a method that identifies one does not automatically identify the other.
It corresponds to the actin-binding region of thymosin beta-4. Commercial synthesis reproduces that seven-residue stretch, usually with an acetyl group on the N-terminus.
It is not authorised as a medicine in the United States or the European Union and is distributed as a research chemical. Labels consequently carry research-use-only statements rather than clinical indications.
Divide it into single-use aliquots and hold them frozen at -20 °C or below, protected from light. Repeated thawing of one container is the main avoidable source of variability.