The short version of synthetic peptide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-12-11 and is reviewed periodically as new material appears.
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.
Several names appear in scientific and commercial contexts for this peptide. The label TB-500 is informal and does not follow standard biochemical nomenclature. Research articles more often describe the compound as a thymosin beta-4 fragment, Tβ4 fragment, or by its sequence Ac-LKKTETQ. Confusing TB-500 with full-length thymosin beta-4 can lead to incorrect assumptions about activity because the fragment lacks the remaining residues of the parent protein. The relationship between fragment and parent protein remains an active area of study.
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.
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.
TB-500 is a synthetic peptide whose sequence corresponds to a short fragment near the N-terminus of thymosin beta-4, a small protein present in most mammalian cells. The fragment is commonly cited as containing the actin-binding region of the parent molecule, which is why it appears in laboratory work on cell migration and tissue repair. Suppliers distribute it as a lyophilised powder intended for research use. Its identity is defined by amino acid sequence and by the presence of an acetyl group on the N-terminal residue.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H68N10O14 | Calculated for the acetylated heptapeptide |
| Molecular weight | ~889 Da | Monoisotopic mass approximately 889.0 Da |
| Amino acid sequence | Ac-LKKTETQ | N-terminal acetylated seven-residue peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Water-soluble | Peptides of this size generally dissolve in aqueous media |
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.
Reconstitution practices affect downstream measurements. The dry powder is typically dissolved in sterile water or a suitable aqueous buffer, then mixed gently rather than vortexed at high speed. Visible particles or cloudiness suggest incomplete dissolution or contamination and should be investigated. For long-term storage, aliquots should be labeled with concentration, solvent, and date. Open questions include how different buffers alter peptide conformation and whether specific container materials adsorb the peptide. Those variables can change apparent concentration in assays even when the chemical identity is correct.
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.
==== Late 1970s ==== By the late 1970s, Rhodesia's front-line forces contained about 25,000 regular troops and police – backed up by relatively strong army and police reserves. Its mechanised contingent consisted of light armoured cars and improvised mine-protected armoured personnel carriers, complemented by eight tanks (Polish built T-55LD tanks), delivered in the last year of the war. The Rhodesian Air Force operated an assortment of both Canberra light bombers, Hawker Hunter fighter bombers, older de Havilland Vampire jets as well as a somewhat antiquated, but still potent, helicopter arm. These forces, including highly trained special operations units, were capable of launching devastating raids on resistance movement camps outside the country, as in Operation Dingo in 1977 and other similar operations. Nevertheless, guerrilla pressure inside the country itself was steadily increasing in the latter 1970s. By 1978–1979, the war had become a contest between the guerrilla warfare placing ever increasing pressure on the Rhodesian regime and civil population, and the Rhodesian government's strategy of trying to hold off the militants until external recognition for a compromise political settlement with moderate black leaders could be secured. By this time, the need to cut a deal was apparent to most Rhodesians, but not to all. Ian Smith had dismissed his intransigent Defence Minister, P. K. van der Byl, as early as 1976. Van der Byl was a hard-line opponent of any form of compromise with domestic opposition or the international community since before UDI.
Quadricyclane is abiotic, unreactive with biomolecules (due to complete saturation), relatively small, and highly strained (~80 kcal/mol). However, it is highly stable at room temperature and in aqueous conditions at physiological pH. It is selectively able to react with electron-poor π systems but not simple alkenes, alkynes, or cyclooctynes. Bis(dithiobenzil)nickel(II) was chosen as a reaction partner out of a candidate screen based on reactivity. To prevent light-induced reversion to norbornadiene, diethyldithiocarbamate is added to chelate the nickel in the product.
== Vaccination Campaign == On 13 November, the government of Sudan requested help from the International Coordinating Group on Yellow Fever Vaccine Provision (YF-ICG) in starting a mass vaccination campaign. Besides the WHO, the YF-ICG consists of representatives of the United Nations Children's Fund (UNICEF), Médecins sans Frontières (MSF) and the International Federation of Red Cross and Red Crescent Societies (IFRC). The United Nations–African Union Mission in Darfur (UNAMID) airlifted the first batches of vaccines from Khartoum to Darfur on 18 November. Mass vaccination began on 20 November. Efforts were also undertaken to eliminate mosquitoes. A team from the Naval Medical Research Unit Three (NAMRU-3) and the WHO Collaborating Center was deployed from Cairo to help collect and test samples and train local personnel. The vaccination campaign, from late November 2012 through early January 2013, covered more than 3 million people and halted the outbreak. A new phase of the campaign beginning in January covered more than 2 million more people at risk. One of the difficulties was maintaining a cold chain for vaccine viability while transporting vaccine by donkey into remote areas. A situation report released on 10 January 2013 reported that 171 people had died of the disease as of 9 January 2013. The number of suspected cases since 2 September 2012 was 847. The Minister of Health had announced on 5 January that no additional cases had appeared in the previous 3 weeks.
=== Narcolepsy === While MCH does promote sleep, there has been no research that links MCH to narcolepsy. Research has instead found that in individuals with narcolepsy there is a decrease in orexin neurons, which would promote wakefulness, while the number of MCH neurons do not vary from the average non-narcoleptic individual.
Sources: en.wikipedia.org
=== Photolysis and thermolysis === Photolysis or thermolysis of mononuclear carbonyls generates di- and polymetallic carbonyls such as diiron nonacarbonyl (Fe2(CO)9). On further heating, the products decompose eventually into the metal and carbon monoxide.
== Chemistry == The medication is extracted from the stem of the pineapple plant (Ananas comosus) by a standardised process, and each lot has to be analysed for its chemical composition. It contains a mixture of proteolytic enzymes, the main compound being stem bromelain. Bromelain is thought to be the active ingredient, but this has not been determined in studies. The gel basis contains water, polyacrylic acid as a gelling agent, and a disodium hydrogen phosphate/sodium hydroxide buffer.
Strontium-90 is a radioactive fission product produced by nuclear reactors used in nuclear power. It is a major component of high-level radioactivity of nuclear waste and spent nuclear fuel. Its 29-year half-life is short enough that its decay heat has been used to power arctic lighthouses, but long enough that it can take hundreds of years to decay to safe levels. Exposure from contaminated water and food may increase the risk of leukemia, bone cancer and primary hyperparathyroidism.
Sources: en.wikipedia.org
Currently approved GnRH antagonists include the peptide molecules abarelix, cetrorelix, degarelix, and ganirelix and the small-molecule compounds elagolix and relugolix. GnRH antagonists are administered by subcutaneous injection (cetrorelix, degarelix, ganirelix), by intramuscular injection (abarelix), or by oral administration (elagolix, relugolix). Another non-peptide and orally-active GnRH antagonist that is in development is linzagolix.
Besides the core data on panning experiments and their results, broad background information on target, template, library and structure is included. An accompanied benchmark has also been compiled for bioinformaticians to develop and evaluate their new models, algorithms and programs. In addition, the MimoDB database provides tools for simple and advanced searches, structure visualization, BLAST and alignment view on the fly. The experimental biologists can easily use the database as a virtual control to exclude possible target-unrelated peptides. The MimoDB database is freely available.
=== Bioinorganic chemistry === In bioinorganic chemistry and bioorganometallic chemistry, coordination complexes serve either structural or catalytic functions. An estimated 30% of proteins contain metal ions. Examples include the intensely colored vitamin B12, the heme group in hemoglobin, the cytochromes, the chlorin group in chlorophyll, and carboxypeptidase, a hydrolytic enzyme important in digestion. Another complex ion enzyme is catalase, which decomposes the cell's waste hydrogen peroxide. Synthetic coordination compounds are also used to bind to proteins and especially nucleic acids (e.g. anticancer drug cisplatin).
Sources: en.wikipedia.org
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.
No. Thymosin beta-4 is a 43-amino-acid protein, while TB-500 represents only a short N-terminal segment. The two should not be treated as interchangeable in experimental design.
It is often called a thymosin beta-4 fragment, Tβ4 fragment, or Ac-LKKTETQ. The name TB-500 is mainly a commercial or catalog label rather than a formal chemical name.
It is a synthetic peptide based on a short sequence near the start of thymosin beta-4. It is supplied as a research chemical rather than as a licensed pharmaceutical product.