If you have been reading about TB-500 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.
Updated 2025-12-26. Numbers and descriptions here follow the published literature rather than marketing material.
Storage recommendations center on keeping the dry powder cold, dry, and dark. A freezer at -20 degrees Celsius or below is conventional, and desiccant is often included to limit moisture uptake. Once dissolved, the peptide is less stable, and solutions are typically kept frozen and thawed only once. Repeated freeze-thaw cycles are a common source of losses because they promote aggregation and adsorption to container surfaces. Working aliquots are therefore prepared in advance, and glass or low-binding plastic is usually preferred over ordinary laboratory plastic.
Identity and purity are assessed with a small set of standard techniques. Reverse-phase high-performance liquid chromatography gives a purity estimate from peak area, usually recorded at 214 or 220 nanometers, where the peptide bond absorbs. Mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidized species. Amino acid analysis or tandem mass spectrometry sequencing can verify the sequence itself. Additional quality attributes include water content, residual trifluoroacetic acid carried over from purification, and endotoxin where the material is intended for biological work.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized cake or fluffy solid |
| Water solubility | High | Dissolves in water and neutral buffers |
| Dry storage | -20 °C or below | Dry, dark, desiccated |
| Reconstituted storage | Frozen, single thaw | Repeated freeze-thaw promotes loss |
| Purity method | Reverse-phase HPLC | Peak area read at 214 or 220 nm |
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.
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.
Dry powder is commonly held at minus twenty degrees Celsius, with some suppliers recommending lower temperatures for long-term archival storage. Once dissolved, solutions are typically kept cold and protected from light, since aqueous peptide solutions can lose integrity through hydrolysis or oxidation over time. Stability data specific to this fragment are limited in the public literature, and much of the guidance comes from general peptide handling practice rather than from controlled degradation studies. Users therefore treat stated shelf lives as approximate rather than fixed.
Identity and purity are normally assessed with reversed-phase high-performance liquid chromatography, paired with mass spectrometry to confirm molecular mass. A certificate of analysis reports a purity percentage, usually derived from chromatographic peak area, but that figure does not by itself prove a correct sequence or the absence of counterions. Independent verification may include amino acid analysis or peptide mapping. Batch-to-batch variation is a documented concern in the research chemical market, and the gap between a quoted purity value and actual peptide content can be substantial when the material is a salt or retains residual water.
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 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.
Supercritical drying, also known as critical point drying, is a process to remove liquid in a precise and controlled way. It is useful in the production of microelectromechanical systems (MEMS), the drying of spices, the production of aerogel, the decaffeination of coffee and in the preparation of biological specimens.
Even following the adoption of measures such as the White Australia Policy and the Chinese Exclusion Act in English-speaking settler colonies, pervasive control of international borders remained a relatively rare phenomenon until the early 20th century, before which many states had open international borders either in practice or due to a lack of any legal restriction. John Maynard Keynes identified World War I in particular as the point when such controls became commonplace. Decolonisation during the twentieth century saw the emergence of mass emigration from nations in the Global South, thus leading former colonial occupiers to introduce stricter border controls. In the United Kingdom this process took place in stages, with British nationality law eventually shifting from recognising all Commonwealth citizens as British subjects to today's complex British nationality law which distinguishes between British citizens, modern British Subjects, British Overseas Citizens, and overseas nationals, with each non-standard category created as a result of attempts to balance border control and the need to mitigate statelessness. This aspect of the rise of border control in the 20th century has proven controversial. The British Nationality Act 1981 has been criticised by experts, as well as by the Committee on the Elimination of Racial Discrimination of the United Nations, on the grounds that the different classes of British nationality it created are, in fact, closely related to the ethnic origins of their holders.
nuclear matrix Also nucleoskeleton. A mesh-like latticework of protein polymers and microfilaments suspended in the nucleoplasm in the nuclei of eukaryotic cells, akin to the cytoskeleton in the cytoplasm. The nuclear matrix functions as a scaffold and an anchor for large DNA molecules such as chromosomes and for the macromolecular complexes that perform essential nuclear activities such as transcription and DNA replication.
Sources: en.wikipedia.org
Pneumatic nebulization of mobile phase from the analytical column forming an aerosol. Aerosol conditioning to remove large droplets. Evaporation of solvent from the droplets to form dried particles. Particle charging using an ion jet formed via corona discharge. Particle selection – an ion trap is used to excess ions and high mobility charged particles. Measurement of the aggregate charge of aerosol particles using a filter/electrometer. The CAD like other aerosol detectors, can only be used with volatile mobile phases. For an analyte to be detected it must be less volatile than the mobile phase. More detailed information on how CAD works can be found on the Charged Aerosol Detection for Liquid Chromatography Resource Center.
Paraquat, for instance, structurally resembles metabolized MPTP, which selectively kills dopaminergic neurons by inhibiting mitochondrial complex 1. It is widely used to model PD. A widely used herbicide, Paraquat has been epidemiologically linked to higher Parkinson's risk, and rodent studies show it causes mitochondrial dysfunction, oxidative stress, and dopaminergic neuron loss. Rotenone, a naturally derived insecticide, inhibits mitochondrial complex 1 and selectively damages dopaminergic neurons in the substantia nigra. Rodent studies show both temporary and chronic exposure can produce Parkinson-like pathology, including enteric nervous system changes. The dithiocarbamate fungicide Maneb, the second most commonly used pesticide in Brazil, interferes with mitochondrial respiration.
Cell signaling is the process by which a cell interacts with itself, other cells, and the environment. Typically, the signaling process involves three components: the first messenger (the ligand), the receptor, and the signal itself. Most cell signaling is chemical in nature, and can occur with neighboring cells or more distant targets. Signal receptors are complex proteins or tightly bound multimer of proteins, located in the plasma membrane or within the interior. Each cell is programmed to respond to specific extracellular signal molecules, and this process is the basis of development, tissue repair, immunity, and homeostasis. Individual cells are able to manage receptor sensitivity including turning them off, and receptors can become less sensitive when they are occupied for long durations. Errors in signaling interactions may cause diseases such as cancer, autoimmunity, and diabetes.
Sources: en.wikipedia.org
A similar platform was used for the SCIEX AROMIC system (part of the CONDOR contraband detection system developed together with British Aerospace) for the detection of drugs, explosives and alcohol in shipping containers at border crossings, by sampling the interior airspace. In the mid-1980s and into the early 1990s, the advantages of performing LC/MS with APCI and with electrospray, both atmospheric pressure ionization techniques, began to capture the attention of the analytical community. Together they have dramatically expanded the role of mass spectrometry in the pharmaceutical industry for both drug development and drug discovery applications. The sensitivity of APCI combined with the specificity of LC-MS and LC-MS/MS often makes it the method of choice for the quantification of drugs and drug metabolites.
Recent studies have shown the presence of microplastics in breast milk, often leading to exposures in very young children. While it has already been established that chemicals such as flame retardants and pesticides have been detected in breast milk, knowledge about microplastics is limited in comparison. A 2022 study detected microplastics in 26 of 34 breast milk samples, with particles ranging from 2 to 12μm in size, raising concerns about infant exposure during critical developmental windows. No safe or harmful exposure level for microplastics has been established, and exposure to MNPs during early developmental stages has raised questions about possible developmental effects or other health issues later in life. Additionally, breast pumps and breastmilk storage bags are frequently made of plastic. Freezing liquid in a plastic container and then heating it up (the "freeze-thaw cycle") has been shown to increase the presence of microplastics. Similar results have been seen from heating plastic reusable food containers in a microwave, showing the increased release of MNPs. It is not recommended that frozen breastmilk ever be thawed in a microwave.
=== Honours and awards === 1990, Meldola Medal awarded from the Royal Society of Chemistry (RSC) 1993, Zeneca Award for Organic Chemistry from AstraZeneca 1997, Hickinbottom Fellowship from the Royal Society of Chemistry 1999, Novartis Chemistry Lectureship 2003, Inaugural winner of the Royal Society's Rosalind Franklin Award. She used the award to fund a series of UK lectureships for internationally renowned female chemists. 2013, Gibson was appointed an Officer of the Most Excellent Order of the British Empire (OBE) for services to Chemistry and Science Education in the 2013 New Year Honours
These studies both reported that all obvious symptoms of scurvy could be completely reversed by supplementation of only 10 mg a day. Treatment of scurvy can be with vitamin C-containing foods or dietary supplements or injection.
Sources: en.wikipedia.org
Short transit at ambient temperature is generally tolerated, but long-term storage at room temperature is not recommended. Heat, moisture, and light all accelerate degradation. Cold, dry, dark storage is the conventional choice.
Suppliers typically quote a percentage derived from reverse-phase HPLC peak area. That figure reflects the relative amount of the main peak and does not by itself confirm identity or exclude related impurities. Mass spectrometry is commonly paired with it for confirmation.
Peptides purified by reverse-phase chromatography often carry trifluoroacetate as a counter-ion, which adds mass and can affect solubility and apparent behavior in assays. Acetate and hydrochloride forms are also offered. Knowing which form is present matters when calculating how much peptide a given weight contains.
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.