This is a working overview of actin binding, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-04-23 and is reviewed periodically as new material appears.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular mass | Approximately 4963 Da for full-length thymosin beta-4 | Value applies to the parent protein; fragment products may differ |
| Appearance | White to off-white lyophilized powder | Typical form of supplied synthetic peptide |
| Solubility | Freely soluble in water | Polar peptide; dissolves readily in aqueous buffer |
| Storage of dry powder | −20 °C, desiccated, protected from light | Standard laboratory practice for peptides |
| Typical detection method | Liquid chromatography–tandem mass spectrometry | Used in purity testing and anti-doping analysis |
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.
Research peptides are typically supplied as a white to off-white lyophilised powder in a sealed vial. The dry solid is more stable than a solution and is normally kept refrigerated or frozen until use. Dissolution is usually done in water, phosphate-buffered saline or a similar aqueous medium, depending on the assay. Because the material is hygroscopic and easily contaminated, opening vials in a low-humidity environment and recording the lot number before use are standard laboratory practices.
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.
Discussion of TB-500 appears in several distinct literatures that rarely cite one another. Peer-reviewed studies usually describe in vitro assays or small animal experiments and are cautious about extrapolation. Veterinary and sports communities circulate anecdotal reports with limited methodological detail. Commercial listings add a third layer, often using the name interchangeably with thymosin beta-4 even though the two molecules differ in size and sequence. Regulatory status varies by country, and the compound is not a licensed medicine in most jurisdictions, so readers comparing sources should check which molecule and which purity each source actually describes.
TB-500 is a synthetic seven-residue peptide whose sequence, LKKTETQ, matches the N-terminal actin-binding region of thymosin beta-4. It is usually supplied in an N-terminally acetylated form, a modification that blocks the free amino terminus and can influence behavior in solution. In the research literature the same sequence appears under several names, including thymosin beta-4 fragment and shortened thymosin beta-4. Because it is a short peptide rather than the full 43-residue parent protein, its measured properties differ from those reported for thymosin beta-4 as a whole, and the two are not interchangeable in experimental design.
== NMR spectroscopy on large proteins == Traditionally, nuclear magnetic resonance spectroscopy has been limited to relatively small proteins or protein domains. This is in part caused by problems resolving overlapping peaks in larger proteins, but this has been alleviated by the introduction of isotope labelling and multidimensional experiments. Another more serious problem is the fact that in large proteins the magnetization relaxes faster, which means there is less time to detect the signal. This in turn causes the peaks to become broader and weaker, and eventually disappear. Two techniques have been introduced to attenuate the relaxation: transverse relaxation optimized spectroscopy (TROSY) and deuteration of proteins. By using these techniques it has been possible to study proteins in complex with the 900 kDa chaperone GroES-GroEL.
== Early life and career == Kennedy was born in Centreville, Mississippi, and raised in Zachary, Louisiana. He graduated from Zachary High School as co-valedictorian in 1969. He then attended Vanderbilt University, where he majored in philosophy, political science, and economics. He graduated in 1973 with a Bachelor of Arts, magna cum laude, and was elected president of his class and to Phi Beta Kappa. Kennedy received a Juris Doctor degree in 1977 from the University of Virginia School of Law. There, he was an executive editor of the Virginia Law Review and, graduating in the top ten percent of his class, he was elected to the Order of the Coif. In 1979, he earned a Bachelor of Civil Law, an advanced degree, with first class honours from Oxford University, where he was a member of Magdalen College and studied under Rupert Cross and J. H. C. Morris. Kennedy was a partner in the New Orleans and Baton Rouge law firm Chaffe McCall from 1985 to 1987 and 1992 to 1996. He also served as an adjunct professor at Louisiana State University's Paul M. Hebert Law Center in Baton Rouge from 2002 to 2016.
Still, during the Soviet era, Jews were encouraged to admire Cossacks as the antitheses of the "parasitic" and "feeble dwellers of the shtetl." A number of Yiddish writers, including Khaim Melamud, Shmuel Gordon, Viktor Fink, and Shmuel Godiner, presented fictionalized accounts of peaceful Jewish-Cossack coexistence, while efforts were made by the pro-Soviet press to present Khmelnytsky as a heroic figure and Cossacks as liberators from the Nazis. Historiography interprets Cossackdom in imperial and colonial terms. In Ukraine, where Cossackdom represents historical and cultural heritage, some people have begun attempting to recreate the images of Ukrainian Cossacks. Traditional Ukrainian culture is often tied in with the Cossacks, and the Ukrainian government actively supports these attempts. The traditional Cossack bulava serves as a symbol of the Ukrainian presidency, and the island of Khortytsia, the origin and center of the Zaporozhian Sich, has been restored. The video game Cossacks: European Wars is a Ukrainian-made game series influenced by Cossack culture. Cossacks are also mentioned outside Europe. The Japanese anime The Doraemons, part of the larger Doraemon anime series, has a Cossack character, Dora-nichov, who is from Russia.
The genes were compared to those of thousands of other species and while blocks of three or more genes co-occurred between squid and octopus, the blocks of genes were not found together in any other animals'. Many of the groupings were in the nervous tissue, suggesting the course they adapted their intelligence.
Sources: en.wikipedia.org
A sarcoma is a rare type of cancer that arises from cells of mesenchymal origin, meaning that sarcomas are cancers of connective tissues such as bone, cartilage, muscle, fat, or vascular tissues. Sarcomas are one of five different types of cancer, classified by the cell type from which they originate. While there are five types under this category, sarcomas are most frequently contrasted with carcinomas which are much more common. Sarcomas are quite rare, making up about 1% of all adult cancer diagnoses and 15% of childhood cancer diagnoses. There are many subtypes of sarcoma, which are classified based on the specific tissue and type of cell from which the tumor originates. Common examples of sarcoma include liposarcoma, leiomyosarcoma, and osteosarcoma. Sarcomas are primary connective tissue tumors, meaning that they arise in connective tissues. This is in contrast to secondary (or "metastatic") connective tissue tumors, which occur when a cancer from elsewhere in the body (such as the lungs, breast tissue or prostate) spreads to the connective tissue. The word sarcoma is derived from the Greek σάρκωμα sarkōma 'fleshy excrescence or substance', itself from σάρξ sarx meaning 'flesh'.
Chocolate is a steadily growing, US$50 billion-a-year worldwide business as of 2009. As of 2006, Europe accounted for 45% of the world's chocolate revenue, and the US spent $20 billion in 2013. Big Chocolate is a grouping of major international chocolate companies in Europe and the US. In 2004, Mars and Hershey's alone accounted for two-thirds of US production.
This microbial biomass serves as a reservoir for stored carbon in the soil, effectively sequestering carbon from the atmosphere. Additionally, soil microbes contribute to the formation of stable soil organic matter through the synthesis of extracellular polymers, enzymes, and other biochemical compounds. These substances help bind together soil particles, forming aggregates that protect organic carbon from microbial decomposition and physical erosion. Over time, these aggregates accumulate in the soil, forming soil organic matter, which can persist for centuries to millennia. The sequestration of carbon in soil not only helps mitigate the accumulation of atmospheric CO2 and mitigate climate change but also enhances soil fertility, water retention, and nutrient cycling, thereby supporting plant growth and ecosystem productivity. Consequently, understanding the role of soil microbes in biological carbon fixation is essential for managing soil health, mitigating climate change, and promoting sustainable land management practices. Biological carbon fixation is a fundamental process that sustains life on Earth by regulating atmospheric CO2 levels, supporting the growth of plants and other photosynthetic organisms, and maintaining ecological balance.
== Malignant neoplasm of bone, connective tissue, skin, and breast (170–175) == 170 Malignant neoplasm of bone and articular cartilage 170.9 Malignant neoplasm of bone and articular cartilage, site unspecified Ewing's sarcoma Osteosarcoma Chondrosarcoma 171 Malignant neoplasm of connective and other soft tissue Rhabdomyosarcoma 172 Malignant melanoma of skin 173 Other malignant neoplasm of skin 174 Malignant neoplasm of female breast 175 Malignant neoplasm of male breast
== Importance of substrate-level phosphorylation in anoxia == During anoxia, provision of ATP by substrate-level phosphorylation in the matrix is important not only as a mere means of energy, but also to prevent mitochondria from straining glycolytic ATP reserves by maintaining the adenine nucleotide translocator in ‘forward mode’ carrying ATP towards the cytosol.
Sources: en.wikipedia.org
Plate heat exchangers can cause the desired evaporation at around 45 °C, with short residence times that reduce the risk of thermal damage. This method can produce an extract with 45% solids. Aroma stripping is done prior to concentration, because those compounds run the risk of being lost during evaporation. Spray drying is the final step in creating instant tea, disregarding control points and packaging. It is the preferred method of drying as opposed to freeze-drying because it is cheaper without sacrificing quality. The principle behind spray drying is one similar to that of aroma stripping, where smaller particles have a greater surface to area ratio. By forcing the liquid extract through a nozzle, the solution atomizes, or becomes very fine droplets. These droplets are met with a countercurrent of hot gas, causing them to evaporate and leave only the solids behind. Droplets are generally dried to around 3-5%, as any lower would increase the risk of burning and anything above could possibly reduce shelf life through increased water activity.
In 1913 the structure of sodium chloride was determined by William Henry Bragg and his son William Lawrence Bragg. This revealed that there were six equidistant nearest neighbours for each atom, demonstrating that the constituents were not arranged in molecules or finite aggregates, but instead as a network with long-range crystalline order. Many other inorganic compounds were also found to have similar structural features. These compounds were soon described as being constituted of ions rather than neutral atoms, but proof of this hypothesis was not found until the mid-1920s, when X-ray reflection experiments (which detect the density of electrons), were performed. Principal contributors to the development of a theoretical treatment of ionic crystal structures were Max Born, Fritz Haber, Alfred Landé, Erwin Madelung, Paul Peter Ewald, and Kazimierz Fajans. Born predicted crystal energies based on the assumption of ionic constituents, which showed good correspondence to thermochemical measurements, further supporting the assumption.
== Current status == PeptideAtlas is still maintained and developed at the Institute for Systems Biology in the research lab of Robert Moritz, led by Eric Deutsch, and with significant efforts by Zhi Sun and Dave Campbell.
One of the most notable infrastructure projects at the time was the construction of the North–South Expressway, a motorway running from the Thai border to Singapore. Mahathir oversaw the establishment of the car manufacturer Proton as a joint venture between the Malaysian government and Mitsubishi. By the end of the 1980s, with the support of protective tariffs, Proton became a profitable enterprise and the largest carmaker in Southeast Asia. Under Mahathir's leadership, Malaysia implemented strict drug laws, considering drug-related offences a significant national security concern. In 1983, Mahathir launched an Anti-Drug Campaign, enacted the Drug Dependants (Treatment and Rehabilitation) Act, and established Pusat Serenti as a rehabilitation centre for drug dependents. The Cabinet also approved the formation of the Anti-Drugs Committee (JKAD) and the Anti-Drugs Task Force (PPAD) under the National Security Council to oversee anti-drug efforts. As the campaign was officially launched on 19 February, this date was later designated as National Anti-Drugs Day in Malaysia. These efforts led to a decrease in drug-related cases, from 14,624 in 1983 to 7,596 in 1987. The number of foreign nationals apprehended for drug trafficking also declined, attributed to strict law enforcement and preventive measures. Between 1983 and 1992, more than 120 individuals were executed for drug-related crimes, with an average of 15 to 16 executions per year recorded between 1980 and 1996, including at least 39 executions in 1992.
Crick was aware that research on consciousness was a difficult task, as he wrote to Martynas Yčas in April 1996:I don't think we shall fully understand consciousness by the end of this century, but it's possible we can get a glimpse of the answer by then. Whether it will all fall into place, as molecular biology did, without a vital force, or whether we need a radical formulation, only time will tell. Best wishes, Yours, Francis. P.S. By the way, I've not been knighted.
Sources: en.wikipedia.org
Not necessarily. TB-500 is a commercial label that suppliers apply to synthetic peptides described as thymosin beta-4 or a fragment of it. Published research most often studies the full-length protein, so statements about one do not automatically transfer to the other.
No. No major regulatory authority lists an approved product under this name, and no pharmacopoeial monograph exists for it. Material sold under the label is therefore supplied outside approved pharmaceutical channels, which affects the quality documentation available.
It falls within a prohibited class covering peptide hormones and growth factors, based on presumed effects on tissue repair and blood vessel formation. Anti-doping laboratories have published mass spectrometry methods for detecting thymosin beta-4 related peptides in urine samples.
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.