The short version of TB-500 fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-10-05 and is reviewed periodically as new material appears.
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.
Thymosin beta-4 itself is a small, widely expressed protein that sequesters monomeric actin and participates in cell migration, angiogenesis, and tissue repair. Researchers have examined the shortened fragment as a possible mimic of some of these activities, reasoning that the actin-binding motif lies within the first few residues. Binding to monomeric actin has been observed in cell-free systems. Whether the fragment reproduces the broader effects of the full protein in living tissue remains an open question, and findings from animal models are frequently cited without a clear bridge to human physiology.
TB-500 is a short synthetic peptide sold under a trade name rather than a systematic chemical name. Suppliers usually describe it as a fragment of thymosin beta-4 and ship it as a lyophilised powder intended for laboratory use. Because the label is commercial, the exact sequence attributed to it is not fully consistent across catalogues, and some listings present a seven-residue peptide while others describe related fragments of similar length. It is not an approved medicine in any major jurisdiction, and it is handled as a research chemical.
Thymosin beta-4 itself is a natural peptide of 43 residues found in many cell types and body fluids. Its best-characterised function is binding and sequestering actin monomers, which influences cytoskeletal dynamics. The sequence most often associated with TB-500, LKKTETQ, corresponds to part of that actin-binding region. A different fragment, Ac-SDKP, is also derived from the same parent peptide and is studied in its own right, which is one reason discussions of thymosin fragments can become confusing. The two are structurally distinct and are not interchangeable.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | N-terminal fragment of thymosin beta-4 |
| Residue count | Seven | Sequence LKKTETQ |
| Approximate mass | 889 Da | Acetylated seven-residue peptide |
| Common synonyms | TB4 fragment, TB500 | Not identical to full-length TB4 |
| Reported activity | Actin binding | Observed mainly in cell-free systems |
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.
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.
Canada's achievements in science and technology include the creation of the modern alkaline battery, the discovery of insulin, the development of the polio vaccine, and discoveries about the interior structure of the atomic nucleus. Other major Canadian scientific contributions include the artificial cardiac pacemaker, mapping the visual cortex, the development of the electron microscope, plate tectonics, deep learning, multi-touch technology, and the identification of the first black hole, Cygnus X-1. Canada has a long history of discovery in genetics, which include stem cells, site-directed mutagenesis, T-cell receptor, and the identification of the genes that cause Fanconi anemia, cystic fibrosis, and early-onset Alzheimer's disease, among numerous other diseases. The Canadian Space Agency runs an active space program focused on deep-space, planetary, and aviation research, along with rockets and satellites. Canada launched its first satellite, Alouette 1, in 1962. It contributes to the International Space Station and is known for its robotic tools, such as multiple Canadarms. Canada has initiated many long-term projects, including the Radarsat satellite series and the Black Brant rocket series.
APCs naturally have a role in fighting tumors, via stimulation of B and cytotoxic T cells to respectively produce antibodies against tumor-related antigen and kill malignant cells. Dendritic cells, presenting tumor-specific antigen to T cells, are key to this process. Cancer therapies have included treating the patient with increased numbers of dendritic cells or cancer-specific T cells. However, newer therapies have turned to genetically engineered artificial antigen-presenting cells designed to prime the immune system to attack malignant cells. Some artificial APCs are derived from human cells; others are acellular, containing MHC proteins, co-stimulatory molecules and the necessary peptides. The APC activator IMP321 is being tested in clinical trials to accelerate the immune reaction to eliminate metastatic breast cancer or melanoma. Antigen: protease degradation on YouTube – PMAP animation Antigen-Presenting+Cells at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
Acids play important roles in the human body. The hydrochloric acid present in the stomach aids digestion by breaking down large and complex food molecules. Amino acids are required for synthesis of proteins required for growth and repair of body tissues. Fatty acids are also required for growth and repair of body tissues. Nucleic acids are important for the manufacturing of DNA and RNA and transmitting of traits to offspring through genes. Carbonic acid is important for maintenance of pH equilibrium in the body. Human bodies contain a variety of organic and inorganic compounds, among those dicarboxylic acids play an essential role in many biological behaviors. Many of those acids are amino acids, which mainly serve as materials for the synthesis of proteins. Other weak acids serve as buffers with their conjugate bases to keep the body's pH from undergoing large scale changes that would be harmful to cells. The rest of the dicarboxylic acids also participate in the synthesis of various biologically important compounds in human bodies.
Sources: en.wikipedia.org
Eq. 2 where: 3 is the number of fatty acids residues per triglyceride 1000 is the conversion factor for milligrams to grams 56.1 is the molar mass of KOH. 38.049 is the molecular mass of glycerol backbone For instance, triolein, a triglyceride occurring in many fats and oils, has three oleic acid residues esterified to a molecule of glycerol with a total MW of 885.4 (g / mol). Therefore, its SV equals 190 mg KOH / g sample. In comparison, trilaurin with three shorter fatty acid residues (lauric acid) has a MW of 639 and an SV of 263. As it can be seen from equation (2), the SV of a given fat is inversely proportional to its molecular weight. Actually, as fats and oils contain a mix of different triglycerides species, the average MW can be calculated according to the following relation:
The medical historian Christoph Gradmann has reconstructed Koch's beliefs regarding the function of tuberculin: the medicine did not kill the bacteria but rather initiated a necrosis of the tubercular tissue, thus "starving" the tuberculosis pathogen. This idea was then outside customary medical theories, as it remains today. The tuberculin scandal was understood as a cautionary tale in regards to testing medicine. Emil von Behring's introduction of his diphtheria antitoxin in 1893 had been preceded by lengthy clinical testing, and the serum was only slowly introduced into practical use, accompanied by a critical discussion among qualified experts. Paul Ehrlich also proceeded with conspicuous caution in 1909 when introducing the first synthetically produced chemotherapeutic agent, Salvarsan, as a cure for an infectious disease, syphilis.
Protomastigineae, in which absorption of food-particles in holozoic nutrition occurs at a localised point of the cell surface, often at a cytostome, although many groups were merely saprophytes; it included the majority of colourless flagellates, and even many "apochlorotic" algae; Pantostomatineae (or Rhizomastigineae), in which the absorption takes place at any point on the cell surface; roughly corresponds to "amoeboflagellates"; Distomatineae, a group of binucleate "double individuals" with symmetrically distributed flagella and, in many species, two symmetrical mouths; roughly corresponds to current Diplomonadida. Presently, these groups are known to be highly polyphyletic. In modern classifications of the protists, the principal flagellated taxa are placed in the following eukaryote groups, which include also non-flagellated forms (where "A", "F", "P" and "S" stands for autotrophic, free-living heterotrophic, parasitic and symbiotic, respectively):
Sources: en.wikipedia.org
Smith was hired to become the defensive quality control coach for the Tennessee Titans in 2011 under new head coach Mike Munchak. Smith then became the offensive quality coach the following season. In 2013, Smith was promoted to the assistant offensive line and assistant tight ends coach. Munchak was fired after the 2013 season and new head coach Ken Whisenhunt retained Smith as the assistant tight ends coach. Midway through the 2015 season, Whisenhunt was fired and replaced by tight ends coach Mike Mularkey. Mularkey was kept as head coach for the 2016 season and Smith was promoted to the new tight ends coach. When Mularkey was fired after the 2017 season, new head coach Mike Vrabel kept Smith as the tight ends coach for 2018. On January 21, 2019, Smith was promoted to offensive coordinator, replacing Matt LaFleur, who departed to become head coach of the Green Bay Packers two weeks prior. In his first year as offensive coordinator, Smith oversaw the highest-scoring Titans team in 16 years, with Derrick Henry, Ryan Tannehill, and Jonnu Smith having career years. Smith was praised for his play-calling in the Titans' 28–12 road victory over the top-seeded Baltimore Ravens in the AFC Divisional Round. In 2020, the Titans ranked fourth in scoring and second in total yards.
Encapsulin shells compromise icosahedral complexes (12 vertices, 20 faces, 30 edges) formed as a result of self-assembly of protomers. These encapsulin shells have diameters between 24 and 42 nm and are defined by the HK97-fold of their shell protein. The HK97-fold protomer has a roughly triangular shape and consists of three conserved domains: the axial domain, the peripheral domain, and the extended loop. The size and symmetry of the capsid are defined by a triangulation number (T), which determines the number of subunits in the assembly. For example: T = 1 encapsulins (Thermotoga martima) consist of 60 protomers. T = 3 encapsulins (Pyrococcus furiosus) consist of 180 protomers. T = 4 encapsulins (Quasibacillus thermotolerans) consist of 240 protomers.
GLD-2 primarily stabilizes mRNAs that are translationally repressed as well as it strongly promotes bulk polyadenylation. Surprisingly, those functions seem to have little impact on dynamizing efficient target mRNA translation, as it is an efficient Poly(A) Polymerase which helps developing polyadenylation activity. This activity is stimulated by its interaction with a putative RNA-binding protein: GLD-3. It is proposed by some studies that GLD-3 stimulates GLD-2 by recruiting it to the RNA. If so, then bringing GLD-2 to the RNA by other means also should stimulate its activity. GLD-2, as a poly(A) polymerase (PAP) acts incorporating ATP at the 3' end of mRNAs in a template-independent manner. ==== Enzymatic activity: Polynucleotide adenylyltransferase activity ==== It has been discovered that this protein has a catalytic activity, in other words, it has the ability to increase the speed of chemical reactions which would not occur so fast. It is known to catalysis the following reaction (which requires the following cofactor: Mg(2+)): ATP + RNA(n) ⇄ diphosphate + RNA(n+1)
Sources: en.wikipedia.org
No. Thymosin beta-4 is a 43-residue protein, while TB-500 refers to a seven-residue fragment corresponding to its N-terminal region. The two names are often used loosely in commercial and community writing, which obscures the difference in size, sequence, and likely behavior.
The fragment contains an actin-binding motif, and cell-free experiments show that it can interact with monomeric actin. That observation is the basis for interest in cell migration and repair processes. Effects reported in animals are not established for humans.
Purity is usually stated by the supplier rather than fixed by a pharmacopoeial monograph, and typical listings report a percentage from reverse-phase HPLC. Independent verification is uncommon. Because no single accepted specification exists, comparisons between lots and between suppliers are difficult.
No. Thymosin beta-4 is a 43-residue natural peptide, while TB-500 is a commercial label applied to a short synthetic fragment of it. The two differ in length, sequence coverage and how they are handled in the laboratory.