The short version of thymosin beta-4 fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-02-20 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.
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.
| 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 |
Interest in the fragment grew during the 1990s and 2000s, when it moved from laboratory work into sports and supplement markets. Anti-doping bodies added thymosin beta-4 fragments to prohibited lists, and a small number of adverse analytical findings have been reported in competition testing. Published controlled human trials remain scarce. Most mechanistic evidence comes from cell culture and animal models, and those studies examine endpoints such as cell migration, wound closure and inflammation markers. That evidence supports research interest but does not establish clinical benefit, and broad regenerative claims should be read as unverified.
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.
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.
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.
b: black – The black mutation was discovered in 1910 by Thomas Hunt Morgan. The black mutation results in a darker colored body, wings, veins, and segments of the fruit fly's leg. This occurs due to the fly's inability to create beta-alanine, a beta amino acid. The phenotypic expression of this mutation varies based on the genotype of the individual; for example, whether the specimen is homozygotic or heterozygotic results in a darker or less dark appearance. This genetic mutation is x-linked recessive. bw: brown – The brown eye mutation results from inability to produce or synthesize pteridine (red) pigments, due to a point mutation on chromosome II. m: miniature – One of the first records of the miniature mutation of wings was also made by Thomas Hunt Morgan in 1911. He described the wings as having a similar shape as the wild-type phenotype. However, their miniature designation refers to the lengths of their wings, which do not stretch beyond their body and, thus, are notably shorter than the wild-type length. He also noted its inheritance is connected to the sex of the fly and could be paired with the inheritance of other sex-determined traits such as white eyes. The wings may also demonstrate other characteristics deviant from the wild-type wing, such as a duller and cloudier color. Miniature wings are 1.5 times shorter than wild-type but are believed to have the same number of cells. This is due to the lack of complete flattening by these cells, making the overall structure of the wing seem shorter in comparison.
Cocaine is known to suppress hunger and appetite by increasing co-localization of sigma σ1R receptors and ghrelin GHS-R1a cell surface receptors, thereby increasing ghrelin-mediated signaling of satiety and possibly via other effects on appetitive hormones. Cocaine effects, further, are shown to be potentiated for the user when used in conjunction with new surroundings and stimuli, and otherwise novel environs.
University of Liège professors Joseph Martial and André Renard established Eurogentec in 1985. Prior to establishing Eurogentec, Martial studied genetic engineering at University of California, San Francisco. Martial then returned to Europe and helped commercialize certain genetic engineering research products of the University of Liège. The company began working out of the university's laboratories and focused on developing a genetically-engineered vaccine to enhance fish breeding. Initially, the company focused on the development of a genetic engineering-based vaccine tailored for enhancing fish breeding. In 1987, Eurogentec started to distribute Oligonucleotides for Research laboratories. The company's first years were difficult but in the very early 1990s, Jean-Pierre Delwart, economist from Brussels University, boarded the ship and put Eurogentec in a favorable current.
==== Adolescents ==== Health Canada has not developed advice for adolescents because of insufficient data. However, they suggest that daily caffeine intake for this age group be no more than 2.5 mg/kg body weight. This is because the maximum adult caffeine dose may not be appropriate for light-weight adolescents or for younger adolescents who are still growing. The daily dose of 2.5 mg/kg body weight would not cause adverse health effects in the majority of adolescent caffeine consumers. This is a conservative suggestion since older and heavier-weight adolescents may be able to consume adult doses of caffeine without experiencing adverse effects.
Sources: en.wikipedia.org
β-Hydroxy β-methylbutyric acid is a monocarboxylic β-hydroxy acid and natural product with the molecular formula C5H10O3. At room temperature, pure β-hydroxy β-methylbutyric acid occurs as a transparent, colorless to light yellow liquid which is soluble in water. β-Hydroxy β-methylbutyric acid is a weak acid with a pKa of 4.4. Its refractive index (
The lack of a separate chromosome 17 probe on the same section is an issue with regards to acceptance of CISH. As of June 2011 Roche has obtained FDA approval for the INFORM HER2 Dual ISH DNA Probe cocktail developed by Ventana Medical Systems. The DDISH (Dual-chromagen/Dual-hapten In-situ hybridization) cocktail uses both HER2 and Chromosome 17 hybridization probes for chromagenic visualization on the same tissue section. The detection can be achieved by using a combination of ultraView SISH(silver in-situ hybridization) and ultraView Red ISH for deposition of distinct chromgenic precipitates at the site of DNP or DIG labeled probes.
==== Reactions of cysteines ==== Because free cysteine rarely occurs on protein surface, it is an excellent choice for chemoselective modification. Under basic condition, the cysteine residues will be deprotonated to generate a thiolate nucleophile, which will react with soft electrophiles, such as maleimides and iodoacetamides (shown in the first two reactions in Figure 2 below). As a result, a carbon-sulfur bond is formed. Another modification of cysteine residues involves the formation of disulfide bond (shown in the third reaction in Figure 2). The reduced cysteine residues react with exogenous disulfides, generating new a disulfide bond on the protein. An excess of disulfides is often used to drive the reaction, such as 2-thiopyridone and 3-carboxy-4-nitrothiophenol. Electron-deficient alkynes were demonstrated to selectively react with cysteine residues of proteins in the presence of other nucleophilic amino acid residues. Depending on the alkyne substitution, these reactions can produce either cleavable (when alkynone derivatives are used), or hydrolytically stable bioconjugates (when 3-arylpropiolonitriles are used; the last reaction below in Figure 2).
However, most contemporary accounts agree that the ANC's presence in South African townships during the mid-1980s was sparse and was vastly insufficient to instigate or direct events. Thula Simpson, a historian of the ANC, says that the ANC was largely a "spectator" in the first year of the uprising, though an interested spectator. Mac Maharaj, a senior ANC official, later said that the Vaal uprising had provided a lesson for the ANC precisely because it "took place in a power vacuum. We were not ready or able to exploit fully the potential unleashed by these uprisings." Some historians argue that the ANC did not accelerate its "ungovernability" strategy until 1985, by which time the strategy was little more than an attempt to "place the ANC at the head of an [already] unfolding social revolution". However, the ANC was not so far removed as to be without influence. At least two founding members of the VCA were members of an underground ANC cell, and some militant youth cells received a degree of training from the ANC's armed wing, MK, or from MK alumni, though this rarely amounted to the full military training that recruits received in MK camps abroad. From 1985, MK cadres began to bring a small number of weapons, such as rifles and hand grenades, to the Vaal area. More significantly, many township activists supported and identified with the ANC. This was particularly the case with militant youths, who, for example, appropriated the symbols of MK's guerrilla war, and who in some cases viewed their local organisations as unofficial cells of MK.
=== 2025 parliamentary and regional elections === On 25 May 2025, Venezuela held elections for all 285 seats in the National Assembly, as well as most state governorships and regional legislatures. The ruling Great Patriotic Pole alliance led by the PSUV won nearly 83% of the vote for the Assembly and 23 of 24 state governorships, amid turnout of about 43% and a divided opposition in which some factions called for a boycott. Under the Constitution, deputies serve five-year terms, which implies that the following parliamentary election is due in 2030 unless early elections are called.
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.
TB-500 is a trade-style label for a synthetic peptide connected to thymosin beta-4. It is sold mainly through research-chemical channels and is not a single chemically defined product across suppliers.