If you have been reading about thymosin beta-4 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.
Last reviewed on 2026-01-10. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white lyophilized powder | Typical form for short synthetic peptides |
| Solubility class | Freely soluble in water and aqueous buffer | Dissolution aided by gentle mixing, not vigorous shaking |
| Typical storage temperature | −20 °C, desiccated | −80 °C used for long-term holding |
| Common analytical method | Reverse-phase HPLC with UV detection near 214 nm | Identity confirmed separately by mass spectrometry |
| Common synonyms | Thymosin beta-4 fragment; TB4 fragment | Naming varies between suppliers and publications |
The regulatory position is broadly consistent across major jurisdictions: no thymosin beta-4 fragment is an approved medicine, and laboratory material is commonly labelled as not intended for human consumption. Anti-doping rules in sport list thymosin beta-4 and its fragments among prohibited peptide hormones. Because these products travel through research-chemical channels rather than pharmaceutical supply chains, quality varies considerably between vendors. Independent testing of identity, purity and sterility is the only dependable check, and a certificate of analysis describes one batch rather than a supplier's whole catalogue.
Lyophilized peptide powder is normally held desiccated at −20 °C, with −80 °C used for longer storage periods. Allowing a sealed vial to reach room temperature before opening is standard practice, because condensation forming on cold powder introduces moisture. Once dissolved, solutions are typically kept cold and shielded from light. Repeated freeze-thaw cycles are avoided because they encourage aggregation and gradual loss of material. These conventions are general to synthetic peptides rather than unique to any one sequence.
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.
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.
Histology image: 08008loa – Histology Learning System at Boston University Atlas image: eye_1 at the University of Michigan Health System—"Sagittal Section Through the Eyeball" MedlinePlus Encyclopedia: 002295
=== Otologic === By the age of 50, about 50% of adults with OI experience significant hearing loss, much earlier as compared to the general population. Hearing loss in OI may or may not be associated with visible deformities of the ossicles and inner ear. Hearing loss frequently begins during the second, third, and fourth decades of life, and may be conductive, sensorineural, or a combination of both ("mixed"). If hearing loss does not occur by age 50, it is significantly less likely to occur in the years afterwards. Mixed hearing loss is most common among those with OI of all age groups, while conductive hearing loss is most likely to affect older people, with sensorineural hearing loss most likely to affect children. Although relatively rare, OI-related hearing loss can also begin in childhood; in a study of forty-five children aged four to sixteen, two were found to be affected, aged 11 and 15. In a different 2008 study, the hearing of 41 people with OI was checked. The results showed that 88% of those over 20 years of age had some form of hearing loss, while only 38% of those under 20 did. Hearing loss is most common in type I OI; it is less common in types III and IV. Other parts of the inner ear may also be affected by OI. causing balance issues; however, only small studies have found links between vertigo and OI. OI may worsen the outcome of medical treatments which correct hearing loss.
Plutonium-244 is one of several extinct radionuclides that preceded the formation of the Solar System. Its half-life of 81.3 million years ensured its circulation across the Solar System before its extinction, and so evidence of it should also be found throughout the Solar System. Radionuclides such as 244Pu, decay to produce fissiogenic (i.e., arising from fission) xenon isotopes that can then be used to time the events of the early Solar System. In fact, by analyzing data from Earth's mantle which indicates that about 30% of existing fissiogenic xenon is from 244Pu decay, it can be inferred that the Earth formed nearly 50–70 million years after the Solar System formed. Before the analysis of mass spectroscopy data from analyzing samples found in meteorites, it was inferential at best to credit 244Pu as being the nuclide responsible for the fissiogenic xenon found. However, an analysis of a laboratory sample of 244Pu compared with that of fissiogenic xenon gathered from the meteorites Pasamonte and Kapoeta produced matching spectra that immediately left little doubt as to the source of the isotopic xenon anomalies. Spectra data was further acquired for another actinide isotope, 244Cm, but such data proved contradictory and helped erase further doubts that the fission was appropriately attributed to 244Pu. Both the examination of spectra data and study of fission tracks led to several findings of plutonium-244. In Western Australia, the analysis of the mass spectrum of xenon in 4.1–4.2-billion-year-old zircons was met with findings of diverse levels of 244Pu fission.
=== Re-hydration === If a dried product cannot be easily or fully re-hydrated, it is considered to be of lower quality. If the final freeze dried product is porous, complete re-hydration can occur in the food. This signifies greater quality of the product and makes it ideal for ready-to-eat instant meals.
Sources: en.wikipedia.org
In March 1946, a preliminary accord signed between the French and Ho Chi Minh which acknowledged the DRV as a free state within an Indochinese Federation in a "French Union" and allowed a limited number of French troops within its borders to replace the Chinese forces which started gradually returning to China. In further negotiations, the French would seek to ratify Vietnam's position within the Union and the Vietnamese main priorities were preserving their independence and the reunification with the Republic of Cochinchina, which had been created by High Commissioner Georges d'Argenlieu in June. In September, once main negotiations had broken down in Paris over these two key issues, Ho Chi Minh and Marius Moutet, the French Minister of the Colonies, signed a temporary modus vivendi which reaffirmed the March Accord, although no specifications were made on the issue of a Nam Bộ (Cochinchina) reunification referendum and negotiations for a definitive treaty were set to begin no later than January 1947. In the north, an uneasy peace had been maintained during the negotiations, in November however, fighting broke out in Haiphong between the Việt Minh government and the French over a conflict of interest in import duty at the port. On November 23, 1946, the French fleet bombarded the Vietnamese sections of the city killing 6,000 Vietnamese civilians in one afternoon. The Việt Minh quickly agreed to a cease-fire and left the cities. This is known as the Haiphong incident.
=== 4th generation cephalosporins === The fourth generation cephalosporins have greater activity against gram-negative bacteria than the second and third generation. This difference is attributed to them being dipolar ionic zwitterion compounds. The C-7 side chain is similar to third generation cephalosporins usually containing iminomethoxy-aminothiazole group or in the case of cefclidin an aminothiadiazole. Because of the positively charged quaternary nitrogen in the C-3 side chain fourth generation cephalosporins can diffuse through the gram-negative bacterial membrane more readily than earlier cephalosporins. It is thought that the positive charge orients the drug molecule to the entrance of the porin channel.
== Commercial performance == The album debuted at No. 145 on Billboard 200, and No. 5 on Top Dance/Electronic Albums for charts dated November 24, 2012, selling 4,000 copies in the first week. The album reached No. 77 on Billboard 200 the following week, and No. 2 on Dance/Electronic Albums. The album has sold 52,000 copies in the United States as of August 2016.
There are more than 500 public higher education institutions in the Philippines that are controlled and managed by the Commission on Higher Education. Of the 500, 436 are state colleges and universities, 31 local colleges and universities, and a handful of community colleges. In 2008, the Philippine Congress passed Republic Act 9500, declaring the University of the Philippines as the national university to distinguish it from all other state universities and colleges. Other notable public colleges and universities include the Polytechnic University of the Philippines, Technological University of the Philippines, Philippine Normal University, Batangas State University, and Mindanao State University.
By 12 January 2020, five genomes of SARS‑CoV‑2 had been isolated from Wuhan and reported by the Chinese Center for Disease Control and Prevention (CCDC) and other institutions; the number of genomes increased to 42 by 30 January 2020. A phylogenetic analysis of those samples showed they were "highly related with at most seven mutations relative to a common ancestor", implying that the first human infection occurred in November or December 2019. Examination of the topology of the phylogenetic tree at the start of the pandemic also found high similarities between human isolates. As of 21 August 2021, 3,422 SARS‑CoV‑2 genomes, belonging to 19 strains, sampled on all continents except Antarctica were publicly available. On 11 February 2020, the International Committee on Taxonomy of Viruses announced that according to existing rules that compute hierarchical relationships among coronaviruses based on five conserved sequences of nucleic acids, the differences between what was then called 2019-nCoV and the virus from the 2003 SARS outbreak were insufficient to make them separate viral species. Therefore, they identified 2019-nCoV as a virus of severe acute respiratory syndrome–related coronavirus. In July 2020, scientists reported that a more infectious SARS‑CoV‑2 variant with spike protein variant G614 has replaced D614 as the dominant form in the pandemic. Coronavirus genomes and subgenomes encode six open reading frames (ORFs). In October 2020, researchers discovered a possible overlapping gene named ORF3d, in the SARS‑CoV‑2 genome.
Sources: en.wikipedia.org
Flare-ups of autoimmune conditions such as systemic lupus erythematosus and rheumatoid arthritis may also occur during this period. Patients on tumor necrosis factor antagonists Patients with chronic inflammatory conditions (Crohn's disease, ulcerative colitis, sarcoidosis, etc.) are often treated with TNF antagonists, such as infliximab, adalimumab, and etanercept. Tumor necrosis factors are critical in macrophage activation and subsequent granuloma formation. Therefore, TNF antagonists impair the host immune response against infections such as tuberculosis. While the patient is taking TNF antagonists, these infections may remain latent and asymptomatic. However, when these medications are discontinued, there may be an associated pro-inflammatory response causing the infection to be uncovered.
== The conserved gene and its alleles == Thy-1 has been conserved throughout vertebrate evolution and even in some invertebrates, with homologs described in many species like squid, frogs, chickens, mice, rats, dogs, and humans. The Thy-1 gene is located at human chromosome 11q22.3 (mouse chromosome 9qA5.1). In AceView, it covers 6.82 kb, from 119294854 to 119288036 (NCBI 37, August 2010), on the reverse strand. This locus is very close to CD3 & CD56/NCAM genes. Some believe that there may be a functional significance of both this gene and CD3 delta subunit (T3D) mapping to chromosome 11q in man and chromosome 9 in mouse, though there is no homology (in fact this speculation led to its localization in chromosome 11q - the human chromosome region syntenic to mouse chromosome 9 which harbored T3D). In mice, there are two alleles: Thy-1.1 (Thy-1a, CD90.1) and Thy-1.2 (Thy-1b, CD90.2). They differ by only one amino acid at position 108; an arginine in Thy-1.1 and a glutamine in Thy-1.2. Thy-1.2 is expressed by most strains of mice, whereas Thy-1.1 is expressed by others such as AKR/J and PL mouse strains.
=== Documentaries === Hofmann's Potion Archived June 16, 2021, at the Wayback Machine a documentary on the origins of LSD, 2002 Inside LSD National Geographic Channel, 2009 How to Change Your Mind Archived June 16, 2022, at the Wayback Machine Netflix docuseries, 2022
=== Computing, environmental, and interdisciplinary research === The National Science Foundation funded the iPlant Collaborative in 2008 with a $50 million grant. In 2013, iPlant Collaborative received a $50 million renewal grant. Rebranded in late 2015 as "CyVerse", the collaborative cloud-based data management platform is moving beyond life sciences to provide cloud-computing access across all scientific disciplines. In June 2011, the university announced it would assume full ownership of the Biosphere 2 scientific research facility in Oracle, Arizona. Biosphere 2 was constructed by private developers (funded mainly by Texas businessman and philanthropist Ed Bass) with its first closed system experiment commencing in 1991. The university had been the official management partner of the facility for research purposes since 2007.
Sources: en.wikipedia.org
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.
Not necessarily. Some vendors use the name for the full 43-residue protein, while others apply it to a short actin-binding fragment or to a related tetrapeptide. The sequence should be confirmed from documentation rather than assumed from the label.
No thymosin beta-4 fragment holds marketing approval as a medicine in major jurisdictions. Material offered for sale is typically labelled for laboratory research only.
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.