TB-500 raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
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 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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H68N10O14 | Calculated for the acetylated heptapeptide |
| Molecular weight | ~889 Da | Monoisotopic mass approximately 889.0 Da |
| Amino acid sequence | Ac-LKKTETQ | N-terminal acetylated seven-residue peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Water-soluble | Peptides of this size generally dissolve in aqueous media |
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.
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.
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.
"Osteogenesis Imperfecta Overview". NIH Osteoporosis and Related Bone Diseases. National Resource Center, National Institutes of Health, U.S. Department of Health and Human Services. 8 May 2023. Archived from the original on 4 October 2017.
== Medical uses == Remifentanil is used as an opioid analgesic that has a rapid onset and rapid recovery time. It has been used effectively during craniotomies, spinal surgery, cardiac surgery, and gastric bypass surgery. While opioids function similarly, with respect to analgesia, the pharmacokinetics of remifentanil allows for quicker post-operative recovery. Remifentanil can be administered as part of an anesthesia technique called TIVA (total intravenous anesthesia) using computer controlled infusion pumps in a process called TCI (target controlled infusion). A target plasma concentration is entered as ng/mL into the pump, which calculates its infusion rate according to patient factors like age and weight. Induction levels of 40 ng/mL are commonly used, but it generally varies between 3–8 ng/mL. For certain surgical procedures that produce particularly strong stimuli a level of up to 15 ng/mL might be needed. The relatively short context-sensitive half-life of remifentanil allows the desired blood plasma level to be achieved quickly, and also for the same reason, recovery occurs quickly. This allows remifentanil to be used in unique circumstances such as cesarean section. Remifentanil's short context-sensitive half-life makes it ideal for intense pain of short duration. As such, it has been used for analgesia in labor successfully; however, it is not as effective as epidural analgesia. In combination with propofol, remifentanil is used for anesthesia of patients undergoing electroconvulsive therapy.
Big Drawer II (ビグドローワー2, Bigu Dorōwā Tsū): A chest-of-drawers-themed Super Kaijuki that he uses in his smear campaign against the Dekarangers before it is destroyed by Deka Base Robo. Abtrex (アブトレックス, Abutorekkusu): Abrella's personal Kaijuki that can assume the Abtrailer (アブトレーラー, Abutorērā) drill-vehicle mode. He tasks the Alienizer Angorl with using it to attack the Deka Base and damage Dekaranger Robo before the Kaijuki is destroyed by Deka Bike Robo and the Deka Wing Cannon. During the events of the crossover film Mahō Sentai Magiranger vs. Dekaranger, Agent X pilots the succeeding model, Abotrex (アボトレックス, Abotorekkusu), before it is blasted into space by Magi Legend and the Deka Wing Cannon and destroyed by Magi King, Dekaranger Robo, Travelion, and Deka Bike Robo. Abrella is voiced by Ryūsei Nakao (中尾 隆聖, Nakao Ryūsei).
Sources: en.wikipedia.org
SWAPO's MPLA allies, with the backing of the Cuban military, were often unable to protect them. These raids demonstrated the SADF's efficiency in combating rural insurgency. Major guerrilla camps were always chief targets, whether on foreign or domestic soil. Consequently, establishing good intelligence and effective assault strategy were commonly reflected in tactical priorities. The SADF's success eventually compelled SWAPO to withdraw over 320 kilometres (199 mi) from the Namibian border, forcing their insurgents to travel great distances across arid bush in order to reach their targets. Many could no longer carry heavy weapons on these treks, occasionally abandoning them as they marched south. Moreover, serious SWAPO losses were already having a negative effect on morale. ANC operations fared little better. Most high-profile terrorist attacks were foiled or offered negative publicity from a normally sympathetic international stage. While it was clear that popular support was growing and guerrilla skills were being improved upon, affrays on South Africa itself did not seriously disrupt the economy or impact the country's superior military and industrial status. By the fall of apartheid in 1991, the SADF was an uneven reflection of both the strengths and weaknesses of South Africa's white society at large. It employed many personnel with developed technical skills; thus, the military could more easily maintain and operate sophisticated hardware than black African forces drawn from underdeveloped regions.
The course of the disease varies greatly. Some people have mild short-term symptoms, but in most the disease is progressive for life. Around 25% will have subcutaneous nodules (known as rheumatoid nodules); this is associated with a poor prognosis.
Intracellular signal transduction is primarily mediated by the reversible phosphorylation of various signalling molecules by enzymes dubbed kinases. Kinases transfer phosphate groups from ATP to specific serine, threonine or tyrosine residues of target molecules. The resultant phosphorylated protein may have altered activity level, subcellular localization or tertiary structure. Phosphoproteomic analyses are ideal for the study of the dynamics of signalling networks. In one study design, cells are exposed to SILAC labelling and then stimulated by a specific growth factor. The cells are collected at various timepoints, and the lysates are combined for analysis by tandem MS. This allows experimenters to track the phosphorylation state of many phosphoproteins in the cell over time. The ability to measure the global phosphorylation state of many proteins at various time points makes this approach much more powerful than traditional biochemical methods for analyzing signalling network behavior. One study was able to simultaneously measure the fold-change in phosphorylation state of 127 proteins between unstimulated and EphrinB1-stimulated cells. Of these 127 proteins, 40 showed increased phosphorylation with stimulation by EphrinB1. The researchers were able to use this information in combination with previously published data to construct a signal transduction network for the proteins downstream of the EphB2 receptor.
=== Canine osteoarthritis === LTCI increases the immune response to foreign antigens and dampens the immune-mediated response to self-antigens by increasing the number of precursors of a regulatory T-Cell population. In a double-blind placebo-controlled study, 11 of the 12 LTCI-treated canines had a 40 percent increase in function while the placebo group had a 17 percent decrease in function. Following the study, LTCI was approved by the USDA to treat osteoarthritis in dogs in 2016.
Sources: en.wikipedia.org
The first five stations, covering the approaches to London, were installed by 1937 and began full-time operation in 1938. Over the next two years, additional stations were built while the problem of disseminating the information to the fighter aircraft led to the first integrated ground-controlled interception network, the Dowding system. By the time the war started, most of the east and south coasts had radar coverage. Chain Home proved important during the Battle of Britain in 1940. CH systems could detect enemy aircraft while they were forming over France, giving RAF commanders ample time to marshal their aircraft in the path of the raid. This had the effect of multiplying the effectiveness of the RAF to the point that it was as if they had three times as many fighters, allowing them to defeat frequently larger German forces. The Chain Home network was continually expanded, with over 40 stations operational by the war's end, including mobile versions for use overseas. Late in the war, when the threat of Luftwaffe bombing had ended, the CH systems were used to detect V2 missile launches. UK radar systems were wound down after the war but the start of the Cold War led to the Chain Home radars being pressed into service in the new ROTOR system until replaced by newer systems in the 1950s. Only a few of the original sites remain.
=== Colour variations === Breeders have created different colour variations, principally varying proportions of red and blue colouring. The powder blue variant is almost entirely bright blue. The reddest variety (flame red) can be confused with the red variety of honey gouramis (Trichogaster chuna). One of the most common color morphs is the turquoise / neon blue, featuring stripes of dark red and bright blue.
Nickel(II) forms compounds with all common anions, including sulfide, sulfate, carbonate, hydroxide, carboxylates, and halides. Nickel(II) sulfate is produced in large amounts by dissolving nickel metal or oxides in sulfuric acid, forming both a hexa- and heptahydrate useful for electroplating nickel. Common salts of nickel, such as chloride, nitrate, and sulfate, dissolve in water to give green solutions of the metal aquo complex [Ni(H2O)6]2+. The four halides form nickel compounds, which are solids with molecules with octahedral Ni centres. Nickel(II) chloride is most common, and its behavior is illustrative of the other halides. Nickel(II) chloride is made by dissolving nickel or its oxide in hydrochloric acid. It is usually found as the green hexahydrate, whose formula is usually written NiCl2·6H2O. When dissolved in water, this salt forms the metal aquo complex [Ni(H2O)6]2+. Dehydration of NiCl2·6H2O gives yellow anhydrous NiCl2. Some tetracoordinate nickel(II) complexes, e.g. bis(triphenylphosphine)nickel chloride, exist both in tetrahedral and square planar geometries. The tetrahedral complexes are paramagnetic; the square planar complexes are diamagnetic. In having properties of magnetic equilibrium and formation of octahedral complexes, they contrast with the divalent complexes of the heavier group 10 metals, palladium(II) and platinum(II), which form only square-planar geometry. Nickelocene has an electron count of 20. Many chemical reactions of nickelocene tend to yield 18-electron products.
Sources: en.wikipedia.org
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.
No. Thymosin beta-4 is a 43-amino-acid protein, while TB-500 represents only a short N-terminal segment. The two should not be treated as interchangeable in experimental design.
It is often called a thymosin beta-4 fragment, Tβ4 fragment, or Ac-LKKTETQ. The name TB-500 is mainly a commercial or catalog label rather than a formal chemical name.
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.