The short version of actin binding fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-07-07. Anything still debated is marked as such rather than presented as settled.
Lyophilised material is stable for extended periods when kept dry and cold, and suppliers typically recommend storage well below freezing. Once dissolved, the peptide is handled at refrigeration temperatures and used within a short period, because peptide bonds and the acetylated terminus can be affected by repeated freeze-thaw cycles, proteases, or extreme pH. Bacteriostatic water and saline are both described as solvents, although preservatives can interfere with some analytical workflows. Reconstituted solutions are inspected for particulates before use.
Sports authorities classify the peptide as a prohibited substance, and it appears on the World Anti-Doping Agency list under peptide hormones, growth factors, and related substances. Racing jurisdictions for horses and dogs have issued separate restrictions, and several national bodies treat it as a controlled or prescription-only item. As a research chemical it is sold without a therapeutic indication, and labels usually state that the product is not for human or veterinary use. Regulatory treatment therefore varies by country.
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.
| Property | Value | Notes |
|---|---|---|
| Analytical method | LC-MS/MS | Preferred confirmatory technique |
| Appearance | White to off-white powder | Lyophilised form |
| Solubility | Freely soluble in water | Also described in saline |
| Storage temperature | Below -20 °C for powder | Short-term refrigeration for solutions |
| Regulatory status | Prohibited in sport | Listed under peptide hormones |
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.
TB-500 is a synthetic seven-amino-acid peptide with the sequence LKKTETQ, corresponding to residues 17 through 23 of the protein thymosin beta-4. The N-terminus is typically acetylated in the described form, giving a monoisotopic mass near 888.5 Da and an average mass of about 889 Da. The designation TB-500 is a catalogue label rather than a formal chemical name, and the same sequence appears in the literature under several alternative abbreviations. It is handled as a research reagent rather than a pharmaceutical product.
Thymosin beta-4 is a 43-residue actin-binding protein found in most mammalian cell types, where it participates in cytoskeletal regulation and cell migration. TB-500 represents only a short fragment of that protein and does not include the remaining residues. Whether the isolated fragment reproduces the full range of activities reported for the intact protein remains an open question. Researchers commonly treat the two as related but distinct entities when comparing results.
The designation TB-500 circulates in laboratory and catalog contexts without a single agreed definition. Most product listings apply it to an N-terminally acetylated seven-residue fragment of thymosin beta-4, while other listings attach the same label to the full 43-residue protein. Because the term is commercial rather than systematic, two entries bearing identical names may describe different molecules. Any documentation should therefore state which sequence a given sample is claimed to contain.
The fragment most often associated with the name carries the sequence Ac-LKKTETQ, matching residues 17 through 23 of thymosin beta-4. That region holds the actin-binding motif responsible for much of the parent protein's biochemical activity. Apart from N-terminal acetylation the peptide is unmodified and contains no disulfide bonds, so it shows little ordered secondary structure in solution. Full-length thymosin beta-4 is instead a 43-residue polypeptide of roughly 4.9 kDa found widely across mammalian cell types.
Thionoesters are isomeric with thioesters. In a thionoester, sulfur replaces the carbonyl oxygen in an ester. Methyl thionobenzoate is C6H5C(S)OCH3. Such compounds are typically prepared by the reaction of the thioacyl chloride with an alcohol.
==== United Kingdom ==== Oxycodone is a Class A drug under the Misuse of Drugs Act 1971. For Class A drugs, which are "considered to be the most likely to cause harm", possession without a prescription is punishable by up to seven years in prison, an unlimited fine, or both. Dealing of the drug illegally is punishable by up to life imprisonment, an unlimited fine, or both. Oxycodone is a Schedule 2 drug under the Misuse of Drugs Regulations 2001 which "provide certain exemptions from the provisions of the Misuse of Drugs Act 1971".
In March 2022, the European Medicines Agency's Committee for Medicinal Products for Human Use recommended Polatuzumab vedotin, in combination with R-CHP or R-CHOP, as a primary treatment. A systematic meta-analysis of randomized trials and real-world evidence confirmed results of Pola-R-CHP. In February 2023, polatuzumab vedotin was recommended by the National Institute for Health and Care Excellence (NICE) to be used in combination with rituximab, cyclophosphamide, doxorubicin and prednisolone (R-CHP) for untreated diffuse large B-cell lymphoma (DLBCL). In April 2023, the FDA approved polatuzumab vedotin in combination with rituximab, cyclophosphamide, doxorubicin and prednisone as first-line therapy for people with previously untreated diffuse large B-cell lymphoma, not otherwise specified or high-grade B-cell lymphoma who have an International Prognostic Index score of two or greater.
Sources: en.wikipedia.org
=== 2007–2013: Repatriation === On June 29, 2009, Tim Hortons Inc. announced that, pending shareholder approval, the chain's operations would be reorganized under a new publicly traded company, also named "Tim Hortons Incorporated", incorporated under the Canada Business Corporations Act. The change was being made primarily for tax purposes. On September 28, 2009, Tim Hortons Inc. announced it had completed the reorganization of its corporate structure to become a Canadian public company. In November 2010, Tim Hortons extended Interac debit payment system acceptance to most of its stores. The company previously began accepting Interac in its stores in Western Canada in 2003 and, later, MasterCard and MasterCard PayPass across most of its stores in 2007. The company often indicated the delay of broader or wider electronic payment acceptance was to "ensure speed of service." In 2012, Tim Hortons began accepting Visa cards, and in 2013, began accepting American Express cards. In late 2013, Tim Hortons had "4,350 cafes across the world, out of which 3,500 are in Canada, 817 in the U.S. and 33 in the GCC. The Toronto Stock Exchange listed company recorded revenues of $794 million and net profit of $111 million in the September quarter."
Trump issued NSPM-7 (National Security Presidential Memorandum-7) on September 25, 2025, directing a government-wide strategy to counter what it characterizes as organized domestic terrorism and political violence. The memorandum cites "common threads" such as "anti-Americanism", "anti-capitalism", "anti-Christianity", support for 'overthrowing' the United States Government, and extremism related to migration, race, and gender. It assigns the National Joint Terrorism Task Force to lead investigations, directs the United States Department of Justice to prioritize prosecutions and consider domestic terrorist organization designations, and instructs the Department of the Treasury and the Internal Revenue Service to disrupt financial networks, while noting that the directive creates no enforceable rights. Thirty-one members of Congress later warned in a letter that NSPM-7 raises constitutional and civil-liberties concerns if used to target political dissent or ideological speech.
The environment of the migrating cell can affect its speed, persistence and direction of migration by stimulating it. The extracellular matrix (ECM) provides not only the structural and biochemical support, but also plays a major role in regulating cell behavior. Different ECM proteins (such as collagen, elastin, fibronectin, laminin, and others) allow cells to adhere and migrate, while forming focal adhesions in the front and disassembling them in the back. Using these adhesion sites, cells also sense the mechanical properties of the ECM. Cells can be guided by a gradient of those proteins (haptotaxis) or a gradient of soluble substrates in the liquid phase surrounding the cell (chemotaxis). Cells sense the substrate through their receptors and migrate toward the concentration (or the opposite direction). Another form of stimulation can be rigidity gradients of the ECM (durotaxis).
Sources: en.wikipedia.org
=== Canada === Although White Castle has never opened any restaurants in Canada, Canadians have been able to purchase White Castle hamburgers from the frozen foods section in select Canadian grocery and convenience stores since 2015 and more recently at Walmart. For the production of the 2004 film Harold & Kumar Go to White Castle, a full-size outlet was built in Caledon, Ontario, but it was never commissioned or opened to the local public. The store later reopened as Yuppie's Burger, only to go quickly bankrupt. The site was subsequently converted to an Ultramar gas station.
==== United Kingdom ==== All drugs in the 2C family are Class A under the Misuse of Drugs Act which means they are illegal to produce, supply or possess. Possession carries a maximum sentence of seven years imprisonment while supply is punishable by life imprisonment and an unlimited fine.
Bont possesses no superhuman abilities, but he occasionally used Mutant Growth Hormone, a substance that temporarily enhanced his speed and strength and caused his eyes to emit a green glow. Sigourney Weaver portrays a female version of Alexander Bont, primarily known as Alexandra, in The Defenders. This version is the leader of the Hand. Alexandra is described as an "adversary" rather than a villain and was intended to be portrayed sympathically as a supporting character in Elektra Natchios' story. Alexandra is one of the five "fingers" of the Hand, who all gained immortality using the healing powers of qi. Following the death of Elektra, Alexandra resurrects her to create the ancient weapon Black Sky, which is prophesied to destroy all enemies of the Hand. Alexandra intends to use Elektra to steal the Iron Fist from Danny Rand. However, Elektra regains her memories of her previous life and kills Alexandra, claiming leadership of the Hand. http://www.marvunapp.com/Appendix4/bontalexander.htm http://www.imdb.com/title/tt1784594/
Sources: en.wikipedia.org
The most common approach is liquid chromatography with tandem mass spectrometry after extraction from blood or urine. Immunoassays exist but are generally treated as screening tools because of cross-reactivity.
Dry lyophilised powder is normally kept frozen and protected from moisture and light. Dissolved material is handled cold and used promptly to limit degradation.
It is not licensed as a medicine in major markets and is distributed as a research chemical. Sports organisations prohibit its use, and some countries restrict import and supply.
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.