Everything below concerns Thymosin beta-4. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-09-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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 |
|---|---|---|
| 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 |
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.
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.
Published work involving this sequence spans actin-binding assays, cell-migration studies, wound-healing models, and cardiovascular or musculoskeletal experiments. Much of the biological rationale derives from in vitro systems and animal models, and the number of controlled human studies is small. Reported outcomes vary across preparations, doses, and routes, which complicates comparison between studies. Reviews generally describe the evidence base as preliminary rather than settled. Mechanistic explanations are often proposed by analogy to the parent protein rather than demonstrated directly.
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.
The compound circulates in the literature as a research reagent rather than an approved therapeutic. Regulatory agencies in several countries have not authorized it for medical use, and sporting bodies list related thymosin beta-4 peptides among prohibited substances. Suppliers typically market it with a purity figure and a certificate of analysis, while peer-reviewed clinical reports remain sparse. Discussions therefore often separate laboratory findings from anecdotal reports, and reviewers tend to note the small size and methodological limits of the available studies.
TB-500 refers to a synthetic peptide fragment derived from the actin-binding region of thymosin beta-4, a protein present in most mammalian cells. The full protein contains forty-three amino acids, while the commonly sold fragment is a much shorter acetylated sequence, often cited as LKKTETQ. The fragment retains part of the actin-binding motif but lacks the remainder of the parent protein. Material sold under this name is usually lyophilized powder intended for laboratory research, and it is not a finished pharmaceutical product.
Proposed activity centers on actin sequestration and on the movement of cells during repair processes. In cell culture and animal models, the fragment has been associated with migration, tube formation, and tissue remodeling. These observations are frequently described as preliminary, because most published work uses rodent or in vitro systems rather than controlled human trials. Whether the short fragment reproduces the effects of the full protein remains an open question, and the relationship between dose, route, and measured outcome is not well characterized.
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== Further reading == Layinka Swinburne (1997). "Dancing with the Mermaids: Ship's Biscuit and Portable Soup". In Harlan Walker (ed.). Food on the Move: Proceedings of the Oxford Symposium on Food and Cookery, 1996. Prospect Books. ISBN 978-0-907325-79-6. Schroeder-Lein, G.R. (2015). The Encyclopedia of Civil War Medicine. Taylor & Francis. p. 228. ISBN 978-1-317-45709-1. Retrieved October 6, 2017.
== Biography == Peter Joseph Moloney and his three sisters, whose father died in 1897, were raised in Powassan by their widowed mother. The four siblings were the grandchildren of Irish Catholics who left Ireland during the Great Famine of Ireland and settled in Warminster, Southern Ontario. He received secondary education at the preparatory school of St. Michael's College, Toronto. He earned a bachelor's degree from the University of Toronto in 1912 and a master's degree with thesis Rate of Solution and Precipitation of Gypsum in chemistry in 1915. During a stay at the University of California at Berkeley for the academic year 1915–1916, he met Angelina Cecilia Chapman. They married in Berkeley on July 6, 1916. Moloney worked between 1917 and 1919 at the Department of Agriculture in Ottawa in food chemistry. From 1919 Moloney worked as a research assistant for Connaught Laboratories, a vaccine manufacturer that emerged from the University of Toronto and now belongs to Sanofi. While working for Connaught Laboratories he studied at the University of Toronto, where his mentor was John G. FitzGerald. After acquiring a Ph.D. with thesis On the Purification of Insulin in 1924 from the University of Toronto, Moloney was in the working group of Charles Best and Frederick Banting from 1921 with the purification of insulin to make it clinically usable, which was achieved for the first time in 1922.
This article incorporates public domain material from The World Factbook (2025 ed.). CIA. (country: Honk Kong) Hong Kong from BBC News Key Development Forecasts for Hong Kong from International Futures Hong Kong in Transition (1995–2020) Archived 20 March 2025 at the Wayback Machine, an open access photographic archive of recent Hong Kong history Government
Sources: en.wikipedia.org
== Structure == This membrane enzyme forms homodimers, partly separated by an internal ~9-Å-wide channel. The metallo beta-lactamase protein fold is adapted to associate with membrane phospholipids. A hydrophobic cavity provides an entry way for the substrate NAPE into the active site, where a binuclear zinc center catalyzes its hydrolysis. Bile acids bind with high affinity to selective pockets in this cavity, enhancing dimer assembly and enabling catalysis. NAPE-PLD facilitates crosstalk between bile acid signals and lipid amide signals.
=== Knoxville in the Gilded Age === Swiss immigrant Peter Staub built Knoxville's first opera house, Staub's Theatre, on Gay Street in 1872. This was also one of the first major structures designed by architect Joseph Baumann, who would design many of the city's more prominent late-19th-century buildings. During this same period, the Lamar House Hotel, located across the street from the theater, was a popular gathering place for the city's elite. The hotel hosted lavish masquerade balls, and served oysters, cigars, and imported wines. Initially a place for farmers to sell produce, Market Square had evolved into one of the city's commercial and cultural centers by the 1870s. The square's most notable business was Peter Kern's ice cream saloon and confections factory, which hosted numerous festivals for various groups in the late 19th century. The square also attracted street preachers, early country musicians, and political activists. Women's suffragist Lizzie Crozier French was delivering speeches on Market Square as early as the 1880s. After the Civil War, Thomas William Humes was named president of East Tennessee University (renamed the University of Tennessee in 1879), and managed to acquire for the institution the state's Morrill Act land-grant funds, allowing the school to expand. In 1886, Charles McClung McGhee established the Lawson McGhee Library, named for his late daughter, which became the basis of Knox County's public library system. In 1873, Humes managed to obtain a Peabody Fund grant that allowed Knoxville to establish a public school system.
Association for Molecular Pathology v. U.S Food and Drug Administration (FDA) The U.S. Food and Drug Administration (FDA) issued a final rule on May 6, 2024, to regulate laboratory-developed test (LDT) as medical devices and to oversee clinical laboratories as manufacturers of medical device. This rule would have increased reporting requirements by clinical laboratories, including registration for FDA premarket approval before launching new LDTs. AMP opposed this legislation and filed a lawsuit against the FDA in August 2024, citing concerns with the negative impact on patient access to LDTs and on laboratory innovation, as well as the expected increased costs of LDTs. On May 31, 2025, a U.S. federal court vacated this rule in favor of AMP and the American Clinical Laboratory Association, which had filed a separate lawsuit against the FDA. The court ruled that the regulation of LDTs as medical device “defies bedrock principles of statutory, common sense and longstanding industry practice” and that “Congress had already considered issues raised by LDTs in CLIA and had given the CMS regulatory authority over LDTs, not the FDA.” The FDA rule was officially withdrawn in September 2025.
== Side effects == Clinical studies have found that deramciclane is well-tolerated in humans at dosages ranging between 0.2–150 mg. All reported side effects were mild-moderate with the most common side effect being headache and dizziness. No severe side effects were reported in any clinical trial, and no side effects were found to be dose-dependent. Trial participants showed no significant increases in liver enzyme activity and no changes in ECGs, systolic blood pressure, diastolic blood pressure, HDL cholesterol, or LDL cholesterol levels. Another advantage to deramciclane is that it did not produce any withdrawal effects after long-term studies, like other anxiolytics do.
== Scaffolds == Scaffolds are materials that have been engineered to cause desirable cellular interactions to contribute to the formation of new functional tissues for medical purposes. Cells are often 'seeded' into these structures capable of supporting three-dimensional tissue formation. Scaffolds mimic the extracellular matrix of the native tissue, recapitulating the in vivo milieu and allowing cells to influence their own microenvironments. They usually serve at least one of the following purposes: allowing cell attachment and migration, delivering and retaining cells and biochemical factors, enabling diffusion of vital cell nutrients and expressed products, and exerting certain mechanical and biological influences to modify the behaviour of the cell phase. In 2009, an interdisciplinary team led by the thoracic surgeon Thorsten Walles implanted the first bioartificial transplant that provides an innate vascular network for post-transplant graft supply successfully into a patient awaiting tracheal reconstruction.
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 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.