LKKTETQ is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
TB-500 is a shorthand label used in supplier catalogs and online discussion for a short synthetic peptide described as a fragment of thymosin beta-4. Most product listings present it as the N-terminally acetylated heptapeptide Ac-LKKTETQ, a sequence corresponding to the actin-binding region of the parent protein. The name is not a formal chemical designation and does not appear in standard nomenclature systems. Because labeling practices vary between vendors, two products sold under the same name may not contain the same molecule, and the stated sequence should be treated as a claim rather than a fixed definition.
Thymosin beta-4 is a naturally occurring protein of 43 amino acids found in most mammalian cells, where it binds actin monomers and influences filament dynamics. It was first isolated from thymus tissue in the early 1980s, and its actin-binding activity was later mapped to a short region near the N-terminus. The synthetic fragment sold as TB-500 was designed to reproduce that region rather than the full protein. Whether a short fragment reproduces the behavior of the intact molecule remains an open question, since the parent protein carries additional structural elements outside the binding region.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H68N10O14 | Acetylated heptapeptide form |
| Monoisotopic mass | 888.5 Da | Average mass about 889 Da |
| Appearance | White to off-white solid | Usually supplied as lyophilised powder |
| Solubility class | Highly water soluble | Also dissolves in aqueous buffers |
| Common synonyms | Tbeta4 fragment, thymosin beta-4 (17-23) | Refer to the same sequence |
Controlled human trials of the short fragment are scarce. Much of what appears in review articles is extrapolated from animal models or from studies of the parent protein, and literature searches return a larger body of cardiac and ophthalmic work on thymosin beta-4 than on the abbreviated peptide. Regulatory treatment differs by jurisdiction, and in several countries the material is handled as a research chemical rather than an approved therapeutic. Statements about human benefit should be read as provisional.
Biological interest in this peptide centers on its relationship to actin dynamics. Thymosin beta-4 binds monomeric actin through an LKKTET motif, and a short sequence carrying that motif can compete with other actin-binding proteins in cell-free preparations. Investigators propose that such competition shifts the balance between filament assembly and disassembly, which in turn affects how readily a cell extends protrusions and migrates. Most of the supporting observations come from cultured cells and purified protein systems rather than from intact organisms.
Animal work has examined the peptide in models of cardiac injury, skin wounding, and corneal repair, with reported outcomes covering cell migration, inflammatory cell influx, and tissue remodeling. Several of those experiments used the full-length protein or longer fragments instead of the seven-residue sequence, which makes direct comparison between reports difficult. Results are generally described as tissue-dependent, and effect sizes vary considerably across laboratories. Independent replication is uneven, so the overall picture is incomplete rather than settled.
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.
=== Brand names === Metandienone was introduced and formerly sold primarily under the brand name Dianabol. It has also been marketed under a variety of other brand names including Anabol, Averbol, Chinlipan, Danabol, Dronabol, Metanabol, Methandon, Naposim, Reforvit-B, and Vetanabol among others.
=== Formation === Cold Cave was founded in 2007 by Wesley Eisold, vocalist of hardcore groups American Nightmare (briefly known as Give Up the Ghost), Some Girls, and Heartworm Press founder. Cold Cave represents Eisold's first venture into instrumentation. Eisold was born with one hand which led him to electronic music.
YAP1 (yes-associated protein 1), also known as YAP or YAP65, is a protein that acts as a transcription coregulator that promotes transcription of genes involved in cellular proliferation and suppressing apoptotic genes. YAP1 is a component in the hippo signaling pathway which regulates organ size, regeneration, and tumorigenesis. YAP1 was first identified by virtue of its ability to associate with the SH3 domain of Yes and Src protein tyrosine kinases. YAP1 is a potent oncogene, which is amplified in various human cancers.
=== Microemulsion === In February 2011, Canadian researchers at the University of Calgary's Schulich School of Engineering announced a microchip for blood tests. Dubbed a microemulsion, a droplet of blood captured inside a layer of another substance. It can control the exact size and spacing of the droplets. The new test could improve the efficiency, accuracy, and speed of laboratory tests while also doing it cheaply.
Sources: en.wikipedia.org
State and local programs are not permitted to participate. The failure to share data has caused foreign governments to refuse donations of expired medications. One exception occurred during the 2010 Swine Flu Epidemic when the FDA authorized expired Tamiflu based on SLEP Data. The SLEP discovered that drugs such as Cipro remained effective nine years after their shelf life, and, as a cost-saving measure, the US military routinely uses a wide range of SLEP tested products past their official shelf life if drugs have been stored properly.
=== Storage methods === Fresh refrigerated tempeh should be sealed in a labeled polyethylene bag and kept in temperatures below 4 °C (40 °F). It can be kept at this temperature for three to five days and sometimes, even as long as a week. Storage life could be extended to two or three weeks if the tempeh is blanched or steamed prior to refrigeration due to the inactivation of enzymes and destruction of bacteria. Freezing is the preferred way to preserve tempeh due to its capability for wide distribution. Tempeh can be frozen whole or in slices, depending on preference. During the freezing process, whole tempeh is placed in its perforated wrapper whereas sliced tempeh is packaged in a labelled polyethylene bag prior to being sealed in an outer bag and then frozen immediately. This method will keep for months with only a small loss of texture and flavor. Blanching tempeh by steaming or parboiling helps to extend the storage life by preventing bacterial growth, stopping mold growth and inactivating enzymes. Steaming appears to have a less negative effect than parboiling in terms of texture, flavor and nutritional value. Blanching is a great method for preserving tempeh prior to refrigeration, though not as beneficial for tempeh that is to be frozen.
== 1961–64 == South Africa's isolation increased in 1960–61 when it declared a republic and left the Commonwealth. SAOCGA was renamed SAONGA (the South African Olympic and National Games Association) as it was no longer eligible for the Commonwealth Games; it was later more usually called SANOC (South Africa National Olympic Committee). In 1962, Jan de Klerk announced a ban on South Africans appearing in mixed-race competition inside or outside the country. In 1963, Dennis Brutus founded the South African Non-Racial Olympic Committee (SANROC) which lobbied the IOC to expel SAONGA. Brutus was subjected to travel restrictions and forbidden from attending meetings, so he fled to London. The IOC moved its 1963 conference from Nairobi to Baden-Baden after the Kenyan government refused to grant a visa to the South African delegate. To bypass its own ban on mixed-race competition, SANOC was prepared to stage its Olympic trials abroad, but the events would still be segregated. The IOC voted to revoke SANOC's invitation to the 1964 Summer Olympics unless it declared its opposition to the government's policy. SANOC did not do so and was excluded from the Games, although it remained affiliated to the IOC.
Hong Kong is situated on China's southern coast, 60 km (37 mi) east of Macau and on the eastern side of the Pearl River estuary. The territory is surrounded by the South China Sea on all sides except the north, where it neighbors the Guangdong city of Shenzhen along the Sham Chun River. Its standard area is approximately 1,110 km2 (430 sq mi), though this figure reaches approximately 2,750 km2 (1,060 sq mi)2 when the open maritime area under its jurisdiction (rather than of mainland China) is included. The territory consists of Hong Kong Island, the Kowloon Peninsula, the New Territories, Lantau Island, and over 200 other islands. Of the standard area, 1,073 km2 (414 sq mi) is land and 35 km2 (14 sq mi) is inland water, such as reservoirs, rivers, and ponds. The territory's highest point is Tai Mo Shan, reaching 957 metres (3,140 ft) above sea level. Urban development is primarily concentrated on the Kowloon Peninsula, Hong Kong Island, and within various new towns throughout the New Territories. Much of this is built on reclaimed land; 70 km2 (27 sq mi) (representing 6% of the total land or about 25% of the territory's developed space) has been reclaimed from the sea.
=== Cancer === Meta-analyses have been performed to examine the association between NQO1 polymorphism and increased cancer risk. The results from some of these analyses have been summarized in the table below:
Sources: en.wikipedia.org
No. TB-500 is a short synthetic peptide matching residues 17 to 23 of thymosin beta-4, while the parent protein contains 43 residues. The fragment lacks the rest of the protein sequence, so the two are related but not identical.
It consists of leucine, lysine, lysine, threonine, glutamic acid, threonine, and glutamine in that order. The N-terminal leucine is usually acetylated in the forms described in catalogues.
Controlled human data is limited, and most published findings come from cell culture or animal work. This makes it difficult to state clinical effects with confidence.
Most listings describe it as a short acetylated peptide with the sequence Ac-LKKTETQ, presented as a region of thymosin beta-4. The label is a trade-style name rather than a standardized chemical name, so the exact content of a given vial depends on the supplier.