The short version of thymosin beta-4 fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
TB-500 is a research peptide whose sequence matches residues 17 to 23 of thymosin beta-4, a 43-residue protein present in most mammalian cells. The chain is seven amino acids long, written as LKKTETQ, and is normally supplied with an acetyl group on the N-terminus. Suppliers list it as a lyophilised powder under the code name TB-500, and the same sequence appears elsewhere in catalogues as the thymosin beta-4 actin-binding fragment. The label is commercial rather than systematic, so no single authority fixes exactly what TB-500 denotes.
Thymosin beta-4 was isolated from calf thymus in the early 1980s and later characterised as an abundant intracellular actin-sequestering protein. Interest in short synthetic fragments grew once the actin-binding motif had been mapped to the middle of the sequence. TB-500 came out of that line of work as a truncated analogue rather than a natural isolate, and it is now sold mainly to laboratories. Published studies on the fragment have been largely in vitro or in animal models, and controlled human trials remain sparse, so claims about effects in people rest on extrapolation.
Literature and online discussion often conflate TB-500 with full-length thymosin beta-4, even though the two differ in size and are not interchangeable in analytical terms. The fragment is produced by solid-phase peptide synthesis, and the product is a defined seven-residue chain rather than a biological extract. Because the term is a trade-style label, two vendors may supply materials of the same nominal sequence but different counter-ion content, purity, or water content. Comparisons across studies are therefore difficult unless the exact sequence and purity are reported.
Full-length thymosin beta-4 consists of roughly forty-three amino acids and ranks among the more abundant small proteins in the cytoplasm. The fragment is much shorter, so it cannot reproduce every function attributed to the intact molecule. In cell culture, short actin-binding motifs can interfere with filament dynamics and cell movement, but such observations come from controlled experiments rather than from whole-animal work. Whether a truncated fragment produces the same effects as the parent protein remains an open question.
Interest in the peptide grew during the 2000s and 2010s, when studies of tendon and ligament injuries in horses reported changes in lesion size after treatment. Those reports circulated widely outside the scientific literature and shaped much of the current online discussion. Subsequent reviews noted inconsistent study design, small groups, and a shortage of independent replication. Popular descriptions often blur the line between the fragment, the complete protein, and unrelated growth factors, which complicates comparisons across sources.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Supplied as a lyophilised cake in sealed vials |
| Solubility class | Freely soluble in water | Polar and charged side chains dominate the sequence |
| Typical storage temperature | -20 °C or below | Dry and dark; a desiccant is often recommended |
| Identity confirmation | Mass spectrometry | Observed mass compared with the theoretical value |
| Common synonyms | Thymosin beta-4 fragment | Also written as T beta 4 fragment 17-23 |
TB-500 is a laboratory label applied to a short synthetic peptide that is widely described as a fragment of thymosin beta-4, an actin-binding protein present in most mammalian cells. Suppliers and review articles usually present TB-500 as the N-terminal region of that protein, but the exact sequence attached to the name is not consistent across sources. Some product descriptions list a seven-residue chain; others use the label loosely for the parent protein itself. Because of that variation, any technical discussion of TB-500 needs to state which sequence is meant.
Thymosin beta-4 contains 43 amino acids and has a reported molecular mass near 4963 Da. The short fragment most often associated with the TB-500 label, an acetylated chain beginning LKKTETQ, has a reported mass near 889 Da, so the two are easily separated in analytical work. Mass spectrometry and amino acid analysis can confirm which material is present in a given sample. Statements treating TB-500 and thymosin beta-4 as interchangeable are therefore imprecise, even though the two appear together in much of the same literature.
Interest in the compound comes largely from studies of the parent protein, which participates in actin sequestration, cell migration and tissue repair processes. Whether a short fragment reproduces those activities is a separate question that remains open in the published record. Many summaries describe mechanisms by analogy to thymosin beta-4 rather than from direct measurements on the fragment. Claims about activity should be treated as provisional unless a cited study specifies the exact peptide, its purity and the assay used.
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.
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.
Material sold under this label typically arrives as a freeze-dried powder in a sealed vial with a certificate of analysis. Such certificates usually report reversed-phase chromatography purity plus a mass confirmation, and stated purities commonly sit between 95 and 99 percent. Counter-ion identity, residual trifluoroacetate, water content, and peptide net weight are separate specifications that a certificate may or may not include. A purity figure alone does not establish sequence identity, so independent mass verification remains the practical check.
(1881), classical scholar and educator Richard James Horatio Gottheil (1881), Zionist scholar, founder of the first Jewish fraternity Zeta Beta Tau Harry Thurston Peck (1881), literary critic and editor of The Bookman A. V. Williams Jackson (1883), specialist on Indo-European languages Charles Knapp (1887), classical scholar Frank Moore Colby (1888), historian and editor of The New International Encyclopedia Charles Sears Baldwin (1888), scholar and professor of rhetoric at Yale University John Dyneley Prince (1888), linguist; U.S. ambassador to Yugoslavia George Louis Beer (1892), renowned historian of the "Imperial school" Benjamin Lord Buckley (1892), educator, founder and headmaster of Buckley School Judah A. Joffe (1893), Yiddish philologist William Robert Shepherd (1893), cartographer, historian John Driscoll Fitz-Gerald (1895), Hispanic scholar Joel Elias Spingarn (1895), professor of comparative literature Mortimer Lamson Earle (1896), classical scholar Alfred L. Kroeber (1896), pioneering cultural anthropologist William Popper (1896), Orientalist and professor Frederick Paul Keppel (1898), educator, former president of the Carnegie Corporation of New York Frank Sutliff Hackett (1899), educator, founder of Riverdale Country School John Erskine (1900), Great Books pioneer Alexander Goldenweiser (1902), Russian-born anthropologist and sociologist Emanuel Goldenweiser (1903), economist and president of the American Economic Association Robert Livingston Schuyler (1903), scholar on American history, president of the American Historical Association Carlton J. H.
Her dissertation work focused on investigating molecular-level surface reactivity and kinetics of metal surfaces using electron spectroscopy, laser desorption, and Fourier transform mass spectrometry techniques. She also designed and built peripheral components for a variable temperature, ultra-high vacuum scanning tunneling microscopy system. In 1997, Caldwell Dyson received the Camille and Henry Dreyfus Postdoctoral Fellowship in Environmental Science to study atmospheric chemistry at the University of California, Irvine. There, she investigated reactivity and kinetics of atmospherically relevant systems using atmospheric pressure ionization mass spectrometry, Fourier transform infrared and ultraviolet absorption spectroscopies. In addition, she developed methods of chemical ionization for spectral interpretation of trace compounds. Caldwell Dyson has published and presented her work in numerous papers at technical conferences and in scientific journals.
==== Pneumococcal vaccine ==== In 2010, as part of a 10-year pneumococcal vaccine Advance Market Commitment, the companies GlaxoSmithKline (GSK) and Pfizer were both allocated $225 million in AMC subsidies to provide 30 million doses annually at a maximum tail price of $3.50 per dose ($10.50 per child for three doses). In 2011, Médecins Sans Frontières (MSF) recommended that Gavi change the ways in which it procures vaccines. MSF argued that the Advance Market Commitment had transferred more money to GSK and Pfizer than the Gavi grants had transferred to low-cost suppliers for technology transfer and product development. MSF said that large pharmaceutical multinationals had been found to put very high markups on prices, and internationally certified vaccine could be made for about 40% less cost by smaller companies in India and China, despite patent-related obstacles. In January 2015, MSF also called upon GSK and Pfizer to cut the price of the pneumococcal vaccine to US$5 per child in developing countries, a price they estimated as competitive. They said that, as Pfizer had made $16 billion in revenue on pneumococcal vaccine in the last four years, a larger price cut would be affordable. In early 2016, they ran the "A fair shot" campaign to pressure GSK and Pfizer to drop prices. Pfizer said that they were already selling the vaccine at "far below" cost, while GSK said that the price enabled them to "just about" cover their costs, and "To discount it further would threaten our ability to supply it to these countries in the long-term".
A writer for Business Insider called it one of the best performances of DiCaprio's career, and Ian Sandwell of Digital Spy particularly liked the duo's chemistry, believing their scenes together to be some of the film's strongest parts. DiCaprio received nominations for an Oscar, a Golden Globe, a BAFTA Award and a Screen Actors Guild Award for Best Actor. The film earned $374 million against a budget of $90 million. In 2020, DiCaprio served as an executive producer for The Right Stuff, a television series adaption of the 1973 namesake book. After being in development at National Geographic, it was released on Disney+. That May, DiCaprio briefly featured in the finale of the miniseries The Last Dance. In 2021, DiCaprio appeared in Adam McKay's satirical comedy Don't Look Up. He spent five months changing the film's script with McKay before agreeing to the part. Starring alongside Jennifer Lawrence as two astronomers attempting to warn humanity about an extinction-level comet, DiCaprio saw this film as an analogy of the world's indifference to the climate crisis. As a frequent supporter of environmentalism, DiCaprio said he has often looked to star in and make films tackling issues related to it, something he found hard due to people's inability to listen. He praised McKay for envisioning a project on how humans would react to a serious issue from a political, social and scientific standpoint. While reviews for the film were mixed, most critics praised DiCaprio's and Lawrence's performances; journalists from Digital Spy and NDTV lauded their pairing.
Sources: en.wikipedia.org
==== Travelling wave ion mobility spectrometry (TWIMS) ==== In TWIMS, ions are separated according to their mobility through a travelling wave in a gas filled cell. Both radio-frequency (RF) and direct current (DC) voltages are applied to a series of ring electrodes called a stacked ring ion guide (SRIG) to confine the ions and create a travelling wave. Based on the speed and magnitude of the travelling wave, ions can be separated. Smaller ions have higher mobility through the wave due to fewer collisions with gas molecules and exit the cell faster than ions of lower mobility (larger ions). Similar to DTIMS, CCS values of ions can be calculated with TWIMS using a calibration derived with known standards. A commercial example of the TWIMS-MS instrumentation is Waters Corp Synapt G2-S instrument.
== History == In September 2005, Pfizer received a non-approvable letter from the U.S. Food and Drug Administration regarding lasofoxifene (trade name Oporia), a selective estrogen receptor modulator for the prevention of osteoporosis. In January 2008, Ligand Pharmaceuticals, through its marketing partner, Pfizer, submitted a New Drug Application for lasofoxifene, which is expected to be marketed under the tradename Fablyn. Lasofoxifene was approved in the EU under the brand name Fablyn by the EMEA in March 2009.
Adrenocorticotropic hormone release is triggered by corticotropin-releasing hormone and inhibited by rising glucocorticoid levels. The gonadotropins—follicle-stimulating hormone and luteinizing hormone regulate the functions of the gonads in both sexes. Follicle-stimulating hormone stimulates sex cell production; luteinizing hormone stimulates gonadal hormone production. Gonadotropin levels rise in response to gonadotropin-releasing hormone. Negative feedback of gonadal hormones inhibits gonadotropin release. Prolactin promotes milk production in human females. Its secretion is prompted by prolactin-releasing hormone and inhibited by prolactin-inhibiting hormone. The intermediate lobe of the pituitary gland secretes only one enzyme that is melanocyte stimulating hormone. It is linked with the formation of the black pigment in our skin called melanin. The neurohypophysis stores and releases two hypothalamic hormones:
Sources: en.wikipedia.org
The citric acid cycle—also known as the Krebs cycle, Szent–Györgyi–Krebs cycle, or TCA cycle (tricarboxylic acid cycle)—is a series of biochemical reactions that release the energy stored in nutrients through acetyl-CoA oxidation. The energy released is available in the form of ATP. The Krebs cycle is used by organisms that generate energy via respiration, either anaerobically or aerobically (organisms that ferment use different pathways). In addition, the cycle provides precursors of certain amino acids, as well as the reducing agent NADH, which are used in other reactions. Its central importance to many biochemical pathways suggests that it was one of the earliest metabolic components. Even though it is branded as a "cycle", it is not necessary for metabolites to follow a specific route; at least three alternative pathways of the citric acid cycle are recognized. Its name is derived from the citric acid (a tricarboxylic acid, often called citrate, as the ionized form predominates at biological pH) that is consumed and then regenerated by this sequence of reactions. The cycle consumes acetate (in the form of acetyl-CoA) and water and reduces NAD+ to NADH, releasing carbon dioxide. The NADH generated by the citric acid cycle is fed into the oxidative phosphorylation (electron transport) pathway. The net result of these two closely linked pathways is the oxidation of nutrients to produce usable chemical energy in the form of ATP. In eukaryotic cells, the citric acid cycle occurs in the mitochondrial matrix.
denotes contact. The second assumption in contact mechanics is related to the fact, that no tension force is allowed to occur within the contact area (contacting bodies can be lifted up without adhesion forces). This leads to an inequality which the stresses have to obey at the contact interface. It is formulated for the normal stress
At about T+5 minutes was SECO (Sustainer Engine Cutoff) and Faith 7 entered orbit at 17,547 mph (7,844 m/s). After the spacecraft separated and turned around to orbit attitude, Cooper watched the spent Atlas lag behind and tumble for about eight minutes. Over Zanzibar on the first orbit, he learned that the orbital parameters were good enough for at least 20 orbits. As the spacecraft passed over Guaymas, Mexico still on the first orbit, capsule communicator Gus Grissom told Cooper the ground computers said he was "go for seven orbits." Atlas performance was overall excellent. The upgraded propulsion system worked well, with slightly above nominal booster engine thrust. Measurable propellant slosh occurred from T+55 to T+120 seconds, caused by slightly lower than nominal autopilot gains. The flight trajectory was slightly more lofted than nominal due to the DC voltage in the booster electrical system being about 0.7 volts above normal, but this was counteracted by the higher than nominal booster engine performance. BECO took place at T+132 seconds, escape tower jettison at T+141 seconds, and SECO at T+303 seconds.
== History == 4-HO-MET was first synthesized and discovered by Alexander Shulgin in the 1970s. It was first described in the scientific literature by David Repke and colleagues by 1981. Subsequently, 4-HO-MET was described by Shulgin in his book TiHKAL (Tryptamines I Have Known and Loved) in 1997 as being- aside from its synthesis- indistinguishable from any other ethyl homologue. It was encountered as a novel recreational and designer drug in Europe by 2008 and recently in the United States in 2025.
Sources: en.wikipedia.org
No. Thymosin beta-4 is a 43-residue protein, while TB-500 matches only residues 17 to 23 of that chain. The two are related but differ in size, and a method that identifies one does not automatically identify the other.
It corresponds to the actin-binding region of thymosin beta-4. Commercial synthesis reproduces that seven-residue stretch, usually with an acetyl group on the N-terminus.
It is not authorised as a medicine in the United States or the European Union and is distributed as a research chemical. Labels consequently carry research-use-only statements rather than clinical indications.
It is a synthetic peptide based on a short sequence near the start of thymosin beta-4. It is supplied as a research chemical rather than as a licensed pharmaceutical product.