This is a working overview of thymosin beta-4, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-17. Anything still debated is marked as such rather than presented as settled.
Identity and purity checks for peptide material typically combine reversed-phase high-performance liquid chromatography with mass measurement, since retention time alone cannot confirm a sequence. Mass measurement verifies the expected molecular mass within instrument tolerance, while chromatographic peak area provides a purity estimate. Anti-doping analysis of urine uses related but more sensitive workflows, sometimes after solid-phase extraction. For research material, batch documentation, certificate content, and independent testing are common points of scrutiny, because supply chains outside pharmaceutical regulation vary widely in the paperwork they provide.
Reconstitution of a lyophilized peptide is normally done with sterile water or a suitable buffer under aseptic conditions. Adding solvent down the vial wall and allowing gentle dissolution instead of vigorous vortexing reduces the chance of aggregation, which can lower the effective concentration of the resulting solution. Concentrated stocks are usually diluted into working buffer shortly before use. Because no standard preparation protocol exists for TB-500 specifically, laboratories adapt general peptide handling practice, and reported results may reflect differing preparation choices.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Reconstitution solvent | Sterile water or aqueous buffer | Aseptic technique recommended |
| Post-reconstitution storage | 2–8 °C short term; frozen for longer periods | Avoid repeated freeze-thaw cycles |
| Typical purity assay | Reversed-phase HPLC | Peak area used to estimate purity |
| Identity confirmation | Mass measurement | Compares observed value with expected mass |
| Main degradation routes | Hydrolysis and oxidation | Accelerated by heat and extreme pH |
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.
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.
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.
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.
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.
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.
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 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.
Generally feared more than any other Australian snake, the coastal taipan is considered the third-most venomous terrestrial snake in the world, behind the inland taipan and eastern brown snake. It is classified as a snake of medical importance by the World Health Organization. In 1935, local health authorities established a register of cases of injury by plants and animals in northern Queensland. By 1940, one survivor (who lost his sense of smell for some months) and two fatalities had been recorded from coastal taipan bites, with another three historical fatalities added in 1944. George Rosendale, a Guugu Yimithirr man, was bitten through his boots and thick socks while stacking wood. He became sick 15–30 minutes later, with ptosis, nausea, and difficulty breathing, and was conveyed to Cooktown Hospital. A doctor visiting the area on holiday treated him with fluids, and tiger snake antivenom flown up from Cairns. He was flown to Cairns Hospital the next day and was discharged after 19 days. He also reported losing his sense of smell. Rosendale became a Lutheran pastor and died at age 89 in 2019. Articles about how dangerous the species was appeared more frequently in newspapers and books from the late 1930s onwards, including wild tales of it hiding in trees and dropping on victims. Australian naturalist and writer Charles Barrett reported that one had pursued a person for two hours before being killed with a brush hook. After a specimen was found in the Northern Territory in 1947, fears were raised it may occur further south in more populated areas of Queensland.
== Early life, education, and career == Wittman was born in Washington, D.C., the son of adoptive parents Regina C. (née Wood) and Frank Joseph Wittman. His father was of German descent and his mother's ancestors included immigrants from Ireland and Canada. He grew up in Henrico County, Virginia. He attended the Virginia Polytechnic Institute and State University (Virginia Tech) as a member of the Corps of Cadets and Army ROTC and studied biology. While at Virginia Tech, he spent the summers working at a tomato cannery and on a fishing vessel. Also while in college, Wittman was a member of the Delta Tau Delta fraternity. He earned a master's degree in public health from the University of North Carolina at Chapel Hill in 1990 and a Ph.D. from Virginia Commonwealth University in 2002. Wittman worked for 20 years with the Virginia Department of Health. He served as an environmental health specialist and was field director for the Division of Shellfish Sanitation. Wittman served on the Montross Town Council from 1986 to 1996 and as mayor of the Town of Montross from 1992 to 1996. Two of his major initiatives in this office were the overhaul of the sewage system and the development of a computerized system for tax billing. From 1996 to 2005, Wittman served on the Westmoreland County Board of Supervisors, the last two years as chair. He helped create new libraries and pushed for raises in teacher salaries.
=== Activation and excretion === In the liver and peripheral tissues of humans, retinol is reversibly converted to retinal by the action of alcohol dehydrogenases, which are also responsible for the conversion of ethanol to acetaldehyde. Retinal is irreversibly oxidized to retinoic acid (RA) by the action of aldehyde dehydrogenases. RA regulates the activation or deactivation of genes. The oxidative degradation of RA is induced by RA – its presence triggers its removal, making for a short-acting gene transcription signal. This deactivation is mediated by a cytochrome P450 (CYP) enzyme system, specifically enzymes CYP26A1, CYP26B1 and CYP26C1. CYP26A1 is the predominant form in the human liver; all other human adult tissues contained higher levels of CYP26B1. CYP26C1 is expressed mainly during embryonic development. All three convert retinoic acid into 4-oxo-RA, 4-OH-RA and 18-OH-RA. Glucuronic acid forms water-soluble glucuronide conjugates with the oxidized metabolites, which are then excreted in urine and feces.
=== Human === The human FPR2 gene encodes the 351 amino acid receptor, FPR2, within an intronless open reading frame. It forms a cluster with FPR1 and FPR3 genes on chromosome 19q.13.3 in the order of FPR1, FPR2, and FPR3; this cluster also includes the genes for two other chemotactic factor receptors, the G protein-coupled C5a receptor (also termed CD88) and a second C5a receptor, GPR77 (i.e. C5a2 or C5L2), which has the structure of G protein receptors but apparently does not couple to G proteins and is of uncertain function. The FPR1, FPR2, and FPR3 paralogs, based on phylogenetic analysis, originated from a common ancestor with early duplication of FPR1 and FPR2/FPR3 splitting with FPR3 originating from the latest duplication event near the origin of primates.
== Examples == In the forearm, the wide gap between the shaft portions of the radius and ulna bones are strongly united by an interosseous membrane. Similarly, in the leg, the shafts of the tibia and fibula are also united by an interosseous membrane. In addition, at the inferior tibiofibular joint, the articulating surfaces of the bones lack cartilage and the narrow gap between the bones is anchored by fibrous connective tissue and ligaments on both the anterior and posterior aspects of the joint. Together, the interosseous membrane and these ligaments form the tibiofibular syndesmosis. However, a syndesmosis does not prevent all movement between the bones, and thus this type of fibrous joint is functionally classified as an amphiarthrosis. In the leg, the syndesmosis between the tibia and fibula strongly unites the bones, allows for little movement, and firmly locks the talus bone in place between the tibia and fibula at the ankle joint. This provides strength and stability to the leg and ankle, which are important during weight bearing. In the forearm, the interosseous membrane is flexible enough to allow for rotation of the radius bone during forearm movements. Thus in contrast to the stability provided by the tibiofibular syndesmosis, the flexibility of the antebrachial interosseous membrane allows for the much greater mobility of the forearm.
Sources: en.wikipedia.org
== Education == Daly attended Hunter College High School, a laboratory high school for girls run by Hunter College faculty, where she was also encouraged to pursue chemistry. She then enrolled in Queens College, a small, fairly new school in Flushing, New York. She lived at home to save money and graduated magna cum laude from Queens College with her bachelor's degree in chemistry in 1942. Upon graduation, she was named a Queens College Scholar, an honor that is awarded to the top 2.5% of the graduating class. Labor shortages and the need for scientists to support the war effort enabled Daly to garner fellowships to study at New York University and Columbia University for her master's and Ph.D. degrees, respectively. Daly worked as a laboratory assistant at Queens College while studying at New York University for her master's degree in chemistry, which she completed in 1943. She became a chemistry tutor at Queens College and enrolled in the doctoral program at Columbia University, where she was supervised by Mary Letitia Caldwell, for a Ph.D. thesis titled, "A Study of the Products Formed By the Action of Pancreatic Amylase on Corn Starch" and received her Ph.D. in chemistry in 1947.
With the advent of the declaration and the British entry into Jerusalem on 9 December, the Vatican reversed its earlier sympathetic attitude to Zionism and adopted an oppositional stance that was to continue until the early 1990s.
== Examples == Some examples of conjugated proteins are lipoproteins, glycoproteins, nucleoproteins, phosphoproteins, hemoproteins, flavoproteins, metalloproteins, phytochromes, cytochromes, opsins, and chromoproteins.
The two German states entered into a currency and customs union in July 1990, and on 3 October 1990, the German Democratic Republic dissolved and the re-established five East German Länder (as well as a unified Berlin) joined the Federal Republic of Germany, bringing an end to the East–West divide.
== Clinical significance == Polymorphisms in ACTC1 have been linked to dilated cardiomyopathy in a small number of Japanese patients. Further studies in patients from South Africa found no association. The E101K missense mutation has been associated with hypertrophic cardiomyopathy and left ventricular noncompaction. Another mutation has in the ACTC1 gene has been associated with atrial septal defects.
Sources: en.wikipedia.org
Standard practice is a desiccated container at −20 °C, protected from light and kept sealed between uses. Letting the vial reach room temperature before opening reduces condensation on the powder. Repeated warming and cooling of the whole container is generally avoided.
There is no broadly accepted figure for TB-500. Laboratory practice is short-term storage at 2–8 °C with longer-term aliquots frozen, and degradation is expected to increase with time and temperature. Users typically rely on their own stability checks rather than published data.
Mass measurement provides the clearest confirmation by matching an observed value to the expected one. Reversed-phase chromatography adds a purity estimate through peak integration. Combining both is standard because neither alone establishes identity and purity together.
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.