This is a working overview of actin binding, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-04-21. Anything still debated is marked as such rather than presented as settled.
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.
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.
| 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 |
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.
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.
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.
The regulatory position is broadly consistent across major jurisdictions: no thymosin beta-4 fragment is an approved medicine, and laboratory material is commonly labelled as not intended for human consumption. Anti-doping rules in sport list thymosin beta-4 and its fragments among prohibited peptide hormones. Because these products travel through research-chemical channels rather than pharmaceutical supply chains, quality varies considerably between vendors. Independent testing of identity, purity and sterility is the only dependable check, and a certificate of analysis describes one batch rather than a supplier's whole catalogue.
Lyophilized peptide powder is normally held desiccated at −20 °C, with −80 °C used for longer storage periods. Allowing a sealed vial to reach room temperature before opening is standard practice, because condensation forming on cold powder introduces moisture. Once dissolved, solutions are typically kept cold and shielded from light. Repeated freeze-thaw cycles are avoided because they encourage aggregation and gradual loss of material. These conventions are general to synthetic peptides rather than unique to any one sequence.
Strontium is named after the Scottish village of Strontian (Scottish Gaelic: Sròn an t-Sìthein), where it was discovered in the ores of the lead mines. In 1790, Adair Crawford, a physician engaged in the preparation of barium, and his colleague William Cruickshank, recognised that the Strontian ores exhibited properties that differed from those in other "heavy spars" sources. This allowed Crawford to conclude on page 355 "... it is probable indeed, that the scotch mineral is a new species of earth which has not hitherto been sufficiently examined." The physician and mineral collector Friedrich Gabriel Sulzer analysed together with Johann Friedrich Blumenbach the mineral from Strontian and named it strontianite. He also came to the conclusion that it was distinct from the witherite and contained a new earth (neue Grunderde). In 1793 Thomas Charles Hope, a professor of chemistry at the University of Glasgow studied the mineral and proposed the name strontites. He confirmed the earlier work of Crawford and recounted: "... Considering it a peculiar earth I thought it necessary to give it an name. I have called it Strontites, from the place it was found; a mode of derivation in my opinion, fully as proper as any quality it may possess, which is the present fashion." The element was eventually isolated by Sir Humphry Davy in 1808 by the electrolysis of a mixture containing strontium chloride and mercuric oxide, and announced by him in a lecture to the Royal Society on 30 June 1808. In keeping with the naming of the other alkaline earths, he changed the name to strontium.
== History == Spontaneous vertebral artery dissection was described in the 1970s. Prior to this, there had been isolated case reports about carotid dissection. In 1971, C. Miller Fisher, a Canadian neurologist and stroke physician working at Massachusetts General Hospital, first noted the "string sign" abnormality in carotid arteries on cerebral angiograms of stroke patients, and subsequently discovered that the same abnormality could occur in the vertebral arteries. He reported the discovery in a paper in 1978.
Past hypersensitivity or allergy to lorazepam, its ingredients in tablets or injections or any other benzodiazepine. Ataxia, a neurological clinical sign, consisting of unsteady and clumsy motion of the limbs and torso, due to the failure of gross muscle movement coordination, most evident on standing and walking. It is the classic way in which acute alcohol intoxication may affect a person. Benzodiazepines are not recommended to be administered to people who are already ataxic. Lorazepam has pupil-dilating effects, which may further interfere with the drainage of aqueous humor from the anterior chamber of the eye, thus worsening narrow-angle glaucoma. Sleep apnea may be worsened by lorazepam's central nervous system depressant effects. It may further reduce the person's ability to protect their airway during sleep. Myasthenia gravis, which is characterized by muscle weakness, may have exacerbated symptoms with muscle relaxants such as lorazepam. Lorazepam belongs to the Food and Drug Administration (FDA) pregnancy category D, which means it is likely to cause harm to the developing baby if taken during the first trimester of pregnancy. The evidence is inconclusive as to whether lorazepam if taken early in pregnancy results in reduced intelligence, neurodevelopmental problems, physical malformations in cardiac or facial structure, or other malformations in some newborns. Lorazepam given to pregnant women antenatally may cause floppy infant syndrome in the neonate, or respiratory depression necessitating ventilation.
Cuesta Valdes from the Grand Lodge of Cuba travelled to Miami to meet with representatives of the Grand Lodge of Florida, where the Grand Lodge of Cuba gained re-recognition, after 56 years, as "regular and correct" by Florida. In 2018, Ernesto Zamora Fernández was elected as Grand Master of the Grand Lodge of Cuba.
Various types of alcohol were also used in ancient medical practices. One of the first uses was wine mixed with oil was a common remedy in the ancient world to cleanse wounds and assuage their pain as noted in the context of Alcohol in the Bible. The Sumerians used beer as an antiseptic along with the dressing of wounds, using up to 19 different types of beer. Other ancient Mesopotamian cultures, including the Sumerians and Akkadians used wine with sesame infusions, which were "purified and pulverized" before application along with the many beers. A medical prescription from Mesopotamia describes a method for healing wounds:
Sources: en.wikipedia.org
== Adverse effects == Although the absorption of betamethasone dipropionate is small, when used for prolonged periods of time (periods exceeding two weeks), or across a large surface area (total use greater than 50 grams per week), it can have adverse effects. One such effect is the ability of the corticosteroid to suppress the hypothalamic–pituitary–adrenal axis. This can lead to a depression in the release of adrenal hormones such as cortisol and adrenocorticotropic hormone, or ACTH. Symptoms of HPA axis suppression are often subtle and variable, but can often be detected using simple blood or urine tests such at ACTH stimulation test or urinary free cortisol. Those at increased risk for HPA axis suppression are those who are more likely to absorb more of the steroid through the skin. These groups include:
== Research contributions == Esimone pioneered research in the use of recombinant viral vectors as surrogates for high-throughput antiviral screening studies, as well as on the use of indigenous medicinal plants as immunomodulators, vaccine adjuvants, and anti-infectives. The vector-based antiviral screening technique developed by Esimone between 2003 and 2005 in Germany significantly revolutionized high-throughput screening for anti-HIV compounds worldwide. In addition to this work, his research led to the discovery of new antimicrobial compounds—including antibacterial, antifungal, and antiviral agents—derived from endophytes, lichens, ferns, herbs, and spices. Esimone was instrumental in the isolation and characterization of resistance genes from clinical settings, abattoirs, and poultry, with a particular focus on extended-spectrum beta-lactamases (ESBLs) and metallo-beta-lactamases (MBLs) identified in the southeastern regions of Nigeria. His team became the first to demonstrate the presence of ESBL-producing bacteria harboring the CTXM-15 gene, which confers resistance to third-generation cephalosporins in Nigeria. Additionally, they were the first to identify MBL-producing bacteria containing the blaIMP-1 and blaVIM-1 genes within poultry and abattoirs in southeastern Nigeria. They also reported the increasing frequency of MBL-producing Klebsiella, Pseudomonas, and Escherichia species in the country.
The objective of an atomic bomb is to produce a device, according to Serber, "...in which energy is released by a fast neutron chain reaction in one or more of the materials known to show nuclear fission." According to Rhodes, "Untamped, a bomb core even as large as twice the critical mass would completely fission less than 1 percent of its nuclear material before it expanded enough to stop the chain reaction from proceeding. Tamper always increased efficiency: it reflected neutrons back into the core and its inertia...slowed the core's expansion and helped keep the core surface from blowing away." Rearrangement of the core material's subcritical components would need to proceed as fast as possible to ensure effective detonation. Additionally, a third basic component was necessary, "...an initiator—a Ra + Be source or, better, a Po + Be source, with the radium or polonium attached perhaps to one piece of the core and the beryllium to the other, to smash together and spray neutrons when the parts mated to start the chain reaction." However, any bomb would "necessitate locating, mining and processing hundreds of tons of uranium ore...", while U-235 separation or the production of Pu-239 would require additional industrial capacity.
== Career and research == Bewley is a senior investigator and Chief of the Laboratory of Bioorganic Chemistry at the National Institute of Diabetes and Digestive and Kidney Diseases. Her scientific focus includes chemical biology, molecular pharmacology, structural biology, microbiology, and infectious diseases. Bewley researches secondary metabolites and basic principles involved in protein-carbohydrate interactions and how these can be exploited to engineer therapeutics. She also designs and synthesizes small molecules and peptides that block, or can be used to probe the events that lead to viral entry. Her scientific focus includes chemical biology, molecular pharmacology, structural biology, microbiology, and infectious diseases.
Some prohormones contain structures other than inactive peptide hormones for the purpose of keeping hormone expression suppressed. For example, proinsulin contains an extra non-hormonal chain called C-peptide that binds two insulin peptide chains together, designed to keep both chains inactive by binding to their ends, specifically, their C-domain junctions, which have been proposed to be their site of binding to hormone-expression receptors in the cell. Despite the restrictions it enables, the C-peptide folds the proinsulin chains to make their junction ends accessible to be cleaved by prohormone convertases later, making the folding of the proinsulin chain containing C-peptide essential for the proper cleavage of proinsulin to successfully produce insulin.
Sources: en.wikipedia.org
Indian Army postings were less prestigious than British Army positions, but the pay was significantly greater so that officers could live on their salaries instead of having to have a private income. Accordingly, vacancies in the Indian Army were much sought after and generally reserved for the higher placed officer-cadets graduating from the Royal Military College, Sandhurst. British officers in the Indian Army were expected to learn to speak the Indian languages of their men, who tended to be recruited from primarily Hindi speaking areas. Prominent British Indian Army officers included Lord Roberts, Sir O'Moore Creagh, Lord Birdwood, Sir Claude Auchinleck ("The Auk") and Lord Slim.
Xerophthalmia, caused by a severe vitamin A deficiency, is described by pathologic dryness of the conjunctival epithelium and cornea. The conjunctiva becomes dry, thick, and wrinkled. Indicative is the appearance of Bitot's spots, which are clumps of keratin debris that build up inside the conjunctiva. If untreated, xerophthalmia can lead to dry eye syndrome, corneal ulceration and ultimately to blindness as a result of cornea and retina damage. Although xerophthalmia is an eye-related issue, prevention (and reversal) are functions of retinoic acid having been synthesized from retinal rather than the 11-cis-retinal to rhodopsin cycle. Throughout southeast Asia, estimates are that more than half of children under the age of six years have subclinical vitamin A deficiency and night blindness, with progression to xerophthalmia being the leading cause of preventable childhood blindness. Estimates are that each year there are 350,000 cases of childhood blindness due to vitamin A deficiency. The causes are vitamin A deficiency during pregnancy, followed by low transfer of vitamin A during lactation and infant/child diets low in vitamin A or β-carotene. The prevalence of pre-school age children who are blind due to vitamin A deficiency is lower than expected from incidence of new cases only because childhood vitamin A deficiency significantly increases all-cause mortality.
in the gray short-tailed opossum (Monodelphis domestica), a marsupial, MHC spans 3.95 Mb, yielding 114 genes, 87 shared with humans. Marsupial MHC genotypic variation lies between eutherian mammals and birds, taken as the minimal MHC encoding, but is closer in organization to that of nonmammals. The IPD-MHC Database was created which provides a centralised repository for sequences of the Major Histocompatibility Complex (MHC) from a number of different species. As of the release on December 19, 2019, the database contains information on 77 species.
A tendon is a tough, flexible band of fibrous connective tissue that connects muscles to bones. The extra-cellular connective tissue between muscle fibers binds to tendons at the distal and proximal ends, and the tendon binds to the periosteum of individual bones at the muscle's origin and insertion. As muscles contract, tendons transmit the forces to the relatively rigid bones, pulling on them and causing movement. Tendons can stretch substantially, allowing them to function as springs during movement. Cartilage is a resilient and smooth type of connective tissue that covers and protects the ends of long bones, and forms a structural component of many body parts including the rib cage, the neck and the bronchial tubes, and the intervertebral discs. It is classified into three types — elastic cartilage, hyaline cartilage, and fibrocartilage. Joints, also known as articulations, are structures that connect individual bones and may allow bones to move against each other to cause movement. Joints can be classified by structure and by function. Structurally, synovial joints are joints that are not directly joined, which are lubricated by a solution called synovial fluid; fibrous, bony, and cartilaginous joints are characterised by the presence of their respective connective tissues. There are three functional divisions of joints: Diarthroses, which allow extensive mobility between two or more articular heads. Amphiarthroses, which allow some movement. False joints or synarthroses, which allow little or no movement and are predominantly fibrous.
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. 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.