actin binding comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-05-19. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| 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 |
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.
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.
will depend on how to extract the desired information from the amino acid sequence of P in Eq.1. The general PseAAC can be used to reflect any desired features according to the targets of research, including those core features such as functional domain, sequential evolution, and gene ontology to improve the prediction quality for the subcellular localization of proteins. as well as their many other important attributes.
=== Pharmacodynamics === Diazoxide acts as a ATP-sensitive potassium channel (KATP) opener. It has been found to act as a positive allosteric modulator of the ionotropic glutamate AMPA and kainate receptors.
Newell has been critical of the direction that Microsoft has taken with making Windows a closed architecture similar to Apple's products, and has stated that he believes that the changes made in Windows 8 are "a catastrophe for everyone in the [personal computer] space". Newell identified the open-source Linux platform as an ideal platform for Steam and said the only thing holding back its adoption is the lack of games. In 2012, Valve announced that they were working on a console-PC hybrid for the living room, dubbed by media as the "Steam Box". A precursor to such a unit is SteamOS, a freely available Linux-based operating system that builds upon the Steam client functionality that includes media services, live streaming across home networks, game sharing within families, and parental controls. SteamOS was officially announced in September 2013 as the first of several announcements related to the Steam Machine platform as well as its unique game controller. In May 2014, Valve announced that the company's own SteamOS-powered Steam Machine would be delayed until 2015 due to problems with the game controller. In 2015, Alienware, ZOTAC, and CyberPowerPC launched its versions of the Steam Machine. By June 2016, fewer than half a million had been sold. While the Steam Machine line has been effectively canceled, Valve continued to manufacture and sell Steam Controllers until late November 2019, and publishes both mobile apps and software for the Steam Link, allowing in-home streaming.
Saliva moistens and softens food, and along with the chewing action of the teeth, transforms the food into a smooth bolus. The bolus is further helped by the lubrication provided by the saliva in its passage from the mouth into the esophagus. Also of importance is the presence in saliva of the digestive enzymes amylase and lipase. Amylase starts to work on the starch in carbohydrates, breaking it down into the simple sugars of maltose and dextrose that can be further broken down in the small intestine. Saliva in the mouth can account for 30% of this initial starch digestion. Lipase starts to work on breaking down fats. Lipase is further produced in the pancreas where it is released to continue this digestion of fats. The presence of salivary lipase is of prime importance in young babies whose pancreatic lipase has yet to be developed. As well as its role in supplying digestive enzymes, saliva has a cleansing action for the teeth and mouth. It also has an immunological role in supplying antibodies to the system, such as immunoglobulin A. This is seen to be key in preventing infections of the salivary glands, importantly that of parotitis. Saliva also contains a glycoprotein called haptocorrin which is a binding protein to vitamin B12. It binds with the vitamin in order to carry it safely through the acidic content of the stomach. When it reaches the duodenum, pancreatic enzymes break down the glycoprotein and free the vitamin which then binds with intrinsic factor.
Sources: en.wikipedia.org
Static-active stretching includes holding an extended position with just the strength of the muscles such as holding the leg in front, side or behind. Static-active flexibility requires a great deal of strength, making it the hardest to develop.
=== Monitoring and combination use === Docetaxel is administered via a one-hour infusion every three weeks over ten or more cycles. Treatment is given under the supervision of an oncologist. Strict monitoring of blood cell counts, liver function, serum electrolytes, serum creatinine, heart function, oxygen saturation and fluid retention is required detect adverse reactions and toxicity so that treatment can be modified or terminated if necessary. Premedication with corticosteroids is recommended before each administration of docetaxel to reduce fluid retention and hypersensitive reactions. Other medications will often be given to aid pain management and other symptoms. The treatment of breast cancer with doxorubicin and cyclophosphamide is enhanced by adjuvant treatment with docetaxel. Docetaxel is also used in combination with capecitabine, a DNA synthesis inhibitor.
== Essentiality in humans == Of the twenty amino acids common to all life forms (not counting selenocysteine), humans cannot synthesize nine: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Additionally, the amino acids arginine, cysteine, glutamine, glycine, proline and tyrosine are considered conditionally essential, which means that specific populations who do not synthesize it in adequate amounts, such as newborn infants and people with diseased livers who are unable to synthesize cysteine, must obtain one or more of these conditionally essential amino acids from their diet. For example, enough arginine is synthesized by the urea cycle to meet the needs of an adult but perhaps not those of a growing child. Amino acids that must be obtained from the diet are called essential amino acids. Eukaryotes can synthesize some of the amino acids from other substrates. Consequently, only a subset of the amino acids used in protein synthesis are essential nutrients.
Sources: en.wikipedia.org
== See also == Chinese herbology Ethnobotany Ethnomedicine Herbal Medicinal fungi List of plants used in herbalism Thomsonianism, a popular 19th century movement Traditional medicine Traditional Knowledge Digital Library
Austin no-showed the Raw after WrestleMania and took a week-long break without the company's consent, citing exhaustion. Austin returned on the April 1 episode of Raw, the first of the new "brand extension" era. The show was centered around which show he would sign with, and he ultimately chose Raw. Austin entered a feud with The Undertaker that resulted in a number-one contender's match for the Undisputed WWF Championship at Backlash on April 21, which Austin lost. In a May interview on WWE's internet program, Byte This!, Austin stunned the company and fans by launching a verbal attack on the direction the company was heading in and slated the creative team for not using him the way he felt they previously did. The WWE rehired Eddie Guerrero for Austin to feud with, while also prepping Austin for a feud with Brock Lesnar. However, Austin balked at the proposition that he lose a King of the Ring qualifying match on Raw to Lesnar, and ultimately walked out of the company. Austin later explained that he thought hot-shotting a rookie made Austin look weak, and airing the match on free television with no build-up did not give Lesnar a proper stage for such a big win over a star of Austin's magnitude. Further fanning the flames among Austin's growing number of detractors was a well-publicized domestic dispute incident between Austin and his wife Debra (see below). After Austin again no-showed the June 10 episode of Raw, his storylines were immediately dropped.
=== Exploring commercial applications === Since the early 2000s, several companies and research laboratories have been working to develop commercial applications of graphene. In 2014, a National Graphene Institute was established with that purpose at the University of Manchester, with a £60 million initial funding. In North East England two commercial manufacturers, Applied Graphene Materials and Thomas Swan Limited have begun manufacturing. Cambridge Nanosystems is a large-scale graphene powder production facility in East Anglia.
=== Measurement methods === Traditional CRP measurement only detected CRP in the range of 10 to 1,000 mg/L, whereas high sensitivity CRP (hs-CRP) detects CRP in the range of 0.5 to 10 mg/L. hs-CRP can detect cardiovascular disease risk when in excess of 3 mg/L, whereas below 1 mg/L would be low risk. Traditional CRP measurement is faster and less costly than hs-CRP, and can be adequate for some applications, such as monitoring hemodialysis patients. Current immunoassay methods for CRP have similar precision to hsCRP performed by nephelometry and could probably replace hsCRP for cardiovascular risk assessment, however, in the United States this would represent off-label use, making it a laboratory-developed test under FDA regulations.
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.
TB-500 is a name used for a short synthetic peptide fragment taken from the actin-binding region of thymosin beta-4. Material sold under this label is usually a lyophilized powder supplied for laboratory research rather than a licensed medicine. The commonly cited sequence is LKKTETQ.