actin-binding fragment raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-05-29 and is reviewed periodically as new material appears.
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.
Laboratory work on thymosin beta-4 describes binding to monomeric actin and effects on cell migration, angiogenesis, and inflammatory signaling in cultured cells. Animal models have examined skin, corneal, and cardiac repair after injury, with outcomes reported mainly in preclinical literature. Most of that evidence concerns the parent protein rather than preparations labelled TB-500, so extrapolation from animal findings to a specific commercial product remains uncertain. Whether the two behave identically in living systems has not been established in controlled human studies.
No major regulatory agency has approved TB-500 for therapeutic use, and it holds no pharmacopoeial monograph. The name appears on the World Anti-Doping Agency prohibited list within the class covering peptide hormones, growth factors, and related substances. Detection in doping control relies on mass spectrometric methods applied to urine, often after preparation steps that concentrate the analyte. Discussion of TB-500 therefore clusters in biochemistry, sports medicine, and anti-doping literature rather than in registered clinical trials.
| Property | Value | Notes |
|---|---|---|
| Molecular mass | ≈889 Da for the 7-residue fragment | Full-length thymosin beta-4 is ≈4.9 kDa; catalogs differ |
| Appearance | White to off-white powder | Hygroscopic; weight shifts with residual moisture |
| Solubility class | Freely soluble in water | Also dissolves in aqueous buffers; poorly soluble in nonpolar solvents |
| Typical storage temperature | −20 °C, desiccated, protected from light | Once rehydrated, short-term holding at 2-8 °C |
| Typical analytical method | Reversed-phase HPLC with mass spectrometry | Purity by UV absorbance; identity by ESI-MS or MALDI-TOF |
Lyophilized peptide arrives as a dry cake that should stay sealed until use. Reconstitution is generally performed with sterile water or a buffered solution, and the resulting liquid should be handled gently to limit mechanical stress. Repeated freeze-thaw cycles are widely described as harmful to short peptides, so dividing a reconstituted batch into single-use portions is a common practice. Laboratories also record the solvent, concentration, and date of preparation on the vial label to keep later measurements traceable.
Dry powder is commonly held at minus twenty degrees Celsius, with some suppliers recommending lower temperatures for long-term archival storage. Once dissolved, solutions are typically kept cold and protected from light, since aqueous peptide solutions can lose integrity through hydrolysis or oxidation over time. Stability data specific to this fragment are limited in the public literature, and much of the guidance comes from general peptide handling practice rather than from controlled degradation studies. Users therefore treat stated shelf lives as approximate rather than fixed.
Identity and purity are normally assessed with reversed-phase high-performance liquid chromatography, paired with mass spectrometry to confirm molecular mass. A certificate of analysis reports a purity percentage, usually derived from chromatographic peak area, but that figure does not by itself prove a correct sequence or the absence of counterions. Independent verification may include amino acid analysis or peptide mapping. Batch-to-batch variation is a documented concern in the research chemical market, and the gap between a quoted purity value and actual peptide content can be substantial when the material is a salt or retains residual water.
Discussion of the compound frequently appears alongside other short peptides described as fragments of larger proteins. That grouping is convenient but can be misleading, because fragment length, charge, and modification state determine how a peptide behaves in solution and in any experimental system. A seven-residue acetylated peptide and a full-length protein differ in mass by roughly an order of magnitude, and they cannot be assumed to share distribution or binding properties. Precision about which molecule is under discussion is the single most useful step when reading such material.
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.
The existence of intermolecular forces was first postulated by Johannes Diderik van der Waals in 1873. However, Nobel laureate Hermann Emil Fischer developed supramolecular chemistry's philosophical roots. In 1894, Fischer suggested that enzyme–substrate interactions take the form of a "lock and key", the fundamental principles of molecular recognition and host–guest chemistry. In the early twentieth century non-covalent bonds were understood in gradually more detail, with the hydrogen bond being described by Latimer and Rodebush in 1920. With the deeper understanding of the non-covalent interactions, for example, the clear elucidation of DNA structure, chemists started to emphasize the importance of non-covalent interactions. In 1967, Charles J. Pedersen discovered crown ethers, which are ring-like structures capable of chelating certain metal ions. Then, in 1969, Jean-Marie Lehn discovered a class of molecules similar to crown ethers, called cryptands. After that, Donald J. Cram synthesized many variations to crown ethers, on top of separate molecules capable of selective interaction with certain chemicals. The three scientists were awarded the Nobel Prize in Chemistry in 1987 for "development and use of molecules with structure-specific interactions of high selectivity". In 2016, Bernard L. Feringa, Sir J. Fraser Stoddart, and Jean-Pierre Sauvage were awarded the Nobel Prize in Chemistry, "for the design and synthesis of molecular machines".
== Research == Breastfeeding research continues to assess prevalence, HIV transmission, pharmacology, costs, benefits, immunology, contraindications, and comparisons to synthetic breast milk substitutes. Factors related to the mental health of the nursing mother in the perinatal period have been studied. While cognitive behavior therapy may be the treatment of choice, medications are sometimes used. The use of therapy rather than medication reduces the infant's exposure to medication that may be transmitted through the milk. In coordination with institutional organisms, researchers are also studying the social impact of breastfeeding throughout history. Accordingly, strategies have been developed to foster the increase of the breastfeeding rates in the different countries.
Adenosine monophosphate deaminase deficiency type 1 or AMPD1, is a human metabolic disorder in which the body consistently lacks the enzyme AMP deaminase, in sufficient quantities. This may result in exercise intolerance, muscle pain and muscle cramping. The disease was formerly known as myoadenylate deaminase deficiency (MADD). In virtually all cases, the deficiency has been caused by an SNP mutation, known as rs17602729 or C34T. While it was initially regarded as a recessive (or purely homozygous) disorder, some researchers have reported the existence of similarly deleterious effects from the heterozygous form of the SNP. In the homozygous form of the mutation, a single genetic base (character) has been changed from cytosine ("C") to thymine ("T") on both strands of Chromosome 1 – in other words, "C;C" has been replaced by "T;T". A rarer but analogous condition, in which two guanine bases ("G;G") bases (in the unmutated form) have been changed to adenine ("A;A") has also been identified. While there has been no consensus on the effects of the heterozygous form – either "C;T" or "A;G" – some evidence has been found that it too has caused AMPD1 deficiency. In addition, some sources have suggested the existence of a rare, acquired form of AMPD1 deficiency. AMPD1 deficiency is caused by a defect in the mechanism for production of AMP deaminase – an enzyme that converts adenosine monophosphate (AMP) to inosine monophosphate (IMP).
A typical Indian meal is built on a plain cereal, complemented by savoury dishes. The cooked cereal could be steamed rice; chapati, a thin unleavened bread; idli, a steamed breakfast cake; or dosa, a griddled pancake. The savoury dishes might include lentils, pulses, vegetables, meat, poultry and fish commonly spiced with ginger and garlic, but also coriander, cumin, turmeric, cinnamon, cardamom and others. In some instances, the ingredients may be mixed during the cooking process. India has distinctive vegetarian cuisines, each a feature of the geographical and cultural histories of its communities. About 20% to 39% of India's population consists of vegetarians. Although meat is eaten widely, the proportional consumption of meat is low. The most significant import of cooking techniques into India during the last millennium occurred during the Mughal Empire, spreading into northern India from regions to its northwest, along with dishes such as pilaf. Onions, garlic, almonds, and spices were added to the simple yogurt marinade of Persia. Rice was partially cooked and layered alternately with sauteed meat, the pot sealed tightly, and slow cooked according to another Persian cooking technique, to produce biryani, a feature of festive dining in many parts of India. The diversity of Indian food served worldwide has been partially concealed by the dominance of Punjabi cuisine.
Sources: en.wikipedia.org
This is a list of investigational substance-related disorder drugs, or drugs that are currently under development for clinical use for the treatment of substance-related disorders but are not yet approved. Substance-related disorders include substance use disorders like alcoholism (alcohol use disorder), amphetamine use disorder, cocaine use disorder, nicotine use disorder, and opioid use disorder, among others. In addition, they include substance withdrawal syndromes like alcohol withdrawal and opioid withdrawal as well as substance overdoses like opioid overdose. Chemical/generic names are listed first, with developmental code names, synonyms, and brand names in parentheses. The format of list items is "Name (Synonyms) – Mechanism of Action – Indication [Reference]". This list was last comprehensively updated in January 2026. It is likely to become outdated with time.
A similar stele fragment (ES 1027), 57 centimeters high by 42 centimeters wide by 20 deep, depicting Naram-Sin was found a few miles north-east of Diarbekr, at Pir Hüseyin in a well, though this was not its original context. It is said to have been first found in Miyafarkin, a village about 75 kilometers northeast of Diarbekr. Fragments of an alabaster stele representing captives being led by Akkadian soldiers is sometimes attributed to Narim-Sin (or Rimush or Manishtushu) on stylistic grounds. In particular, it is considered as more sophisticated graphically than the steles of Sargon of Akkad or those of Rimush or Manishtushu. Two fragments (IM 55639 and IM 59205) are in the National Museum of Iraq, and one (MFA 66.89) is the Boston Museum. The stele is quite fragmentary, but attempts at reconstitution have been made. Depending on sources, the fragments were excavated in Wasit, al-Hay district, Wasit Governorate, or in Nasiriyah, both locations in Iraq. It is thought that the stele represents the result of the campaigns of Naram-Sin to Cilicia or Anatolia. This is suggested by the characteristics of the booty carried by the soldiers in the stele, especially the metal vessel carried by the main soldier, the design of which is unknown in Mesopotamia, but on the contrary well known in contemporary Anatolia.
The first two bus operating contracts for the new Weaver Network were awarded in September 2026 to FirstGroup, covering Huddersfield and parts of Leeds, and Transdev Blazefield, covering Dewsbury. In October 2021, £830 million of funding was announced for the West Yorkshire Combined Authority through the City Region Sustainable Transport Settlement, including funding to develop mass transit proposals for the region. Consultation was undertaken between July and September 2024 on proposed tram routes linking Bradford and Leeds, and St. James Hospital, central Leeds and White Rose Shopping Centre. Following a review by the National Infrastructure and Service Transformation Authority, the programme was moved to a more sequential approach intended to reduce delivery risk, contributing to a delay in the expected timetable for the scheme.
Sources: en.wikipedia.org
Ren H, Han R, Chen X, Liu X, Wan J, Wang L, Yang X, Wang J (May 2020). "Potential therapeutic targets for intracerebral hemorrhage-associated inflammation: An update". J Cereb Blood Flow Metab. 40 (9): 1752–68. doi:10.1177/0271678X20923551. PMC 7446569. PMID 32423330.
== Pharmacokinetics == Cinnarizine is most commonly taken orally, in tablet form, with frequency and amount of dosage varying depending on the reason for taking the medication. Once ingested, the substance is absorbed quite rapidly and reaches a peak plasma concentration in 1–3 hours post-administration. Cmax, the maximum level of the drug in the tested area (typically blood plasma), has been measured to be 275 ± 36 ng/mL; tmax, the time to maximum concentration, was 3.0 ± 0.5 hours. AUC∞, which can be used to estimate bioavailability, was 4437 ± 948 ng·h/mL. The half-life elimination varies from 3.4–60 hours, depending on age. However, the mean terminal half-life elimination for young volunteer subjects administered 75 mg cinnarizine, was found to be 23.6 ± 3.2 hours. A study that administered 75 mg doses of cinnarizine, twice a day for twelve days, to healthy volunteers, observed that cinnarizine did accumulate in the body, with a steady-state accumulation factor of 2.79 ± 0.23. However, the AUCT for this amount of time (T=12 days) was not significantly different from the AUC∞, which was estimated from the single dose administration. As a very weakly basic and also lipophilic compound with low aqueous solubility, cinnarizine is able to cross the blood brain barrier by simple diffusion. It is because of this property that it is able to exert its effects on cerebral blood flow in the brain. Bioavailability of orally administered cinnarizine is typically low and variable due to high incidence of degradation.
Executive mental function was measured with standard tests, including the ability to say the sequence 1-A, 2-B, 3-C..., to name a number of animals in one minute, and with the Stroop test. The study found that those individuals with lower skeletal muscle mass at the start of the study declined in their executive mental function considerably more sharply than those with higher muscle mass. Memory, as well as psychomotor speed, on the other hand, did not correlate with skeletal muscle mass. Thus, larger muscle mass, with a concomitantly larger secretome, appeared to have the endocrine function of protecting the executive mental function of individuals over the age of 65.
Clinical: International assessment of diagnostics and therapy with the aim of improving clinical understanding and treatment procedures. Clinical-translational: Analysis of the significance of plasma and urine steroid profiles / liquid biopsy with the aim of identifying suitable tumor markers. Experimental: Identification of immunohistochemical characteristics and DNA sequencing with the aim of identifying drugable targets, i.e., targets for the drug treatment of tumor cells. This should ensure that healthy cells are spared from the drug as much as possible.
Sources: en.wikipedia.org
Usually not, though usage overlaps. The label most often refers to a short acetylated fragment of the parent protein, while thymosin beta-4 itself is the full 43-residue molecule. Because suppliers vary, a sequence statement is needed to settle the question for any particular lot.
The name is a commercial label rather than a systematic chemical designation, so different vendors and papers attach it to different sequences. Some treat it as a fragment and others as the whole protein. Comparing two reports therefore requires checking what each one actually analyzed.
Typically it reflects the relative area of the main peak in a reversed-phase chromatogram at a given wavelength. It does not confirm the amino acid sequence, the counter-ion, or the amount of peptide by mass. Identity is normally established by a separate mass measurement.
Not necessarily. TB-500 is a commercial label that suppliers apply to synthetic peptides described as thymosin beta-4 or a fragment of it. Published research most often studies the full-length protein, so statements about one do not automatically transfer to the other.