Everything below concerns actin binding. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-07-11. 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.
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.
| 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 |
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.
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.
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography together with mass spectrometry. The chromatogram provides a purity estimate as a percentage of total peak area, while the mass spectrum confirms that the observed mass matches the expected value. Amino acid analysis or tandem mass spectrometry sequencing can provide additional confirmation. Reported purity figures depend on the column, gradient, and detection wavelength, so values from different laboratories are not directly comparable without method details.
Lyophilised peptide is normally reconstituted with sterile water or a neutral buffer shortly before use. Because repeated freeze-thaw cycles can degrade the material, dividing a reconstituted solution into single-use aliquots is a common practice. Working solutions are usually kept cold and protected from light. The exact shelf life depends on concentration, buffer composition, and handling, so it is often determined empirically rather than assumed.
Peptide bonds are susceptible to hydrolysis under extreme pH and to enzymatic cleavage if proteases are present. Heat, oxidising agents, and prolonged exposure to light also contribute to loss of material. Aggregation can occur at high concentrations or in certain buffer systems, and it may not be visible to the eye. Storage at -20 C or below is typical for both powder and aliquoted solutions, and desiccation of the powder is preferred.
Storage recommendations center on keeping the dry powder cold, dry, and dark. A freezer at -20 degrees Celsius or below is conventional, and desiccant is often included to limit moisture uptake. Once dissolved, the peptide is less stable, and solutions are typically kept frozen and thawed only once. Repeated freeze-thaw cycles are a common source of losses because they promote aggregation and adsorption to container surfaces. Working aliquots are therefore prepared in advance, and glass or low-binding plastic is usually preferred over ordinary laboratory plastic.
Identity and purity are assessed with a small set of standard techniques. Reverse-phase high-performance liquid chromatography gives a purity estimate from peak area, usually recorded at 214 or 220 nanometers, where the peptide bond absorbs. Mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidized species. Amino acid analysis or tandem mass spectrometry sequencing can verify the sequence itself. Additional quality attributes include water content, residual trifluoroacetic acid carried over from purification, and endotoxin where the material is intended for biological work.
The compound is most often distributed as a lyophilized powder, appearing white to off-white and forming a loose cake or fluffy solid. It is hygroscopic to some degree, so brief exposure to humid air can add water weight and complicate weighing. The peptide dissolves readily in water and in neutral aqueous buffers, and aqueous solubility is generally described as high, well above the concentrations used in typical assays. Some polar organic solvents are also usable, which matters when a concentrated stock is prepared before dilution into buffer.
6 September PAVN/VC rocket and mortar hit the training center of the National Police Field Force in Dalat, killing five trainees and wounding 26. North Vietnam announced that Ho Chi Minh would be succeeded by a committee consisting of Lê Duẩn, Trường Chinh, Võ Nguyên Giáp and Phạm Văn Đồng, in fact Lê Duẩn had effectively led the North Vietnamese government since 1964 with Ho being largely a figurehead.
== Prizes and honours == 1997, 1999 Merit scholarship to study Medical Laboratory Technology at Institute of Medicine, Tribhuvan University 2005 Gallwas membership Grant, AACC 2005 and 2007 International travel grant, AACC 2006 Young Achievers Award 2007 International Travel Grant, Asian & Pacific Federation of Clinical Biochemistry (APFCB) 2008 and 2010 KNU Honors Scholarship for Graduation Study (MS and PHD) 2012 Featured member of AACC, interview published at AACC website 2013 KNU Best Publication Award 2014 KNU Cell-Matrix Research Institute Winter Seminar Award
==== GABAA receptor positive allosteric modulators ==== Alpidem (Ananxyl; SL800342; SL-800342) – GABAA receptor positive allosteric modulator and nonbenzodiazepine/imidazopyridine – discontinued/withdrawn due to toxicity [43] Alprazolam (Xanax) – GABAA receptor positive allosteric modulator and benzodiazepine
As such, it appears that there may be species differences in the central penetration of bicalutamide and that the medication does indeed cross the blood–brain barrier and affect central function in humans. This is supported by potential side effects of bicalutamide, in spite of increased testosterone levels, like hot flashes and decreased sexual interest in men. However, a clinical study comparing bicalutamide and flutamide in men found that bicalutamide had less influence on the HPG axis than flutamide, suggesting that bicalutamide might have a limited degree of peripheral selectivity, at least compared to other NSAAs, in humans. Bicalutamide has been identified as a substrate of P-glycoprotein and of the breast cancer resistance protein (BCRP), though not of the multidrug resistance-associated protein 1 (MRP1). This may be involved in tumor resistance to bicalutamide. P-Glycoprotein is also known to play a major role in excluding drugs from the brain due to efflux back across the blood–brain barrier. It is known that there are prominent species differences in the role of P-glycoprotein in limiting permeation of P-glycoprotein substrates across the blood–brain barrier.
Sources: en.wikipedia.org
In this method, polyvinylpyrrolidone (PVP) is dissolved in water by sonication and mixed with silver colloid particles. Active stirring ensures the PVP has adsorbed to the nanoparticle surface. Centrifuging separates the PVP coated nanoparticles which are then transferred to a solution of ethanol to be centrifuged further and placed in a solution of ammonia, ethanol and Si(OEt4) (TES). Stirring for twelve hours results in the silica shell being formed consisting of a surrounding layer of silicon oxide with an ether linkage available to add functionality. Varying the amount of TES allows for different thicknesses of shells formed. This technique is popular due to the ability to add a variety of functionality to the exposed silica surface.
The Space Race (Russian: космическая гонка, romanized: kosmicheskaya gonka, IPA: [kɐsˈmʲitɕɪskəjə ˈɡonkə]) was a 20th-century competition between the Cold War rivals, the United States and the Soviet Union, to achieve superior spaceflight capability. It had its origins in the ballistic missile-based nuclear arms race between the two nations that followed World War II and the onset of the Cold War. The technological advantage demonstrated by spaceflight achievement was seen as necessary for national security, particularly in regard to intercontinental ballistic missile and satellite reconnaissance capability, but also became part of the cultural symbolism and ideology of the time. The Space Race brought pioneering launches of artificial satellites, robotic landers to the Moon, Venus, and Mars, and human spaceflight in low Earth orbit and ultimately to the Moon. Public interest in space travel originated in the 1951 publication of a Soviet youth magazine and was promptly picked up by US magazines. The competition began on July 29, 1955, when the United States announced its intent to launch artificial satellites for the International Geophysical Year. Five days later, the Soviet Union responded by declaring they would also launch a satellite "in the near future". The launching of satellites was enabled by developments in ballistic missile capabilities since the end of World War II. The competition gained Western public attention with the "Sputnik crisis", when the USSR achieved the first successful satellite launch, Sputnik 1, on October 4, 1957.
Night sweats, also known as nocturnal hyperhidrosis, is the occurrence of excessive sweating during sleep. The person may or may not also perspire excessively while awake. One of the most common causes of night sweats in women over 40 is the hormonal changes related to menopause and perimenopause. This is a very common occurrence during the menopausal transition years. While night sweats might be relatively harmless, it can also be a sign of a serious underlying disease. It is important to distinguish night sweats due to medical causes from those that occur simply because the sleep environment is too warm, either because the bedroom is unusually hot or because there are too many covers on the bed. Night sweats caused by a medical condition or infection can be described as "severe hot flashes occurring at night that can drench sleepwear and sheets, which are not related to the environment". Some of the underlying medical conditions and infections that cause these severe night sweats can be life-threatening and should promptly be investigated by a medical practitioner.
==== Cardiotoxins / Cytotoxins ==== Cardiotoxins are components that are specifically toxic to the heart. They bind to particular sites on the surface of muscle cells and cause depolarisation → the toxin prevents muscle contraction. These toxins may cause the heart to beat irregularly or stop beating, causing death. An example is the three-fingered cardiotoxin III from Chinese cobra, an example of the short three-fingered family (InterPro: IPR003572). Snake example: mambas, and some Naja species
== Early life == Carlisle was selected by Essendon with pick 24 in the 2009 National Draft. Like fellow draftee Jake Melksham, he is a local to the Essendon area. He played with the Calder Cannons in the TAC Cup and Craigieburn in the EDFL. He represented Vic Metro in the 2009 AFL National Under 18 Championships and was part of the 2009 Premiership team.
Sources: en.wikipedia.org
=== LSD substitute overdose === Although LSD is relatively safe in overdose, 25-NB (NBOMe) psychedelics like 25I-NBOMe and 25B-NBOMe are often sold as "LSD" and are highly toxic in overdose, with many reported severe intoxications and deaths. Owing to their high potency analogous to LSD, these drugs are also regularly sold as "LSD" in blotter papers. Fatalities involved in NBOMe intoxication suggest that a significant number of individuals ingested the substance which they believed was LSD, and researchers report that "users familiar with LSD may have a false sense of security when ingesting NBOMe inadvertently". Researchers state that the alleged physiological toxicity of LSD is likely due to psychoactive substances other than LSD. NBOMe compounds are reported to have a bitter taste, are not active orally, and are usually taken sublingually. When NBOMes are administered sublingually, numbness of the tongue and mouth followed by a metallic chemical taste was observed, and researchers describe this physical side effect as one of the main discriminants between NBOMe compounds and LSD. Despite its high potency, recreational doses of LSD have only produced low incidents of acute toxicity, but NBOMe compounds have extremely different safety profiles. Testing with Ehrlich's reagent gives a positive result for LSD and a negative result for NBOMe compounds.
Asymmetric Catalysis: Wennemers led the development of tripeptides containing H-Pro-Pro-Xaa type sequences (Pro: proline, Xaa: any amine) as organocatalysts for C–C bond formations based on an enamine mechanism. High reactivity, stereo- and chemoselectivity for aldol or conjugate addition reactions can be achieved by varying the absolute configuration of the single amino acids as well as the functional group of the Xaa residue. The modularity of the peptides enabled creation of catalysts capable of catalyzing the conjugate addition reactions of aldehydes to nitroolefins with as little as 0.05 mol% of tripeptidic catalyst. She also worked on other organocatalyzed transformations. Inspired by natural polyketide synthases—which use malonic acid half thioesters (MAHTs) as thioester enolate equivalents — she developed organocatalytic methods for stereoselective addition reactions of MAHTs (and protected variants monothiomalonates, MTMs) to electrophiles using cinchona alkaloid derived catalysts. The introduction of fluorinated MAHTs and MTMs allowed for the stereoselective introduction of fluorine substituents in fluoroacetate aldol reactions as well as further addition reactions to imines and nitroolefins.
Matrix metalloproteinases (MMPs), also known as matrix metallopeptidases or matrixins, are metalloproteinases that are calcium-dependent zinc-containing endopeptidases; other family members are adamalysins, serralysins, and astacins. The MMPs belong to a larger family of proteases known as the metzincin superfamily. Collectively, these enzymes are capable of degrading all kinds of extracellular matrix proteins, but also can process a number of bioactive molecules. They are known to be involved in the cleavage of cell surface receptors, the release of apoptotic ligands (such as the FAS ligand), and chemokine/cytokine inactivation. MMPs are also thought to play a major role in cell behaviors such as cell proliferation, migration (adhesion/dispersion), differentiation, angiogenesis, apoptosis, and host defense. They were first described in vertebrates in 1962, including humans, but have since been found in invertebrates and plants. They are distinguished from other endopeptidases by their dependence on metal ions as cofactors, their ability to degrade extracellular matrix, and their specific evolutionary DNA sequence.
==== Cancer ==== A meta-analysis of observational studies has determined an association between benzodiazepine use and cancer, though the risk across different agents and different cancers varied significantly. In terms of experimental basic science evidence, an analysis of carcinogenetic and genotoxicity data for various benzodiazepines has suggested a small possibility of carcinogenesis for a small number of benzodiazepines.
In 1998 Andrew Wakefield et al. published a fraudulent paper about twelve children, reportedly with bowel symptoms and autism or other disorders acquired soon after administration of MMR vaccine, while supporting a competing vaccine. In 2010, Wakefield's research was found by the General Medical Council to have been "dishonest", and The Lancet fully retracted the paper. Three months following The Lancet's retraction, Wakefield was struck off the UK medical register, with a statement identifying deliberate falsification in the research published in The Lancet, and was barred from practising medicine in the UK. The research was declared fraudulent in 2011 by the British Medical Journal. Since Wakefield's publication, multiple peer-reviewed studies have failed to show any association between the vaccine and autism. The US Centers for Disease Control and Prevention, the Institute of Medicine of the US National Academy of Sciences, the UK National Health Service and the Cochrane Library review have all concluded that there is no evidence of a link. Administering the vaccines in three separate doses does not reduce the chance of adverse effects, and it increases the opportunity for infection by the two diseases not immunized against first. However, on August 10, 2026, US president Donald Trump signed an executive order requiring the MMR vaccine to be split into three separate shots, and recommending that "to the maximum extent feasible, all childhood immunizations should be administered at separate medical visits".
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.
No. Thymosin beta-4 is a 43-residue protein, while TB-500 refers to a seven-residue fragment corresponding to its N-terminal region. The two names are often used loosely in commercial and community writing, which obscures the difference in size, sequence, and likely behavior.