Everything below concerns synthetic peptide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Full-length thymosin beta-4 consists of roughly forty-three amino acids and ranks among the more abundant small proteins in the cytoplasm. The fragment is much shorter, so it cannot reproduce every function attributed to the intact molecule. In cell culture, short actin-binding motifs can interfere with filament dynamics and cell movement, but such observations come from controlled experiments rather than from whole-animal work. Whether a truncated fragment produces the same effects as the parent protein remains an open question.
Interest in the peptide grew during the 2000s and 2010s, when studies of tendon and ligament injuries in horses reported changes in lesion size after treatment. Those reports circulated widely outside the scientific literature and shaped much of the current online discussion. Subsequent reviews noted inconsistent study design, small groups, and a shortage of independent replication. Popular descriptions often blur the line between the fragment, the complete protein, and unrelated growth factors, which complicates comparisons across sources.
| Property | Value | Notes |
|---|---|---|
| Physical form | Lyophilised powder | Sealed vial; reconstituted before laboratory use |
| Appearance | White to off-white solid | Visual descriptor used on certificates of analysis |
| Solubility class | Water-soluble | Dissolves in water and aqueous buffers |
| Reported mass, fragment | Near 889 Da | Value depends on the stated sequence |
| Reported mass, parent protein | Near 4963 Da | 43-residue thymosin beta-4 |
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.
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.
Published research on the intact protein is substantial, covering actin regulation, cell migration, and wound models. Research using the heptapeptide fragment specifically is far smaller, and much of the circulating material originates in supplier documentation rather than peer-reviewed reports. Where fragment studies do exist, they often employ different sequences, chain lengths, or terminal modifications, which complicates direct comparison across papers. Readers encountering claims about TB-500 should therefore separate evidence about thymosin beta-4 from evidence about the fragment itself.
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.
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.
Dry peptide powder is commonly kept at −20 °C in a desiccated container away from light, a practice that limits moisture uptake and oxidation. Once dissolved, solutions are generally held at 2–8 °C for short periods or frozen at −20 °C or lower for longer storage, with repeated freeze-thaw cycles avoided. Hydrolysis and oxidation are the main degradation routes for peptides in solution, and both accelerate at higher temperature or extreme pH. Published stability data specific to TB-500 are limited, so shelf life should be treated as uncertain.
== Medical uses == Chlorpromazine is used in the treatment of both acute and chronic psychoses, including schizophrenia and the manic phase of bipolar disorder, as well as amphetamine-induced psychosis. Controversially, some psychiatric patients may be given chlorpromazine by force, even if they do not suffer any of the typical conditions the drug is prescribed for. In a 2013 comparison of fifteen antipsychotics in schizophrenia, chlorpromazine demonstrated mild-standard effectiveness. It was 13% more effective than lurasidone and iloperidone, approximately as effective as ziprasidone and asenapine, and 12–16% less effective than haloperidol, quetiapine, and aripiprazole. A 2014 systematic review carried out by Cochrane included 55 trials that compared the effectiveness of chlorpromazine versus placebo for the treatment of schizophrenia. Compared to the placebo group, patients under chlorpromazine experienced less relapse during 6 months to 2 years follow-up. No difference was found between the two groups beyond two years of follow-up. Patients under chlorpromazine showed a global improvement in symptoms and functioning. The systematic review also highlighted the fact that the side effects of the drug were 'severe and debilitating', including sedation, considerable weight gain, a lowering of blood pressure, and an increased risk of acute movement disorders. They also noted that the quality of evidence of the 55 included trials was very low and that 315 trials could not be included in the systematic review due to their poor quality.
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The first docking of Soviet spacecraft was finally realized in January 1969 by the Soyuz 4 and Soyuz 5 missions. It was the first-ever docking of two crewed spacecraft, and the first transfer of crew from one space vehicle to another.
Sources: en.wikipedia.org
=== Sexual dysfunction === Activation of 5-HT2C receptor subtype has been reported to mediate numerous effects, such as penile erection. Based on multiple studies, results show that several 5-HT2C receptor agonists, including mCPP and YM348 induce penile erections in rats, but mCPP seems to mimic both vasodilation and vasoconstriction. The vasodilator action is mediated by 5-HT1D receptors, whereas the vasoconstriction effect involves 5-HT2 receptor activation. YM-348 is a highly selective 5-HT2C agonist and results show that YM348 can induce penile erections and hypolocomotion (induced at a high dose) in rats, as did other 5-HT2C receptor agonists. These effects were completely inhibited by a selective 5-HT2C receptor antagonist, SB-242,084. Therefore, results suggest that YM348 is a potent and orally active 5-HT2C receptor agonist.
=== ROTOR === The British radar defences were rapidly run down during the last years of the war, with many sites closed and others placed on "care and maintenance". However, immediate postwar tensions with the Soviet Union resulted in recommissioning of some wartime radars as a stopgap measure. Specific radars were remanufactured to peacetime standards of quality and reliability, which gave significant increases in range and accuracy. These rebuilt systems were the first phase of Chain Home's replacement system, ROTOR, which progressed through three phases from 1949 to 1958. It had been pointed out from the start that due to the inherent timing of the interception task, about 23 minutes was required to carry out a single interception from initial detection. If the target was a high-speed jet bomber, this required about 240 miles (390 km) initial detection range. CH, even in its upgraded form, was barely capable of this under the best conditions. The GCI radars were not even close to this, and the entire ROTOR system relied on a new radar system becoming available by 1957 at the latest. In one of the few instances of this occurring, this requirement was actually beaten, with the first AMES Type 80 systems entering service in 1954. The very last Chain Home Type 1 systems were retired in 1955 along with the wholesale demolition of most of the steel and timber towers.
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Sources: en.wikipedia.org
No. TB-500 is a trade-style label used for a synthetic peptide described as a fragment of thymosin beta-4, while thymosin beta-4 is the full 43-residue protein. The two differ in size and are not interchangeable terms in analytical work.
Naming for research peptides is not standardised, and suppliers sometimes apply the same label to different chain lengths. Certificates of analysis and mass data are the practical way to determine what a given lot contains.
The fragment commonly cited under this label is reported near 889 Da, and the parent protein near 4963 Da. Reported values shift with the exact sequence and with residual counter-ions or water in the sample.
It is a synthetic peptide based on a short sequence near the start of thymosin beta-4. It is supplied as a research chemical rather than as a licensed pharmaceutical product.