Thymosin Beta-4 (TB-500)
Naturally occurring 43-amino-acid actin-sequestering peptide (synthetic form)
Also known as Tβ4, Thymosin β4, TB-500, TB4
A 43-amino-acid peptide present in most mammalian cells, where it is the principal sequestering protein for monomeric actin. Synthetic thymosin β4 and its fragments are widely used in cell-migration, cardiac and dermal wound-healing research.
Technical information
Values are shown with their status. “Verified” means the value has been checked against a primary database such as PubChem.
- Classification
- Naturally occurring 43-amino-acid actin-sequestering peptide (synthetic form)
- CAS number
- 77591-33-4 Pending
- Molecular formula
- C212H350N56O78S Pending
- Molecular weight
- 4963.4 g/mol Pending
- Sequence / structure
- Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES (N-terminally acetylated, 43 aa) Pending
Some values are still being checked and should be treated as provisional until marked verified.
How this compound is tested
A 43-residue peptide requires LC-MS with adequate mass resolution to confirm identity; the acetylated N-terminus should be reflected in the observed mass. HPLC purity should be read together with the counter-ion and water content where the laboratory reports them.
Research background
Thymosin β4 is an abundant intracellular peptide first isolated from calf thymus. Its best-characterised biological role is binding monomeric (G-) actin, thereby regulating actin polymerisation and cytoskeletal dynamics. Because of this role it has been studied extensively in cell migration, angiogenesis and tissue remodelling.
"TB-500" is a trade-style name used in research-supplier catalogues; it is generally described as synthetic thymosin β4 or a fragment thereof. Researchers should confirm from the batch documentation whether a given material is the full 43-residue peptide or a shorter fragment, as these are not interchangeable.
Mechanisms investigated in published research
These are the mechanisms examined in the cited literature. Describing them is not a claim that the compound produces any effect in humans.
- Actin sequestration — the central actin-binding motif (LKKTET) regulates the pool of polymerisation-competent actin.
- Cell migration and integrin-linked kinase (ILK) signalling — reported in cardiac cell models (Bock-Marquette et al., 2004).
- Angiogenesis and endothelial cell behaviour — investigated in vitro and in rodent models.
- Anti-inflammatory signalling — reduction of inflammatory mediators reported in several preclinical injury models.
Summary of evidence
Laboratory and animal findings are kept separate from human clinical evidence.
Preclinical findings
1 cited- Mouse myocardial-infarction models reported improved cardiac cell survival and function with thymosin β4 (Bock-Marquette et al., 2004).
- Dermal wound models in rodents reported accelerated closure.
- Corneal injury models reported effects on epithelial cell migration.
Human clinical evidence
Clinical investigation has been limited to early-phase trials of pharmaceutical-grade thymosin β4 formulations in specific indications (for example, ophthalmic formulations for corneal conditions and topical formulations for wounds). These studies concern regulated investigational products and do not establish safety or efficacy for research-grade material. Thymosin β4 is not an approved medicine in the UK, EU or US as of the date of this profile.
Limitations and open questions
- Many supplier materials labelled "TB-500" are not fully characterised as full-length thymosin β4; identity must be confirmed by mass spectrometry.
- Clinical data relate to pharmaceutical formulations in narrow indications.
- The peptide is prohibited in sport under the WADA list.
Scientific references
Publications cited on this page. Links open the publisher or PubMed record.
[1]Bock-Marquette I, Saxena A, White MD, DiMaio JM, Srivastava D. Thymosin β4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature (2004).
Preclinical Citation pendingMouse myocardial infarction model and cell studies.
[2]Goldstein AL, Hannappel E, Kleinman HK. Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends in Molecular Medicine (2005).
Review Citation pending
Research use only
Thymosin Beta-4 (TB-500) is described here for laboratory research. It is not approved for human or veterinary use unless a regulator has said otherwise, and nothing on this page is medical advice or guidance on administration. A disclaimer does not by itself make any activity lawful. Full disclaimer.
Contact options
Talk to the Positive Peptides team about Thymosin Beta-4 (TB-500)
Order enquiries, documentation requests and technical questions about this compound — we answer directly, usually within two working days.
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