TB500 (Thymosin B4 Acetate)

TB-500 here denotes full-length thymosin β4, an acetylated 43-residue peptide studied in actin binding and tissue-model research.

Identity

Sequence

Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES-OH

Residues

43

Molecular formula

C₂₁₂H₃₅₀N₅₆O₇₈S

Average molecular weight

4963 g/mol

Monoisotopic mass (calculated)

4960.4863 Da

CAS number

77591-33-4

PubChem CID

16132341

Strengths

5–10 mg

Other names

Thymosin beta-4 · Timbetasin

This product is listed as thymosin β4 acetate (TB500). TB-500 also names the synthetic 17–23 fragment Ac-LKKTETQ. This profile describes full-length thymosin β4.

Identity data from: PubChem CID 16132341

Research overview

TB-500 is used here for full-length thymosin β4: a 43-residue peptide with an acetylated amino terminus and a free carboxyl terminus. The name is also used for the synthetic seven-residue 17–23 fragment Ac-LKKTETQ. The biochemical paper cited here examined full-length thymosin β4 and established its identity with Fx, a peptide associated with unpolymerized actin in platelets [1].

In that study, the complete amino-acid sequence of purified Fx matched thymosin β4. The authors used nondenaturing polyacrylamide gel electrophoresis to identify a complex of Fx with muscle G-actin. Thymosin β4 formed a complex containing one peptide and one actin monomer, and complex formation inhibited actin polymerization under the experimental conditions. This biochemical work identified thymosin β4 as an actin-sequestering peptide [1].

The subsequent reviews discuss cell migration, tissue-injury models and experimental fibrosis research. The fibrosis review examines inflammatory cells, fibroblast-to-myofibroblast changes and extracellular-matrix organisation in animal models. It discusses macrophage-derived TGFβ alongside CTGF, PDGF and IL-10 as mediators in the fibrosis literature. It also considers Ac-SDKP, the amino-terminal fragment, in models involving liver, lung, heart and kidney fibrosis. Ac-SDKP and the 17–23 fragment Ac-LKKTETQ have different sequences. The broader review includes platelets, macrophages and stem/progenitor cells in its discussion of tissue biology [2][3].

Laboratory storage and handling

Store the sealed vial at the temperature specified in the lot documentation, protected from light and moisture. Allow the closed vial to reach room temperature before opening to limit condensation on the material. Avoid repeated freezing and thawing of laboratory stocks. Record the lot identifier and storage history with the experiment, and use standard laboratory protective equipment when handling the peptide.

Questions about TB-500

References

1. Thymosin beta 4 and Fx, an actin-sequestering peptide, are indistinguishable. J Biol Chem 1991. PMID 1999398
2. Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opin Biol Ther 2012. PMID 22074294
3. Thymosin β4 and the anti-fibrotic switch. Int Immunopharmacol 2023. PMID 36580759

Identity data checked on 2026-09-24. Literature summaries describe published research models and are not specifications of any product lot.