TB-500 is the widely-studied bioactive fragment of thymosin β4 — an actin-sequestering peptide central to cytoskeletal and tissue-research literature. Full profile: structure, mechanism, stability and COA.
TB-500 corresponds to the bioactive fragment of thymosin β4 (Tβ4), a 43-residue actin-sequestering peptide that is one of the most abundant intracellular proteins in mammalian cells. TB-500 preserves the central LKKTETQ actin-binding motif, which is the mechanistic core referenced across cytoskeletal, angiogenesis and tissue-research literature.
This reference consolidates the structural identity of TB-500, the published in-vitro signalling profile, the mechanistic rationale for pairing with BPC-157 and the analytical documentation researchers should expect on the COA. All content is strictly research-use-only.
Structural identity
| Attribute | Value |
|---|---|
| Parent peptide | Thymosin β4 (Tβ4), 43 residues |
| Active motif | LKKTETQ (residues 17–23 of Tβ4) |
| Class | Actin-sequestering β-thymosin fragment |
| Disulfide bridges | None |
| Modifications | None (native fragment sequence) |
Published research signalling
| Reported activity | Model system | Reference axis |
|---|---|---|
| G-actin sequestration | Cell-free biochemistry | Cytoskeletal research |
| VEGF upregulation | Endothelial cultures | Angiogenesis research |
| PGE2 pathway modulation | Fibroblast cultures | Tissue-remodelling research |
| Cell migration promotion | Wound-model cultures | Tissue-model repair literature |
In-vitro and animal-model literature reports G-actin binding via the LKKTETQ motif, upregulation of VEGF and PGE2 pathways, and enhanced cell migration in cultured cell studies. These are model-system observations and do not establish human outcomes.
Why the LKKTETQ motif matters
The LKKTETQ heptapeptide is the minimum actin-binding element within Tβ4. Peer-reviewed structural work has mapped the interaction between this motif and G-actin monomers, providing the mechanistic basis for the actin-sequestering activity referenced throughout the TB-500 literature. Preservation of this motif is what distinguishes bioactive Tβ4 fragments from inactive truncations.
Stability & handling
- Lyophilised powder stable long-term at −20 °C, desiccated and light-protected.
- Reconstituted aqueous stocks typically retain integrity at 2–8 °C for short-term assay windows.
- Aliquot on reconstitution; avoid repeated freeze–thaw of working stocks.
Documentation checkpoints on a TB-500 COA
- Batch identifier and synthesis date traceable to the lot record
- HPLC purity ≥98% (typically ≥99% for peptides under 30 residues)
- LC-MS confirmed monoisotopic or average mass within ±0.5 Da of theoretical
- Counterion identity and content (acetate or trifluoroacetate) reported
- Bacterial endotoxin and residual solvents per the analytical method
What is TB-500?
TB-500 is the widely-studied bioactive fragment of thymosin β4 (Tβ4), a 43-residue actin-sequestering peptide. TB-500 preserves the central LKKTETQ actin-binding motif that is the mechanistic core of the Tβ4 literature.
Is TB-500 the same as thymosin β4?
No. Thymosin β4 is the full 43-residue parent peptide; TB-500 is the bioactive fragment that preserves the LKKTETQ actin-binding motif. In practical research use they are often referenced interchangeably, but they are structurally distinct.
What is the LKKTETQ motif?
LKKTETQ is the seven-residue actin-binding heptapeptide located at residues 17–23 of thymosin β4. Structural literature identifies it as the minimum motif required for G-actin sequestration, and it is preserved in TB-500.
What pathways does TB-500 engage in the published literature?
In-vitro literature reports G-actin sequestration via LKKTETQ, upregulation of VEGF and PGE2 pathways in cultured cells, and enhanced cell migration in wound-model cultures. All observations are within the model systems studied.
Why is TB-500 frequently paired with BPC-157?
TB-500 acts through actin sequestration while BPC-157 acts through VEGFR2/NO signalling. The two mechanisms are independent and non-overlapping, which is why they are commonly co-profiled in tissue-research protocols.
Is TB-500 approved for human use in New Zealand?
No. TB-500 is not an approved therapeutic in New Zealand. It is supplied strictly as a research-use-only reference standard for in-vitro laboratory work.
