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TB-500

TB-500 (CAS 77591-33-4) is a synthetic peptide fragment corresponding to the active N-terminal actin-binding domain (amino acids 17–23, LKKTETQ) of thymosin beta-4, with a molecular weight of 889 Da and formula C₃₈H₆₈N₁₀O₁₄. This acetylated heptapeptide retains the potent actin-sequestering and cell migration-promoting properties of full-length thymosin β4 while being substantially shorter and more stable. TB-500 is a widely utilized research tool for studying cytoskeletal dynamics, cell motility, and tissue regeneration.

Technical Specifications

Property Value
CAS Number 77591-33-4
Molecular Formula C₃₈H₆₈N₁₀O₁₄
Molecular Weight 889 Da
Purity ≥99% (HPLC-verified)
Appearance Lyophilized white powder
Solubility Soluble in sterile water and aqueous buffers
Storage -20°C (lyophilized), 2–8°C (reconstituted)

Mechanism of Action

TB-500 functions primarily by binding to G-actin (globular actin) monomers through its highly conserved LKKTETQ motif, sequestering them and maintaining a pool of polymerization-competent actin. This lowers the critical concentration for actin filament assembly, promoting rapid actin polymerization at the leading edge of migrating cells — a prerequisite for directed cell migration, wound closure, and angiogenesis. Beyond actin binding, the TB-500 domain has been shown to activate the Akt (protein kinase B) signaling pathway in endothelial cells and keratinocytes, promoting cell survival and anti-apoptotic signaling. TB-500 also upregulates matrix metalloproteinase (MMP) expression, particularly MMP-2 and MMP-9, facilitating extracellular matrix remodeling necessary for cell migration through tissue. Angiogenesis is promoted via VEGF and HIF-1α pathway activation in endothelial progenitor cells. Critically, unlike full-length thymosin β4, TB-500 resists rapid degradation by endogenous proteases.

Research Applications

  • Primary: Cell migration and cytoskeletal dynamics — actin polymerization, wound healing
  • Secondary: Angiogenesis research, dermal wound repair models, cardiac and muscle repair after injury
  • Model Systems: In vitro (HUVEC tube formation assays, fibroblast scratch wound assays, dermal keratinocyte migration), in vivo rodent models (full-thickness excisional wounds, myocardial infarction models)

Quality Control & Analytical Methods

  • HPLC: ≥99% purity verification at 214/220 nm (C18 reversed-phase column)
  • Mass Spectrometry: ESI-MS for molecular weight confirmation (889 ±1.0 Da)
  • Peptide Content: Amino acid analysis (AAA) for net peptide content determination
  • Endotoxin: <1 EU/mg (LAL assay)
  • TFA Content: <1% (ion chromatography)

Stability & Storage

Condition Stability
-20°C (lyophilized) 24 months
4°C (lyophilized) 6 months
25°C (lyophilized) 1 month
Reconstituted (4°C) 7 days
Reconstituted (-20°C) 30 days

Key Research References

  • Philp et al. (2004) — Thymosin β4 promotes angiogenesis, wound repair, and hair follicle growth. Ann N Y Acad Sci. PMID: 15215923
  • Goldstein et al. (2012) — Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. PMID: 22982264
  • Smart et al. (2007) — Thymosin β4 facilitates epicardial neovascularization in the injured adult heart. Nature. PMID: 17529981

Source & Purchase

For researchers requiring research-grade TB 500 with full analytical documentation including HPLC, LC-MS, and Certificate of Analysis, visit the HK Peptides product page for specifications, bulk pricing, and ordering.

View TB 500 Product →

FAQ

Q: What purity level is standard for TB-500? A: HK Peptides supplies TB-500 at ≥99% purity by HPLC with full COA documentation.

Q: How should TB-500 be stored for research use? A: Lyophilized TB-500 should be stored at -20°C. Reconstituted solutions at 4°C for short-term use (up to 7 days).