TB-500: A Reference on the Thymosin Beta-4 Fragment

TB-500 is a synthetic peptide derived from a sequence in Thymosin Beta-4 (Tβ4) — one of the most abundant proteins in mammalian cells. The “TB-500” designation refers to a 17-amino-acid fragment that reproduces much of Tβ4’s apparent activity in research models without the full protein’s manufacturing complexity.

Structure

The sequence: Ac-LKKTETQ (acetylated N-terminus) — the central actin-binding domain of Tβ4, with C-terminal acetylation for synthesis stability. Full Tβ4 is 43 amino acids; TB-500 reproduces the most-studied functional region.

Proposed mechanism

In published research:

• Actin sequestration. Tβ4 (and TB-500’s central region) binds G-actin, modulating actin polymerization dynamics — a key process in cell migration and wound contraction.
• Cell migration. Tβ4 is upregulated in tissue undergoing repair and appears to promote endothelial-cell migration in angiogenesis assays.
• Inflammatory modulation. Decreased pro-inflammatory cytokine expression has been reported in wound-healing rodent models.
• Anti-fibrotic effects. TB-500 has been studied in cardiac-injury models for fibrosis modulation.

Half-life

Plasma half-life in animal models is short — minutes after IV administration. Like BPC-157, observed effects in tissue persist beyond what plasma kinetics suggest, consistent with local-tissue persistence or downstream signaling.

Why it pairs with BPC-157

The two compounds have complementary mechanisms in published tissue-research:

• BPC-157 modulates angiogenesis through nitric oxide pathways
• TB-500 modulates cell migration through actin dynamics

The combination is the most-cited tissue-research peptide pair in animal-model literature for tendon, ligament, and gastric-tissue work.

Sourcing notes

Purity figures from reference suppliers should be >98% HPLC. TB-500 is acetate-salt by convention (the TFA standard interferes with downstream assays in some configurations). Mass-spec confirmation should match theoretical molecular weight closely.

The peptide is stable in lyophilized form at -20°C. Reconstituted, 4°C is the standard storage temperature; 28 days is the conventional bacteriostatic-water window.

For pairing notes, see What Is BPC-157.