TB-500 and Thymosin Beta-4: A Research Overview

"TB-500" is one of the most common names in research-peptide catalogues, and one of the most loosely used. This overview explains what it refers to, what the science around thymosin beta-4 covers, and how to compare listings sensibly.

Thymosin beta-4 vs "TB-500"

Thymosin beta-4 (Tβ4) is a natural 43-amino-acid protein and one of the most abundant peptides inside mammalian cells. Its main known job is binding monomeric actin — the building block of the cytoskeleton — and controlling how much is available to form filaments.

TB-500 is a synthetic product name. It usually refers to a short fragment built around Tβ4's actin-binding region (the LKKTETQ motif), but definitions vary between suppliers. Some listings labelled TB-500 contain the full-length protein; others contain a fragment. That matters because the two have different masses, so the same "10 mg" label means a different number of molecules. Our separate TB4 listing covers the full-length form.

What the research looks at

Published work on thymosin beta-4 spans cell culture and animal models:

• Actin dynamics and cell migration. Tβ4 changes how readily cells crawl, which is measured in wound-closure and migration assays.
• Angiogenesis. Endothelial-cell tube-formation assays and related signalling.
• Cardiac fibrosis models. Some of the most cited Tβ4 work looks at scar formation and progenitor-cell activity in rodent heart-injury models. Interest centres on whether it shifts the balance between fibrosis and functional tissue repair.
• Inflammation. Effects on NF-κB signalling and cytokine expression in cell models.

Limits of the evidence

• Results with full-length Tβ4 do not automatically apply to short TB-500 fragments.
• Human clinical data are limited, and early trials of Tβ4 formulations did not lead to licensed medicines.
• Much online discussion mixes up the two forms and overstates the findings.

Comparing TB-500 listings in the UK

1. Confirm the exact sequence. Ask whether the vial contains full-length Tβ4 or a fragment, and check the mass-spec result matches.
2. Compare on price per mg, within the same form. See live prices on our TB-500 comparison page.
3. Check blends carefully. TB-500 often appears in blends with BPC-157. Compare per-component content, not the blend name. Our blends guide explains what to look for.
4. Request a batch-specific CoA. Generic or undated certificates are a warning sign.

Summary

Thymosin beta-4 is a well-characterised actin-binding protein with an interesting preclinical literature. "TB-500" is a less precise commercial label, so identity checks matter more than usual. PeptideCompare provides no dosing or usage guidance, and nothing here is for human or veterinary use.