8 min read · updated 2026-08-21
BPC-157 and TB-500: Structural and Analytical Comparison
Two compounds routinely discussed together, with almost nothing structural in common.
Different origins entirely
BPC-157 is a synthetic fifteen-residue sequence corresponding to a partial region of a compound isolated from human gastric juice. TB-500 is a synthetic fragment corresponding to the actin-binding region of thymosin beta-4, a 43-residue actin-sequestering protein. Neither is derived from the other and they belong to unrelated protein families. The pairing in general discussion reflects overlapping research contexts rather than any structural relationship, which is worth stating plainly because the assumption that similar compounds behave similarly under storage and analysis does not hold here.
Size and composition
BPC-157 has a molecular weight of 1419.53 g/mol against a formula of C62H98N16O22, and is classified as a pentadecapeptide for its fifteen residues. TB-500 is substantially larger at 4963.44 g/mol. The size difference is not incidental to analysis: mass spectrometric identity confirmation of a compound near 1400 g/mol typically observes a different charge-state distribution than one near 5000 g/mol, and the adducts reported on a certificate will differ accordingly. A certificate reporting the same observed masses for both would be an error worth questioning.
Where the laboratory interest sits
Published investigation of BPC-157 centres on fibroblast migration assays measuring cell outgrowth, endothelial models measuring VEGFR2 expression and nitric oxide synthase pathway activity, and characterisation of stability under gastric conditions relative to peptides of comparable length. TB-500 work centres on G-actin binding, cytoskeletal reorganisation, and endothelial migration, with published models in corneal and cardiac tissue measuring migration distance. These are different mechanisms under investigation, not two routes to a common endpoint.
Analytical implications
Both are supplied lyophilised and both are analysed by RP-HPLC for purity and LC-MS for identity, but the figures they should produce differ. Sequence composition determines which degradation pathways are relevant, so storage guidance derived from one does not transfer to the other. BPC-157 contains multiple proline residues and an Asp-Asp motif; TB-500 has a different residue profile with correspondingly different oxidation and deamidation susceptibility. The practical consequence is that lot-specific data matters more than class-level generalisation for both.
Why they are grouped anyway
The pairing persists because both appear in the same research literature contexts and are frequently supplied by the same vendors, sometimes as a combined preparation. Neither fact establishes a structural or mechanistic relationship. A buyer evaluating either should read the certificate for the specific compound rather than treating documentation for one as informative about the other, and should note that a blended preparation carries no single CAS number, formula, or molecular weight because it is a mixture rather than a compound.
Frequently asked
Are BPC-157 and TB-500 related compounds?
No. BPC-157 is a fifteen-residue synthetic sequence derived from a gastric juice compound. TB-500 is a fragment of thymosin beta-4, a 43-residue actin-sequestering protein. They belong to unrelated families and differ substantially in size.
What are the molecular weights of each?
BPC-157 is 1419.53 g/mol with formula C62H98N16O22. TB-500 is 4963.44 g/mol. The difference affects the charge states and adducts observed in mass spectrometric identity confirmation.
Does a blended preparation have a CAS number?
No. A blend is a mixture rather than a single chemical substance, so it carries no single CAS number, molecular formula, or molecular weight. Identity confirmation for a blend addresses each component separately.
See the practice, not just the principle
Every lot we release is published in full — assay, method, and measured result — and the record stays online after the lot sells out.
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