Comparison
BPC-157 vs TB-500
Two sequences routinely catalogued together in tissue-model research, from entirely different structural origins — a 15-residue gastric-protein fragment against a 7-residue acetylated thymosin fragment.
Side by side
| Property | BPC-157 | TB-500 |
|---|---|---|
| CAS number | 137525-51-0 | 885340-08-9 |
| Molecular formula | C62H98N16O22 | C38H68N10O14 |
| Average molecular weight | 1,419.53 g/mol | 889.02 g/mol |
| Amino-acid count | 15 | 7 |
| Peptide class | linear pentadecapeptide | N-acetylated linear heptapeptide |
| Physical form | Lyophilized powder | Lyophilized powder |
| Research area | Tissue & matrix research | Tissue & matrix research |
| Solubility | Soluble in sterile or bacteriostatic water; consult the lot COA for solvent guidance | Soluble in sterile or bacteriostatic water; consult the lot COA for solvent guidance |
| Primary sequence | Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val | Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln |
Why these two get shelved together
BPC-157 and TB-500 appear side by side in nearly every research catalogue, and the pairing is a matter of category rather than chemistry. Structurally they have almost nothing in common.
BPC-157 is a 15-residue peptide with free termini, derived from a partial sequence of a gastric protein, notable for a proline-rich core. TB-500 is a 7-residue N-acetylated fragment corresponding to residues 17-23 of thymosin beta-4. One is more than twice the length and 1.6 times the mass of the other, and their sequences share no motif.
The nomenclature trap
TB-500 is routinely described as “synthetic thymosin beta-4.” The parent protein is 43 residues and roughly 4,960 g/mol; the fragment supplied under this name is 889 g/mol. A certificate quoting a mass near 4,960 for a product sold as TB-500 is describing a different molecule.
This is worth checking specifically when comparing suppliers, because vendor pages frequently quote the parent’s residue count alongside the fragment’s formula — an internal contradiction that indicates the description was not written from analytical data.
Handling differences
Both are water-soluble and neither carries cysteine, methionine or tryptophan, so both are chemically robust.
The practical divergence is charge. TB-500’s two lysines against one glutamate give it net positive character, so it carries more counterion mass and adsorbs more readily to negatively charged plastic at dilute concentrations. BPC-157, with two aspartates and a glutamate against one lysine, is mildly acidic and less adsorptive.
TB-500’s C-terminal glutamine is a slow deamidation site; BPC-157 has neither asparagine nor glutamine.