Peptide Reference Desk
Thymosin Beta-4 vs TB-500: full-length protein, fragment, or an unresolved label?
TB-500 is used inconsistently across catalogs. A reliable comparison starts with the disclosed sequence rather than assuming it means full-length Thymosin Beta-4.
TB-500 is not a sufficient structure
Thymosin Beta-4 is a defined 43-residue peptide. TB-500 is a marketplace and research label that may be used for full-length material, an acetylated short fragment or a product with no complete sequence disclosed. Those possibilities cannot share one molecular-weight field.
A simple triage rule
- If the complete sequence is present, calculate the expected mass.
- If only a fragment name appears, request residue boundaries and termini.
- If neither is available, mark identity unresolved.
Do not infer the structure from “synthetic Thymosin Beta-4” in marketing copy.
Evidence follows the construct
Actin-binding, cell-migration and tissue-model studies on full-length Thymosin Beta-4 do not automatically apply to a shorter fragment. Conversely, a fragment experiment should not be summarized as though it tested the native-length peptide.
LC-MS, peptide mapping, HPLC and net content should all refer to the same disclosed construct and lot.
Verify with primary records
Use the primary paper, current regulator label or lot-linked analytical file for the claim it supports. A search result is a route to evidence, not the evidence itself.