The Common Confusion
Search any peptide vendor catalog and you’ll find TB-500 listed interchangeably with Thymosin Beta-4 (Tβ4). Many vendors treat them as identical. They are not.
Thymosin Beta-4 (Tβ4)
Thymosin Beta-4 is a naturally-occurring 43-amino-acid peptide found in nearly all human and animal cells. It is one of the most abundant intracellular proteins, particularly concentrated in platelets, white blood cells, and wound tissue. Its primary documented role is binding G-actin and regulating actin sequestration.
TB-500
TB-500 is a synthetic peptide fragment representing the active region of Thymosin Beta-4 — specifically the sequence Leu-Lys-Lys-Thr-Glu-Thr-Gln (sometimes referred to as the actin-binding domain). It is significantly shorter than the full Thymosin Beta-4 molecule and easier to manufacture synthetically at scale via solid-phase peptide synthesis.
Why the Distinction Matters
For laboratory research, this distinction is critical. A research protocol calling for “Thymosin Beta-4” cannot simply be substituted with TB-500 without acknowledging the structural difference. The full 43-amino-acid Tβ4 has biological interactions and folding patterns that a 7-amino-acid fragment cannot replicate.
What VialPepLab Sells
Our TB-500 product is the synthetic fragment, identified clearly on the label and COA. We do not sell full Thymosin Beta-4 — the manufacturing complexity for a 43-amino-acid peptide at research scale is significantly higher and price points for genuine Tβ4 in research catalogs are correspondingly elevated. TB-500 sits in our Healing & Regeneration category alongside BPC-157 and related short peptides.
For Researchers
When designing a research protocol, specify which compound you need. “TB-500” and “Thymosin Beta-4” are not synonymous terms despite vendor conventions suggesting otherwise. If your protocol requires the full molecule, source it from a vendor that explicitly markets Thymosin Beta-4 (Tβ4) with the appropriate molecular weight (4,963 Da) verified on the COA.
For broader context on short regeneration peptides, see our pentadecapeptide family comparison. Storage guidance: storage protocols.