TB-500: The Thymosin Beta-4 Fragment, Explained

TB-500 is one of those compounds where the label hides a subtlety: it isn’t Thymosin Beta-4 itself, but the synthetic fragment built around its active region. That distinction matters for understanding what it’s referenced for.

What the fragment actually is

Thymosin Beta-4 is a 43-amino-acid protein involved in actin regulation and cell motility. TB-500 — the version used in research — is the synthetic fragment containing its actin-binding domain. Think of it as the working part of the protein, isolated and stabilized for research use.

Its molecular weight works out to roughly 4,963 g/mol. That’s a heavy molecule compared to most peptides in the catalog — BPC-157, for comparison, is about 1,419 g/mol. When a protocol moves from mass to molar amounts, that difference shows up immediately, so the molecular weight calculator comes in handy.

Reconstitution and handling

TB-500 ships as a 5 mg lyophilized vial — identical reconstitution math to any other peptide:

• 5 mg + 2 mL bacteriostatic water → 2,500 µg/mL
• A 250 µg dose = 10 units on a U-100 syringe

The reconstitution calculator has the TB-500 preset. Storage is −20 °C lyophilized; reconstituted solutions go in the refrigerator and follow the COA window.

Research context

The fragment’s actin-binding domain puts it in cell migration, motility and tissue-repair pathway studies. See TB-500 for CAS, purity and full specifications, and the BPC-157 vs TB-500 comparison for how the two repair-pathway peptides differ.

For laboratory research use only. Not medical advice.