TB-500 (Thymosin Beta-4) Testing
Synthetic Thymosin Beta-4; involved in actin sequestration and tissue repair.
Mechanism of action
Synthetic Thymosin Beta-4. Sequesters G-actin monomers via its β-thymosin domain, regulating cytoskeletal dynamics. Promotes endothelial cell migration, angiogenesis, and stem cell recruitment to injury sites. Sold under the name 'TB-500' in research markets; the actual molecule is full-length Thymosin β-4 — or sometimes only the active LKKTETQ fragment, which is much shorter and cheaper to make.
Sequence & structure
N-terminal acetylation is required for full activity. 'TB-500' sold without N-acetyl is technically a different molecule.
Research areas
- ●Tissue repair
- ●Cardiac regeneration (RegeneRx Phase 2 trials)
- ●Corneal wound healing
- ●Hair growth
Dosing in the literature
Veterinary use in racehorses is well-established at ~2 mg twice weekly. No FDA-approved human indication.
For research/informational purposes only — not medical advice.
What we test on TB-500 (Thymosin Beta-4)
Intact-mass LC-MS is the make-or-break test. RP-HPLC purity, N-acetyl confirmation by MS/MS, endotoxin for injectable lots.
- ✓RP-HPLC purity
- ✓MS/MS sequence confirmation
- ✓ICP-MS (Cu for GHK-Cu)
- ✓Endotoxin (LAL)
Common impurities & failure modes
- Active fragment substitution
The most common counterfeit: vendors ship the 7-residue LKKTETQ active fragment labeled as full-length TB-500. Intact mass immediately catches this (fragment is ~860 Da, full-length is ~4960 Da).
- Missing N-acetyl group
−42 Da shift; reduces activity.
- Truncation at Met residue
Methionine cleavage during synthesis.
- Oxidation of Met6
+16 Da shift.
Regulatory status
Not FDA-approved. Banned by WADA for athletic use.
Frequently asked questions
Is 'TB-500' the same as Thymosin Beta-4?+
Marketed as such, but check the molecular weight. Full-length is ~4963 Da. If your vial mass-specs at ~860 Da, you have the active fragment, not TB-500.