Every TB-500 (Thymosin β4 fragment) Question Answered, in 21 Studies

21 referenced articles

• TB-500 Side Effects: No Human Safety Record Exists3 sources
• TB-500 Benefits: What Is Established and What Is Not3 sources
• What Is TB-500? The Heptapeptide and Its Parent Protein4 sources
• BPC-157 and TB-500 Together: What the Evidence Says3 sources
• TB-500: Names, Spellings and What Each Finds3 sources
• What Does TB-500 Stand For?2 sources
• Fragment Research: The Logic and Its Limits3 sources
• TB-500 in the Published Research3 sources
• Angiogenesis: What the Literature Reports3 sources
• Cell Migration: What the Studies Report3 sources
• TB-500 Half-Life and Clearance2 sources
• TB-500 Storage, Stability and Reconstitution3 sources
• TB-500 Molecular Structure and Physical Properties2 sources
• TB-500: Structure and Where It Comes From3 sources
• How Thymosin Beta-4 Was Discovered3 sources
• How Actin Sequestration Works3 sources
• LKKTETQ: The Actin-Binding Motif3 sources
• Fragment or Full Protein: Which the Research Uses3 sources
• TB-500 vs Thymosin Beta-43 sources
• TB-500 CAS Number and Chemical Identity3 sources
• TB-500 Molecular Weight, and the Figure That Is Wrong3 sources

Open research questions

• Is TB-500 the same as Thymosin Beta-4?
• How does TB-500 bind actin?
• What is the molecular weight of TB-500?
• How is TB-500 reconstituted for research?
• Is TB-500 legal to buy in the UK for research?

Deep dive: TB-500 vs full-length Thymosin Beta-4

'TB-500' is a synthetic peptide corresponding to the active 17-amino-acid actin-binding region of the endogenous 43-residue Thymosin Beta-4 protein. The two are not identical — TB-500 lacks the flanking sequence that gives full-length TB-4 additional binding partners. In the research literature, papers use 'Thymosin β4' when they mean the full protein and 'TB-500' or 'AcSDKP fragment' when they mean the shorter synthetic peptide. Reading a CoA carefully to see which molecule is in the vial matters — mass spec is the definitive check.

Actin-binding as the core mechanism

The N-terminal region of TB-4 (and TB-500 by inheritance) contains the canonical actin-binding motif. This motif sequesters G-actin monomers, modulating the G:F actin equilibrium in cell cultures. That mechanism is why almost every mechanistic paper on TB-500 traces back to cytoskeletal reorganisation, cell migration, and models of tissue repair.

Handling considerations unique to TB-500

TB-500 is a 17-residue peptide with modest amphipathicity; it reconstitutes cleanly in bacteriostatic water but is sensitive to repeated freeze/thaw. Aliquoting into single-use volumes on first reconstitution preserves potency across a batch. HPLC on the batch CoA should show a single dominant peak; a doublet suggests deamidation.

Handling checklist

• Store lyophilised vials at −20 °C long-term
• Reconstitute with bacteriostatic water (0.9% benzyl alcohol)
• Aliquot immediately to avoid freeze/thaw cycles
• Refrigerate reconstituted aliquots at 2–8 °C; use within 28 days
• Confirm mass (~4,963 Da for TB-500) via CoA before study use

Common mistakes

Assuming TB-500 = full Thymosin β4

TB-500 is the 17-residue actin-binding fragment; check the CoA sequence.

Repeated freeze/thaw

Aliquot at first reconstitution; each cycle degrades yield.

Using tap water

Use bacteriostatic or sterile water only.