Is TB-500 the same as Thymosin Beta-4?

No — TB-500 is a fragment; full-length Tβ4 is a 43-residue protein.

No — it is investigational and prohibited in sport by WADA.

TB-500 (Thymosin β4 fragment)

What Is TB-500? Research Overview

JMWritten & reviewed by Jack Muncaster · Founder, UK PeptidesLast reviewed 2026-07-032 cited sources

TB-500 is a synthetic peptide corresponding to the active actin-binding region of Thymosin Beta-4 (Tβ4), a naturally occurring 43-residue protein. It is studied in the peer-reviewed literature primarily for actin sequestration, cell migration, and angiogenesis in in vitro and animal models.

Key facts

Class: Synthetic peptide fragment
Parent protein: Thymosin Beta-4 (Tβ4)
Active motif: Actin-binding LKKTETQ sequence
Status: Investigational — WADA prohibited in sport

Where does TB-500 come from?

Full-length Tβ4 was first isolated from calf thymus in 1981. TB-500 corresponds to the peptide's core actin-binding region and is chemically synthesised for research use.

What is it studied for?

Published research examines actin sequestration, cell migration, and angiogenesis, largely in in vitro cell models and animal studies of wound healing and tissue repair.

Research material referenced

TB-500 5mg — third-party HPLC tested

View — £23.99

Extended research context

The TB-500 (Thymosin β4 fragment) deep dive

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.

Research applications

▸In vitro actin-polymerisation assays (G:F actin ratio measurement)
▸Cell-migration and wound-scratch assays in fibroblast lines
▸Angiogenesis models: tube-formation and endothelial migration assays
▸Analytical method development for short peptides on RP-HPLC
▸Reference-material comparisons against endogenous Thymosin β4

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 research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Assuming TB-500 = full Thymosin β4

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

✗ Repeated freeze/thaw

Fix: Aliquot at first reconstitution; each cycle degrades yield.

✗ Using tap water

Fix: Use bacteriostatic or sterile water only.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Frequently asked questions

Is TB-500 the same as Thymosin Beta-4?: No — TB-500 is a fragment; full-length Tβ4 is a 43-residue protein.
Is TB-500 approved?: No — it is investigational and prohibited in sport by WADA.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

Written and reviewed by

Jack Muncaster · Founder, UK Peptides

Jack founded UK Peptides in Manchester after repeatedly receiving research compounds with missing or recycled paperwork. He is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate.

How we write and check this content Report a factual error in this article

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