TB-500 (Thymosin β4 fragment)
TB-500 vs Thymosin Beta-4: The Difference
Thymosin Beta-4 (Tβ4) is a naturally occurring 43-residue protein present in most human cells. TB-500 is a synthetic peptide fragment derived from Tβ4's actin-binding region. The two overlap functionally at that region but differ in molecular size and in reported behaviour in some models.
Key facts
- Tβ4
- 43-residue full-length native protein
- TB-500
- Synthetic fragment
- Overlap
- Actin-binding LKKTETQ region
Why the distinction matters
Research literature sometimes uses 'TB-500' and 'Tβ4' interchangeably. For rigorous citation, check whether a paper used full-length recombinant Tβ4 or a synthetic fragment.
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.
Related questions researchers ask
- 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?
Frequently asked questions
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.
- PubMedGoldstein & Hannappel reviewpubmed.ncbi.nlm.nih.gov
- PubMedGoldstein et al., Thymosin β4: a multi-functional regenerative peptide — Ann NY Acad Sci 2012 (PMID 22574954)pubmed.ncbi.nlm.nih.gov
- PubMedCrockford et al., Thymosin β4 in acute myocardial infarction — Expert Opin Biol Ther (PMID 20095868)pubmed.ncbi.nlm.nih.gov
- PubMedSosne et al., Thymosin β4 corneal wound healing — Ann NY Acad Sci (PMID 20955324)pubmed.ncbi.nlm.nih.gov
- TrialClinicalTrials.gov · Thymosin β4 (RGN-259) dry eye Phase 3 (NCT03925727)clinicaltrials.gov
- PubChemPubChem · Thymosin β4 (CID 16132341)pubchem.ncbi.nlm.nih.gov
- PubMedNIH PubMed — Thymosin beta-4 tissue repairpubmed.ncbi.nlm.nih.gov
- GuidelineGoogle — Creating helpful, reliable, people-first contentdevelopers.google.com
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.
More TB-500 (Thymosin β4 fragment) articles
- What Does TB-500 Stand For?TB-500 stands for 'Thymosin Beta-500', a development code for a synthetic Thymosin Beta-4 fragment. Origin of the name and naming context explained.
- TB-500 Mechanism: Actin Sequestration ExplainedTB-500 mechanism: sequesters G-actin monomers via the LKKTETQ motif, regulating actin polymerisation dynamics. Molecular mechanism explained.
- TB-500 Studied Effects in the LiteratureTB-500 studied effects: actin sequestration, cell migration, angiogenesis, and wound repair in animal models. Peer-reviewed literature summarised.
- The Discovery of Thymosin Beta-4 (1981)Thymosin Beta-4 was isolated from calf thymus in 1981 by Low, Hu and Goldstein. Discovery history and subsequent characterisation summarised.
- TB-500 and Cell Migration ResearchCell migration research on TB-500 and Tβ4: in vitro assays and animal models showing modulation of endothelial and epithelial cell movement.
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