The short answer
TB-500, TB500 and TB 500 are the same code. Thymosin beta-4, Tβ4 and beta-thymosins refer to the parent protein family. LKKTETQ names the motif. Which term you search determines whether you find research literature or commercial listings.
Key facts
- Code variants
- TB-500, TB500, TB 500
- Parent protein
- Thymosin beta-4, Tβ4, thymosin β4
- Family
- Beta-thymosins
- Motif
- LKKTETQ
- Finds research
- Thymosin beta-4, LKKTETQ
- Finds listings
- TB-500
The Greek letter problem
Thymosin β4 is frequently written with the Greek beta, and equally frequently transliterated as beta-4, b4 or B4. Databases and search engines handle these inconsistently, so a search using one form can miss records using another. Trying both the Greek and the transliterated form is worth the extra query.
Hyphenation
TB-500, TB500 and TB 500 are used interchangeably with no distinction whatever. Similarly thymosin beta-4, thymosin beta 4 and thymosin-beta-4. None of these variations signals anything about the compound; they are typographic preferences.
Research material referenced
TB-500 5mg, third-party HPLC tested
Which term returns what
Searching TB-500 returns predominantly commercial and forum content, because researchers do not use the code. Searching thymosin beta-4 returns the scientific literature. Searching LKKTETQ returns work specifically on the motif, which is the narrowest and most fragment-relevant set. The three searches produce strikingly different pictures of the same subject.
Descriptive names in circulation
Thymosin Beta-4 Fragment and Ac-LKKTETQ both appear on supplier documentation. The second is the most informative, since it states the actual sequence and the acetylation rather than describing a relationship to a parent.
Why this matters more here than usual
Because the naming ambiguity tracks a real chemical ambiguity. When one name covers both a 889 Da heptapeptide and a 4,963 Da protein, imprecise naming is not a cosmetic issue. It is the mechanism by which the two get confused. Preferring the sequence over the code is the simplest available fix.
Frequently asked questions
- Is TB500 different from TB-500?
- No. Hyphenation and spacing vary freely and signal nothing about the compound.
- Why do searches for TB-500 and thymosin beta-4 differ so much?
- TB-500 is a market-side code; researchers publish under thymosin beta-4. The two terms reach different bodies of content.
- What is the most precise name?
- Ac-LKKTETQ, which states the sequence and the acetylation rather than a relationship to a parent protein.
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
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.
- PubChemPubChem · TB-500 (CID 62707662)pubchem.ncbi.nlm.nih.gov
- PubChemPubChem · Thymosin beta-4 (CID 16132341)pubchem.ncbi.nlm.nih.gov
- PubMedHannappel E, beta-Thymosins: Ann N Y Acad Sci 2007 (PMID 17468232)pubmed.ncbi.nlm.nih.gov
- PubMedGoldstein AL et al., Thymosin β4: a multi-functional regenerative peptide. Expert Opin Biol Ther 2012 (PMID 22074294)pubmed.ncbi.nlm.nih.gov
- PubMedShrivastava S et al., Thymosin beta4 and cardiac repair. Ann N Y Acad Sci 2010 (PMID 20536454)pubmed.ncbi.nlm.nih.gov
- PubMedSosne G et al., Thymosin beta 4 promotes corneal wound healing. Exp Eye Res 2002 (PMID 11950239)pubmed.ncbi.nlm.nih.gov
- TrialClinicalTrials.gov · Thymosin β4 (RGN-259) dry eye Phase 3 (NCT03925727)clinicaltrials.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
The UK Peptides Editorial Team · Research library, UK Peptides
The editorial team 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. Corrections are made in place and the review date updated.
More TB-500 (Thymosin β4 fragment) articles
- BPC-157 and TB-500 Together: What the Evidence SaysThe two are frequently combined commercially, including in blends. Whether the research literature supports studying them together is a separate question.
- TB-500 Side Effects: No Human Safety Record ExistsNo controlled human study has been published. What the rodent work reports, the concern that follows from promoting cell migration, and what is unmeasured.
- What Is TB-500? The Heptapeptide and Its Parent ProteinTB-500 is normally the acetylated heptapeptide Ac-LKKTETQ at 889 Da — not the 4,963 Da full thymosin beta-4 it derives from. The distinction matters.
- TB-500 Molecular Weight, and the Figure That Is WrongTB-500 as supplied is 889.0 Da. The widely repeated 4.9 kDa belongs to full-length thymosin beta-4 — a 5.6-fold error in any molarity calculation.
- TB-500 CAS Number and Chemical IdentityCAS 77591-33-4 belongs to thymosin beta-4, not TB-500. The heptapeptide is PubChem CID 62707662. Why the two identifier sets are constantly merged.
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