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TB-500 — research-grade lyophilized peptide vial from Peptide.Express, ≥99% HPLC purity
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≥99% PurityUS SynthesizedOut of Stock

TB-500 — Synthetic Thymosin Beta-4 (Tβ4) | Actin-Sequestering Systemic Tissue Repair Research Compound

Research-Grade Compound

TB-500 is the research-market name for synthetic Thymosin β-4 (Tβ4), an endogenous protein present in virtually all nucleated human cells at cytosolic concentrations of roughly 0.5 mM — one of the most abundant intracellular proteins there is. Molecular weight 4,963.4 Da, CAS 77591-33-4.

Purity standard: TB-500 is sourced to ≥99% by HPLC. That is the specification every batch must meet, not a measurement of any one vial — the measured figure for a batch is on that batch's Certificate of Analysis.

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BPC-157 + TB-500 Wolverine Stack research guide →

In-depth research overview, mechanism of action, and study applications.

No variant-specific CoA for 5mg — showing product CoA
Certificate Details
Purity≥99%
Methodology
HPLCLC-MS/MS
CAS Number77591-33-4
Molecular FormulaC212H350N56O78S
Molecular Weight4963.4 g/mol
SequenceSynthetic Thymosin β-4 (43 aa, Ac-SDKPDMAEIEKFDKSKLKTETQEKNPLPSKETIEQEKQAGES) containing the LKKTET actin-binding motif
Verify Results with Testing Laboratory
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This Certificate of Analysis was issued by an independent third-party laboratory. Peptide.Express does not conduct in-house testing. Results are provided as-is from the testing facility and confirm batch identity, purity, and analytical methodology. For questions about specific CoA results, contact support@peptide.express.

Safety Data Sheet (SDS)
≥99% by HPLCLC-MS/MS VerifiedCoA Every BatchIn-Vitro Research Use Only

What is TB-500?

TB-500 is the research-market name for synthetic Thymosin β-4 (Tβ4), an endogenous protein present in virtually all nucleated human cells at cytosolic concentrations of roughly 0.5 mM — one of the most abundant intracellular proteins there is. Molecular weight 4,963.4 Da, CAS 77591-33-4.

A note on naming, because it causes real confusion in the literature: "TB-500" is used inconsistently. Some suppliers use it for the full 43-amino-acid Tβ4 sequence; others use it for shorter fragments containing the LKKTET actin-binding motif, such as the 7-mer Ac-LKKTETQ. Peptide.Express supplies the full synthetic Tβ4 sequence, and the batch Certificate of Analysis confirms the 4,963.4 Da mass. If you are comparing against a paper or another supplier, verify which molecule is actually being discussed before assuming equivalence.

What distinguishes TB-500 from most tissue-repair compounds is scope. It does not act locally at the site where it is introduced — it distributes and coordinates repair across multiple tissues at once. That systemic character is the reason it is studied in combination with locally-acting compounds rather than as a substitute for them.

How Does TB-500 Work? Mechanism of Action

TB-500 regulates G-actin (monomeric, globular actin) sequestration through the LKKTET binding domain. Actin is the cytoskeletal protein that determines whether a cell can change shape, divide, and move. By binding free G-actin and modulating the G-actin to F-actin (filamentous) equilibrium, TB-500 alters the polymerization dynamics that hold a cell in place.

The consequence is cell migration. Endothelial cells, keratinocytes and progenitor populations become able to move toward an injury site from wherever they happen to be. Migration is the prerequisite step for everything downstream in tissue repair — a repair site with adequate vasculature but no arriving cells does not heal.

The distinction from BPC-157 matters for study design. BPC-157 upregulates VEGF and promotes angiogenesis at the local site. TB-500 acts systemically, mobilizing cells from distant tissue. These are sequential requirements of the same cascade, not competing mechanisms, which is the pharmacological basis for the BPC-157 + TB-500 combination studied as the "Wolverine Stack."

TB-500 also promotes angiogenesis in its own right and reduces pro-inflammatory cytokine activity in injury models. The strongest preclinical signal appears in cardiac, corneal and dermal wound models — Thymosin β-4 has been investigated in human corneal and cardiac clinical trials, which is more than can be said for most compounds in this category.

Research Applications of TB-500

Cell Migration and Cytoskeletal Research

  • G-actin sequestration assays: the direct mechanistic readout, measuring the shift in G-actin to F-actin ratio in treated cell populations.
  • Wound-edge migration models: keratinocyte and endothelial migration rates across a scratch or gap are the standard functional endpoint.
  • Progenitor cell mobilization: epicardial and dermal progenitor recruitment in cardiac and skin repair preparations.

Angiogenesis and Tissue Repair Models

  • Corneal repair: among the best-characterized Tβ4 applications, with human trial data behind it — unusual for this compound class.
  • Cardiac injury models: neovascularization and epicardial progenitor mobilization following induced ischemic injury.
  • Dermal and skeletal muscle repair: capillary density and closure rate as endpoints, often run alongside a BPC-157 arm for mechanism separation.

Combination Pharmacology

  • Wolverine Stack design: pairing systemic cell recruitment (TB-500) with local repair activation (BPC-157) in a single preparation.
  • Mechanism separation: running TB-500 and BPC-157 arms independently is the only way to attribute an effect to migration versus angiogenesis.
  • Multi-peptide blends: TB-500 is a component of both the Wolverine Blend and the four-peptide KLOW Blend.

TB-500 vs BPC-157

FeatureTB-500BPC-157
IdentitySynthetic Thymosin β-4Gastric pentadecapeptide fragment
Amino acids43 (LKKTET motif)15 (GEPPPGKPADDAGLV)
Molecular weight4,963.4 Da1,419.5 Da
CAS number77591-33-4137525-51-0
Primary mechanismG-actin sequestration → cell migrationVEGF upregulation → local angiogenesis
Scope of actionSystemicLocal to administration site
Human trial precedentCorneal and cardiac Tβ4 trialsNone completed
Gastrointestinal evidenceLimitedStrong
WADA statusProhibited at all timesProhibited at all times

Researchers frequently treat these as interchangeable tissue-repair peptides. They are not. One moves cells; the other builds vasculature where the cells arrive. A protocol that substitutes one for the other is measuring a different mechanism.

Read the full BPC-157 vs TB-500 comparison

TB-500 Technical Specifications

Technical specifications for TB-500, including molecular data, purity standard, testing methods and storage requirements.
Compound NameTB-500 (synthetic Thymosin β-4)
Common SynonymsTB500, Tβ4, thymosin beta-4, Tβ4 fragment
Parent ProteinThymosin β-4, 43 amino acids
Active MotifLKKTET actin-binding sequence
CAS Number77591-33-4
Molecular FormulaC212H350N56O78S
Molecular Weight4,963.4 Da
Purity≥99% by HPLC
Purity ConfirmationLC-MS/MS molecular weight verification
Endotoxin TestingLAL (Limulus Amebocyte Lysate) method
Physical FormLyophilized powder
AppearanceWhite to off-white powder
ReconstitutionBacteriostatic water or sterile 0.9% sodium chloride
Storage (lyophilized)-20°C, desiccated, protected from light
Storage (reconstituted)2–8°C, use within 14–28 days
Shelf Life24 months from manufacture (lyophilized)
Testing MethodsHPLC, LC-MS/MS, LAL Endotoxin
DocumentationCertificate of Analysis (CoA) per batch
WADA StatusProhibited at all times
FDA StatusNot approved for human use
Intended UseIn-vitro laboratory research only

How to Reconstitute TB-500 for Research

At 4,963.4 Da, TB-500 is a larger molecule than most peptides in this catalog and takes noticeably longer to go into solution than BPC-157 does. Expect the full 90 seconds of swirling, and do not be tempted to accelerate it by shaking — mechanical shear on a peptide this size is a real degradation route.

  1. Bring the vial to room temperature before opening.
  2. Draw the calculated volume of bacteriostatic water. For a 5 mg vial, 2.5 mL yields 2 mg/mL; for a 10 mg vial, 2 mL yields 5 mg/mL.
  3. Swab the septum with alcohol and allow 30 seconds to dry.
  4. Inject the diluent slowly down the inner vial wall.
  5. Swirl gently for 60–90 seconds. Larger peptides dissolve more slowly — give it time rather than agitation.
  6. Verify the solution is clear and colorless with no visible particulate.
  7. Label with date and concentration.
  8. Store at 2–8°C and use within 14–28 days.

Diluent: bacteriostatic water for peptide reconstitution. Full protocol: step-by-step peptide reconstitution guide. Concentration maths: peptide reconstitution calculator.

Frequently Asked Questions — TB-500

What is TB-500 used for in research?

TB-500 is studied in cell-migration and tissue-repair models. Its mechanism — G-actin sequestration via the LKKTET motif — makes it the standard tool compound when the research question is whether cells can reach an injury site, as distinct from what happens once they arrive. Sold for in-vitro laboratory research use only.

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

The Peptide.Express product is synthetic Thymosin β-4, confirmed at 4,963.4 Da by LC-MS/MS. The naming is not consistent across the market, though — some suppliers apply "TB-500" to short LKKTET-containing fragments such as Ac-LKKTETQ, which is a very different molecule at roughly 890 Da. Check the molecular weight on any Certificate of Analysis before assuming two products are the same compound.

What is the TB-500 actin binding mechanism?

The LKKTET motif binds monomeric G-actin, holding it in a sequestered pool and shifting the equilibrium between G-actin and polymerized F-actin. Because the actin cytoskeleton is what physically anchors a cell, changing that equilibrium changes whether the cell can deform and migrate.

How does TB-500 work systemically?

Thymosin β-4 is present throughout the body already and distributes readily rather than concentrating at an administration site. In research models this means cells at tissues distant from the injury become mobilized, which is why TB-500 studies report effects across multiple tissue types in the same preparation.

What is the difference between TB-500 and BPC-157?

TB-500 is roughly 3.5 times the molecular weight, acts systemically, and works by freeing cells to migrate. BPC-157 is a 15-residue peptide that acts locally and works by upregulating VEGF to build vasculature. Different mechanism, different scope, different stage of the repair cascade.

Can TB-500 and BPC-157 be studied together?

They frequently are — the combination is known informally as the Wolverine Stack, and the mechanistic rationale is sound because the pathways do not overlap. What does not exist is combination pharmacokinetic data. Any protocol pairing them is inferring from single-compound literature, and study designs should say so explicitly.

What is the Wolverine Stack?

The informal name for a BPC-157 + TB-500 research combination. Peptide.Express supplies it pre-blended as the Wolverine Blend and as a separate-vial kit for protocols requiring independent dose and timing control of each component.

Is TB-500 WADA prohibited?

Yes, at all times, both in and out of competition. TB-500 falls under WADA section S2 as a growth factor affecting tissue regeneration and angiogenesis.

Are there theoretical safety concerns with TB-500 in research models?

Yes, and they should be designed around. TB-500 promotes cell proliferation and angiogenesis, which are the same processes that support tumor vasculature. Preclinical models with pre-existing malignancies, or models where neoplastic transformation is a possible confounder, need to account for that. This is a mechanistic concern raised in the literature, not an observed clinical finding.

What purity standard does Peptide.Express use for TB-500?

≥99% by reverse-phase HPLC with LC-MS/MS confirming the 4,963.4 Da mass. Because TB-500 naming is inconsistent across the market, the mass confirmation on the CoA is the most useful field on the document — it tells you which molecule you actually have.

How should TB-500 be stored before and after reconstitution?

Lyophilized: -20°C, desiccated, light-protected, stable for 24 months. Reconstituted: 2–8°C, used within 14–28 days. Avoid repeated freeze-thaw cycles — larger peptides are more vulnerable to aggregation under thermal cycling than small ones.

What testing does TB-500 undergo before shipping?

Reverse-phase HPLC for purity, LC-MS/MS for molecular weight identity, LAL endotoxin testing, and visual QC. All performed by an independent third-party laboratory, with a batch-specific Certificate of Analysis issued for each lot.

Where is the Certificate of Analysis for TB-500?

Available on this page and in the Peptide.Express lab results library. Each CoA is tied to a specific production batch and lists the HPLC chromatogram, mass spectrometry data, endotoxin result, testing laboratory and test date.

Research References

  1. Goldstein AL, Hannappel E, Kleinman HK. "Thymosin Beta4: Actin-Sequestering Protein Moonlights to Repair Injured Tissues." Trends in Molecular Medicine, 2005. Read the thymosin β4 actin-sequestration and tissue-repair review on PubMed
  2. Smart N, Risebro CA, Melville AAD, Moses K, Schwartz RJ, Chien KR, Riley PR. "Thymosin β4 Induces Adult Epicardial Progenitor Mobilization and Neovascularization." Nature, 2007. Read the thymosin β4 epicardial progenitor neovascularization study on PubMed
  3. Sosne G, Kleinman HK, Springs C, Gross RH, Sung J, Kang S. "0.1% RGN-259 (Thymosin β4) Ophthalmic Solution Promotes Healing and Improves Comfort in Neurotrophic Keratopathy Patients in a Randomized, Placebo-Controlled, Double-Masked Phase III Clinical Trial." International Journal of Molecular Sciences, 2023. Read the RGN-259 thymosin β4 Phase III corneal healing trial on PMC

All products are sold for in-vitro laboratory research use only. Not intended for human consumption, clinical use, or veterinary use. Peptide.Express makes no medical claims. Consult the published literature for research application guidance.

Further Reading

Related Research Compounds

BPC-157The locally-acting VEGF counterpart studied alongside TB-500 in the Wolverine Stack.Wolverine BlendPre-blended BPC-157 + TB-500 in a single lyophilized vial.KLOW BlendFour-peptide formulation adding GHK-Cu and KPV to the BPC-157 + TB-500 base.BPC-157 + TB-500 KitSeparate vials for independent control of each compound.