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Thymosin beta-4 fragment (TB-500), lyophilized reference standard for in vitro laboratory research.
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Price
$42.52
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Quantity
In Stock · 8 Units Available
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- Third-party HPLC tested. Every lot ships with a batch-linked certificate of analysis naming the laboratory, the method and the measured result. Browse certificates
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Certificate of Analysis & Specifications
HPLC Purity
99.99% HPLC
Area Normalization
Assay Content
10.62mg
Quantitative Target
Testing Lab
KMD Analytical
Lot Number
KRSTB-10-260908-01
Tested Sep 22, 2026
Storage
36°F to 46°F
Retest Date
Sep 18, 2028
Released COA Library
Published Certificates of Analysis for TB-500. All released analytical records are preserved here. Pending and in-testing lots are reachable only through the QR printed on the vial.
10mg1 released lot
- View COA
Lot KRSTB-10-260908-01
Tested Sep 22, 2026 · KMD Analytical · HPLC 99.99% · Assay 10.62
Research Data
Chemical & Structural Identifiers
- Chemical Name (IUPAC)
- N-acetyl-L-leucyl-L-lysyl-L-lysyl-L-threonyl-L-glutamyl-L-threonyl-L-glutamine (thymosin β4 active fragment)
- CAS Registry Number
- 885340-08-9
- PubChem CID
- 62707662
- Molecular Formula
- C38H68N10O14
- Molecular Weight
- ≈ 889.0 Da (average, free peptide); monoisotopic ≈ 888.5 Da; observed [M+H]⁺ = 889.5 Da
- Sequence
- Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln (single-letter: Ac-LKKTETQ, thymosin β4 residues 17-23)
- Salt / Counter-Ion
- Supplied as a high-purity lyophilized acetate (CH₃COO⁻) or trifluoroacetate (CF₃COO⁻) salt.
- Synonyms
- TB-500, Thymosin beta-4 fragment, Thymosin β4 (17-23), LKKTETQ, Thymosin β4 active fragment
- Registry Cross-Reference: CAS 885340-08-9 and PubChem CID 62707662 describe the N-terminally acetylated 17-23 fragment (Ac-LKKTETQ) shown above. CAS 77591-33-4, which some listings print against TB-500, is the registry number for full-length thymosin β4 (timbetasin, 43 residues, ≈ 4963 Da) and does not describe this fragment.
- Fragment Identity: TB-500 is the acetylated heptapeptide corresponding to residues 17-23 of thymosin β4, the region reported to carry the actin-binding motif. It is not full-length thymosin β4; the two differ in mass by roughly 4000 Da. Confirm the fragment length on the batch Certificate of Analysis before use.
- Composition Note: The Ac-LKKTETQ sequence contains no methionine residue, so oxidative-loss precautions that apply to full-length thymosin β4 do not apply to this fragment.
Analytical & COA Specifications
- Analytical Purity (RP-HPLC)
- ≥ 98.0% area normalization under UV detection at λ = 214 nm and 220 nm.
- Identity Confirmation (RP-HPLC RT + UV vs. reference)
- Main peak retention time and UV spectrum conform to the reference standard.
- Physical Characterization
- Dense, white to off-white lyophilized solid cake/powder.
Handling & Stability
Storage. Store dry solid desiccated at −20°C to −80°C, protected from atmospheric moisture and direct light.
Solubility. Soluble in sterile laboratory-grade deionized water (≥ 10 mg/mL) or sterile Phosphate-Buffered Saline (PBS, pH 7.4) for in vitro assay application.
- Handling & Aliquoting: Prepare concentrated stock solutions freshly or aliquot into single-use fractions at −20°C to eliminate degradation from repeated freeze-thaw cycles.
Mechanism & Literature
Structural Origin & Classification: Synthetic active fragment of the β-thymosin actin-binding peptide thymosin β4, corresponding to the acetylated heptapeptide LKKTETQ (residues 17-23).
Actin Dynamics & Cytoskeletal Remodeling: Investigated in vitro for stoichiometric sequestration of globular actin (G-actin) and regulation of actin filament turnover, which underpin directed cell migration and cytoskeletal reorganization in cell culture models.
Cell Motility & Extracellular Matrix Signaling: Reported in endothelial, fibroblast, and myoblast culture models in connection with matrix metalloproteinase (MMP-2, MMP-9) expression and directed cell migration. These are in vitro observations in cultured cells and are not measurements of an effect in a living organism.
References (3)
- Esposito, S., Deventer, K., Goeman, J., Van der Eycken, J., & Van Eenoo, P. (2012). Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential. Drug Testing and Analysis, 4(9), 733–738.
- Database record: National Center for Biotechnology Information. PubChem Compound Summary for CID 62707662, Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln. PubChem, U.S. National Library of Medicine. Registry cross-reference for CAS 885340-08-9 (record reviewed 2026-09-15).
- Database record: National Center for Biotechnology Information. PubChem Compound Summary for CID 16132341, Timbetasin (thymosin β4). PubChem, U.S. National Library of Medicine. Registry cross-reference for CAS 77591-33-4 (record reviewed 2026-09-15).
Technical Laboratory FAQs
What is the sequence and classification of TB-500?
TB-500 is the synthetic N-terminally acetylated 17-23 fragment of thymosin β4, with the sequence Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln (Ac-LKKTETQ), CAS 885340-08-9, and an observed monoisotopic [M+H]⁺ of 889.5 Da. It is not full-length thymosin β4.
How is TB-500 evaluated in actin-dynamics and cell-migration assays in vitro?
Published in vitro literature examines TB-500 and the corresponding thymosin β4 region for G-actin sequestration, actin filament turnover, MMP expression, and directed cell migration in endothelial, fibroblast, and myoblast culture models.
What solvent matrix is used for preparing in vitro TB-500 stock solutions?
Sterile deionized water or sterile PBS (pH 7.4) provides rapid dissolution at 10 mg/mL or greater for in vitro assay stock preparation. Because the Ac-LKKTETQ fragment contains no methionine residue, the degassing precautions applied to full-length thymosin β4 do not apply here.
For Research Use Only. Not for human or animal administration. Not intended to diagnose, treat, cure, or prevent any disease. Sold for laboratory research purposes only.