What is TB-500?
TB-500 is a short synthetic peptide classified as an acetylated heptapeptide fragment. It reproduces residues 17-23 of Thymosin β4 (Tβ4), a 43-amino-acid actin-sequestering protein found broadly across mammalian tissues. Rather than the full parent protein, TB-500 represents the isolated active fragment region, making it a defined, low-molecular-weight analog suited to controlled in-vitro and preclinical laboratory investigation.
Structurally, the compound carries the sequence Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln-OH, in which an N-terminal acetyl group caps the leucine residue and a free carboxyl terminus completes the glutamine at position seven. The molecule comprises 7 amino acids with the molecular formula C38H68N10O14 and a molecular weight of 889.02, and is catalogued under CAS 885340-08-9. The two adjacent lysine residues confer a net cationic character at physiological pH, while the threonine, glutamate, and glutamine residues contribute polar, hydrophilic surface chemistry that influences solubility behavior in aqueous buffers.
Within the scientific literature, the Thymosin β4 fragment is studied in connection with actin dynamics, cytoskeletal organization, and cell-motility research models, and is frequently referenced in tissue-repair and cellular-migration investigation. American Peptides supplies TB-500 strictly as a reference reagent for in-vitro and non-clinical research; it is not a drug, supplement, or article intended for human or veterinary use, and no physiological outcomes are represented or implied.
Reconstitution & handling
TB-500 is provided as a lyophilized powder that is typically reconstituted in a small volume of sterile or bacteriostatic water to yield a clear, colorless working stock. The peptide's paired lysine residues and multiple polar side chains generally support ready dissolution in aqueous solvents; the diluent should be introduced slowly down the wall of the vial and allowed to solubilize by gentle swirling rather than vigorous vortexing or agitation, which can shear peptide chains and promote foaming. If particulate remains, brief resting at room temperature usually completes dissolution.
For handling, allow the sealed vial to equilibrate to room temperature before opening to minimize condensation onto the hygroscopic powder, and avoid repeated exposure to atmospheric moisture. The reconstituted solution sits near neutral pH in water; where a specific buffer system is required, compatibility should be confirmed empirically at the bench. All manipulation should follow standard laboratory practice for research chemicals, and any references to concentration or volume are matters of experimental preparation, not administration.
Storage & stability
In lyophilized form, TB-500 is stable for extended periods when stored sealed, desiccated, and protected from light at -20°C, with brief transit at ambient temperature generally tolerated without loss of integrity. Once reconstituted, the peptide is best held refrigerated at 2-8°C for short-term use and at -20°C or below for longer-term storage; aliquoting the stock into single-use portions before freezing limits degradation from repeated freeze-thaw cycles. Minimizing exposure to heat, light, and oxygen preserves the acetylated N-terminus and the intact peptide backbone over the working lifetime of the material.
How it's tested
Each lot of TB-500 is characterized by reversed-phase high-performance liquid chromatography (HPLC) to establish chromatographic purity of ≥99%, resolving the target peptide from process-related impurities and truncated sequences. Identity and molecular integrity are confirmed by mass spectrometry, which compares the observed mass against the expected average molecular weight of 889.02 for the C38H68N10O14 composition. A lot-specific Certificate of Analysis (COA) documenting purity, identity, and analytical results is available, providing traceable verification consistent with rigorous reference-reagent standards.