Compound Profile: TB-500

TB-500 is a synthetic peptide corresponding to residues 17–23 of thymosin beta-4 (Tβ4), with an acetylated N-terminus: Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln, or Ac-LKKTETQ. Its molecular formula is C38H68N10O14 and its molecular weight is approximately 889 g/mol. Thymosin beta-4 itself is a 43-amino-acid protein of about 4,963 g/mol; TB-500 is therefore a small fragment of it, not the full protein, despite the two names often being used interchangeably in supplier listings.

Thymosin beta-4 is the most abundant actin-sequestering protein in most cells: it binds monomeric G-actin and regulates its availability for polymerisation into filaments. The actin-binding activity has been mapped to a short central motif, LKKTET, and the 17–23 fragment reproduces this motif. The fragment is therefore used in research as a minimal actin-binding peptide and as a proxy for Tβ4 in models where the full protein is impractical to synthesise.

Research on thymosin beta-4 and its fragments concerns actin dynamics and cell migration in culture, wound-model studies in animals including dermal and corneal models, and cardiovascular models of tissue repair. Much of this literature uses the full protein; work specifically on the 17–23 fragment examines whether the actin-binding motif alone reproduces its effects. Controlled human data on the fragment is minimal.

TB-500 and BPC-157 are routinely studied together and we supply them both individually and as a combined 20 mg blend. They are chemically unrelated: one is a seven-residue thymosin fragment acting on the actin cytoskeleton, the other a fifteen-residue gastric-derived peptide with proposed activity on nitric-oxide and growth-factor pathways. The pairing reflects research interest in whether distinct mechanisms are complementary in repair models rather than any similarity between the molecules.

TB-500 is a hydrophilic peptide that elutes early on reversed-phase HPLC and gives a clean single peak. Identity is confirmed by mass spectrometry; the acetyl group adds 42 Da to the mass of the unmodified sequence, which is a straightforward check that the correct modified peptide is present. Regent Peptides supplies TB-500 in 5 mg and 10 mg vials, UK manufactured and independently tested batch by batch by Janoshik Analytical.