TB-500 (Thymosin Beta-4 Fragment)

Relationship to thymosin beta-4

Thymosin beta-4 is a 43-amino-acid protein abundant in platelets and many tissues, best known for binding monomeric G-actin and holding it in a sequestered pool. Its central heptapeptide is the region most closely tied to that binding in structural studies, and TB-500 reproduces that heptapeptide with an acetylated N-terminus. Whether the fragment fully reproduces the parent protein's behaviour is an open question that individual papers answer differently.

Cell migration and wound models

Angiogenesis and cardiac research

Several groups have examined thymosin beta-4 and its fragments in models of myocardial infarction, reporting effects on epicardial cell activation and vessel density in mice. Related in-vitro work looks at endothelial tube formation and at the peptide's interaction with cytoskeletal regulators. These findings sit in the animal and culture literature and have not been established in people.

Practical characteristics

At 889 g/mol the peptide is small, highly water-soluble and straightforward to handle, which is part of its appeal as a reagent. Purity is reported as an HPLC area percentage, with identity confirmed by mass spectrometry; laboratories doing quantitative work often determine net peptide content separately because lyophilized material retains counter-ion and residual moisture.

Regulatory context

TB-500 appears on the World Anti-Doping Agency prohibited list and is not approved for human or veterinary administration in any jurisdiction. It is offered here solely as a research chemical for qualified laboratory personnel.

Store sealed vials at −20 °C, dry and away from light, and allow them to warm to room temperature before breaking the seal so moisture does not condense onto the cake. Reconstitution in the laboratory is normally done with bacteriostatic or sterile water added slowly against the vial wall; swirl until clear and avoid vortexing, which foams and denatures peptide. The small heptapeptide dissolves rapidly and gives a clear, colourless solution. Keep reconstituted material at 2–8 °C, protected from light, and aliquot before freezing so repeated freeze–thaw cycles are avoided.