Thymosin α1 is an acidic 28-residue peptide with an acetylated N-terminus (Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN). It was first isolated and sequenced in 1977 from calf thymus fraction 5, and corresponds to the N-terminal fragment of prothymosin α. The N-terminal acetyl group is part of the native structure.

In aqueous solution the peptide is largely unstructured. In membrane models it adopts a helical conformation and inserts its N-terminus into the lipid bilayer. It has been reported to interact with exposed phosphatidylserine on membranes and cells, to use serum albumin as a carrier, and to bind hyaluronic acid electrostatically through its C-terminal LKEKK sequence.

Thymosin α1 is cited in thymic peptide biochemistry, peptide–membrane interaction studies and immune-cell signalling models. Its high content of acidic residues makes it hygroscopic, so vials should equilibrate to room temperature before opening.

Research use only. This material is sold for in-vitro laboratory research and development purposes exclusively. It is not a drug, food, or dietary supplement, has not been evaluated by the FDA, and must not be used in humans or animals.