TPSAB1, also known as tryptase alpha/beta-1, is a tryptase that is the major neutral protease present in mast cells and is secreted upon the coupled activation-degranulation response of this cell type. It is enzymatically active only as a heparin-stabilized tetramer, and it is resistant to all known an endogenous proteinase inhibitor. This protein has been implicated as mediators in the pathogenesis of asthma and other allergic and inflammatory disorders. Recombinant human TPSAB1 protein, fused to His-tag at N-terminus, was expressed in E.coli.