Expression of Biologically Active Human Calpastatin in Baculovirus-infected Insect Cells and in Escherichia coli

Abstract

  Calpastatin, an endogeneous inhibitor protein acting on calpain (Ca²⁺-dependent cysteine proteinase), is widely distributed in animal tissues and cells. Two different expression systems, baculovirus-infected Spodoptera frugiperda (Sf9) insect cells and Escherichia coli, were used for overexpression of the human calpastatin tagged with N-terminal hexahistidine peptide. Recombinant calpastatin was purified to homogeneity by nickel ion affinity chromatography and gel filtration separation. Purified recombinant proteins from both systems have similar inhibitory activity for calpain.