Overexpression of Squalene-Hopene Cyclase by the pET Vector in Escherichia Coli and First Identification of Tryptophan and Aspartic Acid Residues inside the QW Motif as Active Sites

Abstract

  An overexpression system for squalene-hopene cyclase (SHC) was constructed by using the pET3a vector, which is responsible for high expression with help from the strong T7 promoter when incorporated into E. coli BL21(DE3). Site-directed mutagenesis experiments prove that two amino acid residues of tryptophan and aspartic acid inside the QW-motif 5 resided as active sites.