In order to achieve the soluble expression of Mn-SOD gene in E.coli,Mn-SOD gene was amplified from the genomic DNA of Bacillus subtilis ATCC 9372 according to the sodA gene sequence of B.subtilis 168.The cloned Mn-SOD gene was inserted into the expression vector pET-28a to be recombinant plasmid pET-28a-Mn-SOD and was then transformed for expression in E.coli BL21(DE3). The Mn-SOD protein with molecular weight of about 26 kD was expressed in E.coli after induction with isopropyl -β-D- thiogalactoside (IPTG),which accounted for approximately 35.6% of total bacterial protein.The enzyme activity of Mn-SOD was assayed with improved pyrogallic acid autoxidation method.The results showed that the specific activity of SOD in the total soluble protein was 51.09 U·mg-1,and was 4.84 times of control group.Mn-SOD gene of B.subtilis ATCC 9372 is first successfully expressed in E.coli BL21(DE3),and its products possess high dissolubility and enzyme activity.
