Production And Characterization Of Recombinant Superoxide Dismutase Protein Expressed In E.Coli
Volume 1 - Issue 4, October 2017 Edition
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Author(s)
Sushma Kudari, Murali Patrana
Keywords
Cloning, Expression, Escherichia coli BL21 (DE3), pET 24a, pET 28a, Purification, Recombinant superoxide dismutase
Abstract
Superoxide dismutases are currently attracting enormous attention because of their biotechnological potential. Superoxide dismutase is an enzyme that catalyzes the dismutation of superoxide radicals (O2â») to H2O2 and water in cells. It was thus aimed in the present study to isolate gene for the Cu, Zn -superoxide dismutase (SOD) from the Bacillus cereus was cloned, characterized and expressed in the Escherichia coli BL21 (DE3) and the desired enzyme was purified. The SOD gene sequence obtained has an open reading frame of 540 bp and encodes 179 amino acid residues and estimated molecular size of 19.6 kDa. The SOD gene sequence was cloned into the pET 24a and pET 28a vector. The linearized DNA, digested with restriction enzymes Nde1 and BamH1, which was transformed into Escherichia coli BL21 (DE3). The expressed SOD protein exhibited 46.2% inhibition. Non-His tagged SOD (pET 24a) showed fold purity of 8.18 by ammonium sulfate precipitation and also showed 48.5% inhibition at 60% saturation. His-tagged SOD (pET 28a) showed fold purity of 10.76 by Ni-affinity chromatography and showed 82.5% inhibition. The characterization of the purified SOD exhibited maximum activity at room temperature and at pH 7.4. This relatively simple purification method produced a single band on analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), which indicated that the SOD protein obtained attained to higher purity and specific activity.
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