Characterization of superoxide dismutase from the fall webworm, Hyphantria cunea: Comparison of its properties to superoxide dismutase from the silkworm Bombyx mori

Superoxide dismutase (SOD) is a regulatory enzyme involved in the degradation of superoxide anions in living organisms. In this study, we examined SOD from the fall webworm, Hyphantria cunea (hcSOD). A cDNA encoding hcSOD was cloned by reverse transcriptase-polymerase chain reaction. The deduced amino acid sequence of hcSOD revealed that six of seven highly conserved residues forming the Cu/Zn-binding sites were present. The hcSOD mRNA and the enzyme activity were distributed in larval tissues including fat body, midgut and hemocyte of H. cunea. A recombinant hcSOD (rhcSOD) functionally overexpressed in Escherichia coli in a soluble form that was purified to homogeneity. It was stable at pHs between 5 and 11. Incubation for 30 min at temperatures below 50°C scarcely affected the activity. All these properties, as well as CD spectra, of hcSOD or rhcSOD were highly similar to those of the Bombyx mori counterparts except for the number of Cu/Zn-binding sites and the specific activity dismutating superoxide anion to peroxide and oxygen.