Isolation and reconstitution of iron- and manganese-containing superoxide dismutases from Bacteroides thetaiotaomicron.

摘要: Superoxide dismutase (SOD) from extracts of anaerobically maintained Bacteroides thetaiotaomicron was a dimer equally sized 23,000-molecular-weight monomers joined noncovalently. A preparation with specific activity 1,200 U/mg contained 1.1 g-atom Fe, 0.6 Zn, and less than 0.05 Mn per mol dimer. The apoprotein, prepared by dialysis iron-SOD in 5 M guanidinium chloride-20 mM 8-hydroxyquinoline, had no superoxide-scavenging when renatured without exogenous metal. Enzymatic restored to the denatured apoprotein against either 1 Fe(NH4)2 or MnCl2 20 Tris (pH 7.0). Fe-reconstituted enzyme native were inhibited approximately 50% 0.2 NaN3, whereas Mn-reconstituted 60% 10 NaN3. Aeration anaerobic cells resulted fourfold induction an azide-resistant SOD. (43,000 molecular weight) isolated aerated subunits. metal content 1.0 Mn, 0.55 0.3 Zn this also on addition iron manganese. constitutive Fe-SOD O2-induced Mn-SOD, tested alone combination, migrated identically acrylamide gels, similar amino acid compositions, alanine as sole N-terminal acid. These data are consistent synthesis single oxygenated cells. We have observed phenomenon SOD fragilis (E. M. Gregory, Arch. Biochem. Biophys. 238:83-89, 1985).