FIG. 6.

When purified, AcnA remains resistant to EDTA but becomes sensitive to oxidants. Purified AcnA (7 U/ml in 40 mM Tris-HCl, pH 8.0) was exposed to 300 μM EDTA anaerobically or oxygen and superoxide in air (see Materials and Methods) (A); 400 μM (squares) or 4 mM (diamonds) H₂O₂ anaerobically (B); 400 μM ferricyanide anaerobically (C); or 5 mM oxidized glutathione anaerobically (D). At indicated time points, aliquots were removed and residual aconitase activity was measured. In panel D, 2.5 mg of extract/ml was added to the indicated sample. The extract itself contributed insignificantly to the aconitase activity (data not shown). Time courses are representative of at least three experiments