Figure 2.

Effect of H₂O₂ treatment on durum wheat mitochondria (DWM)-aconitase activity, evaluated in both the presence and absence of catalase. Measurements were carried out as described in Methods, by incubating DWM proteins (150 μg) for 15 min in a reaction medium containing 100 mM Tris–HCl pH 8.0, 0.1% (v/v) Triton X-100, and different H₂O₂ concentrations (250, 500, 750, and 1000 μM), both in the absence and presence of 20 E.U. catalase (CAT). Aconitase activity values are expressed as a percentage of the control (i.e., the reaction measured at time 0 in the absence of both H₂O₂ and CAT) and reported as the mean value ± SD (n = 3). The dependence of DWM-aconitase activity on the H₂O₂ concentration is reported, as evaluated in both the absence and presence of CAT. In this set of experiments, DWM-aconitase activity under control conditions was equal to 28 ± 2 (SD, n = 3) nmol·min⁻¹·mg⁻¹of protein.