Figure 2. Rates of autoxidation of SFH and MP4 in the presence and absence of catalase.

The left panel (A) shows the inhibition of catalase activity by KCN. pO₂ was measured in an anaerobic cell containing 2 ml PBS and 0.1 ml catalase (final nominal activity 1000 units/ml). The reaction was started by adding 5 μl of 3% H₂O₂ (arrow) and pO₂ was monitored for an additional 60 s at 37 °C. The reaction was performed at KCN concentrations of 0, 20 and 50 mM. The right panel (B) shows the autoxidation of SFHb and MP4 in the presence of PBS only (■), 1000 units/ml catalase (△) and 50 mM KCN (●). Best fit lines were obtained as explained in the text, and Table 1 reports the values of the rate constants.