Fig. S2.

Cytochrome bo and bd oxidases require millimolar doses of H₂O₂ for effective turnover. The rates of NADH oxidation by the bo and bd oxidases were measured using inverted membrane vesicles under anoxic conditions. The vesicles were prepared from Δcyd (AL454) or Δcyo (JEM1513) strains. The figure shows a representative curve from three independent experiments. The cytochrome bd-1 oxidase also exhibits some catalase activity, but this action similarly requires millimolar levels of H₂O₂ for rapid turnover (82).