Figure 1.

Reaction of 10 μM aminophenyl fluorescein (APF), 50 mM phosphate pH 7.40 buffer, H₂O₂, and 0.2 μM horseradish peroxidase (HRP). The experiment was performed aerobically and in the absence of molecular oxygen. The top curve (HRP and molecular oxygen) is used as a calibration curve for all further experiments and expressed as "hROS reactivity (nM H₂O₂)". Fluorescence expressed as arbitrary units.