Figure 5.

Effect of HRP-catalyzed oxidation on the pH-dependency of fluorescein-dextran fluorescence. Fluorescein-dextran (final concentration at 30 μg/ml) was prepared in MES calibration buffers with pHs ranging from 3.0 to 7.3. These solutions were then incubated at 37°C for 30 min, in the absence (●) or presence (○) of H₂O₂ and HRP (final concentrations are 1 μM and 4 μg/mL, respectively). The fluorescence emission ratio of F₅₃₅(λ₄₈₅)/F₅₃₅ (λ₄₄₀) was then measured.