Figure 6. Comparison of the efficiency of NADH versus NADPH in preventing the formation of compound II.

Additions were carried out at 5 min, the 3 reaction mixtures had a volume of 3.0 ml and contained, in the following final concentrations: in all three, 0.05 M phosphate buffer, pH 6.5, 1.6 μg·ml⁻¹ glucose oxidase, 4.0 μM catalase. Reaction mixture A contained neither NADPH nor NADH. Reaction mixture B contained NADPH, and reaction mixture C contained NADH, both at final concentrations of 10 μM. After 5 min at 37 °C (arrow), the generation of H₂O₂ was started at a rate of 180 nmol·ml⁻¹·h⁻¹ in all 3 reaction mixtures by the addition of 0.05 ml of 100 mM glucose. For clarity, absorbance readings of reaction C were decreased by 0.01.