Figure 7.

NADH- and NADPH-dependent reduction of Cyt b₅. Recombinant Cyt b₅ (AtB5-A) was reduced at 25°C in a reaction mixture containing 10 mm potassium phosphate buffer, pH 7.25, 1.5 μm Cyt b₅, either NADH or NADPH (100 μm), and a catalytic amount of AtCBR (A) or NADPH-Cyt P450 reductase (B). The reaction was initiated by addition of either NADH (solid line, 100 μm) or NADPH (dashed line, 100 μm) as an electron donor.