Double-reciprocal plots of initial velocities of EmoB versus
substrate concentrations. A, enzyme activity was assayed with
constant concentrations of NADH: 19 μm (⋄), 32
μm (♦), 56 μm Δ, and 78
μm (▴). B, enzyme activity was assayed with
constant concentrations of FMN: 0.5 μm (♦), 1
μm (⋄), 2 μm ▴, 3 μm
Δ, and 4 μm (▪). C, shown is the deduced
ping-pong reaction mechanism of EmoB from kinetic analysis.