FIG 1.

Transient-state reduction of FMN by NfoR. (A) The initial reduction of FMN from 0.0012 s⁻¹, observed when anaerobic NfoR (6.25 μM) in the presence of 12.5 μM FMN was mixed with a range of anaerobic NADPH solutions: 0, 3.12, 6.25, 12.5, 25, 50, 100, and 200 μM. The data were fit globally (red dashed lines) to the model depicted in Fig. 9, assuming an active enzyme concentration of 6.1 μM and a change in extinction coefficient of 8,800 M⁻¹ cm⁻¹ for FMN reduction. (B) The ensuing reduction of residual FMN from 0.01 to 200 s. The data shown are for 12.5, 25, 50, 100, and 200 μM NADPH. The data were fit analytically to equation 1 (dashed line). Arrows indicate increasing NADPH concentrations.