Figure 4.

Single-turnover time course of fully reduced S5HH (30 μM) reacted with salicylate (2.9 mM) and O₂ (900 μM) at (top) long and (bottom) short times (concentrations after mixing) in standard buffer at 4 °C. The reaction was monitored at 453 nm (blue) and 700 nm (red). The fits to summed exponential equations are shown as white dashed lines over the data and the residuals are shown as insets in the bottom panel. The kinetic parameters from the fits (n = 5) are shown in Table 2. In the absence of salicylate, the S5HH oxidizes very slowly with a rate constant k of ≤0.0144 s⁻¹.