Oxidative half-reaction of 16 μM StyA2B with chemically reduced FAD (only protein bound FAD was used) was investigated by rapid mixing experiments (25 mM Tris-HCl, pH 7.25, 15°C, various styrene: 50 or 550 μM). Reactions were followed with absorbance (375 nm, 390 nm, and 450 nm) and fluorescence (520 nm, excitation at 375 nm). Results were combined and analysed by exponential fitting. Best fits derived with 5 rate constants are shown here as solid lines passing through the experimental data points. Values of the best fitting rate constants are listed in the legend of Scheme 2.