Figure 3. Steady-state Kinetic Assay and Catalytic Mechanism of Ficin.

(a–d) The velocity (v) of the reaction was measured using 1.0 μg mL⁻¹ ficin (a,b) or 1.0 ng mL⁻¹ HRP (c,d) under optimal conditions. Error bars represent the standard deviations of three independent experiments. (a,c) The concentration of H₂O₂ was 0.80 mM (ficin) or 1.0 mM (HRP) and varied concentration of TMB. (b,d) The concentration of TMB was 0.40 mM (ficin) or 0.60 mM (HRP) and varied concentration of H₂O₂. (e,f) Double-reciprocal plots of activity of ficin at a fixed concentration of one substrate versus varying concentration of the second substrate.