Fig. 4. (A) Digital photos of MG (10 μM) oxidized by F43H/H64A Mb (2 μM) with different H₂O₂ concentrations ((a) 0 μM; (b) 100 μM; (c) 200 μM; (d) 300 μM; (e) 400 μM; (f) 600 μM; (g) 800 μM; (h) 1000 μM), in KPi buffer (100 mM, pH 6.0) at 25 °C for 2 h. (B) UV-Vis spectra of MG (10 μM) oxidized by F43H/H64A Mb (2 μM) with H₂O₂ (200 μM) under the same conditions. (C) Kinetic changes of absorption at 617 nm upon oxidation of MG catalyzed by F43H/H64A Mb. The digital photos of the solution before and after reaction were shown as insets. (D) Effect of pH values on the catalytic oxidation rate of MG by F43H/H64A Mb the similar conditions.