Fig. 2

The cyclic voltammetry. a The cyclic voltammograms of phosphate buffer (50 mM, pH 6.5) and tyrosinase with and without veratryl alcohol in phosphate buffer (50 mM, pH 6.5). Only in tyrosinase in the coexistence of veratryl alcohol, the oxidation peak was shown at +1.22 V vs. Ag/AgCl, which might be corresponding to +1.42 V vs. NHE. b The cyclic voltammogram of veratryl alcohol (1.7 mM) and veratraldehyde (1.7 mM) in phosphate buffer (pH 6.5). NO oxidation and reduction peaks were observed in each of veratryl alcohol and veratraldehyde. In all the cyclic voltammetries, glassy carbon, coiled Pt wire, and Ag/AgCl electrode were used as the working, counter, and reference electrode, respectively. Cyclic voltammetry was carried out using potentiostat/galvanostat controlled by commercial WMPG software. The scan rate was 50 mVs⁻¹