The mechanism of redox interactions between the heme‐enzyme, lignin peroxidase (LiP), and the FAD‐enzyme, cellobiose:quinone oxidoreductase (CBQ) (EC 1.1.5.1), was investigated under various conditions. Veratryl alcohol oxidation by LiP was inhibited by CBQ in the presence of cellobiose. Lineweaver‐Burk plots at various CBQ concentrations suggest that this inhibition is non‐competitive. The oxidation rate of the reduced CBQ (FADH2) by LiP plus H2O2 increased significantly only in the presence of veratryl alcohol. Furthermore, the cation radical derived from 1,2,4,5‐tetramethoxybenzene was reduced by CBQ in the presence of cellobiose. It is concluded from these results that CBQ can reduce aromatic cation radicals and that veratryl alcohol acts as a radical mediator of the redox interactions between LiP and CBQ.
