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Mechanisms of redox interactions between lignin peroxidase and cellobiose:quinone oxidoreductase
1Department of Biochemistry, University of Georgia, Athens 30602.
Abstract:
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.