A Co-Immobilized Enzyme-Mediator System for Facilitating Manganese Peroxidase Catalysis in Solution Free of Divalent Manganese Ions

Manganese peroxidase (MnP) offers significant potential in various environmental and industrial applications; however, its reliance on Mn2+ ions for electron shuttling limits its use in Mn2+-deficient systems. Herein, a novel approach is presented to address this limitation by co-immobilizing MnP and Mn2+ in silica gels. These gels were synthesized following the standard sol-gel method and found to effectively immobilize Mn2+ ions, primarily through electrostatic interactions. The MnP co-immobilized with Mn2+ ions in the silica gel exhibited 4-5 times higher activity than the MnP immobilized alone in activity assays, and generated Mn3+ within the gel, indicating the immobilized Mn2+ ions remain capable of shuttling electrons to the co-immobilized MnP. In decolorization tests with two organic dyes, the co-immobilized system also outperformed the MnP immobilized without Mn2+ ions, resulting in 2-4 times higher dye removals. This study will enable a broader application of MnP enzymes in sustainable environmental remediation and industrial catalysis.