The degradation of lignocellulosic biomass can be enhanced by using the laccase-mediator system, specifically with ABTS for lignin depolymerization. Ionic liquids like [EMIM][EtSO4] and [EMIM][Ac] improve lignin solubility and enzymatic access, yet they also reduce enzyme activity. The kinetics of the laccase-mediator reaction were studied and modeled in both buffer and ionic liquid co-solvent solutions. Laccase exhibited higher activity in buffer compared to 5, 15, and 30% (v/v) concentrations of [EMIM][EtSO4] and [EMIM][Ac]. However, lower concentrations of ionic liquids helped stabilize laccase activity over time. Correlations were established between ionic liquid concentrations, enzyme stability, and the kinetics of both the laccase-mediator reaction and the mediator-substrate reaction. These correlations allowed for the evaluation of the entire laccase-mediator system's kinetics at varying ionic liquid concentrations. Generally, lower concentrations of ionic liquids enhance the reaction rate between the substrate and mediator while improving laccase stability, potentially increasing product formation. Despite these benefits, lower ionic liquid concentrations can also decrease enzyme activity, impacting process efficiency and economic viability. By exploring the reaction kinetics, optimal concentrations for enzyme, mediator, substrate, and ionic liquids can be identified to maximize product yield.
