Oxidation of arylamines, such as aniline, is of high industrial interest, and laccases have been proposed as biocatalysts to replace harsh chemical oxidants. However, the reaction is hampered by the redox potential of the substrate at acid pH, and enzyme engineering is required to improve the oxidation. In this work, instead of trying to improve the redox potential of the enzyme, we aim toward the (transient) substrate’s potential and propose this as a more reliable strategy. We have successfully combined a computational approach with experimental validation to rationally design an improved biocatalyst. The in silico protocol combines classical and quantum mechanics to deliver atomic and electronic level detail on the two main processes involved: substrate binding and electron transfer. After mutant expression and comparison to the parent type, kinetic results show that the protocol accurately predicts aniline’s improved oxidation (2-fold k_cat increase) in the engineered variant for biocatalyzed polyaniline production.

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