Computer-aided laccase engineering: toward biological oxidation of arylamines

Abstract

Oxidation of arylamines, such as aniline, is of high industrial interest and laccases have been proposed as biocata-lysts 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 en-zyme, we aim towards the (transient) substrate’s one 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 kcat increase) in the engineered variant for biocatalyzed polyaniline production.This study was supported by the INDOX (KBBE-2013-7-613549) EU-project, and the NOESIS (BI0201456388-R) and OxiDesign (CTQ2013-48287-R) Spanish project. GS thanks an FPI grant of the Spanish Ministry of Competitiveness.Peer ReviewedPostprint (author's final draft