Three-dimensional catalysis and the efficient bioelectrocatalysis beyond surface chemistry

Abstract

The exceptional catalysis for the oxygen reduction reaction (ORR) of bilirubin oxidase (BOD) encouraged us to reevaluate the existing catalytic models. Experimental evidence of the electron-transfer reaction's dependence on the three-dimensional structure of BOD is demonstrated by operando X-ray absorption spectroscopy (XAS) combined with Quantum Mechanics/Molecular Mechanics (QM/MM). We suggest that if a catalytic reaction occurs in a three-dimensional environment (3D-catalysis), the energies involved in the transition states during the electron transfer cannot be explained by adsorption kinetics. In contrast, there is the formation of a three-dimensional complex (TDC). Our data suggest influence of the metallic cofactor electronic structure as well as the spatial disposition of its surrounding ligands on the electron transfer that promotes the biocatalysis. We propose that investigating enzymatic redox processes involving a dynamic three-dimensional enzymatic structure can provide further insights as how heterogeneous catalysis can work beyond single atoms and surface chemistry.