On the bio-electrocatalytic activity of tyrosinase for oxygen reduction reaction

Abstract

The application of tyrosinase, a type 3 di-nuclear copper enzyme, as a catalyst for electrochemical oxygen reduction reaction (ORR) has been explored. During the reaction, O₂ binds to the coupled type 3 copper atoms inside the redox site of tyrosinase and gets reduced to water. Besides the lack of the type 1 copper atom in its structure, unlike the multi-copper oxidases, tyrosinase exhibited direct electro-catalytic activity upon employing the electrode as a pseudo-substrate. The electrocatalytic activity of tyrosinase was further enhanced by using catechol/quinone as the redox shuttle for mediated electron transfer. This enhanced bio-electrocatalytic activity of tyrosinase for ORR has been reported in detail, which could open a new frontier in mediated enzyme reactions for biological fuel cell applications.