Activation of Cellobiose Dehydrogenase Bioelectrocatalysis by Carbon Nanoparticles

Abstract

Protein‐nanoparticle (NP) interactions offer a powerful tool to modulate enzymatic activity and activate biocatalysis. However, strong scattering effects may complicate conventional spectrophotometric studies of NP‐assisted biocatalysis. Here, bioelectrocatalytic oxidation of cellobiose by the Humicola insolens cellobiose dehydrogenase (CDH) was electrochemically interrogated with two redox mediators, ferricyanide and cytochrome c, and two types of carbon NPs (CNPs), unmodified (CNP) and negatively charged 4‐sulfophenyl‐modified (CNP‐) ones. We show that both CNPs activate the bioelectrocatalytic oxidation of cellobiose and improve the enzymatic specificity reflected in the kf/KM relationship of 6680 (no CNPs), 15500 (CNP‐) and 10444 M−1 s−1 (CNP) shown for ferricyanide‐mediated and 1262 (no CNPs), 3630 (CNP‐), and 6375 M−1 s−1 (CNP) for cytochrome c‐mediated reactions. The bioelectrocatalysis activation by CNPs apparently results from the interfacial/conformational regulation of the CDH activity and the CDH‐electron acceptor reactivity, which may also be the case of other nanomaterials such as frequently used in bioelectrochemistry carbon nanotubes.