Effects of electrolyte on the mediated electrocatalytic glucose oxidation reaction catalyzed by flavin adenine dinucleotide glucose dehydrogenase

Abstract

Flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) become a key enzyme for electrochemical oxidation of glucose. Here, we investigated the effects of electrolyte, especially at high concentration, on the bioelectrocatalytic activity of FAD-GDH from Aspergillus terreus using a ferricyanide as a redox mediator. In the low ionic strength region, an increase of bimolecular reaction rate constant (k2) between FAD-GDH and ferricyanide was observed due to the reduction of the ionic repulsive interaction between negatively charged enzyme and mediator. Above 0.5 M concentration, ion-specific increments in k2 were observed; ammonium ions most efficiently increased k2, owing to adsorption via dispersion force on the enzyme surface likely proximal to the active site.