Interaction between D-fructose dehydrogenase and methoxy-substituent-functionalized carbon surface to increase productive orientations

Highlights: • Methoxy-functionalized surface improves the DET-type bioelectrocatalysis of FDH. • Methoxy-functionalized surface increases productive orientations. • The total catalytic activity of FDH is almost independent of the modification. • High current density as well as good stability is useful for biofuel cells. - Abstract: D-Fructose dehydrogenase (FDH) from Gluconobacter japonicus NBRC3260 catalyzes the two-electron oxidation of D-fructose to 5-keto-D-fructose, and it is widely used in biofuel cells and biosensors. In this study, methoxy-substituent-functionalized carbon electrodes are constructed by electrochemical oxidation of methoxy-aniline derivatives on Ketjen Black (KB)-modified electrodes to improve the immobilization and bioelectrocatalysis of FDH. It is proposed that the specific interaction between FDH, especially the heme c moiety, and methoxy substituent(s) of amines on carbon electrode increases the proportion of the productively oriented FDH molecules to the total FDHs. Consequently, the limiting catalytic current density of the D-fructose oxidation increases to as much as 23 ± 2 mA cm⁻² in FDH/2,4-dimethoxyaniline/KB/glassy carbon electrode, for example.