Ultimate downsizing of d-fructose dehydrogenase for improving the performance of direct electron transfer-type bioelectrocatalysis.

Abstract d -Fructose dehydrogenase (FDH), a membrane-bound heterotrimeric enzyme, shows strong activity in direct electron transfer (DET)-type bioelectrocatalysis. An FDH variant (Δ1 c 2 c FDH) which lacks 199 amino acid residues including two heme c moieties from N-terminus was constructed, and its DET-type bioelectrocatalytic performance was evaluated with cyclic voltammetry at Au planar electrodes. A DET-type catalytic current of d -fructose oxidation was clearly observed on Δ1 c 2 c FDH-adsorbed Au electrodes. Detailed analysis of the steady-state catalytic current indicated that Δ1 c 2 c FDH transports the electrons to the electrode via heme 3 c at a more negative potential and at more improved kinetics than the recombinant (native) FDH. Graphical abstract Unlabelled Image Highlights • An FDH variant which lacks heme 1 c and heme 2 c moieties (Δ1 c 2 c FDH) was constructed. • Δ1 c 2 c FDH showed high activity of the direct electron transfer-type bioelectrocatalysis. • Δ1 c 2 c FDH transferred the electrons at potentials more negative than the native FDH. • The energy loss in the DET-type bioelectrocatalysis of FDH has decreased. • The interfacial electron transfer kinetics has been improved. [ABSTRACT FROM AUTHOR]