Downsizing effect on direct electron transfer-type bioelectrocatalysis by d-fructose dehydrogenase with structural...

Area of Science:

• Biochemistry
• Bioelectrochemistry
• Enzyme Engineering

Background:

• Membrane-bound heterotrimeric d-fructose dehydrogenase (FDH) from Gluconobacter japonicus displays direct electron transfer (DET)-type bioelectrocatalytic activity.
• FDH possesses three heme c moieties; variants lacking heme 1c (Δ1c FDH) or hemes 1c and 2c (Δ1c2c FDH) were previously constructed.

Purpose of the Study:

• To quantitatively analyze the impact of downsizing FDH variants (Δ1c FDH and Δ1c2c FDH) on DET-type bioelectrocatalysis.
• To evaluate kinetic parameters and electron transfer rates of FDH variants.

Main Methods:

• Construction of downsized FDH variants (Δ1c FDH, Δ1c2c FDH).
• Electrochemical analysis to obtain non-catalytic redox signals and DET-type catalytic waves.
• Quantitative analysis of kinetic parameters and electron transfer rate constants.

Main Results:

• Non-catalytic redox signals of adsorbed enzymes were successfully obtained.
• Electron transfer rate constants were enhanced by 7-fold for Δ1c FDH and 4-fold for Δ1c2c FDH.
• Downsizing effect on bioelectrocatalysis was quantitatively analyzed.

Conclusions:

• FDH downsizing significantly enhances DET-type bioelectrocatalytic activity.
• Structural predictions correlate with observed acceleration factors in variants.
• This study provides insights into enzyme engineering for improved bioelectrocatalysis.