摘要：SummaryOxidation of formate to CO2is catalyzed via the donation of electrons from formate dehydrogenase (FDH) to nicotinamide adenine dinucleotide (NAD+), and thus the charge transport characteristics of FDH become essential but remain unexplored. Here, we investigated the charge transport through single-enzyme junctions of FDH using the scanning tunneling microscope break junction technique (STM-BJ). We found that the coupling of NAD+with FDH boosts the charge transport by ∼2,100%, and the single-enzyme conductance highly correlates with the enzyme activity. The combined flicker noise analysis demonstrated the switching of the coenzyme-mediated charge transport pathway and supported by the significantly reduced HOMO-LUMO gap from calculations. Site-specific mutagenesis analysis demonstrated that FDH-NAD+stably combined own higher bioactivity and boosts charge transport, and the coupling has been optimized via the natural selection. Our work provides evidence of hydrogen bond coupling in bioactivity but also bridges the charge transport through single-enzyme junctions and enzyme activities.Graphical AbstractDisplay OmittedHighlights•Binding of NAD+with FDH boosts the charge transport by more than 2,100%•Single-enzyme conductance highly correlates with the enzyme activity•Hydrogen bond bridges the charge transport and enzyme activities•Experiments combined with calculations probe switching of charge transport pathwayAnalytical Chemistry; Biotechnology; Molecular Biology
