NADH-dependent CO2 reductase on graphite for capacitive electrocatalytic interfacing mediated by solid-binding peptide

NAD⁺/NADH-dependent CO₂ reductase (CR) adapted from Candida methylica (E.C. 1.17.1.9) was introduced with a non-native graphite-specific peptide (Gr; IMVTESSDYSSY) as molecular binder to modify the native enzyme (CR-WT) with peptide insertion at N, C and NC terminus (CR-GrN, CR-GrC and CR-GrNC) to assess the influence of site-specific fusion on electrode binding. Graphite surface-binding activity relative to the electrode topography was evaluated for both native and synthetic CRs to establish the enzyme-electrode interfacing potentiality for efficient electron channelling. Impact of site-specific peptide fusion and amino-acids positioning was assessed for the active site binding availability and adsorption/desorption capability towards competent CO₂-based redox catalysis. Solid-binding peptide and graphite surface interactive ability on direct electron transfer was studied with structural, enzymatic and electrochemical characterizations for efficient CO₂ electrosynthesis. Overall, enzymatic CO₂ reduction to formate based on interactive potentiality of enzyme-electrode complex with peptide modifications and graphite surface towards possibility of bioelectronics upscaling was depicted.