Direct Electrochemical Investigation into the Mechanism and Thermodynamics of Mofe-Dependent Nitrogenase

Abstract

Enzymatic bioelectrocatalysis often requires an artificial redox mediator to observe significant electron transfer rates. The use of such mediators can add a substantial overpotential and obfuscate the protein’s native kinetics, which limits the voltage of a biofuel cell and alters the analytical performance of biosensors. We have recently developed a material for facilitating direct electrochemical communication with redox proteins based on a novel pyrene-modified linear poly(ethyleneimine). By immobilizing the catalytic subunit of nitrogenase (MoFe protein), to demonstrate the ATP-independent direct electroenzymatic reduction of N2 to NH3. In addition, this novel hydrogel material has enabled us to study the electron transfer kinetics of each electroactive cofactor for the MoFe protein (P-cluster and FeMoco) independently, and has been combined with stop-flow IR spectroscopy to study changes in global conformational changes of the protein during catalysis.