Electrical connection of enzyme redox centers to electrodes

Abstract

Electrically insulating proteins can be made redox-conducting through incorporation of a high density of electron relaying redox centers. Electrons diffuse in the resulting redox conductors by self-exchange between identical and electron transfer between different relaying centers. When the self-exchange rate of the relays and their density are high, the flux of electrons through a 1 micrometer thick film of a 3-dimensional macromolecular network can match or exceed the rate of supply of electrons to or from the ensemble of enzyme molecules covalently bound to it. The network now molecularly wires the enzyme molecules to the electrode and the current measures the turnover of the wired enzyme molecules. When the enzyme turnover is substrate-flux, i.e. concentration limited, the current increases with the concentration of the substrate.