Electrical Communication Between Chemically Modified Enzymes and Metal Electrodes

In homogeneous solutions, redox enzymes accept electons from, and transfer electrons to, small redox ions or molecules, but do not exchange electrons with simple metal electrodes. This lack of exchange is attributed to excessive distances between the redox centers of the enzymes and the electrode surfaces. Electrical communication between the redox centers of enzymes and electrodes required until recently diffusing redox molecules that mediated the electron transfer, i.e., shuttled electrons between the redox centers and the electrodes. 

We have shown that direct electrical communication between the redox centers of enzymes and simple metal electrodes can also be established through covalently binding a sufficient number of electron relays to the enzymes' proteins. In the chemically modified enzymes, electrons can be transferred at practical rates between the enzymes' redox centers and the relays, and, because the distance between some of the relays and the electrode surfaces is sufficiently short, also form the relays to the electrodes. 

As a result, substrate concentration-dependent currents flow between these modified enzymes and metal electrodes. Direct electrical communication between electron-relay modified enzymes and metal electrodes opens a new route to biosensors and to the direct electrosynthesis of biochemicals.