Exploring the Electrical Conductivity of Myoglobin

The electrical conductance of single myoglobin proteins was measured to study its electron transfer properties. We examined the electronic properties of myoglobin, using apomyoglobin (myoglobin without a heme group) as a reference. The differential conductivity of the proteins deposited on Pt nanometer-scale electrodes was measured using a lock-in technique as a function of bias and gate voltages. Nano- electrodes were fabricated by creating small Pt channels 100 nm - 300 nm wide via e-beam lithography and then creating a break junction by electromigration at low temperatures (4 K - 77 K). The conductance of apomyoglobin was very different from that of myoglobin, with a predominant peak at ~50 meV. On the other hand, myoglobin had a rich structure that we surmise results from the presence of the heme group.