Scanning Tunneling Microscopy of E. coli RNA Polymerase Electrochemically Deposited onto an Au Substrate

An electrodeposition method to bind E. coli RNA polymerase onto a monoatomically flat gold surface is described. The enzyme is imaged by the STM in a high humidity or water/glycerol environment which allows direct observation without a metal coating. The enzyme molecules appear as ordered arrays or disordered arrays depending on the deposition conditions used. Cyclic voltammetry reveals the blocking of the Au electrode as the electrodeposition proceeds and suggests that the attachment of the polymerase takes place by a physisorption mechanism and not by chemical bonding to the surface.