The electrochemistry and scanning tunnelling microscopy of the flavoprotein putidaredoxin reductase on alkanethiol-modified gold

Cyclic voltammetry studies of putidaredoxin reductase (PdR) were carried out on 1-hexanethiol- and 1-dodecanethiol-modified gold electrodes, and the effect of NAD+/NADH were investigated. Electron transfer rate constants were calculated for both electrode modifiers, and a catalytic reduction current was observed in the presence of NAD+ at dodecanethiol-modified gold surfaces. Complementary in situ scanning tunnelling microscopy images of the electrode surface at high resolution were obtained in fluid which show that the PdR molecules are immobilised in a highly uniform manner on the modified gold surface. The results suggest that the immobilised enzyme is both electrochemically and catalytically active.