DNA facilitating electron transfer reaction of xanthine oxidase

Xanthine oxidase has potential multi electrochemical active centers (one molybdenum center, two Fe2-S2 centers and one flavin adenine dinucleotide (FAD)). The FAD and molybdenum group can exchange electron with electrode, because the active centers have cave connecting to the protein surface. Fe2-S2 centers bury in the protein framework and act as wire conduction the electron transfer between FAD and molybdenum groups. But there is still no report that electrochemical signals of these two active sites have been observed simultaneously. In this paper, we use DNA as a matrix to embed xanthine oxidase, and obtained the electrochemical responds of FAD and molybdenum center of xanthine oxidase. Moreover, the enzyme keeps its native catalytic activity to hypoxanthine in the DNA film. So, DNA can be considered as a “conductive molecular wire” to facilitate electron transfer between the enzyme and electrode.