Control of Bioelectrocatalytic Transformations on DNA Scaffolds

The spatial organization of biomolecutes on a DNA scaffold linked'to an electrode leads to programmed biocatalytic transformations. This is exemplified by the electrical contacting of glucose oxidase (GOx) linked to the DNA scaffold with the electrode. A nucleic acid functionalized with a ferrocene relay unit was hybridized with the DNA scaffold at a position adjacent to the electrode, and GOx functionalized with nucleic acid units complementary to the specific domain of the DNA template was hybridized with the DNA scaffold in a position remote from the electrode. Under these conditions, ferrocene-mediated oxidation of the redox center of GOx occurred, and the effective bioelectrocatalytic oxidation of glucose was activated. Exchange of the position of GOx and the electron-mediator groups prohibited the bioelectrocatalytic oxidation of glucose. In another system, a nucleic acid-functionalized microperoxidase-11 (MP-11) and the nucleic acid-modified GOx were hybridized with the adjacent and remote sites, respectively, on the DNA scaffold associated with the electrode. In this configuration, effective MP-11-catalyzed reduction of H2O2 generated by the GOx-catalyzed oxidation of glucose occurred, and the resulting bioelectrocatalytic cathodic currents were controlled by the concentration of glucose. Exchanging the positions of MP-11 and GOx on the DNA scaffold eliminated the MP-11-electrocataLyzed reduction of H2O2.