Direct electron transfer observed for peroxidase to screen-printed graphite electrodes

Native and recombinant horseradish peroxidase were immobilized onto screen- printed graphite electrodes by depositing and drying an enzyme solution ont o the transduce(-) surface followed by coverage with an UV-polymerizable pa ste. Direct electron transfer from the transducer to the enzymes was obtain ed by applying a potential of -100 mV (vs. Ag/AgCl reference electrode) in the presence of hydrogen peroxide as substrate. Docking of the enzymes to g raphite was modelled to estimate the distances from the active site to the electrode surface. The electrode current was ir creased threefold by adding Gafquat 755N to the enzyme solution. Modelling calculations indicated unsp ecific but strong binding of Garquat subunits to the protein.