MODULATION OF THE FUNCTION OF AN ENZYME IMMOBILIZED IN A CONDUCTIVE POLYMER BY ELECTROCHEMICAL CHANGING OF THE SUBSTRATE CONCENTRATION

A modulation system analogous to in vivo systems controlled by substrate and product inhibition was demonstrated by immobilizing an enzyme catalyst in a conductive polymer film. A phosphate-requiring enzyme, pyruvate oxidase, was selected to provide the system. Reversible electrochemical oxidation and reduction of the polypyrrole accompanying doping and undoping were performed to induce a change in the phosphate concentration in the polymer membrane. This electrochemical changing of the substrate concentration was exploited as a means of modulating the enzyme in the polypyrrole matrix. Local enrichment of phosphate was favourable for the catalytic function of the enzyme immobilized in the conductive polymer. With this approach the apparent enzyme activity was successfully enhanced by 10%-56% even though the anion concentration in the bulk solution was very low.