The Effect of o-phenanthroline on the Kinetics of the Immobilized Uricase Catalyzed Reaction

The activation energy of the enzyme-catalyzed reaction for uric acid decreases markedly in the presence of o-phenanthroline, which activates the bioelctrochemical activity of the polypyrrole uricase electrode. The response current of the enzyme electrode is independent of the concentration of o-phenanthroline. Based on the experimental results, the mechanism of the enzyme-catalyzed reaction for uric acid in the presence of o-phenanthroline is presented as follows: E+A -> EA, EA+S reversible arrow EAS, EAS -> EA+P, where E, A, S and P are the enzyme, activator, substrate and product, respectively. The effects of pH value, potential and the uric acid concentration on the response currents of the uricase electrode have been studied in the presence of p-phenanthroline, In the presence of o-phenanthroline, the response current of the enzyme electrode increases linearly with increasing concentration of uric acid in the region of 0.07 to 0.67 mmol.L-1, therefore the polypyrrole uricase electrode which has once lost its activity can be activated and used again to determine the substrate concentration.