Abstract:

 The effect of theophylline on the immobilized enzyme has been investigated using polyaniline uricase electrode. The activity of the immobilized uricase is markedly inhibited by theophylline. However, this is a reversible inhibition. In the presence of theophylline, the effect of pH on the response current of the enzyme electrode is different from that without theophylline; the response current of the enzyme electrode rapidly increase with increasing potential from 0.20-0.50V, and then increases slowly with further increasing potential. The activation energy of the enzyme-catalyzed reaction is 47.8kJ?mol-1 in the presence of theophylline, which is much larger than that without theophylline (29.9kJ?mol-1). This indicates that the path of the enzyme-catalyzed reaction was changed by theophylline.

Key words: Polyaniline, Uricase, Theophylline, Inhibition, Activation energy