CALORIMETRIC INVESTIGATIONS OF UREASE INHIBITION BY HEAVY-METAL IONS

The subject of this publication is calorimetric investigations on the inhibitor effect of heavy metal ions on the enzyme urease. The obtaine d results allow quantification of the inhibitors (Cd2+-, As3+-, Zn2+-, Pb2+-ions) via the initial reaction rate of enzymatically catalysed u rea hydrolysis. The interpretation potential of the calorimetric measu rements is underlined by the determination of the inhibiting mechanism s for the example of Cd2+- and As3+-ions, the findings on the time reg ime of the inhibition process, and the detection of heavy metal ions i n the ppm range. The use of several different buffer substance reveale d the influence of the latter on the intensity of heavy metal inhibiti on. This opens the path to both the selective analysis of heavy metals via pattern recognition and to the improvement of detection sensitivi ty. (C) 1998 Elsevier Science B.V.