Immobilized uricase for automated assay of uric acid in serum

The wide use of bound enzyme coils with hexokinase and glucose-6-phosphate dehydrogenase in automated analysis for serum-glucose assay [1, 2-] demonstrates the potential of open tubular heterogeneous enzyme reactors [3] in clinical analysis. Such reactors have also been prepared with other enzymes I-4, 5] and in this paper the authors describe a continuous-flow method for uric acid assay with immobilized uricase, as well as some of the characteristics of bound uricase coils. The classic alkaline phosphotungstate method for uric acid assay has been gradually replaced by enzymic methods that employ uricase and measure the concentration of one of the reaction products: allantoin or hydrogen peroxide [6-12]. The authors used tubes with immobilized uricase at the inner wall on Technicon's SMA and SMAC continuous-flow analysers and the reaction scheme is shown in figure 1. Dialysed uric acid enters the reactor coil and is oxidized in a reaction catalysed by l_xy..