AMPEROMETRIC FLOW-INJECTION ANALYSIS OF PURINE NUCLEOTIDES - COMPARISON OF SELECTIVITY FOR HYDROLYTIC CLEAVAGE OF PURINE NUCLEOTIDES

Four hydrolases (alkaline phosphatase, apyrase, 5'-nucleotidase, and adenosine-5'-triphosphatase) are immobilized onto the controlled-pore glass, respectively. They are used as the reactor for the enzyme-catalyzed hydrolytic cleavage of purine nucleotides, in a flow-injection system based on the combined use of the following coimmobilized purine nucleoside phosphorylase-xanthine oxidase reactor and amperometric detector downstream. Four hydrolase-immobilized reactors possess interesting differences in the selectivity for the hydrolytic cleavages of purine nucleotides.The alkaline phosphatase reactor catalyzes enzymatically the complete conversion of all the purine nucleotides to the corresponding nucleosides. The apyrase reactor converts completely both nucleoside triphosphate and diphosphate to nucleoside monophosphate. The 5'-nucleotidase reactor is selective for the hydrolytic cleavage of nucleoside monophosphate to nucleoside. The analytical importance of these hydrolase-immobilized reactors is discussed for the selective detection of purine nucleotides.