Purification and Properties of a Nucleoside Triphosphate Pyrophosphohydrolase from Red Cells of the Rabbit

Abstract Nucleoside triphosphate pyrophosphohydrolase has been isolated from rabbit reticulocytes. The enzyme has been purified over 2000-fold from the cell lysate. Isolation and analysis procedures are described. The enzyme has been shown to catalyze the hydrolysis of ITP to yield IMP and PPi. Other substrates are dITP, XTP, and, to a lesser extent GTP, dGTP, UTP, and dUTP. ATP, dATP, CTP, and dCTP are not hydrolyzed. The activity of this enzyme in reticulocytes of the rabbit is approximately six times greater per mg of protein than in erythrocytes. Activity comparable to that of rabbit erythrocytes has also been found in human erythrocytes.