Human erythrocyte 5'-AMP aminohydrolase. Purification and characterization

Human erythrocyte 5'-AMP aminohydrolase has been obtained using phosphocellulose chromatography and affinity chromatography on a GTP-agarose column to yield a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme has a molecular weight of 285,000, and is comprised of four subunits. Since limited quantities of the homogeneous enzyme were available, the kinetic properties of a nonhomogeneous preparation purified about 20,000-fold over the red blood cell lysate by phosphocellulose chromatography were examined. Like the muscle enzyme, it exhibits a sigmoid AMP saturation curve in the absence of activating monovalent cations; a hyperbolic saturation curve is observed in the presence of 0.15 M KCl. Activation by monovalent cations and ATP, and inhibition by Pi, PPi, GDP, GTP, and 2,3-diphosphoglyceric acid were studied in more detail.