An Improved Purification, Crystallization, and Some Properties of Rabbit Muscle 5’9Adenylic Acid Deaminase*

A rapid method for the preparation of crystalline 5’-adenylic acid deaminase from rabbit skeletal muscle is presented. The enzyme remains bound to cellulose phosphate under conditions at which apparently no other proteins are bound; thus it was possible to develop, in essence, a one-step method for its purification. The crystalline preparation is homogeneous as indicated by its elution profile, by ultracentrifugation, and by acrylamide gel electrophoresis. The new method results in enzyme that has 5 times the specific activity of the previously reported crystalline preparation and differs in stability and kinetic properties. The enzyme is stable in dilute solution for extended periods at room temperature provided the diluting medium is of high ionic strength and contains /%mercaptoethanol. The enzyme follows normal Michaelis-Menten kinetics with respect to adenosine monophosphate concentration when assayed in the presence of KCl, and with respect to potassium concentration. Sodium and potassium, at 0.15 M, function equally efficiently as cation activators.