Calf Intestinal Alkaline Phosphatase I. Improved Isolation Method and Molar Composition of the Purified Phosphatase

A modified and improved method for isolation of calf intestinal alkaline phosphatase is described. By this method 300 to 400 mg of pure enzyme was prepared in a relatively short time. On the basis of the results of ultracentrifugation and of the free, polyacrylamide and immunoelectrophoresis the phosphatase obtained is found to be a homogenous glycoprotein, containing firmly bound zinc, magnesium and phosphoric acid. The molar composition of the enzyme and the catalytic activity were determined with different substrates and buffers.