Some properties of alkaline phosphatase of cow's milk and calf intestinal mucosa.

The purification of the alkaline phosphatases of cow's milk and calf intestinal mucosa as previously described (Morton, 1950, 1953a, 1954a) was initiated in order to enable investigation of the properties of these enzymes. The need for such a study has been well recognized (see Moog, 1946, for example), but hitherto all work has been carried out with crude or partially purified enzyme preparations. Moreover, all previous workers have used prolonged autolysis or proteolysis to separate alkaline phosphatases from animal tissues, and the extent of modification of these proteins by such treatments is still uncertain. These undesirable procedures may be avoided, however, by using the butanol procedure (Morton, 1950) to separate alkaline phosphatases from the lipoprotein material with which they are normally associated (Kabat, 1941; Chantrenne, 1947; Hers, Berthet, Berthet & de Duve, 1951; Morton, 1953b, 1954a, b). Some ofthe properties ofthe purified enzymes are described in this paper. Particular attention has been given to the chemical constitution, the activity-pH relationship, metal activation and the effects of alanine and glycine. All these have been the subjects of conflicting statements in the extensive literature conceming alkaline phosphatases. It has been found that bovine milk and intestinal phosphatases are two different enzymes but of similar substrate specificity. No evidence has been obtained in support of numerous claims for an organic coenzyme of alkaline phosphatase.