Hydrolysis of phosphatidate by human placental alkaline phosphatase.

Highly purified alkaline phosphatase of human placenta catalyzed the hydrolysis of phosphatidate with quantitative formation of almost stoichiometric amounts of diglyceride and inorganic phosphate. In the presence of sodium deoxycholate, the activity was maximal at pH 8.8. The activity was strongly inhibited by L-phenylalanine but scarcely affected by NaF. These results show that alkaline phosphatase hydrolyzes phosphatidate under different conditions from those for activity of phosphatidate phosphohydrolase.