Phosphoprotein phosphatase activity of bovine intestinal alkaline phosphatase

The phosphoprotein phosphatase activity of a commercial preparation of bovine intestinal alkaline phosphatase (EC 3.1.3.1) was examined using phosvitin and dentine phosphoprotein as substrates. Over 90% and 70% of the phosphorus from dentine phosphoprotein and phosvitin were hydrolyzed in 2 h. The optimum pH of the enzyme for the dephosphorylation of phosvitin and dentine phosphoprotein was nearly 6. No protein phosphatase activity was observed when the alkaline phosphatases from bovine liver and pulp were investigated.