Properties of alkaline phosphatase in crude homogenates of human diploid fibroblasts.

The kinetic properties of the "constitutive" and the "induced" alkaline phosphatase in diploid fibroblasts are compared with those of the enzymes in crude tissue homogenates. Both the constitutive as the induced enzyme have properties comparable with those of the liver-bone-kidney group. The induced alkaline phosphatase clearly differs from the "constitutive" alkaline phosphatase concerning the effect of high concentrations of L-phenylalanine and the effect of Mg2+ ions. The induced alkaline phosphatase seems to be identical with the enzyme in liver, but the constitutive alkaline phosphatase could not be identified.