Metal Requirements of Alkaline Phosphatases of Human and Rabbit Leukocytes

Abstract

Ethylene diamine tetra acetate (EDTA) inhibits the alkaline phosphatase activity of the human leukocyte but has no effect on the rabbit leukocyte. Mg and Zn are required for the reactivation of the human enzyme. Inhibition of phos phatase activity in the human leukocyte is partially reversed by addition to the system of Mg in final concentration of 5x103 [image]. However, Zn is a more potent activator, and in final concentration of 5x10-5 [image] restores complete activity.. Human leukocytes isolated from whole blood collected with EDTA as anticoagulant also show a decrease in alkaline phosphatase activity which can be restored to one-half of normal levels by the addition of 5xl0-5 [image] Zn. Data suggest the presence of at least 2 alkaline phosphatases in the human leukocytes.