Alkaline phosphatase activity improved by the addition of zinc in granulocytes from leukemic subjects (in vitro...

Granulocyte alkaline phosphatase (GAP) was extracted from the leukocyte suspensions of 15 subjects with chronic myeloid leukemia (CML), determining the Zn content by atomic absorption spectrophotometry. The purified enzymatic preparation was dialyzed against a ZnCl2 solution (.01 mg%) in TRIS-HCl 0.1 M, pH 7.5, for 48 hours. After dialysis Zn concentration and GAP activity reached normal values. This suggests that the GAP molecule isolated from CML subjects is not altered as it is able to receive at most 2 Zn moles responsible for the enzymatic function.