A biochemical comparison of the hydrolysis of cysteamine-s-phosphate and para-nitrophenyl phosphate by murine alkaline phosphate, 1977

Alkaline phosphatase (APase) hydrolyzes phosphate esters at an alkaline pH. For this study APase was extracted from the thymic lymphoma and placental tissue of sixteen day pregnant C57BL mice. In an effort to determine the function of APase the hydrolysis of substrates pNPP and GASP by APase was compared biochemically. The tested parameters demonstrated that APase extracted from the thymic lymphoma hydrolyzed GASP with a similar biochemical characterization to the hydrolysis of pNPP. However pNPP was hydrolyzed at approximately three times the rate of GASP hydrolysis. The results in this study are conflicting with Neumann et al., 1974. They isolated an APase from the thymic lymphoma of C57BL mice which did not hydrolyze CASP while it did hydrolyze pNPP. The reason for this contrast in data is unknown since the method used for the assay of CASP hydrolysis was that used by Neumann. Due to the consistent results in our data, we feel that we have isolated only one type of APase