Studies on inhibition, activation and substrate specificity of the alkaline phosphatase activity from the thymic lymphomas of C57B1 mice, 1971

Alkaline phosphatase activity in C57B1 mice thymic lymphomas has been characterized using pH optima, heat inactivation, substrate ratio and electrophoretic mobility as parameters. This study was undertaken to further characterize the alkaline phosphatase activity of the thymic lymphomas of C57B1 mice using metal ion activation, inhibition and substrate specificity as parameters. Magnesium chloride, potassium chloride and sodium chloride were used as activators of alkaline phosphatase activity. Ethylenediamine tetraacetic acid (EDTA), L-phenylalanine and zinc sulfate were used as inhibitors of alkaline phosphatase activity. Para-nitrophenyl phosphate, fructose 1, 6 diphosphate, adenosine triphosphate and sodium pyrophosphate were used in studies on substrate specificity. Paranitrophenyl phosphate (p-NPP) was used as the substrate to assay for alkaline phosphatase activity by measuring the concentration of p-nitrophenol (p-NP) by absorbance at 400 nm. All phosphate assays were done using the Molydo-Vanadate method. Results show that magnesium potassium and sodium ions activate alklaine phosphate activity, with magnesium and potassium showing the greater activation effect. Studies on inhibition show that EDTA, L-phenylalanine and zinc sulfate significantly inhibit alkaline phosphatase activity, with zinc sulfate being the strongest inhibitor. Preliminary studies on substrate specificity indicate that the enzyme is more active toward fructose 1,6 diphosphate, than the others tested. The enzyme exhibits very little inorganic pyrophosphatase activity. The enzymes activity toward ATP was found to be comparable to its activity toward p-NPP