STUDIES ON THE INHIBITION OF IMMOBILIZED ALKALINE-PHOSPHATASE BY METAL-IONS AND EDTA IN A FLOW-INJECTION SYSTEM

Inhibition of immobilized alkaline phosphatase by several metal ions a nd EDTA was studied in a single-channel flow-injection system. The enz yme was immobilised on controlled pore glass. The same enzyme preparat ion was used for three months. The inhibition by the tested compounds is reversible, the inhibitors are removed from the enzyme reactor just by passing glycine buffer. The metal ion inhibition response is linea r in the range 1X10(-4)-1X10(-6) M, while for EDTA the linearity is be tween 1X10(-5)-5X10(-5) M. The relative standard deviation at mid-cali bration range is below 5% in all cases. The nature of the inhibition w as studied for beryllium and EDTA. Non-competitive inhibition was foun d at low substrate concentrations, while for substrate concentrations higher than 10(-3) M inhibitor and substrate compete for the enzyme.