Metallophosphoryl and Apophosphoryl Alkaline Phosphatases.
The noncovalent phosphate (E-P) and covalent phosphory (E-P) complexes of Zn(II), Cd(II), and apoalkaline phosphatases of Escherichia coli have been studied by stopped flow kinetic methods and 32P-labeling techniques. With 2,4-dinitrophenylphosphate as substrate, preincubation of the Zn(II) enzyme with Pi at pH 8 slows the pre-steady state burst rate, but does not affect the burst magnitude of 1 mol of ROH per enzyme dimer. Preincubation of the enzyme with Pi at pH 5.5 reduces the burst magnitude by one-half, as well as reducing the burst rate. Reduction of the burst magnitude as a function of the pH of the preincubation with Pi follows the same function as that previously established for the formation of E-P. Hence, ROP phosphorylates the enzyme by displacing phosphate from E-P during a pre-steady state reaction, while E-P turns over at the steady state velocity.
D000469:Alkaline Phosphatase / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D002104:Cadmium; D004926:Escherichia coli / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology; D008667:Metalloproteins / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism
D008667:Metalloproteins; D010710:Phosphates; D010750:Phosphoproteins; D002104:Cadmium; D008345:Manganese; D000469:Alkaline Phosphatase