The Specific Binding of Zinc(II) to Alkaline Phosphatase of Escherichia coli

Abstract

The binding of Zn2+ to Escherichia coli alkaline phosphatase has been studied by pH titrations and equilibrium dialysis using 1,10‐phenanthroline as competing chelating agent. Measurements of the strength of binding under different experimental conditions have been performed: At constant pH with different concentrations of chelating agent. At different pH with constant concentration of chelating agent. In the presence of denaturing agent at pH 8.0. It was found on the basis of equilibrium dialysis experiments that the binding of the two zinc atoms to alkaline phosphatase may be described as coordination to the two equivalent and independent sites. The high values of the binding constants, and the fact that denaturation destroys the specific binding of zinc to alkaline phosphatase indicates chelate formation with the protein, unless some unknown prosthetic groups are involved. Copyright © 1969, Wiley Blackwell. All rights reserved