Zinc Interdependencies

Because electrons are neither products nor reactants in chemical reactions, the two processes are interdependent and neither can occur alone. The zinc metal dissolution must furnish electrons for the copper metal plating. The reaction of zinc and copper sulfate solution is a spontaneous reaction involving a transfer of electrons, i.e., is a spontaneous redox process. The spontaneity of the reaction is commonly explained by saying that zinc loses electrons more readily than copper or, alternatively, that Cu2+ ions gain electrons more readily than Zn2+ ions. 

The pKa of Zn H20 in the isoenzymes are determined from the pH dependence of 4-nitrophenyl acetate esterase activity and spectroscopic properties of the metal substituted (essentially Co11) enzyme (142 146). In bovine isoenzyme II, the titration behavior of zinc-H20 and His-64 are interdependent and both have similar pKa values. Similar behavior has been reported for human isoenzyme II (147). 

The data in Table X extend the conclusions reached on the basis of the analyses of crystals. The concomitant increases of specific activity, activity/protein, and zinc content, zinc/protein, imply an interdependence typical of a metalloenzyme. 

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