An Introduction to the Biochemistry of Zinc

Abstract

There are certain advantageous properties of metal ions both in their binding strengths and their rates of exchange of ligands which make them a potential source of chemically and hence biologically interesting selective properties. Zinc is the case in point here. Its most obvious distinction is its highly concentrated charge, Zn²⁺. It is also a small ion, radius 0.65 Å. In itself, however, an electrostatic charge of two and small size gives quite modest binding even to anions such as carboxylate and phosphate and even where several anions occur together. This is due to competition from water of hydration. Furthermore the electrostatic binding by zinc is a property shared almost equally with Mg²⁺ and, to a lesser degree, Ca²⁺ as well as with other metal cations such as Cu²⁺ and Ni²⁺, but it is not strong amongst organic ions. Thus although this part of its chemistry is special to metal ions it is not peculiar to zinc.