Furthermore, a metal ion in the body’s metallo-enzyme
can be conveniently replaced by another metal ion of
similar size. Thus Cd can replace Zn in some dehydrogenating enzymes
, leading to cadmium toxicity. In the
process of inhibition, the structure of a protein molecule
can be mutilated to a bio-inactive form, and in the case of
an enzyme can be completely destroyed. For example,
and can attack –SH groups in enzymes to inhibit their
bioactivities as shown below (Ogwuegbu and Ijioma,
2003).