Biometals play important roles in biological process by different chemical actions. The biomembranes enable different metals to acquire different distribution mode among compartments in a biological system.Metalloproteins or metal chaperones are required to maintain cellular metal ions homeostasis. In cells and intracellular organelles there are many proteins whose metal binding sites consist of more metal ions and are not equivalent in thermodynamics. The functions of metalloproteins are mediated by the binding of metal ions, such as that of concanavalin A, Cu/Zn superoxide dismutase, centrin, and zinc fingers protein. That the binding of metal ions to proteins are investigated is of great significance for bioinorganic chemists to understand the roles of metal ions in mediating the functional changes of metalloproteins.

Contents
1 Introduction
2 Concanavalin A
2.1 Structure
2.2 Functional changes mediated by the binding of metal ions
3 Cu/Zn superoxide dismutase
3.1 Structure
3.2 Biological functions
3.3 Functional changes mediated by the binding of metal ions
4 Centrin
4.1 Biological functions
4.2 Structure
4.3 Functional changes mediated by the binding of metal ions
5 Zinc fingers protein
5.1 Structures of zinc fingers
5.2 The binding of metal ions
5.3 Regulation of biological functions by zinc ion
6 Conclusion and outlook