BCSJ : Vol. 80 (2007) , No. 9 pp.1691-1702

Demonstration of the Importance of Metal Ion Speciation in Bioactive Systems

Tamás Kiss¹⁾ and Akira Odani²⁾

1) Department of Inorganic and Analytical Chemistry, University of Szeged
2) Department of Chemistry, Graduate School of Science, Nagoya University

(Received January 23, 2007)

This paper gives insight into chemical speciation. After a brief introduction, the methods available to study solution state of metal ions and the importance of speciation in biology are discussed through different examples. Speciation of toxic Al^III, beneficial Cu^II and Ca^II and potentially medicinal Pd^II and VO^IV in various biofluids and tissues is discussed in order to describe the solution state of these metal ions in an organism. The relevance of ternary complex formation with endogenous biomolecules is emphasised. The importance of the biospeciation of Al^III ion in its transport and involvement in neurological disorders, of the actual chemical form of the insulin-mimetic VO^IV complexes in its biological occurrence and Ca^II in mineralization/demineralization processes is discussed. The role of time, i.e., the kinetic aspects of biospeciation, is discussed in the case of the transport of Al^III and Cu^II and some Pd^II complexes (models of the anticancer Pt^II complexes) in blood serum.

Examples from different fields of bioinorganic chemistry are given to demonstrate the importance of the solution state and solution speciation of metal ions or metal complexes in biology.