THE BIOINORGANIC CHEMISTRY OF VANADIUM

Vanadium is a trace element that plays an important, perhaps essential and general role in the regulation of enzymatic phosphorylations. Several forms of life, including the fly agaric toadstool (Amanita muscaria) and certain sea squirts (ascidians), are able to concentrate vanadium. In other organisms vanadium is part of the active site of some enzymes. Well-studied examples are the nitrogen-fixing bacterium Azotobacter and various seaweeds that use vanadate-dependent peroxidases to synthesize halogenated organic compounds. Despite its importance as a "biometal" both in primitive, prokaryotic organisms (Azotobacter) and in the highly organized ascidians, which represent an early stage in the evolution of vertebrates, the bioinorganic chemistry of vanadium is still in its infancy. Just as young, but undergoing explosive development, is the chemistry of model compounds for vanadium-containing biomolecules, a domain of the bioinorganic coordination chemist, who almost daily discovers compounds with new and surprising structural features. This article reviews this fascinating area of bioinorganic chemistry.