Vanadium in Biology
Published Online: 15 DEC 2011
Copyright © 2011 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Inorganic and Bioinorganic Chemistry
How to Cite
Wever, R., Renirie, R. and Hasan, Z. 2011. Vanadium in Biology. Encyclopedia of Inorganic and Bioinorganic Chemistry. .
- Published Online: 15 DEC 2011
In this article, the role of vanadium in a number of biological systems will be discussed. The metal oxide (vanadate) is present as the prosthetic group in the haloperoxidases, enzymes that are able to oxidize halides in the presence of hydrogen peroxide to hypohalous acids. The bromoperoxidases seem to be involved in the production of the huge amounts of brominated compounds formed by several seaweeds. The enzymes have unusual properties in terms of stability and structural organization. X-ray structures at high resolution are available now for four vanadium haloperoxidases and details of the events occurring at the active site during catalysis are known. The metal oxide binds peroxide in a side-on fashion and seems to acts as a Lewis acid in polarizing the bound peroxide for further nucleophilic attack by an incoming halide. These enzymes are also able to mediate in the presence of hydrogen peroxide, the enantioselective sulfoxidation of organic sulfides yielding chiral sulfoxides with high enantiomeric excess. The active site of the haloperoxidases is very similar to that found in acid phosphatases that hydrolyze phosphate monoesters and there is some evidence that the haloperoxidases have evolved from the phosphatases. Vanadium is found in the vanadiumIII state in certain blood cells of tunicates (Ascidians) under very acidic conditions. Despite many studies, there is no clue as to the physiological role of the metal and there are many questions regarding the mechanism of accumulation and reduction of the metal in these organisms. The metal also seems to be used as an electron sink by certain bacteria under anaerobic conditions. Furthermore, vanadium is accumulated in Amanita species. These toadstools contain up to 10 mM of a vanadiumIV compound with very special structure in which the vanadiumIV is eightfold coordinated in an unusual geometry. Although the compound has been reported to carry out redox reactions, the physiological function is elusive.
- vanadium bromoperoxidase;
- vanadium chloroperoxidase;
- X-ray structures;
- active site;
- sulfoxidation reactions;
- terminal electron acceptor;