B. R. Nechay
1984
Citations
8
Influential Citations
307
Citations
Quality indicators
Journal
Annual review of pharmacology and toxicology
Abstract
Vanadium is widely distributed, the twenty-first most abundant element in the Earth's crust, with an average content of 135 ppm. In sea water, vanadium ranks thirty-fourth in abundance, with an average concentration of only 2 ppb. Because it evolved as an essential element for certain forms of life and also because of its wide industrial use, the biological actions of vanadium are of interest to scientists. Excellent accounts of the history and previous know ledge of vanadium are available. (1-7). The chemistry of vanadium is complex because the metal can exist in oxidation states from -1 to +5 and forms polymers frequently (8). Recently Rubinson (9) reviewed the material concerning the form of biochemically active vanadium. The following generalizations appear justified. At low normal concentrations in mammals and birds, any free vanadium will be in hydrated, monomeric form. In the body fluids at pH 4-8, the predominant species will be VOi ( + 5 oxidation state), vanadate (metavanadate). VOi may enter certain cells by an anion transport system and be reduced by glutathione to VOH (+4 oxidation state), vanadyl. By way of speculation, the oxidation reduction reactions may be as follows: H+ + VOi + 2GSH � Y02+ + G2S2 + OH+ e + H20. Extensive binding to extraand intracellular ligands may be expected. Since phosphate and Mg2+ are ubiquitous in biological processes, YOi as the analogue of phosphate and Y02+, which resembles the size of Mg2+ (respective ionic radii: 0.60 and 0.65 ft.), potentially have many bio chemical and cellular sites of action. For example, vanadium compounds in hibit ATP phosphohydrolases, ribonuclease, adenylate kinase, phosphofructo kinase, squalene synthetase, glyceraldehyde-3-phosphate dehydrogenase (10),