The impact of metal ion chemistry on our understanding of enzymes

Abstract

The study of the biological role of metal ions has a long history in medicine, in pharmacology and in toxicology, but it is only recently that the extent and variety of metal ion involvement has been appreciated. For example, among the transition metals, the elements V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Mo have been shown to be essential to life and the elements Au, Ag, Pt, Pd, Ir, Os, Ti, and others have either been used in therapy or claimed to be of therapeutic value. In recent years the toxic nature of the complexes of many transition metals and of main group metals, such as cadmium, lead, mercury and aluminium, has evoked much worry and stimulated research into the effect of these metals on terrestial and marine biochemical systems. The ecological and health effects of these elements are often exacerbated by environmental transformation of less hazardous forms to extremely toxic compounds. An example of the latter is the biosynthesis of methylmercury cations from inorganic mercury salts by, amongst others, sulphate-reducing bacteria in marine sediments (Campion and Barthia, 1985).