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The Chemistry and Metabolism of Arsenic
Citation:
Thomas, D. The Chemistry and Metabolism of Arsenic. Edition 1, Chapter 4, J. Christopher States (ed.), Arsenic: Exposure Sources, Health Risks, and Mechanisms of Toxicity. John Wiley & Sons Incorporated, New York, NY, 1:149-202, (2015).
Impact/Purpose:
This chapter serves to summarize a wide range of chemical and biochemical information and that is relevant to understanding the wide scope of arsenic metabolism in humans. This approach is especially valuable to those interested in aggregate exposure to arsenic from water, soil, food, and air media in which arsenic occurs in wide range of chemical forms.
Description:
I. IntrodctionA century of study of the process by which many organisms convert inorganic arsenic into an array of methylated metabolites has answered many questions and has posed some new ones. The capacity of microorganisms to. form volatile arsenic compounds was first recognized in the 19th century (CuIlen, 2008). This observation prompted Frederick Challenger and his colleagues to study arsenic methylation in microorganisms and to postulate a chemically plausible sequence of reactions in which pentavalent arsenic is reduced to trivalency and the resulting trivalent arsenical is oxidatively methylated (for a historical review see Chasteen etal., 2003). Identification of genes encoding arsenic methyltransferase in the three domains of the tree of life — Bacteria, Archaea, and Eukarya - provide an opportunity to test the chemical plausibility of Challenger’s scheme and other alternate schemes for arsenic methylatlon. Although our understanding of molecular aspects of enzymatically catalyzed methylation of arsenic remains in flux, data are sufficient to assert that conversion of inorganic arsenic to methylated species is a major determinant of the distribution and retention of arsenic among tissues and is an important factor in its actions as a toxicant and carcinogen.