||Transfer of Arsenite from Glutathione to Dithiols: A Model of Interaction.
Delnomdedieu, M. ;
Basti, M. M. ;
Otvos, J. D. ;
Thomas, D. J. ;
||North Carolina Univ. at Chapel Hill. Center for Environmental Medicine and Lung Biology. ;North Carolina State Univ. at Raleigh. Dept. of Biochemistry.;Health Effects Research Lab., Research Triangle Park, NC. Pharmacokinetics Branch.
Chemical models ;
Nuclear magnetic resonance spectroscopy ;
Binding sites ;
Carbon 13 ;
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The interactions of arsenate and arsenite with meso-2,3-dimercaptosuccinic acid (DMSA) have been characterized using carbon-13 nuclear magnetic resonance. These studies show that DMSA reduces arsenate to arsenite and complexes arsenite. Monitoring the carbon-13 signals of complexed DMSA and liberated glutathione shows that DMSA readily extracts arsenite from a glutathione(sub 3)-arsenite complex, proving the affinity of arsenite for dithiols is greater than that for monothiols. Competition between DMSA (vicinal thiols) and dithioerythritol (1,4-dimercapto-2,3-butanediol) for binding of arsenite indicates that the binding affinity is inversely related to the distance between the two thiol groups. On the basis of these findings, a model for the interaction of arsenic with mono- and dithiol-containing molecules is proposed. (Copyright (c) 1993 by the American Chemical Society.)