Transfer of arsenite from glutathione to dithiols: a model of interaction.
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)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.
Delnomdedieu
M
M
Center for Environmental Medicine, University of North Carolina, Chapel Hill 27599-7310.
Basti
M M
MM
Otvos
J D
JD
Thomas
D J
DJ
D001149:Arsenates / Q000737:chemistry; D018053:Arsenites / Q000737:chemistry*; D004226:Dithioerythritol / Q000737:chemistry; D005978:Glutathione / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D010084:Oxidation-Reduction; D004113:Succimer / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*
D001149:Arsenates; D018053:Arsenites; D013438:Sulfhydryl Compounds; D004226:Dithioerythritol; D004113:Succimer; D005978:Glutathione; C015001:arsenite