In vitro effect of arsenical compounds on glutathione-related enzymes

被引:90
作者
Chouchane, S
Snow, ET
机构
[1] Deakin Univ, Sch Biol & Chem Sci, Ctr Cellular & Mol Biol, Burwood, Vic 3125, Australia
[2] CUNY City Coll, New York, NY 10031 USA
[3] NYU, Sch Med, Nelson Inst Environm Med, Tuxedo Pk, NY 10987 USA
关键词
D O I
10.1021/tx000123x
中图分类号
R914 [药物化学];
学科分类号
100701 ;
摘要
The mechanism of arsenic toxicity is believed to be due to the ability of arsenite (As-III) to bind protein thiols. Glutathione (GSH) is the most abundant cellular thiol, and both GSH and GSH-related enzymes are important antioxidants that play an important role in the detoxification of arsenic and other carcinogens. The effect of arsenic on the activity of a variety of enzymes that use GSH has been determined using purified preparations of glutathione reductase (GR) from yeast and bovine glutathione peroxidase (GPx) and equine glutathione S-transferase (GST). The effect on enzyme activity of increasing concentrations (from 1 muM to 100 mM) of commercial sodium arsenite (As-III) and sodium arsenate (As-V) and a prepared arsenic(III)-glutathione complex [As-III(GS)(3)] and methylarsenous diiodide (CH3AsIII) has been examined. GR, GPx, and GST are not sensitive to As-V (IC50 > 50 mM), and none of the enzymes are inhibited or activated by physiologically relevant concentrations of As-III, As-III(GS)(3), or CH3-As-III, although CH3AsIII is the most potent inhibitor (0.3 mM < IC50 < 1.5 mM). GPx is the most sensitive to arsenic treatment and GST the least. Our results do not implicate a direct interaction of As with the glutathione-related enzymes, GR, GPx, and GST, in the mechanism of arsenic toxicity. CH3AsIII is the most effective inhibitor, but it is unclear whether this product of arsenic metabolism is produced at a sufficiently high concentration in critical target tissues to play a major role in either arsenic toxicity or carcinogenesis.
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页码:517 / 522
页数:6
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