Thermodynamics of the As(III)-thiol interaction: Arsenite and monomethylarsenite complexes with glutathione, dihydrolipoic acid, and other thiol ligands
Thermodynamics of the As(III)-thiol interaction: Arsenite and monomethylarsenite complexes with glutathione, dihydrolipoic acid, and other thiol ligands
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DOI：
10.1021/ic048694q
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发表时间：
2005-04-18
影响因子：
4.6
通讯作者：
Wilcox, DE
中科院分区：
文献类型：
--
作者：
Spuches, AM;Kruszyna, HG;Wilcox, DE
用比色法（近紫外吸收光谱法）和量热法（等温滴定量热法）定量测定了与谷胱甘肽（GSH）和二硫醇二巯基琥珀酸（DMSA）、二氢硫酸（DHLA）和二硫代苏糖醇（DTT）配位的亚砷酸盐和单甲基亚硒酸盐（MMA）的平衡和热力学。我们发现亚砷酸盐和MMA与谷胱甘肽形成中等稳定的配合物(β = 10(6)-10(7))；亚砷酸盐与生物辅助因子DHLA形成特别稳定的2:3复合物（β接近10(18)）；MMA对硫醇配体的亲和力略高于亚砷酸盐；熵因子调节As（III）与硫醇配合物的整体稳定性，有利于As(III)-硫醇键的放热形成。讨论了这些结果对砷毒性的影响。
Colorimetric (near-UV absorption spectroscopy) and calorimetric (isothermal titration calorimetry) methods have been used to quantify the equilibrium and thermodynamics of arsenite and mono methylarsenite (MMA) coordinating to glutathione (GSH) and the dithiols dimercaptosuccinic acid (DMSA), dihydrolipoic acid (DHLA), and dithiothreitol (DTT). We found that both arsenite and MMA form moderately stable complexes (beta = 10(6)-10(7)) with GSH; that arsenite forms a particularly stable 2:3 complex (beta approximate to 10(18)) with the biological cofactor DHLA; that MMA has a somewhat higher affinity than arsenite for thiol ligands; and that entropic factors modulate the overall stability of As(III) complexes with thiols, which are favored by the exothermic formation of As(III)-thiolate bonds. The implications of these results for arsenic toxicity are discussed.