REACTIONS OF ARSENIC(III) AND ARSENIC(V) SPECIES WITH GLUTATHIONE
REACTIONS OF ARSENIC(III) AND ARSENIC(V) SPECIES WITH GLUTATHIONE
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DOI：
10.1021/tx00031a016
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发表时间：
1993-01-01
影响因子：
4.1
通讯作者：
CARTER, DE
中科院分区：
文献类型：
--
作者：
SCOTT, N;HATLELID, KM;CARTER, DE
砷通过氧化还原和甲基化反应被生命系统代谢，还原型谷胱甘肽（GSH）已被证明在这种代谢中很重要。在这项研究中，GSH和砷酸盐，亚砷酸盐，和它们的甲基化代谢产物，一甲基胂酸（MMA）和二甲基胂酸（DMA）之间的溶液反应，其特征在于使用H-1和C-13 NMR在氮气气氛下。通过巯基与GSH结合后，主要是与半胱氨酰残基的巯基结合的碳原子发生位移，即，甲基化的代谢物也显示出与GSH反应后连接到砷原子上的甲基发生了位移。核磁共振谱表明，亚砷酸钠（As（III））在溶液中与GSH结合形成As（SG）3络合物。分离化合物后，通过FAB-MS确认复合物的身份。砷酸钠、As（V）和GSH的混合物表明，在pH 7的D2 O溶液中，砷酸盐氧化GSH形成氧化型谷胱甘肽（GSSG）。当As：GSH的摩尔比超过1：2时，观察到形成As（SG）3的证据。MMA和DMA都是As（V）物种，并且与GSH的混合物显示首先氧化为GSSG，然后分别形成CH 3·As（SG）2和（CH 3）2·As·SG。GSH对砷代谢的影响可能是由两种化合物之间的直接反应引起的。
Arsenic is metabolized by living systems using oxidation-reduction and methylation reactions, and reduced glutathione (GSH) has been shown to be important in that metabolism. In this study, the solution reactions between GSH and arsenate, arsenite, and their methylated metabolites, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), were characterized using H-1 and C-13 NMR under a nitrogen atmosphere. Binding to GSH through the thiol group was primarily followed by shifts in the carbon atom bonded to the sulfhydryl group of the cysteinyl residue, i.e., the CH2 carbon atom and the protons bonded to it. The methylated metabolites also showed shifts in the methyl groups attached to the arsenic atom after reaction with GSH. Sodium arsenite, As(III), bound to GSH to form an As(SG) 3 complex in solution as indicated by NMR spectra. The identity of the complex was confirmed by FAB-MS after isolation of the compound. Mixtures of sodium arsenate, As(V), and GSH showed that arsenate oxidized GSH in D2O solutions at pH 7 to form oxidized glutathione (GSSG). When the molar ratio of As:GSH exceeded 1:2, evidence for the formation of As(SG)3 was observed. MMA and DMA are both As(V) species, and mixtures with GSH showed oxidation to GSSG initially followed by formation of CH3.As(SG)2 and (CH3)2.As.SG, respectively. The effects of GSH on arsenic metabolism may result from direct reactions between the two compounds.