Cadmium(II) complex formation with glutathione
Cadmium(II) complex formation with glutathione
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DOI：
10.1007/s00775-009-0616-3
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发表时间：
2010-03-01
影响因子：
3
通讯作者：
Jalilehvand, Farideh
中科院分区：
文献类型：
--
作者：
Mah, Vicky;Jalilehvand, Farideh
重金属离子与谷胱甘肽（GSH）形成络合物被认为是生物体内许多解毒过程的起始步骤。在这项研究中，镉（II）离子和GSH之间的结构和协调进行了研究，在水溶液中（pH 7.5和11.0），并在固态下，使用光谱技术的组合。在pH 3.0沉淀的固体化合物[Cd（GS）（GSH）] ClO_4中心点3 H（2）O的Cd K边和L-3边X射线吸收光谱的相似性，与先前研究的半胱氨酸化合物{Cd（HCys）（2）中心点H2O}（2）中心点H3 O+中心点ClO 4（-）对应于Cd（S-GS）（3）O Cd（S-GS）（4）为四配位，Cd-S和Cd-O的平均键距分别为2.51 +/-A0.02和2.24 +/-A0.04。对于pH值为7.5且GSH适度过量的镉（II）溶液（C（Cd（II））类似于0.05 M）（C（GSH）/C（Cd（II））= 3.0-5.0），Cd（S-GS）（3）O（主要）和Cd（S-GS）（4）物质的混合物与632-658 ppm范围内的宽Cd-113 NMR共振一致。在pH 11.0和C（GSH）/C（Cd（II））= 2.0或3.0的碱性溶液中，在322和674 ppm处得到两个明显的峰。第一个峰表明六配位的单核和双核配合物与CdS_2N_2（N/O）（2）和CdSN_3O_2配位，而第二个峰对应于Cd（S-GS）（4）位点。在高配体过量下，四硫醇盐络合物Cd（S-GS）（4）占主导地位，其特征在于在677 ppm处的尖锐δ（Cd-113）NMR信号。从X-射线吸收光谱获得的平均Cd-S距离在2.49-2.53的窄范围内变化，对于所有溶液（pH 7.5和11.0），无论配位几何形状如何。
Complex formation between heavy metal ions and glutathione (GSH) is considered as the initial step in many detoxification processes in living organisms. In this study the structure and coordination between the cadmium(II) ion and GSH were investigated in aqueous solutions (pH 7.5 and 11.0) and in the solid state, using a combination of spectroscopic techniques. The similarity of the Cd K-edge and L-3-edge X-ray absorption spectra of the solid compound [Cd(GS)(GSH)]ClO4 center dot 3H(2)O, precipitating at pH 3.0, with the previously studied cysteine compound {Cd(HCys)(2)center dot H2O}(2)center dot H3O+center dot ClO4 (-) corresponds to Cd(S-GS)(3)O (dominating) and Cd(S-GS)(4) four-coordination within oligomeric complexes with mean bond distances of 2.51 +/- A 0.02 for Cd-S and 2.24 +/- A 0.04 for Cd-O. For cadmium(II) solutions (C (Cd(II)) similar to 0.05 M) at pH 7.5 with moderate excess of GSH (C (GSH)/C (Cd(II)) = 3.0-5.0), a mix of Cd(S-GS)(3)O (dominating) and Cd(S-GS)(4) species is consistent with the broad Cd-113 NMR resonances in the range 632-658 ppm. In alkaline solutions (pH 11.0 and C (GSH)/C (Cd(II)) = 2.0 or 3.0), two distinct peaks at 322 and 674 ppm are obtained. The first peak indicates six-coordinated mononuclear and dinuclear complexes with CdS2N2(N/O)(2) and CdSN3O2 coordination in fast exchange, whereas the second corresponds to Cd(S-GS)(4) sites. At high ligand excess the tetrathiolate complex, Cd(S-GS)(4), characterized by a sharp delta(Cd-113) NMR signal at 677 ppm, predominates. The average Cd-S distance, obtained from the X-ray absorption spectra, varied within a narrow range, 2.49-2.53 , for all solutions (pH 7.5 and 11.0) regardless of the coordination geometry.