An X-ray absorption spectroscopy investigation of speciation and biotransformation of copper in Elsholtzia splendens
An X-ray absorption spectroscopy investigation of speciation and biotransformation of copper in Elsholtzia splendens
复制标题
X射线吸收光谱研究香薷中铜的形态形成和生物转化
DOI：
10.1007/s11104-007-9463-6
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发表时间：
2008-01-01
期刊：
影响因子：
4.9
通讯作者：
Hu, Tiandou
中科院分区：
文献类型：
--
作者：
Shi, Jiyan;Wu, Bei;Hu, Tiandou
海州香薷是生长在我国南方铜矿区的一种耐铜植物。本研究采用X射线吸收光谱法（XAS）研究了铜在大肠杆菌中的形态分布和生物转化。300 μ M Cu处理10 ~ 60 d。结果表明，300 μ M的Cu对E. spendens。Cu K边X射线吸收近边结构（XANES）表明，根、茎、叶中的Cu主要以二价态存在。Cu形态的变化取决于处理时间，但没有在根，茎，叶的单向趋势。通过用线性组合拟合XANES光谱来估计所有样品中潜在Cu配体的百分比。根、茎、叶中的Cu主要与细胞壁和组氨酸（His）类配体结合，而少量的Cu与草酸根和谷胱甘肽类配体结合。对Cu K边扩展X射线吸收精细结构（EAXFS）的拟合结果表明，该植物根、茎、叶中氮/氧（N/O）配体占优势，而S配体很少。这些结果表明，N/O配体结合的Cu在E.和经典的金属解毒S配体，如金属硫蛋白和植物螯合素，在铜解毒E。在本研究中不支持splendens。由于300 μ M Cu对E. splendens的研究，S配体是否在E.应进一步研究暴露于较低水平的Cu的一串红。
Elsholtzia splendens is a Cu-tolerant plant growing in copper mine areas in the south of China. In this study, X-ray absorption spectroscopy (XAS) was used to investigate the Cu speciation and biotransformation in E. splendens with 300 mu M Cu treatment from 10 days to 60 days. The results showed that 300 mu M Cu was phytotoxic to E. spendens. The Cu K-edge X-ray absorption near edge structure (XANES) revealed that most copper in roots, stems and leaves exists as divalent Cu. Cu speciation changed depending on the treatment time, but there was no unidirectional trend in roots, stems, and leaves. The percentages of potential Cu ligands in all samples were estimated by fitting the XANES spectra with linear combinations. Most Cu in roots, stems and leaves was bound with cell wall and histidine (His)-like ligands, while a minor proportion of the Cu was bound to oxalate and glutathione-like ligands. The fitting results of Cu K-edge extended X-ray absorption fine structure (EAXFS) showed that nitrogen/oxygen (N/O) ligands were dominant in roots, stems and leaves of the plant, while S ligands were rare. All these results suggest that Cu bound by N/O ligands plays a key role in Cu detoxification of E. splendens, and a role for classical metal-detoxifying S ligands, such as metallothioneins and phytochelatins, in Cu detoxification of E. splendens is not supported in the present study. Due to the phytotoxicity of 300 mu M Cu to E. splendens, the question of whether S ligands play a significant role in Cu detoxification in E. splendens exposed to lower levels of Cu should be further studied.