Structural Study of the Vanadium Complex in Living Ascidian Blood Cells by X-ray Absorption Spectroscopy
Structural Study of the Vanadium Complex in Living Ascidian Blood Cells by X-ray Absorption Spectroscopy
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X射线吸收光谱法研究活海鞘血细胞中钒配合物的结构
DOI：
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发表时间：
1980
期刊：
影响因子：
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通讯作者：
H. Frauenfelder
中科院分区：
文献类型：
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作者：
R. Austin;K. Beeson;L. Eisentein;H. Frauenfelder
用X射线吸收光谱法研究了钒在活的海鞘血细胞（钒细胞）中的直接配位环境。X射线吸收边数据的分析清楚地显示，在活的或自发裂解的钒细胞中，仅少量（小于10%）的钒作为V 〇 2+离子存在。V EXAFS曲线拟合分析的参数确定半经验的数据模型复杂的已知结构，并已测试的振幅和相位transferability通过使用其他结构特征的V复合物。从钒细胞的EXAFS数据的分析建立，钒在活细胞中是作为V（II 1）离子包围在第一配位球的对称，单壳的低原子量的散射。这些数据最适合于平均距离为1.99埃的六个氧原子的单个壳层。EXAFS数据没有显示VO2+存在的证据。没有明确定义的第二层散射体表明，活细胞中的钒络合物只是钒（III）水溶液，不与含有有序的更远的壳（如卟啉或咪唑）的配体缔合。在自发裂解时，观察到钒配位环境的变化很小（由边缘或EXAFS判断）。
The immediate coordination environment of vanadium in living ascidian blood cells (vanadocytes) has been studied by X-ray absorption spectroscopy. Analysis of the X-ray absorption edge data shows clearly that only a small amount (less than 10%) of the vanadium is present as the V02+ ion in either living or spontaneously lysed vanadocytes. Parameters for curve-fitting analysis of V EXAFS were determined semiempirically from data on model complexes of known structure and have been tested for amplitude and phase transferability by using other structurally characterized V complexes. Analysis of the EXAFS data from the vanadocytes establishes that the vanadium in the living cells is present as V(II1) ions surrounded in the first coordination sphere by a symmetric, single shell of low-atomic-weight scatterers. The data are best fit by a single shell of six oxygen atoms at an average distance of 1.99 A. The EXAFS data show no evidence for the presence of V02+. Absence of a well-defined second shell of scatterers suggests that the vanadium complex in the living cells is simply aquo- vanadium(III), not associated with a ligand containing ordered, more distant shells (such as porphyrin or imidazole). Upon spontaneous lysis, little change in the vanadium coordination environment (as judged by the edge or EXAFS) is observed.