School of Chemistry and Physics, The University of Adelaide, Adelaide, SA 5005, Australia.
Nutrients. 2013 May 21;5(5):1734-56. doi: 10.3390/nu5051734.
Determining the speciation of selenium in vivo is crucial to understanding the biological activity of this essential element, which is a popular dietary supplement due to its anti-cancer properties. Hyphenated techniques that combine separation and detection methods are traditionally and effectively used in selenium speciation analysis, but require extensive sample preparation that may affect speciation. Synchrotron-based X-ray absorption and fluorescence techniques offer an alternative approach to selenium speciation analysis that requires minimal sample preparation. We present a brief summary of some key HPLC-ICP-MS and ESI-MS/MS studies of the speciation of selenium in cells and rat tissues. We review the results of a top-down approach to selenium speciation in human lung cancer cells that aims to link the speciation and distribution of selenium to its biological activity using a combination of X-ray absorption spectroscopy (XAS) and X-ray fluorescence microscopy (XFM). The results of this approach highlight the distinct fates of selenomethionine, methylselenocysteine and selenite in terms of their speciation and distribution within cells: organic selenium metabolites were widely distributed throughout the cells, whereas inorganic selenium metabolites were compartmentalized and associated with copper. New data from the XFM mapping of electrophoretically-separated cell lysates show the distribution of selenium in the proteins of selenomethionine-treated cells. Future applications of this top-down approach are discussed.
确定体内硒的形态对于了解这种必需元素的生物活性至关重要，由于其抗癌特性，硒是一种很受欢迎的膳食补充剂。传统上，结合分离和检测方法的键合技术在硒形态分析中得到了有效应用，但需要广泛的样品制备，这可能会影响形态。基于同步加速器的 X 射线吸收和荧光技术为硒形态分析提供了一种替代方法，该方法需要的样品制备较少。我们简要总结了一些关于细胞和大鼠组织中硒形态的高效液相色谱-电感耦合等离子体质谱（HPLC-ICP-MS）和电喷雾串联质谱（ESI-MS/MS）的关键研究。我们回顾了一种自上而下的方法在人类肺癌细胞中对硒形态的研究结果，该方法旨在使用 X 射线吸收光谱（XAS）和 X 射线荧光显微镜（XFM）相结合的方法将硒的形态和分布与其生物活性联系起来。该方法的结果突出了硒代蛋氨酸、甲基硒代半胱氨酸和亚硒酸盐在细胞内的形态和分布方面的不同命运：有机硒代谢物在细胞内广泛分布，而无机硒代谢物则分隔开并与铜有关。来自电泳分离的细胞裂解物的 XFM 图谱的新数据显示了硒代蛋氨酸处理细胞中蛋白质内的硒分布。讨论了这种自上而下方法的未来应用。
