作者:C. Bresson、S. Esnouf、C. Lamouroux、P. L. Solari、C. Den Auwer
DOI:10.1039/b514454j
日期:——
Cobalt is an essential element of biological cycles involved in numerous metallobiomolecules, but it becomes a toxic element at high concentration or a radiotoxic element because of its use in the nuclear industry. “Molecular speciation” in biological media is an essential prerequisite to evaluate its chemical behaviour as well as its toxic or beneficial effects. In this scheme, we have focused on the coordination properties of the thiol-containing amino acid cysteine (Cys) and the pseudo-peptide N-(2-mercaptopropionyl)glycine (MPG) towards the Co2+ cation in aqueous media. XAS at the Co K edge and traditional spectroscopic techniques have been coupled in order to structurally characterize the cobalt coordination sphere. Oxidation states and geometries of the bis- and tris-cysteinato Co(III) complexes are in agreement with the literature data. In addition, bond lengths between the metallic centre and the donor atoms have been determined. The structure of a new dimeric N-(2-mercaptopropionyl)glycinato Co(II) complex in solution is also reported. The coordination of MPG to Co(II) through the thiolate and carboxylate functions is ascertained. This work provides fundamental structural information about biorelevant complexes of cobalt, which will contribute to our understanding of the chemical behaviour and the biological role of this radionuclide.
钴是众多金属生物大分子所涉及的生物循环中的一种基本元素,但由于在核工业中的应用,钴在高浓度时成为一种有毒元素或放射性毒物。生物介质中的 "分子标型 "是评估其化学特性及其毒性或有益影响的必要前提。在本方案中,我们重点研究了含硫醇氨基酸半胱氨酸(Cys)和伪肽 N-(2-巯基丙酰基)甘氨酸(MPG)在水介质中与 Co2+ 阳离子的配位特性。为了从结构上描述钴配位层的特征,我们将钴 K 边的 XAS 与传统的光谱技术相结合。双-和三-氰基钴(III)配合物的氧化态和几何形状与文献数据一致。此外,还确定了金属中心和供体原子之间的键长。还报告了一种新的二聚 N-(2-巯基丙酰基)甘氨酸 Co(II) 复合物在溶液中的结构。确定了 MPG 通过硫酸酯和羧酸酯功能与 Co(II) 的配位。这项工作提供了钴的生物相关配合物的基本结构信息,有助于我们了解这种放射性核素的化学行为和生物作用。