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首页> 外文学位 >Lanthanide(III) ions as probes of bioinorganic systems: Long-range electron transfer in proteins and hydration of magnetic resonance imaging contrast agents.
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Lanthanide(III) ions as probes of bioinorganic systems: Long-range electron transfer in proteins and hydration of magnetic resonance imaging contrast agents.

机译：镧系元素离子作为生物无机系统的探针：蛋白质中的远距离电子转移和磁共振成像造影剂的水合作用。

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摘要

The spectroscopic and redox properties of lanthanide ions, Ln 3+, are used determine if the anions carbonate and phosphate are able to displace water molecules from the first coordination sphere of Eu 3+ analogs of Gd3+ magnetic resonance imaging, MRI, contrast agents and to study the electron transfer, ET, reaction between a photoexcited tryptophan residue, Trp, of the Ca2+ binding protein parvalbumin and the Eu3+ or Yb3+ ions substituted for Ca2+ in the two metal ion binding sites of parvalbumin.; In the study of the MRI contrast agents, a lengthening of the Eu 3+ excited state lifetime in the presence of millimolar concentrations of carbonate or phosphate indicates that water molecules are displaced by an anion. Only those metal complexes that contain negatively charged ligands and more than one water molecule in the first coordination sphere of Eu 3+ have their water molecules displaced by saturating concentrations of carbonate or phosphate. Our results show that under physiological conditions, phosphate and carbonate will, on average, displace less than half of a water molecule from the first coordination sphere of a typical contrast agent and suggest that the effect on proton spin relaxation is likely to be minimal.; The study of electron transfer required the characterization of mutants of the protein parvalbumin from carp. The removal of the first, second and last acidic residue of each of the classic EF-loop Ca2+ binding sites of parvalbumin is found to be sufficient to rid the loop of the ability to bind Ln3+ ions.; The mechanism of ET between the Trp and the two Ln3+ ions bound to parvalbumin, both 11 Å from the Trp, is found adhere to the β theory of exponential decay of the ET rate constant with distance, k ET = 1013 e−βr, rather than the Pathway theory which states that the structural motif of the protein, rather than the distance between the electron donor and acceptor, dictates the distance dependence of ET. The measured value for the reorganization energy, λ, from Marcus ET theory for our system is high, at 2 eV, compared to typical λ value of 1 eV measured in ET proteins.
机译：利用镧系离子Ln 3 + 的光谱和氧化还原特性确定碳酸根和磷酸根阴离子是否能够取代Eu 3 + Gd 3 + 磁共振成像，MRI和造影剂的类似物，并研究Ca 2 + 结合蛋白小白蛋白和在小白蛋白的两个金属离子结合位点中用Eu 3 + 或Yb 3 + 离子代替Ca 2 + 。 ;在MRI造影剂的研究中，在毫摩尔浓度的碳酸盐或磷酸盐存在下，Eu 3 + 激发态寿命的延长表明水分子被阴离子置换。只有那些在Eu 3 + 的第一配位球中带有带负电荷的配体和一个以上水分子的金属络合物，才能通过饱和碳酸盐或磷酸盐的浓度置换其水分子。我们的结果表明，在生理条件下，磷酸盐和碳酸盐平均会从典型造影剂的第一个配位球中置换不到一半的水分子，这表明对质子自旋弛豫的影响可能很小。电子转移的研究需要表征鲤鱼小白蛋白的突变体。发现去除小白蛋白的每个经典EF-环Ca 2 + 结合位点的第一个，第二个和最后一个酸性残基足以消除该环结合Ln 3 + 离子。发现Trp与两个结合到小白蛋白的Ln 3 + 离子之间的ET机理，都距Trp 11Å，遵循β理论，即ET速率常数随距离呈指数衰减， k ET = 10 13 e -βr，而不是通路理论，该理论指出蛋白质的结构基序，而不是蛋白质之间的距离电子给体和受体决定了ET的距离依赖性。根据我们系统中的Marcus ET理论，重组能量λ的测量值很高，为2 eV，而ET蛋白中的典型λ值为1 eV。

著录项

  • 作者

    Supkowski, Ronald Michael.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Chemistry Inorganic.; Chemistry Analytical.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 211 p.
  • 总页数 211
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 无机化学;化学;
  • 关键词

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