The gadolinium(III)-water hydrogen distance in MRI contrast agents
The gadolinium(III)-water hydrogen distance in MRI contrast agents
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DOI：
10.1021/ic034414f
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发表时间：
2003-06-30
影响因子：
4.6
通讯作者：
Raitsimring, AM
中科院分区：
文献类型：
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作者：
Caravan, P;Astashkin, AV;Raitsimring, AM
Gd(III) 与配位水质子 r(Gd-H) 的离子核距离对于理解钆基 MRI 造影剂的功效至关重要。对造影剂有效的偶极弛豫机制具有 1/r(6) 依赖性。文献中对该距离的估计跨度为 0.8 埃（2.5-3.3 埃）。本研究描述了使用垂直于脉冲 ENDOR 光谱的各向异性超精细常数 T 直接测定 rGd-H。检查了五种 Gd(III) 配合物：[Gd(H2O)(8)](3+)、[Gd(DTPA)(H2O)](2-)、[Gd(BOPTA)(H2O)](2-)、MS-325 和 [Gd(HP-DO3A)(H2O)]。所有五个复合物的距离 r(Gd-H) 的误差范围相同：3.1 +/- 0.1 埃。这些距离估计应该有助于新造影剂的设计，以及影响弛豫度的其他分子因素的解释。
The ion-nuclear distance of Gd(III) to a coordinated water proton, r(Gd-H), is central to the understanding of the efficacy of gadolinium-based MRI contrast agents. The dipolar relaxation mechanism operative for contrast agents has a 1/r(6) dependence. Estimates in the literature for this distance span 0.8 Angstrom (2.5-3.3 Angstrom). This study describes a direct determination of rGd-H using the anisotropic hyperfine constant T-perpendicular to determined from pulsed ENDOR spectra. Five Gd(III) complexes were examined: [Gd(H2O)(8)](3+), [Gd(DTPA)(H2O)](2-), [Gd(BOPTA)(H2O)](2-), MS-325, and [Gd(HP-DO3A)(H2O)]. The distance, r(Gd-H), was the same within error for all five complexes: 3.1 +/- 0.1 Angstrom. These distance estimates should aid in the design of new contrast agents, and in the interpretation of other molecular factors influencing relaxivity.