Raitsimring Arnold M, Astashkin Andrei V, Feng Changjian, Enemark John H, Nelson Kimberly Johnson, Rajagopalan K V
Department of Chemistry, University of Arizona, Tucson, AZ 85721-0041, USA.
J Biol Inorg Chem. 2003 Jan;8(1-2):95-104. doi: 10.1007/s00775-002-0393-8. Epub 2002 Aug 30.
Electron spin echo envelope modulation (ESEEM) spectroscopy has been used to determine the hyperfine ( hfi) and quadrupole ( nqi) interactions of the exchangeable deuteron (proton) at the Mo(V) site of DMSO reductase. The data obtained have been translated into structure-related parameters. It was found that isotropic hfi constant of the proton is not unique, but is distributed within a range of 26-36 MHz. From this hfi distribution, a 30 degrees -wide distribution of the OH bond orientations due to a rotation around the Mo-O bond was estimated. The angle between the axes of the nqi and anisotropic hfi tensors was found to be anomalously small in comparison with that expected from the Mo-O-D bond geometry. This peculiarity was attributed to the effect of spin density on the hydroxyl oxygen atom. The orientation of the Mo-OH fragment with respect to the g-frame was determined from the experimental orientations of the nqi and hfi tensor axes and a theoretical evaluation of the anisotropic hfi axis direction.
电子自旋回波包络调制（ESEEM）光谱已被用于确定二甲基亚砜还原酶钼（V）位点上可交换氘核（质子）的超精细（hfi）和四极（nqi）相互作用。所获得的数据已转化为与结构相关的参数。发现质子的各向同性hfi常数并非唯一，而是分布在26 - 36 MHz范围内。根据这种hfi分布，估计由于围绕Mo - O键的旋转导致OH键取向有30度宽的分布。与从Mo - O - D键几何结构预期的角度相比，发现nqi和各向异性hfi张量轴之间的角度异常小。这种特殊性归因于自旋密度对羟基氧原子的影响。通过nqi和hfi张量轴的实验取向以及对各向异性hfi轴方向的理论评估，确定了Mo - OH片段相对于g框架的取向。
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