Ravindranathan Sapna, Kim Chul-Hyun, Bodenhausen Geoffrey
Institut de Chimie Moléculaire et Biologique, Ecole Polytechnique Fédérale de Lausanne, BCH, 1015 Lausanne, Switzerland.
J Biomol NMR. 2003 Dec;27(4):365-75. doi: 10.1023/a:1025827017409.
Two sets of cross-correlated relaxation rates involving chemical shift anisotropy and dipolar interactions have been measured in an RNA kissing complex. In one case, both the CSA and dipolar interaction tensors are located on the same nucleotide base and are rigidly fixed with respect to each other. In the other case, the CSA tensor is located on the nucleotide base whereas the dipolar interaction is located on the adjoining ribose unit. Analysis of the measured rates in terms of isotropic or anisotropic rotational diffusion has been carried out for both cases. A marked difference between the two models is observed for the cross-correlation rates involving rigidly fixed spin interactions. The influence of internal motions about the glycosidic linkage between the nucleotide base and the ribose unit on cross-correlated relaxation rates has been estimated by applying a model of restricted rotational diffusion. Local motions seem to have a more pronounced effect on cross-correlated relaxation rates when the two spin interactions are not rigidly fixed with respect to each other.
在一个RNA亲吻复合体中测量了两组涉及化学位移各向异性和偶极相互作用的交叉相关弛豫率。在一种情况下，化学位移各向异性（CSA）张量和偶极相互作用张量都位于同一个核苷酸碱基上，并且彼此刚性固定。在另一种情况下，CSA张量位于核苷酸碱基上，而偶极相互作用位于相邻的核糖单元上。针对这两种情况，均根据各向同性或各向异性旋转扩散对测量速率进行了分析。对于涉及刚性固定自旋相互作用的交叉相关速率，观察到两种模型之间存在显著差异。通过应用受限旋转扩散模型，估计了核苷酸碱基与核糖单元之间糖苷键的内部运动对交叉相关弛豫率的影响。当两个自旋相互作用彼此不是刚性固定时，局部运动似乎对交叉相关弛豫率有更显著的影响。
