Clore G M, Gronenborn A M, Bax A
National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 5, Bethesda, Maryland, 20892-0520, USA.
J Magn Reson. 1998 Jul;133(1):216-21. doi: 10.1006/jmre.1998.1419.
It has recently been shown that the degree of alignment of macromolecules in an aqueous dilute liquid crystalline medium of bicelles is sufficient to permit accurate values of residual 15N-1H, 13C-1H, and 13Calpha-C' dipolar couplings to be obtained on a routine basis, thereby providing potentially unique long-range structural information. To make use of this information in macromolecular structure determination, the magnitude of the axial and rhombic components of the molecular alignment tensor must be determined. This can be achieved by taking advantage of the fact that different, fixed-distance internuclear vector types are differently distributed relative to the alignment tensor. A histogram of the ensemble of normalized residual dipolar couplings for several such vector types approximates a powder pattern from which the magnitude of the axial and rhombic components are readily extracted in the absence of any prior structural information. The applicability of this method is demonstrated using synthetic data derived from four proteins representative of different sizes, topologies, and secondary structures, and experimental data measured on the small protein ubiquitin.
最近研究表明，在双分子层的水性稀液晶介质中，大分子的排列程度足以在常规基础上获得准确的残余(^{15}N - ^{1}H)、(^{13}C - ^{1}H)和(^{13}C_{\alpha}-C')偶极耦合值，从而提供潜在独特的长程结构信息。为了在大分子结构测定中利用这些信息，必须确定分子排列张量的轴向和菱形分量的大小。这可以通过利用不同的、固定距离的核间矢量类型相对于排列张量的不同分布来实现。几种此类矢量类型的归一化残余偶极耦合集合的直方图近似于粉末图案，从中可以在没有任何先验结构信息的情况下轻松提取轴向和菱形分量的大小。使用从代表不同大小、拓扑结构和二级结构的四种蛋白质衍生的合成数据以及在小蛋白质泛素上测量的实验数据，证明了该方法的适用性。
