Yokoyama S, Inagaki F, Miyazawa T
Biochemistry. 1981 May 12;20(10):2981-8. doi: 10.1021/bi00513a041.
An advanced method was developed for lanthanide-probe analyses of the conformations of flexible biomolecules such as nucleotides. The new method is to determine structure parameters (such as internal-rotation angles) and population parameters for local conformational equilibria of flexible sites, together with standard deviations of these parameters. As the prominent advantage of this method, the interrelations among local conformations of flexible sites may be quantitatively elucidated from the experimental data of lanthanide-induced shifts and relaxations and vicinal coupling constants. As a structural unit of ribonucleic acids, the molecular conformations and conformational equilibria of uridine 3'-monophosphate in aqueous solution were analyzed. The stable local conformers about the C3'-O3' bond are the G+ (phi' = 281 +/- 11 degrees) and G- (phi' = 211 +/- 8 degrees) forms. The internal rotation about the C3'-O3' bond and the ribose-ring puckering are interrelated; 97 +/- 5% of the C3'-endo ribose ring is associated with the G- form while 70 +/- 22% o the C2'-endo ribose ring is associated with the G+ form. An interdependency also exists between the internal rotation about the C4'-C5' bond and the ribose-ring puckering. These short-range conformational interrelations are probably important in controlling the dynamic aspects of ribonucleic acid structures.
已开发出一种先进方法，用于对诸如核苷酸等柔性生物分子的构象进行镧系元素探针分析。新方法是确定柔性位点局部构象平衡的结构参数（如内旋转角）和总体参数，以及这些参数的标准偏差。作为该方法的突出优点，可以从镧系元素诱导位移和弛豫以及邻位耦合常数的实验数据中定量阐明柔性位点局部构象之间的相互关系。作为核糖核酸的结构单元，分析了尿苷3'-单磷酸在水溶液中的分子构象和构象平衡。围绕C3'-O3'键的稳定局部构象体是G+（φ' = 281±11度）和G-（φ' = 211±8度）形式。围绕C3'-O3'键的内旋转与核糖环的褶皱相互关联；97±5%的C3'-内型核糖环与G-形式相关，而70±22%的C2'-内型核糖环与G+形式相关。围绕C4'-C5'键的内旋转与核糖环的褶皱之间也存在相互依赖性。这些短程构象相互关系可能对控制核糖核酸结构的动态方面很重要。
