NUCLEAR MAGNETIC RESONANCE--NEW METHODS AND MOLECULAR STRUCTURE DETERMINATION

质子关联新方法的早期进展 低伽马原子核的化学位移已经被 继续。第一次，它被证明是可能的 记录的质子-碳和质子-氮位移关联 天然同位素丰度下的小蛋白质(大于15kD)。 一种完全不同的方法已经被开发出来用于关联 质子和磷的化学位移及其在研究中的应用 寡核苷酸。 已经开发出记录相敏材料的新方法 无水溶液中的二维质子核磁共振谱 预饱和的必要性。与现有技术相比， 新方法分两个阶段实现水抑制：IN 第一级获得相对较低的抑制，足够 要克服接收器中的动态范围问题，请在 第二阶段循环从光谱中去除水信号 几乎完全是。新方法已被演示用于 重要的NOE、自旋锁定NOE和同核哈特曼- 哈恩实验。 已经开发了一种新的测量程序来测量 以前无法解析的耦合常量。通过抑制 除相互作用外的所有标量耦合的影响 对二维实验的兴趣成为可能 提取感兴趣的耦合常数。该程序具有 已应用于J(C3‘H-O-P)联轴器的测量 寡核苷酸d(CGCGAATTCGCG)2。相应的 二面体夹角与X射线有显著差异 结晶学工作。

Earlier developments of new methods for correlating proton chemical shifts with shifts of low-gamma nuclei have been continued. For the first time, it has been shown possible to record proton-carbon and proton-nitrogen shift correlation of small proteins (greater than 15 kD) at natural isotopic abundance. A quite different approach has been developed for correlating proton and phosphorous chemical shifts and applied to the study of oligonucleotides. New methods have been developed for recording phase-sensitive two-dimensional proton NMR spectra in water solution without the need for presaturation. In contrast to existing techniques, the new methods accomplish the water suppression in two stages: in the first stage a relatively low suppression is obtained, sufficient to overcome dynamic range problems in the receiver, in the second stage cycling removes the water signal from the spectrum almost completely. The new methods have been demonstrated for the important NOE, spin-locked NOE and homonuclear Hartmann- Hahn experiments. A new procedure has been developed for measurements of previously unresolvable coupling constants. By suppressing the effect of all scalar couplings apart from the interaction of interest in a two-dimensional experiment it becomes possible to extract the coupling constants of interest. The procedure has been applied to measurement of J(C3'H-O-P) couplings in the oligonucleotide d(CGCGAATTCGCG)2. The corresponding dihedral epsilon angles show significant differences with X-ray crystallographic work.