Khaneja Navin, Li Jr-Shin, Kehlet Cindie, Luy Burkhard, Glaser Steffen J
Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
Proc Natl Acad Sci U S A. 2004 Oct 12;101(41):14742-7. doi: 10.1073/pnas.0404820101. Epub 2004 Oct 4.
Many applications of magnetic resonance are limited by rapid loss of spin coherence caused by large transverse relaxation rates. In NMR of large proteins, increased relaxation losses lead to poor sensitivity of experiments and increased measurement time. In this article, we develop broadband relaxation-optimized pulse sequences that approach fundamental limits of coherence transfer efficiency in the presence of very general relaxation mechanisms that include cross-correlated relaxation. These broadband transfer schemes use techniques of chemical shift refocusing (specific trajectory adapted refocusing echoes) that are tailored to specific trajectories of coupled spin evolution. We present simulations and experimental data indicating significant enhancement in the sensitivity of multidimensional NMR experiments of large molecules through these methods.
磁共振的许多应用都受到大横向弛豫率导致的自旋相干快速丧失的限制。在大蛋白质的核磁共振中，弛豫损失增加会导致实验灵敏度降低和测量时间增加。在本文中，我们开发了宽带弛豫优化脉冲序列，在存在包括交叉相关弛豫在内的非常一般的弛豫机制的情况下，该序列接近相干转移效率的基本极限。这些宽带转移方案使用化学位移重聚焦技术（特定轨迹适配的重聚焦回波），该技术是针对耦合自旋演化的特定轨迹量身定制的。我们展示的模拟和实验数据表明，通过这些方法，大分子多维核磁共振实验的灵敏度有显著提高。
