Multispin Recoupling in Solid-State Nuclear Magnetic Resonance

核磁共振是一种技术，它利用了这样一个事实，即许多原子核充当微小的无线电发射器，以精确定义的频率发射无线电信号，可以由仔细调整的探测器检测到。发射的频率取决于特定原子核的电子环境。这种效应被称为化学位移，并允许使用核磁共振来获得关于物质化学成分的信息。如果两个磁核在空间上靠得很近，它们就会稍微相互影响，就像两个并排放置的条形磁铁。可以利用这种效应来估计磁核之间的距离。人们可以通过估计许多核间距离来建立蛋白质分子的三维结构的准确图像。目前的固态核磁共振实验能够准确地估计这些核间距离。然而，现有的方法只有在分子只包含两个相同同位素类型的磁核的情况下才有效。这类样品可以用同位素标记法合成，但这一过程费时费钱。在这个项目中，我们将开发允许在同一多标记样本上测量许多核间距的方法。这将大大加快用核磁共振估计固体分子结构的过程。这将使我们能够确定膜蛋白等分子的三维结构，大大增加我们对化学信号处理系统的了解，这些系统对我们体内细胞的生命过程至关重要。

Nuclear Magnetic Resonance (NMR) is a technique which uses the fact that the nuclei of many atoms act as tiny radiotransmitters, emitting radio signals at precisely-defined frequencies, which can be detected by a carefully-tuned detector. The frequencies which are emitted depend on the electronic environment of a particular nucleus. This effect is called the chemical shift and allows NMR to be used to obtain information on the chemical composition of a substance. If two magnetic nuclei are close to each other in space, they slightly influence each other, rather like two bar magnets placed side-by-side. It is possible to use this effect to estimate the distances between the magnetic nuclei. One can build up an accurate picture of the three-dimensional structure of a protein molecule by estimating many internuclear distances. Current solid-state NMR experiments are able to estimate these internuclear distances accurately. However, existing methods only work well if the molecule only contains two magnetic nuclei of the same isotopic type. Samples of this kind may be synthesized using isotopic labelling methods but the procedure is laborious and expensive. In this project, we will develop methods which allow many internuclear distances to be measured on the same multiply-labelled sample. This will greatly speed up the procedures for estimating molecular structures in the solid state by using NMR. This will allow the determination of the three-dimensional structures of molecules such as membrane proteins, adding greatly to our understanding of the chemical signal processing systems which are vital to the life processes of the cells in our bodies.