Institute of Molecular Biology and Biophysics, ETH Zurich, 8093, Zurich, Switzerland.
J Biomol NMR. 2012 Feb;52(2):141-50. doi: 10.1007/s10858-011-9588-z. Epub 2011 Dec 4.
A five-dimensional (5D) APSY (automated projection spectroscopy) HCNCH experiment is presented, which allows unambiguous correlation of sugar to base nuclei in nucleic acids. The pulse sequence uses multiple quantum (MQ) evolution which enables long constant-time evolution periods in all dimensions, an improvement that can also benefit non-APSY applications. Applied with an RNA with 23 nucleotides the 5D APSY-HCNCH experiment produced a complete and highly precise 5D chemical shift list within 1.5 h. Alternatively, and for molecules where the out-and-stay 5D experiment sensitivity is not sufficient, a set of out-and-back 3D APSY-HCN experiments is proposed: an intra-base (3D APSY-b-HCN) experiment in an MQ or in a TROSY version, and an MQ sugar-to-base (3D APSY-s-HCN) experiment. The two 3D peak lists require subsequent matching via the N1/9 chemical shift values to one 5D peak list. Optimization of the 3D APSY experiments for maximal precision in the N1/9 dimension allowed matching of all (15)N chemical shift values contained in both 3D peak lists. The precise 5D chemical shift correlation lists resulting from the 5D experiment or a pair of 3D experiments also provide a valuable basis for subsequent connection to chemical shifts derived with other experiments.
介绍了一个五维（5D）APS（自动投影光谱）HCNCH 实验，该实验能够明确相关的糖碱基核在核酸。脉冲序列使用多个量子（MQ）演变使所有维度的长时间恒定时演变，这一改进也可以受益于非 APSY 应用。与一个 23 个核苷酸的 RNA 一起应用，5D APSY-HCNCH 实验在 1.5 小时内产生了一个完整且高度精确的 5D 化学位移列表。或者，对于那些出和停留 5D 实验灵敏度不足的分子，提出了一组出和返回 3D APSY-HCN 实验：一个在 MQ 或 TROSY 版本中的内部碱基（3D APSY-b-HCN）实验，以及一个 MQ 糖到碱基（3D APSY-s-HCN）实验。两个 3D 峰列表需要通过 N1/9 化学位移值进行后续匹配，以获得一个 5D 峰列表。通过优化 3D APSY 实验以获得 N1/9 维度的最大精度，允许匹配两个 3D 峰列表中包含的所有（15）N 化学位移值。来自 5D 实验或一对 3D 实验的精确 5D 化学位移相关列表也为随后与其他实验衍生的化学位移进行连接提供了有价值的基础。
