Bishop K D, Borer P N, Pelczer I
Department of Chemistry, Michigan State University, East Lansing 48824, USA.
J Magn Reson B. 1996 Jan;110(1):9-15. doi: 10.1006/jmrb.1996.0002.
A unique combination of aliasing and dispersive-absorptive (DA) phasing of two-quantum correlated spectroscopy (2 Q-COSY) NMR data is shown to enhance proton chemical-shift assignments in DNA oligonucleotides by (i) reducing the time necessary for acquiring NMR data or, alternatively, improving the spectral resolution in a given time, (ii) reducing the number of spectra necessary for NMR data processing and analysis, and (iii) increasing the complexity of oligonucleotide sequences and structures which are accessible to 2D NMR analysis. Aliasing allows a reduction in the size of the acquired data without significant risk of losing information. Phasing the 2Q-COSY dispersive in the F2 dimension reduces the primary antiphase doublet into a pseudo-singlet and increases the apparent signal-to-noise. A single 2Q-COSY spectrum can provide an amount of chemical-shift information comparable to that from a series of COSY, relayed-COSY, and/or spin-lock COSY spectra optimized for various coupling constants. The low signal-to-noise inherent in the most popular two-quantum-filtered correlated spectroscopy (2QF-COSY) of samples with naturally broad lines is largely avoided due to less cancellation. There is no diagonal in a 2Q-COSY which can obscure correlations between protons which are nearly isochronous. As an example of this efficient application, the assignment of 139 of the 143 proton resonances from a single 2Q-COSY and a 2D-NOE spectrum of the DNA hexadecamer [d(AAATATAGCTATATTT)]2 is demonstrated.
双量子相关光谱（2Q-COSY）核磁共振（NMR）数据的混叠与色散吸收（DA）相位的独特组合，被证明可通过以下方式增强DNA寡核苷酸中质子化学位移的归属：（i）减少获取NMR数据所需的时间，或者在给定时间内提高光谱分辨率；（ii）减少NMR数据处理和分析所需的光谱数量；（iii）增加可通过二维NMR分析的寡核苷酸序列和结构的复杂性。混叠允许在不显著丢失信息风险的情况下减小采集数据的大小。在F2维度对2Q-COSY色散进行相位调整，可将主要的反相双峰转化为伪单峰，并增加表观信噪比。单个2Q-COSY光谱可提供的化学位移信息量，与针对各种耦合常数优化的一系列COSY、中继COSY和/或自旋锁定COSY光谱相当。由于较少的抵消作用，在具有天然宽线的样品的最流行的双量子滤波相关光谱（2QF-COSY）中固有的低信噪比在很大程度上得以避免。2Q-COSY中不存在对角线，不会掩盖几乎等时的质子之间的相关性。作为这种有效应用的一个例子，展示了从DNA十六聚体[d(AAATATAGCTATATTT)]2的单个2Q-COSY和二维NOE光谱中对143个质子共振中的139个进行归属。
