论文标题

Hadamard磁化转移在蛋白质,多糖和核酸的不稳定位点的同核多维NMR相关性中实现了显着的灵敏度增强。

Hadamard magnetization transfers achieve dramatic sensitivity enhancements in homonuclear multidimensional NMR correlations of labile sites in proteins, polysaccharides and nucleic acids

论文作者

Novakovic, Mihajlo, Kupce, Eriks, Oxenfarth, Andreas, Battistel, Marcos D., Freedberg, Daron I., Schwalbe, Harald, Frydman, Lucio

论文摘要

Exsy,Tocsy和Noesy在于有机和药物化学以及结构生物学中的同核NMR实验的基础。有限的磁化转移效率是这些方法的内在缺点,尤其是在靶向迅速交换物种(如蛋白质的多糖,侧chain和侧链和骨架中,以及核酸的基础和糖的碱基和糖的碱)时:快速的镇压通过这些质子通过替代的实验,这些质子的实验范围很大。最近,我们讨论了如何将这些解饰视为一种抗ZENO效应,可以利用,以提高循环投影光谱法(L-prosy)内的均核转移效率(L-prosy),从而在生物蛋白酶中的近米和Tocsy跨峰中增强了200-300%的增强。这项研究表明,可以通过循环反转或使用饱和程序来实现每单位时间更大的灵敏度增长,等同于在实验期间减少几百倍的敏感性。在随后的实验中,根据Hadamard食谱对选定的频率进行了编码,随后通过线性组合沿间接维度解决。磁化转移(MT)过程让人联想到CEST中发生的磁力转移(MT)在所得的交叉峰值中仅提供了显着的增强,仅在正常2D实验的一小部分获取时间中。随之而来的三向极化转移相互作用在水,不稳定质子和非比质质子之间的有效性是在蛋白质,同醇和核酸的实验中证实的。在所有情况下,在常规2D NMR对应物中几乎无法检测到的交叉峰都测量了CA。 Hadamard MT对应物更快10倍,并具有200-600%的信号增强。

EXSY, TOCSY and NOESY lie at the foundation of homonuclear NMR experiments in organic and pharmaceutical chemistry, as well as in structural biology. Limited magnetization transfer efficiency is an intrinsic downside of these methods, particularly when targeting rapidly exchanging species such as labile protons ubiquitous in polysaccharides, sidechains and backbones of proteins, and in bases and sugars of nucleic acids: the fast decoherence imparted on these protons through solvent exchanges, greatly reduces their involvement in homonuclear correlation experiments. We have recently discussed how these decoherences can be visualized as an Anti-Zeno Effect, that can be harnessed to enhance the efficiency of homonuclear transfers within Looped PROjected SpectroscopY (L-PROSY) leading to 200-300% enhancements in NOESY and TOCSY cross-peaks for amide groups in biomolecules. This study demonstrates that even larger sensitivity gains per unit time, equivalent to reductions by several hundred-folds in the duration of experiments, can be achieved by looping inversion or using saturation procedures. In the ensuing experiments a priori selected frequencies are encoded according to Hadamard recipes, and subsequently resolved along the indirect dimension via linear combinations. Magnetization-transfer (MT) processes reminiscent of those occurring in CEST provide significant enhancements in the resulting cross-peaks, in only a fraction of acquisition time of a normal 2D experiment. The effectiveness of the ensuing three-way polarization transfer interplay between water, labile and non-labile protons was corroborated experimentally for proteins, homo-oligosaccharides and nucleic acids. In all cases, cross-peaks barely detectable in conventional 2D NMR counterparts, were measured ca. 10-fold faster and with 200-600% signal enhancements by the Hadamard MT counterparts.

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