Kulminskaya Natalia, Vasa Suresh Kumar, Giller Karin, Becker Stefan, Linser Rasmus
Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077, Göttingen, Germany.
J Biomol NMR. 2015 Nov;63(3):245-53. doi: 10.1007/s10858-015-9980-1. Epub 2015 Aug 30.
Multiple-bond carbon-carbon homonuclear mixing is a hurdle in extensively deuterated proteins and under fast MAS due to the absence of an effective proton dipolar-coupling network. Such conditions are now commonly employed in solid-state NMR spectroscopy. Here, we introduce an isotropic homonuclear (13)C-(13)C through-bond mixing sequence, MOCCA, for the solid state. Even though applied under MAS, this scheme performs without rotor synchronization and thus does not pose the usual hurdles in terms of power dissipation for fast spinning. We compare its performance with existing homonuclear (13)C-(13)C mixing schemes using a perdeuterated and partially proton-backexchanged protein. Based on the analysis of side chain carbon-carbon correlations, we show that particularly MOCCA with standard 180-degree pulses and delays leading to non-rotor-synchronized spacing performs exceptionally well. This method provides high magnetization transfer efficiency for multiple-bond transfer in the aliphatic region compared with other tested mixing sequences. In addition, we show that this sequence can also be tailor-made for recoupling within a selected spectral region using band-selective pulses.
由于缺乏有效的质子偶极耦合网络，在高度氘代蛋白质以及快速魔角旋转（fast MAS）条件下，多键碳 - 碳同核混合是一个难题。这种条件目前在固态核磁共振光谱学中普遍采用。在此，我们介绍一种用于固态的各向同性同核（¹³C）-（¹³C）通过键混合序列，即MOCCA。尽管该序列是在魔角旋转条件下应用，但它无需转子同步即可运行，因此在快速旋转的功耗方面不存在常见的障碍。我们使用全氘代且部分质子回交换的蛋白质，将其性能与现有的同核（¹³C）-（¹³C）混合序列进行比较。基于对侧链碳 - 碳相关性的分析，我们表明，特别是采用标准180°脉冲且延迟导致非转子同步间隔的MOCCA表现格外出色。与其他测试的混合序列相比，该方法在脂肪族区域的多键转移中提供了高磁化转移效率。此外，我们表明该序列还可以使用带选择性脉冲针对选定光谱区域内的再耦合进行定制。
