Munich Center for Integrated Protein Science (CIPS-M) at, Department Chemie, Technische Universität München (TUM), Lichtenbergstr. 4, 85747, Garching, Germany.
Dept. of Chemistry, Faculty of Science, Charles University, Hlavova 8, CZ-12842, Prague 2, Czech Republic.
Angew Chem Int Ed Engl. 2018 Oct 26;57(44):14514-14518. doi: 10.1002/anie.201805002. Epub 2018 Jul 31.
Dipolar recoupling in solid-state NMR is an essential method for establishing correlations between nuclei that are close in space. In applications on protein samples, the traditional experiments like ramped and adiabatic DCP suffer from the fact that dipolar recoupling occurs only within a limited volume of the sample. This selection is dictated by the radiofrequency (rf) field inhomogeneity profile of the excitation solenoidal coil. We employ optimal control strategies to design dipolar recoupling sequences with substantially larger responsive volume and increased sensitivity. We show that it is essential to compensate for additional temporal modulations induced by sample rotation in a spatially inhomogeneous rf field. Such modulations interfere with the pulse sequence and decrease its performance. Using large-scale optimizations we developed pulse schemes for magnetization transfer from amide nitrogen to carbonyl (NCO) as well as aliphatic carbons (NCA). Our experiments yield a signal intensity increased by a factor of 1.5 and 2.0 for NCA and NCO transfers, respectively, compared to conventional ramped DCP sequences. Consistent results were obtained using several biological samples and NMR instruments.
固态 NMR 中的偶极重聚是建立空间上接近的核之间相关性的一种重要方法。在蛋白质样品的应用中，传统的实验，如 ramped 和 adiabatic DCP，存在一个事实，即偶极重聚仅在样品的有限体积内发生。这种选择是由激发螺线管线圈的射频 (rf) 非均匀性轮廓决定的。我们采用最优控制策略来设计具有更大响应体积和更高灵敏度的偶极重聚序列。我们表明，补偿空间不均匀 rf 场中样品旋转引起的额外时间调制是至关重要的。这种调制会干扰脉冲序列并降低其性能。通过大规模优化，我们开发了用于酰胺氮到羰基 (NCO) 以及脂肪碳 (NCA) 的磁化转移的脉冲方案。与传统的 ramped DCP 序列相比，我们的实验分别使 NCA 和 NCO 转移的信号强度增加了 1.5 倍和 2.0 倍。使用几种生物样品和 NMR 仪器获得了一致的结果。
