Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702-1201, USA.
J Biomol NMR. 2020 May;74(4-5):223-228. doi: 10.1007/s10858-020-00312-2. Epub 2020 Apr 24.
Recent methyl adiabatic relaxation dispersion experiments provide examination of conformational dynamics across a very wide timescale (10-10 s) and, particularly, provide insight into the hydrophobic core of proteins and allosteric effects associated with modulators. The experiments require efficient decoupling of H and C spin interactions, and some artifacts have been discovered, which are associated with the design of the proton decoupling scheme. The experimental data suggest that the original design is valid; however, pulse sequences with either no proton decoupling or proton decoupling with imperfect pulses can potentially exhibit complications in the experiments. Here, we demonstrate that pulse imperfections in the proton decoupling scheme can be dramatically alleviated by using a single composite π pulse and provide pure single-exponential relaxation data. It allows the opportunity to access high-quality methyl adiabatic relaxation dispersion data by removing the cross-correlation between dipole-dipole interaction and chemical shift anisotropy. The resulting high-quality data is illustrated with the binding of an allosteric modulator (G2BR) to the ubiquitin conjugating enzyme Ube2g2.
最近的甲基绝热弛豫弥散实验提供了对跨越非常宽时间尺度（10-10 s）的构象动力学的检查，特别是提供了对蛋白质疏水区和与调节剂相关的变构效应的深入了解。该实验需要有效地解耦 H 和 C 自旋相互作用，并且已经发现了一些与质子去耦方案设计相关的伪影。实验数据表明原始设计是有效的；然而，没有质子去耦或质子去耦具有不完美脉冲的脉冲序列可能在实验中表现出复杂性。在这里，我们证明通过使用单个复合 π 脉冲，可以显著减轻质子去耦方案中的脉冲不完整性，并提供纯净的单指数弛豫数据。它通过去除偶极-偶极相互作用和化学位移各向异性之间的交叉相关，为获得高质量的甲基绝热弛豫弥散数据提供了机会。所得到的高质量数据通过结合别构调节剂（G2BR）与泛素结合酶 Ube2g2 进行了说明。
