采用哈达玛编码的质子演化局域场固态核磁共振:在膜蛋白中的理论与应用。
Proton evolved local field solid-state nuclear magnetic resonance using Hadamard encoding: theory and application to membrane proteins.
机构信息
Department of Biochemistry, Molecular Biology, and Biophysics, Minneapolis, Minnesota 55455, USA.
出版信息
J Chem Phys. 2011 Aug 21;135(7):074503. doi: 10.1063/1.3622604.
NMR anisotropic parameters such as dipolar couplings and chemical shifts are central to structure and orientation determination of aligned membrane proteins and liquid crystals. Among the separated local field experiments, the proton evolved local field (PELF) scheme is particularly suitable to measure dynamically averaged dipolar couplings and give information on local molecular motions. However, the PELF experiment requires the acquisition of several 2D datasets at different mixing times to optimize the sensitivity for the complete range of dipolar couplings of the resonances in the spectrum. Here, we propose a new PELF experiment that takes the advantage of the Hadamard encoding (HE) to obtain higher sensitivity for a broad range of dipolar couplings using a single 2D experiment. The HE scheme is obtained by selecting the spin operators with phase switching of hard pulses. This approach enables one to detect four spin operators, simultaneously, which can be processed into two 2D spectra covering a broader range of dipolar couplings. The advantages of the new approach are illustrated for a U-(15)N NAL single crystal and the U-(15)N labeled single-pass membrane protein sarcolipin reconstituted in oriented lipid bicelles. The HE-PELF scheme can be implemented in other multidimensional experiments to speed up the characterization of the structure and dynamics of oriented membrane proteins and liquid crystalline samples.
NMR 各向异性参数,如偶极耦合和化学位移,是确定取向膜蛋白和液晶结构和取向的核心。在分离的局部场实验中,质子演化局部场(PELF)方案特别适合测量动态平均偶极耦合,并提供关于局部分子运动的信息。然而,PELF 实验需要在不同的混合时间采集几个 2D 数据集,以优化对谱中共振的完整偶极耦合范围的灵敏度。在这里,我们提出了一种新的 PELF 实验,该实验利用 Hadamard 编码(HE)在单个 2D 实验中获得更广泛偶极耦合的更高灵敏度。HE 方案是通过选择具有硬脉冲相位切换的自旋算符获得的。这种方法可以同时检测四个自旋算符,将其处理成两个覆盖更广泛偶极耦合范围的 2D 光谱。该新方法的优点在 U-(15)N NAL 单晶和在定向脂质双分子层中重组的 U-(15)N 标记的单通道肌浆蛋白中得到了说明。HE-PELF 方案可在其他多维实验中实施,以加快对取向膜蛋白和液晶样品的结构和动力学的表征。