Hong M, Gross J D, Rienstra C M, Griffin R G, Kumashiro K K, Schmidt-Rohr K
Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
J Magn Reson. 1997 Nov;129(1):85-92. doi: 10.1006/jmre.1997.1242.
A technique for amplifying the apparent magnitudes of 13C-1H and 15N-1H dipolar interactions in magic-angle spinning experiments is described. By inserting rotor-synchronized 180 degrees pulses in the evolution period of a 2D dipolar-chemical shift experiment, heteronuclear dipolar couplings are doubled or quadrupled relative to the spinning speed. The increased number of dipolar sidebands is desirable for retaining structural information in the indirectly detected dipolar dimension while resolving inequivalent sites in the isotropic chemical shift dimension at relatively high spinning speeds. This coupling amplification method is incorporated into an experiment that determines the peptide torsion angle phi through the relative orientation of the Calpha-Halpha and N-HN bonds. It is shown both experimentally and theoretically that the angular resolution of the measurement is enhanced significantly by the selective doubling of the N-HN coupling.
描述了一种在魔角旋转实验中放大¹³C-¹H和¹⁵N-¹H偶极相互作用表观强度的技术。通过在二维偶极-化学位移实验的演化期插入转子同步180°脉冲，相对于旋转速度，异核偶极耦合加倍或四倍。增加的偶极边带数量对于在间接检测的偶极维度中保留结构信息，同时在相对较高的旋转速度下分辨各向同性化学位移维度中的不等价位点是有利的。这种耦合放大方法被纳入一个通过Cα-Hα和N-HN键的相对取向来确定肽扭转角φ的实验中。实验和理论均表明，通过选择性地使N-HN耦合加倍，测量的角分辨率显著提高。
