Approach to High-Resolution nmr in Solids

Complete resolution of the solid-state NMR spectrum of a uniformly 15 N-labeled membrane protein in phospholipid bilayers

“…The seminal developments of multiple-pulse methods (43) for narrowing the resonances of abundant ( 1 H) spins, and doubleresonance methods (19) for sensitivity enhancement and highresolution spectroscopy of dilute ( 15 N) spins, provide the fundamental basis for high resolution NMR spectroscopy of immobile molecules, including those as complex as proteins (44). The data in Fig.…”

Scalar operators in solid-state NMR

“…Unfortunately, the numerical simulations have not yet been accomplished and are left for future work. [56,57,58], dynamic angle spinning (DAS) [78,76], double rotation (DOR) [72,104]' and multiple pulse (MP) [114]. The principle involved in these methods is the coherently motional averaging under which the orientation dependence of the resonance frequency can be completely or partially removed, and the NMR spectra contain only the isotr<;>pic chemical shifts.…”

“…An example of particular interest is the case of two dipolar coupled spin one half nuclei because in zero field there is only the dipolar interaction of a lone spin pair and in high field there is only the chemical shift anisotropy, assuming 22 that the dipolar interaction has been eliminated in high field by applying a multiple pulse sequenre (e.g. WAHUHA) [114]. In general, the principle axis systems for these interactions are not the same, so we will introduce a molecular frame which differs from the principle axis systems.…”

“…After a moment more thought, we know that the correlations between zero field and high field are also destroyed by spin-locking detection. However such a correlation spectrum [18] will lead to a new type of separation of a usual high field powder pattern based on the high resolution spectrum in the zero field domain and also takes advantage both of zero field and high field after combination with multiple pulse techniques in high field [19,114]. In this section, we will provide a brief theoretical description of the zero field and high field correlation spectra and show a set of simulations which potentially could be verified by some experiments.…”

“…This latter option, that of supplying the motion externally, was inherent in the spin echo experiment[52J and its generalizations [53] in which the spin angular momenta are perturbed while leaving the molecules in place; and in the sample-spinning experiments of Anderson [54], in which the sample is rotated. Averaging in spin space has progressed from simple spin echoes to the prolonged trains introduced by Waugh and later workers for solids [55]. Averaging in spatial space was extended to solids by magic-angle spinning (MAS) [56,57,58] which is a routine feature of solid state NMR.…”