REDOR-based heteronuclear dipolar correlation experiments in multi-spin systems: rotor-encoding, directing, and multiple distance and angle determination.
We review a variety of recently developed 1H-X heteronuclear recoupling techniques, which rely only on the homonuclear decoupling efficiency of very-fast magic-angle spinning. All these techniques, which are based on the simple rotational-echo, double-resonance (REDOR) approach for heteronuclear recoupling, are presented in a common context. Advantages and possibilities with respect to the complementary application of conventionally X and 1H-inversely detected variants are discussed in relation to the separability and analysis of multiple couplings. We present an improved and more sensitive approach to the determination of 1H-X dipolar couplings by spinning-sideband analysis, termed REREDOR, which is applicable to XHn groups in rigid and mobile systems and bears some similarity to more elaborate separated local-field methods. The estimation of medium-range 1H-X distances by analyzing signal intensities in two-dimensional REDOR correlation spectra in a model-free way is also discussed. More specifically, we demonstrate the possibility of combined distance and angle determination in H-X-H or X-H-X three-spin systems by asymmetric recoupling schemes and spinning-sideband analysis. Finally, an 1H-X correlation experiment is introduced which accomplishes high sensitivity by inverse (1H) detection and is therefore applicable to samples with 15N in natural abundance.
Saalwächter
Kay
K
Institut für Makromolekulare Chemie, Universität Freiburg. Stefan-Meier-Str. 31, D-79104 Freiburg, Germany. kays@makro.uni-freiburg.de
Schnell
Ingo
I
D000409:Alanine / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry*; D002247:Carbon Isotopes; D003198:Computer Simulation; D006639:Histidine / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000295:instrumentation / Q000379:methods*; D011522:Protons; D011786:Quality Control; D012399:Rotation; D012680:Sensitivity and Specificity; D012833:Siloxanes / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry; D014501:Uranium
D000596:Amino Acids; D002247:Carbon Isotopes; D011522:Protons; C470747:Q8M8 compound; D012833:Siloxanes; D014443:Tyrosine; D014501:Uranium; D006639:Histidine; D000409:Alanine