Magic angle spinning in solid state n.m.r. spectroscopy

Rapid specimen rotation about an axis inclined at the ‘magic angle’ of 54° 44' to the Zeeman field direction can remove many sources of broadening from the n.m.r. spectrum of a solid and enable finer features to be revealed. In this paper the basic principles of magic angle spinning are given and the effects on the chemical shift interaction, the magnetic dipolar and pseudo-dipolar interactions, both homonuclear and heteronuclear, and the electric quadrupolar interactions are examined. The anisotropic parts of these interactions are removed from the central spectrum and appear as spinning sidebands. The interactions that remain are the isotropic shifts and J couplings as in isotropic fluids. Examples of the effects of magic angle spinning on a variety of interactions are given. When applied to metals the anisotropy of Knight shift is removed, isotropic Knight shifts may be measured with precision, and the Ruderman-Kittel interaction may be determined in the presence of a much larger dipolar interaction. The effects of spinning on homogeneous and inhomogeneous spectra are distinguished. Sources of residual broadening are identified. Magic angle spinning may be used on its own, and may also be successfully combined with multiple-pulse and double resonance n.m.r. methods to obtain high-resolution n.m.r. spectra of powders and polymers.

2000 ◽  
Vol 146 (1) ◽  
pp. 132-139 ◽  
Author(s):  
Christopher P Jaroniec ◽  
Brett A Tounge ◽  
Chad M Rienstra ◽  
Judith Herzfeld ◽  
Robert G Griffin

2021 ◽  
Vol 2 (1) ◽  
pp. 343-353
Author(s):  
Evgeny Nimerovsky ◽  
Kai Xue ◽  
Kumar Tekwani Movellan ◽  
Loren B. Andreas

Abstract. The radio-frequency-driven recoupling (RFDR) pulse sequence is used in magic-angle spinning (MAS) NMR to recouple homonuclear dipolar interactions. Here we show simultaneous recoupling of both the heteronuclear and homonuclear dipolar interactions by applying RFDR pulses on two channels. We demonstrate the method, called HETeronuclear RFDR (HET-RFDR), on microcrystalline SH3 samples at 10 and 55.555 kHz MAS. Numerical simulations of both HET-RFDR and standard RFDR sequences allow for better understanding of the influence of offsets and paths of magnetization transfers for both HET-RFDR and RFDR experiments, as well as the crucial role of XY phase cycling.


2015 ◽  
Vol 112 (47) ◽  
pp. 14611-14616 ◽  
Author(s):  
Si Yan ◽  
Changmiao Guo ◽  
Guangjin Hou ◽  
Huilan Zhang ◽  
Xingyu Lu ◽  
...  

Microtubules and their associated proteins perform a broad array of essential physiological functions, including mitosis, polarization and differentiation, cell migration, and vesicle and organelle transport. As such, they have been extensively studied at multiple levels of resolution (e.g., from structural biology to cell biology). Despite these efforts, there remain significant gaps in our knowledge concerning how microtubule-binding proteins bind to microtubules, how dynamics connect different conformational states, and how these interactions and dynamics affect cellular processes. Structures of microtubule-associated proteins assembled on polymeric microtubules are not known at atomic resolution. Here, we report a structure of the cytoskeleton-associated protein glycine-rich (CAP-Gly) domain of dynactin motor on polymeric microtubules, solved by magic angle spinning NMR spectroscopy. We present the intermolecular interface of CAP-Gly with microtubules, derived by recording direct dipolar contacts between CAP-Gly and tubulin using double rotational echo double resonance (dREDOR)-filtered experiments. Our results indicate that the structure adopted by CAP-Gly varies, particularly around its loop regions, permitting its interaction with multiple binding partners and with the microtubules. To our knowledge, this study reports the first atomic-resolution structure of a microtubule-associated protein on polymeric microtubules. Our approach lays the foundation for atomic-resolution structural analysis of other microtubule-associated motors.


2000 ◽  
Vol 323 (5-6) ◽  
pp. 490-497 ◽  
Author(s):  
Simon J Kitchin ◽  
Kenneth D.M Harris ◽  
Abil E Aliev ◽  
David C Apperley

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