Parthasarathy S.,University of Illinois at Chicago |
Nishiyama Y.,JEOL Resonance Inc. |
Ishii Y.,University of Illinois at Chicago
Accounts of Chemical Research | Year: 2013
Recent research in fast magic angle spinning (MAS) methods has drasticallyimproved the resolution and sensitivity of NMR spectroscopy of biomolecules and materials in solids. In this Account, we summarize recent and ongoing developments in this area by presenting 13C and 1H solid-state NMR (SSNMR) studies on paramagnetic systems and biomolecules under fast MAS from our laboratories.First, we describe how very fast MAS (VFMAS) at the spinning speed of at least20 kHz allows us to overcome major difficulties in 1H and 13C high-resolution SSNMR of paramagnetic systems. As a result, we can enhance both sensitivity and resolution by up to a few orders of magnitude. Using fast recycling (∼ms/scan) with short 1H T1 values, we can perform 1H SSNMR microanalysis of paramagnetic systems on the microgram scale with greatly improved sensitivity over that observed for diamagnetic systems. Second, we discuss how VFMAS at a spinning speed greater than ∼40 kHz can enhance the sensitivity and resolution of 13C biomolecular SSNMR measurements. Low-power 1H decoupling schemes under VFMAS offer excellent spectral resolution for 13C SSNMR by nominal 1H RF irradiation at ∼10 kHz. By combining the VFMAS approach with enhanced 1H T 1 relaxation by paramagnetic doping, we can achieve extremely fast recycling in modern biomolecular SSNMR experiments. Experiments with 13C-labeled ubiquitin doped with 10 mM Cu-EDTA demonstrate how effectively this new approach, called paramagnetic assisted condensed data collection (PACC), enhances the sensitivity.Lastly, we examine 13C SSNMR measurements for biomolecules under faster MAS at a higher field. Our preliminary 13C SSNMR data of Aβ amyloid fibrils and GB1 microcrystals acquired at 1H NMR frequencies of 750-800 MHz suggest that the combined use of the PACC approach and ultrahigh fields could allow for routine multidimensional SSNMR analyses of proteins at the 50-200 nmol level. Also, we briefly discuss the prospects for studying bimolecules using 13C SSNMR under ultrafast MAS at the spinning speed of ∼100 kHz. © 2013 American Chemical Society.
JEOL Resonance Inc. | Date: 2013-05-08
An NMR sample tube is offered which can be spun at high speed stably. The NMR sample tube is adapted for use in solid-state NMR spectroscopy and includes a tubular member, spacers, and cover bodies. The spacers are disposed inside the tubular member. Each spacer has first and second surfaces located on opposite sides. The first surfaces of the spacers define a space filled up with a sample. The tubular member has openings which are closed off by the cover bodies.
JEOL Resonance Inc. | Date: 2013-09-04
A method of NMR measurement which achieves background suppression based on a technique employing differences in RF magnetic field strength while alleviating the problem that less latitude is allowed in setting the number of signal accumulations. This method suppresses a background-derived signal emanating from the material of an NMR probe. The method starts with applying an RF pulse sequence consisting of a 90 pulse and subsequent one or more 180 pulses to a sample to induce an NMR signal and detecting the signal. This application is repeated while varying the RF phases of the pulses to induce NMR signals in accordance with a cogwheel phase-cycling scheme to induce NMR signals. The NMR signals are detected. The detected NMR signals are accumulated.
JEOL Resonance Inc. | Date: 2013-01-02
An NMR spectrometer and method in the following three steps are performed. (1) An external magnetic field is set to H
JEOL Resonance Inc. | Date: 2013-10-08
There is disclosed an NMR (nuclear magnetic resonance) spinner having a turbine structure and a rotor whose spinning rate can be increased. A vortical channel (