The strategy of using π pulses in conjunction with continuous-wave radio-frequency fields to refocus spin interactions has lead to robust and efficient family of heteronuclear decoupling schemes in magic-angle spinning solid-state NMR, denoted as, rCW schemes. Here, we investigate the generality of the application of such refocussing pulses in other phase-modulated decoupling schemes, notably the super-cycled XiX decoupling. XiX is a commonly used heteronuclear decoupling scheme under conditions of fast MAS and low-amplitude radio-frequency irradiation. The refocussing of interactions is achieved by inserting π pulses with a phase of 135° in the supercycled XiX scheme. The refocussed XiX, rXiX, scheme has improved decoupling efficiency, better offset tolerance, and easier experimental setup compared to the XiX scheme.
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http://dx.doi.org/10.1016/j.jmr.2017.09.010 | DOI Listing |
J Biomol NMR
January 2025
Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center (CERM), University of Florence, Florence, Italy.
Intrinsically disordered proteins and protein regions are central to many biological processes but difficult to characterize at atomic resolution. Nuclear magnetic resonance is particularly well-suited for providing structural and dynamical information on intrinsically disordered proteins, but existing NMR methodologies need to be constantly refined to provide greater sensitivity and resolution, particularly to capitalise on the potential of high magnetic fields to investigate large proteins. In this paper, we describe how N-detected 2D NMR experiments can be optimised for better performance.
View Article and Find Full Text PDFJ Vis Exp
November 2024
Institute of Biological Information Processing (IBI-7), Forschungszentrum Jülich; Institute of Physical Biology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf;
Nuclear magnetic resonance (NMR) spectroscopy allows studying proteins in solution and under physiological temperatures. Frequently, either the amide groups of the protein backbone or the methyl groups in side chains are used as reporters of structural dynamics in proteins. A structural dynamics study of the protein backbone of globular proteins on N labeled and fully protonated samples usually works well for proteins with a molecular weight of up to 50 kDa.
View Article and Find Full Text PDFJ Phys Chem Lett
October 2024
Department of Chemical and Biological Physics, Weizmann Institute, 7610001 Rehovot, Israel.
NMR finds a wide range of applications, ranging from fundamental chemistry to medical imaging. The technique, however, has an inherently low signal-to-noise ratio (SNR)─particularly when dealing with nuclei having low natural abundances and/or low γs. In these cases, sensitivity is often enhanced by methods that, similar to INEPT, transfer polarization from neighboring Hs via -couplings.
View Article and Find Full Text PDFAdv Mater
September 2024
Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, 32310, USA.
In this study, an innovative and cost-effective ionic polymer for CO capture and utilization for the first time, using abundant and nonfood-based biomass lignin is reported. The modified ionic polymer synthesizes through the reaction of glycidyltrimethylammonium chloride with lignin under alkaline conditions to yield quaternary ammonium ionic functionality. Subsequently, the hydroxide-based pure ionic lignin polymer is employed for CO capture from both direct air and concentrated CO sources at room temperature and atmospheric pressure.
View Article and Find Full Text PDFJ Magn Reson
August 2024
Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, United States; National Magnetic Resonance Facility at Madison (NMRFAM), University of Wisconsin-Madison, Madison, WI, 53706, United States; Morgridge Institute for Research, University of Wisconsin-Madison, Madison, WI, 53715, United States. Electronic address:
Improving the spectral sensitivity and resolution of biological solids is one of the long-standing problems in nuclear magnetic resonance (NMR) spectroscopy. In this report, we introduce low-power supercycled variants of two-pulse phase-modulated (TPPM) sequence for heteronuclear decoupling. The utility of the sequence is shown by improvements in the transverse relaxation time of observed nuclei (with H decoupling) with its application to different samples (uniformly C, N, H-labeled GB1 back-exchanged with 25% HO and 75% DO, uniformly C, N, H-labeled human derived Asyn fibril back-exchanged with 100% HO and uniformly C, N -labeled human derived Asyn fibril) at fast MAS using low radiofrequency (RF) fields.
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