High Resolution NMR Spectroscopy in Solids

Mehring, M.; Garroway, A. N.

doi:10.1007/978-3-642-96332-2

Cited by 389 publications

(344 citation statements)

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“…The theory of NMR of quadrupolar nuclei (74,75,(77)(78)(79)(80), relaxation-induced sodium single and multiple quantum coherences (MQC) and their applications in the studies of biological systems has been extensively discussed in several original and review articles (81)(82)(83)(84)(85)(86)(87)(88)(89)(90)(91). Here a brief overview of steps involved in the calculation of spin dynamics using the density matrix approach is presented.…”

Section: Sodium Nmrmentioning

confidence: 99%

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

et al. 2006

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In this article, both sodium magnetic resonance (MR) and T 1r relaxation mapping aimed at measuring molecular changes in cartilage for the diagnostic imaging of osteoarthritis are reviewed. First, an introduction to structure of cartilage, its degeneration in osteoarthritis (OA) and an outline of diagnostic imaging methods in quantifying molecular changes and early diagnostic aspects of cartilage degeneration are described. The sodium MRI section begins with a brief overview of the theory of sodium NMR of biological tissues and is followed by a section on multiple quantum filters that can be used to quantify both bi-exponential relaxation and residual quadrupolar interaction. Specifically, (i) the rationale behind the use of sodium MRI in quantifying proteoglycan (PG) changes, (ii) validation studies using biochemical assays, (iii) studies on human OA specimens, (iv) results on animal models and (v) clinical imaging protocols are reviewed. Results demonstrating the feasibility of quantifying PG in OA patients and comparison with that in healthy subjects are also presented. The section concludes with the discussion of advantages and potential issues with sodium MRI and the impact of new technological advancements (e.g. ultra-high field scanners and parallel imaging methods). In the theory section on T 1r , a brief description of (i) principles of measuring T 1r relaxation, (ii) pulse sequences for computing T 1r relaxation maps, (iii) issues regarding radio frequency power deposition, (iv) mechanisms that contribute to T 1r in biological tissues and (v) effects of exchange and dipolar interaction on T 1r dispersion are discussed. Correlation of T 1r relaxation rate with macromolecular content and biomechanical properties in cartilage specimens subjected to trypsin and cytokineinduced glycosaminoglycan depletion and validation against biochemical assay and histopathology are presented. Experimental T 1r data from osteoarthritic specimens, animal models, healthy human subjects and as well from osteoarthritic patients are provided. The current status of T 1r relaxation mapping of cartilage and future directions is also discussed. Copyright # 2006 John Wiley & Sons, Ltd. KEYWORDS: cartilage; arthritis; spin-lock; T1rho; sodium; MRI OSTEOARTHRITIS Osteoarthritis (OA) affects more than half of the population above the age of 65 (1,2) and has a significant negative impact on the quality of life of elderly individuals (3). The economic costs in the USA from OA have been estimated to be more than 1% of the gross domestic product (4). OA is now increasingly viewed as a metabolically active joint disorder of diverse etiologies. The biochemistry of the disease is characterized by the following changes in cartilage: reduced proteoglycan (PG) concentration, possible changes in the size of collagen fibril and aggregation of PG, increased water content and increased rate of synthesis and degradation of matrix macromolecules. The earliest changes in the cartilage due to OA result in a partial breakdown in the proteoglyc...

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Section: Sodium Nmrmentioning

confidence: 99%

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

et al. 2006

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“…Irreducible spherical tensors, Wigner matrices and Euler angles are discussed thoroughly in the literature. 4 A particularly useful compilation is given in Ref. 53 The article Internal Spin Interactions & Rotations in Solids, Volume 4, summarizes many key results.…”

Section: Spin Interactionsmentioning

confidence: 99%

“…MAS, in combination with Hartmann-Hahn cross-polarization and heteronuclear decoupling, became a standard method for examining the NMR spectra of rare spin species such as 13 C and 15 N in solids. 4 Commercial NMR companies began to offer MAS equipment as options for their spectrometers, allowing an explosion of applications.…”

Section: Introductionmentioning

confidence: 99%

Symmetry‐Based Pulse Sequences in Magic‐Angle Spinning Solid‐State NMR

Levitt

2003

ChemInform

181

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“…The T 1F H values were evaluated by a nonlinear least-squares fitting of the 15 N NMR signal intensities I(t) with 5-7 contact times with t between 0.1 and 8 ms according to eq 1, where I(0) denotes the initial peak intensities (60). 15 N spin-spin relaxation times (T 2 ) were measured by the Hahn-echo method together with CP and proton decoupling.…”

Section: Samplementioning

confidence: 99%

Functionally Relevant Coupled Dynamic Profile of Bacteriorhodopsin and Lipids in Purple Membranes

Kamihira

Watts

2006

Biochemistry

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The dynamics of bacteriorhodopsin (bR) and the lipid headgroups in oriented purple membranes (PMs) was determined at various temperatures and relative humidity (rh) using solid-state NMR spectroscopy. The 31 P NMR spectra of the R-and γ-phosphate groups in methyl phosphatidylglycerophosphate (PGP-Me), which is the major phospholipid in the PM, changed sensitively with hydration levels. Between 253 and 233 K, the signals from a fully hydrated sample became broadened similarly to those of a dry sample at 293 K. The 15 N cross polarization (CP) NMR spectral intensities from [ 15 N]Gly bR incorporated into fully hydrated PMs were suppressed in 15 N CP NMR spectra at 293 K compared with those of dry membranes but gradually recovered at low temperatures or at lower hydration (75%) levels. The suppression of the NMR signals, which is due to interference with proton decoupling frequency (∼45 kHz), coupled with short spin-spin relaxation times (T 2 ) indicates that the loops of bR, in particular, have motional components around this frequency. The motion of the transmembrane R-helices in bR was largely affected by the freezing of excess water at low temperatures. While between 253 and 233 K, where a dynamic phase transition-like change was observed in the 31 P NMR spectra for the phosphate lipid headgroups, the molecular motion of the loops and the C-and N-termini slowed, suggesting lipidloop interactions, although protein-protein interactions between stacks cannot be excluded. The results of T 2 measurements of dry samples, which do not have proton pumping activity, were similar to those for fully hydrated samples below 213 K where the M-intermediates can be trapped. These results suggest that motions in the 10s µs correlation regime may be functionally important for the photocycle of bR, and protein-lipid interactions are motionally coupled in this dynamic regime.Bacteriorhodopsin (bR) 1 is one of the most extensively studied light-driven proton pumps in Haloarchaea. It contains seven transmembrane R-helices surrounding the retinal chromophore and has been the structural paradigm of G-protein-coupled receptors and other membrane proteins (1-5). It forms a protein-lipid complex of defined composition in the purple membrane (PM), where bR is arranged in trimeric units assembled in 2D crystalline patches in a hexagonal lattice. High-resolution X-ray (6-11) and electron (12, 13) crystallography have been used to determine the 3D structure of bR and the structural changes at K, L, M, N, and O photointermediates to understand the unidirectional translocation of proton pumping activity (14-23). Solid-state NMR spectroscopy has been used to provide detailed information about the local structural changes of retinal (24,25) around the key residues involved in proton pumping activity (26,27) and the local mobility of bR (28-30) under physiological conditions. Also, the structure and orientation of some R-helices of membrane-embedded bR have been determined by polarization inversion spin exchange at the magic angle (PISE...

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High Resolution NMR Spectroscopy in Solids

Cited by 389 publications

References 0 publications

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

Symmetry‐Based Pulse Sequences in Magic‐Angle Spinning Solid‐State NMR

Functionally Relevant Coupled Dynamic Profile of Bacteriorhodopsin and Lipids in Purple Membranes

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High Resolution NMR Spectroscopy in Solids

Cited by 389 publications

References 0 publications

Sodium and T1ρ MRI for molecular and diagnostic imaging of articular cartilage

Sodium and T1ρ MRI for molecular and diagnostic imaging of articular cartilage

Symmetry‐Based Pulse Sequences in Magic‐Angle Spinning Solid‐State NMR

Functionally Relevant Coupled Dynamic Profile of Bacteriorhodopsin and Lipids in Purple Membranes

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Product

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Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage