A general two-site solution for the chemical exchange produced dependence of T2 upon the carr-Purcell pulse separation

Carver, Jeremy P.; Richards, R. E.

doi:10.1016/0022-2364(72)90090-x

Cited by 261 publications

(327 citation statements)

References 10 publications

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“…9 shows representative dispersion curves. CPMG relaxation dispersion curves were analyzed as an equilibrium between two sites characterized by resonance frequencies A and B with populations p A and p B , respectively, exchanging at a rate k ex ϭ k ϩ ϩ k Ϫ (34). A preliminary analysis of the relaxation dispersion curves of individual residues showed dynamics in 12 residues with similar apparent k ex values distributed along the entire sequence: Leu-7 in helix1, Glu-24 and Lys-27 in helix 2, Asp-33, Tyr-39, Ala-42, and Asp-43 in helix 3, Tyr-55 and Ile-58 in a loop, and Val-62, Gln-64, and His-65 in the C-terminal helical region.…”

Section: Resultsmentioning

confidence: 99%

A Three-protein Charge Zipper Stabilizes a Complex Modulating Bacterial Gene Silencing

Cordeiro

García

Bernadó

et al. 2015

Journal of Biological Chemistry

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Section: Resultsmentioning

confidence: 99%

A Three-protein Charge Zipper Stabilizes a Complex Modulating Bacterial Gene Silencing

Cordeiro

García

Bernadó

et al. 2015

Journal of Biological Chemistry

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“…Recently, a reduced SAR version of a T 1r mapping sequence was developed (194). This method exploits a partial k-space acquisition approach in which a full power spin-lock pulse is applied only to the central phaseencode lines of k-space, while the remaining phase encode lines receive a low-power (50% amplitude of the maximum) spin-lock pulse.…”

Section: A Low Sar T 1r Pulse Sequencementioning

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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“…Relaxation dispersion profiles on apo-SOD1 were fitted both to a constant value and to the general expression for a 2-state process (49). Relaxation dispersion profiles on Zn-SOD1 were fitted to a constant and the expression for a 2-state process in slow exchange (50).…”

Section: Nmr Experimentsmentioning

confidence: 99%

Transient structural distortion of metal-free Cu/Zn superoxide dismutase triggers aberrant oligomerization

Teilum

Smith

Schulz

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease linked to the misfolding of Cu/Zn superoxide dismutase (SOD1).ALS-related defects in SOD1 result in a gain of toxic function that coincides with aberrant oligomerization. The structural events triggering oligomerization have remained enigmatic, however, as is the case in other protein-misfolding diseases. Here, we target the critical conformational change that defines the earliest step toward aggregation. Using nuclear spin relaxation dispersion experiments, we identified a short-lived (0.4 ms) and weakly populated (0.7%) conformation of metal-depleted SOD1 that triggers aberrant oligomerization. This excited state emanates from the folded ground state and is suppressed by metal binding, but is present in both the disulfide-oxidized and disulfide-reduced forms of the protein. Our results pinpoint a perturbed region of the excited-state structure that forms intermolecular contacts in the earliest nonnative dimer/ oligomer. The conformational transition that triggers oligomerization is a common feature of WT SOD1 and ALS-associated mutants that have widely different physicochemical properties. But compared with WT SOD1, the mutants have enhanced structural distortions in their excited states, and in some cases slightly higher excited-state populations and lower kinetic barriers, implying increased susceptibility to oligomerization. Our results provide a unified picture that highlights both (i) a common denominator among different SOD1 variants that may explain why diverse mutations cause the same disease, and (ii) a structural basis that may aid in understanding how different mutations affect disease propensity and progression.amyotrophic lateral sclerosis ͉ nuclear magnetic resonance relaxation ͉ protein misfolding

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A general two-site solution for the chemical exchange produced dependence of T2 upon the carr-Purcell pulse separation

Cited by 261 publications

References 10 publications

A Three-protein Charge Zipper Stabilizes a Complex Modulating Bacterial Gene Silencing

A Three-protein Charge Zipper Stabilizes a Complex Modulating Bacterial Gene Silencing

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

Transient structural distortion of metal-free Cu/Zn superoxide dismutase triggers aberrant oligomerization

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A general two-site solution for the chemical exchange produced dependence of T2 upon the carr-Purcell pulse separation

Cited by 261 publications

References 10 publications

A Three-protein Charge Zipper Stabilizes a Complex Modulating Bacterial Gene Silencing

A Three-protein Charge Zipper Stabilizes a Complex Modulating Bacterial Gene Silencing

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

Transient structural distortion of metal-free Cu/Zn superoxide dismutase triggers aberrant oligomerization

Contact Info

Product

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