The influence of manganese(II) and copper(II) on 13C nuclear relaxation rates in imidazole

1976 ◽  
Vol 54 (4) ◽  
pp. 617-623 ◽  
Author(s):  
Roderick E. Wasylishen ◽  
Moira R. Graham
Keyword(s):  
Aqueous Solutions ◽  
Line Width ◽  
Important Influence ◽  
Nuclear Relaxation ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Width Measurements

13C nuclear relaxation rates have been measured for aqueous solutions of imidazole at 31 °C for several values of pH. The influence of Mn(II) and Cu(II) on these relaxation rates has been examined. The results indicate that 13C transverse relaxation rates of imidazole in the presence of these metals are completely dominated by the scalar mechanism. Because of the important influence of this mechanism it is not possible to obtain the geometry of complexes between imidazole-like ligands and Mn(II) or Cu(II) from 13C line-width measurements.

scholarly journals Measuring transverse relaxation in highly paramagnetic systems

2020 ◽  
Vol 74 (8-9) ◽  
pp. 431-442
Author(s):  
Michele Invernici ◽  
Inês B. Trindade ◽  
Francesca Cantini ◽  
Ricardo O. Louro ◽  
Mario Piccioli
Keyword(s):  
Structural Biology ◽  
Paramagnetic Center ◽  
Metal Ion ◽  
Biological Function ◽  
Nuclear Relaxation ◽  
The Novel ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Powerful Source ◽  
Ca 50

Abstract The enhancement of nuclear relaxation rates due to the interaction with a paramagnetic center (known as Paramagnetic Relaxation Enhancement) is a powerful source of structural and dynamics information, widely used in structural biology. However, many signals affected by the hyperfine interaction relax faster than the evolution periods of common NMR experiments and therefore they are broadened beyond detection. This gives rise to a so-called blind sphere around the paramagnetic center, which is a major limitation in the use of PREs. Reducing the blind sphere is extremely important in paramagnetic metalloproteins. The identification, characterization, and proper structural restraining of the first coordination sphere of the metal ion(s) and its immediate neighboring regions is key to understand their biological function. The novel HSQC scheme we propose here, that we termed R2-weighted, HSQC-AP, achieves this aim by detecting signals that escaped detection in a conventional HSQC experiment and provides fully reliable R2 values in the range of 1H R2 rates ca. 50–400 s−1. Independently on the type of paramagnetic center and on the size of the molecule, this experiment decreases the radius of the blind sphere and increases the number of detectable PREs. Here, we report the validation of this approach for the case of PioC, a small protein containing a high potential 4Fe-4S cluster in the reduced [Fe4S4]2+ form. The blind sphere was contracted to a minimal extent, enabling the measurement of R2 rates for the cluster coordinating residues.

63,65Cu NMR and NQR in YBa2Cu3O7-δ

1987 ◽  
Vol 99 ◽  
Author(s):  
W. W. Warren ◽  
R. E. Walstedt ◽  
R. F. Bell ◽  
G. F. Brennert ◽  
R. J. Cava ◽  
...  
Keyword(s):  
Superconducting State ◽  
High Field ◽  
Nuclear Relaxation ◽  
Relaxation Rates ◽  
Structural Units ◽  
Nmr Spectrum ◽  
Electron Pairing

ABSTRACTNMR and NQR results are reported for 63,65Cu in YBa2Cu3O7-δ. Analysis of the high-field NMR spectrum indicates substantial disorder in the copper-oxygen planes. Nuclear relaxation rates are significantly different for copper in the chains and planes both above and below Tc and yield sharply different electron pairing energies on these structural units in the superconducting state.

scholarly journals 45Scandium NMR Investigations in Aqueous Solutions

1983 ◽  
Vol 38 (3) ◽  
pp. 317-321 ◽  
Author(s):  
E. Haid ◽  
D. Köhnlein ◽  
G. Kössler ◽  
O. Lutz ◽  
W. Messner ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Chemical Shifts ◽  
Isotope Effects ◽  
Larmor Frequency ◽  
Relaxation Rates ◽  
Nmr Chemical Shifts ◽  
Typical Behaviour ◽  
Solvent Isotope ◽  
Scandium Chloride ◽  
Solvent Isotope Effects

Abstract45Sc NMR chemical shifts, linewidths, and longitudinal relaxation rates have been measured in aqueous solutions of scandium chloride and sulphate as a function of the appropriate acid. A common typical behaviour of these parameters without sudden changes has been observed. Also signals in the basic range have been obtained. H2O -D2O solvent isotope effects on Larmor frequency and relaxation rates are presented.

Sodium ion and solvent nuclear relaxation results in aqueous solutions of DNA

Biopolymers ◽  
1987 ◽  
Vol 26 (2) ◽  
pp. 261-284 ◽  
Author(s):  
Leendert Van Dijk ◽  
Marco L. H. Gruwel ◽  
Wim Jesse ◽  
Jan De Bleijser ◽  
Jaap C. Leyte
Keyword(s):  
Aqueous Solutions ◽  
Sodium Ion ◽  
Nuclear Relaxation

scholarly journals Transverse relaxation rates of pulmonary dissolved‐phase Hyperpolarized 129 Xe as a biomarker of lung injury in idiopathic pulmonary fibrosis

2020 ◽  
Vol 84 (4) ◽  
pp. 1857-1867
Author(s):  
Jeff Kammerman ◽  
Andrew D. Hahn ◽  
Robert V. Cadman ◽  
Annelise Malkus ◽  
David Mummy ◽  
...  
Keyword(s):  
Idiopathic Pulmonary Fibrosis ◽  
Pulmonary Fibrosis ◽  
Lung Injury ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Dissolved Phase

scholarly journals In Vivo Quantification of Cerebral R2*-Response to Graded Hyperoxia at 3 Tesla

2015 ◽  
Vol 5 ◽  
pp. 1 ◽  
Author(s):  
Grigorios Gotzamanis ◽  
Roman Kocian ◽  
Pinar S. Özbay ◽  
Manuel Redle ◽  
Spyridon Kollias ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Relaxation Rate ◽  
Tumor Therapy ◽  
Cerebrovascular Reactivity ◽  
Oxygen Intake ◽  
Transverse Relaxation Rate ◽  
Dependent Manner ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Arterial Blood

Objectives: This study aims to quantify the response of the transverse relaxation rate of the magnetic resonance (MR) signal of the cerebral tissue in healthy volunteers to the administration of air with step-wise increasing percentage of oxygen. Materials and Methods: The transverse relaxation rate (R2*) of the MR signal was quantified in seven volunteers under respiratory intake of normobaric gas mixtures containing 21, 50, 75, and 100% oxygen, respectively. End-tidal breath composition, arterial blood saturation (SaO2), and heart pulse rate were monitored during the challenge. R2* maps were computed from multi-echo, gradient-echo magnetic resonance imaging (MRI) data, acquired at 3.0T. The average values in the segmented white matter (WM) and gray matter (GM) were tested by the analysis of variance (ANOVA), with Bonferroni post-hoc correction. The GM R2*-reactivity to hyperoxia was modeled using the Hill's equation. Results: Graded hyperoxia resulted in a progressive and significant (P < 0.05) decrease of the R2* in GM. Under normoxia the GM-R2* was 17.2 ± 1.1 s-1. At 75% O2 supply, the R2* had reached a saturation level, with 16.4 ± 0.7 s-1 (P = 0.02), without a significant further decrease for 100% O2. The R2*-response of GM correlated positively with CO2 partial pressure (R = 0.69 ± 0.19) and negatively with SaO2 (R = -0.74 ± 0.17). The WM showed a similar progressive, but non-significant, decrease in the relaxation rates, with an increase in oxygen intake (P = 0.055). The Hill's model predicted a maximum R2* response of the GM, of 3.5%, with half the maximum at 68% oxygen concentration. Conclusions: The GM-R2* responds to hyperoxia in a concentration-dependent manner, suggesting that monitoring and modeling of the R2*-response may provide new oxygenation biomarkers for tumor therapy or assessment of cerebrovascular reactivity in patients.

scholarly journals High-Resolution CMRO2 Mapping in Rat Cortex: A Multiparametric Approach to Calibration of BOLD Image Contrast at 7 Tesla

2000 ◽  
Vol 20 (5) ◽  
pp. 847-860 ◽  
Author(s):  
Ikuhiro Kida ◽  
Richard P. Kennan ◽  
Douglas L. Rothman ◽  
Kevin L. Behar ◽  
Fahmeed Hyder
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Spin Echo ◽  
7 Tesla ◽  
Relaxation Rates ◽  
Resonance Imaging ◽  
Gradient Echo ◽  
Transverse Relaxation ◽  
Physiologic Parameters ◽  
Spin Echo Sequences

The blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) method, which is sensitive to vascular paramagnetic deoxyhemoglobin, is dependent on regional values of cerebral metabolic rate of oxygen utilization (CMRO2), blood flow (CBF), and volume (CBV). Induced changes in deoxyhemoglobin function as an endogenous contrast agent, which in turn affects the transverse relaxation rates of tissue water that can be measured by gradient-echo and spin-echo sequences in BOLD fMRI. The purpose here was to define the quantitative relation between BOLD signal change and underlying physiologic parameters. To this end, magnetic resonance imaging and spectroscopy methods were used to measure CBF, CMRO2, CBV, and relaxation rates (with gradient-echo and spin-echo sequences) at 7 Tesla in rat sensorimotor cortex, where cerebral activity was altered pharmacologically within the autoregulatory range. The changes in tissue transverse relaxation rates were negatively and linearly correlated with changes in CBF, CMRO2, and CBV. The multiparametric measurements revealed that CBF and CMRO2 are the dominant physiologic parameters that modulate the BOLD fMRI signal, where the ratios of (ΔCMRO2/CMRO2)/(ΔCBF/CBF) and (ΔCBV/CBV)/(ΔCBF/CBF) were 0.86 ± 0.02 and 0.03 ± 0.02, respectively. The calibrated BOLD signals (spatial resolution of 48 μL) from gradient-echo and spin-echo sequences were used to predict changes in CMRO2 using measured changes in CBF, CBV, and transverse relaxation rates. The excellent agreement between measured and predicted values for changes in CMRO2 provides experimental support of the current theory of the BOLD phenomenon. In gradient-echo sequences, BOLD contrast is affected by reversible processes such as static inhomogeneities and slow diffusion, whereas in spin-echo sequences these effects are refocused and are mainly altered by extravascular spin diffusion. This study provides steps by which multiparametric MRI measurements can be used to obtain high-spatial resolution CMRO2 maps.

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