scholarly journals Nonlinear detection of secondary isotopic chemical shifts in NMR through spin noise

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Maria Theresia Pöschko ◽  
Victor V. Rodin ◽  
Judith Schlagnitweit ◽  
Norbert Müller ◽  
Hervé Desvaux
Keyword(s):  
Chemical Shifts ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Spin Noise ◽  
Detection Circuit ◽  
Increased Sensitivity ◽  
Main Components ◽  
Small Chemical ◽  
Isotopic Measurements ◽  
Nmr Signals

Abstract The detection of minor species in the presence of large amounts of similar main components remains a key challenge in analytical chemistry, for instance, to obtain isotopic fingerprints. As an alternative to the classical NMR scheme based on coherent excitation and detection, here we introduce an approach based on spin-noise detection. Chemical shifts and transverse relaxation rates are determined using only the detection circuit. Thanks to a nonlinear effect in mixtures with small chemical shift dispersion, small signals on top of a larger one can be observed with increased sensitivity as bumps on a dip; the latter being the signature of the main magnetization. Experimental observations are underpinned by an analytical theory: the coupling between the magnetization and the coil provides an amplified detection capability of both small static magnetic field inhomogeneities and small NMR signals. This is illustrated by two-bond 12C/13C isotopic measurements.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

73Ge, 119Sn and 207Pb: general cooperative effects of single atom ligands on the NMR signals observed in tetrahedral [MXnY4−n] (M = Ge, Sn, Pb; 1 ≤ n ≤ 4; X, Y = Cl, Br, I) coordination compounds of heavier XIV group elements

2017 ◽  
Vol 46 (9) ◽  
pp. 2855-2860 ◽  
Author(s):  
M. Benedetti ◽  
F. De Castro ◽  
F. P. Fanizzi
Keyword(s):  
Linear Relationship ◽  
Coordination Compounds ◽  
Chemical Shifts ◽  
Single Atom ◽  
Ionic Radii ◽  
Nmr Chemical Shifts ◽  
Cooperative Effects ◽  
Nmr Signals

An inverse linear relationship between 73Ge, 119Sn and 207Pb NMR chemical shifts and the sum of ionic radii of coordinated halides has been found in [MXnYm] (M = Ge, Sn, Pb; n + m = 4; X, Y = Cl, Br, I) compounds.

scholarly journals The long-standing relationship between Paramagnetic NMR and Iron-Sulfur proteins: the mitoNEET example. An old method for new stories or the other way around?

2021 ◽  
Author(s):  
Francesca Camponeschi ◽  
Angelo Gallo ◽  
Mario Piccioli ◽  
Lucia Banci
Keyword(s):  
The Other ◽  
Paramagnetic Nmr ◽  
Relaxation Rates ◽  
Iron Sulfur ◽  
Iron Sulfur Proteins ◽  
Metal Cofactor ◽  
Function Relationship ◽  
Nmr Properties ◽  
Nmr Signals ◽  
S Proteins

Abstract. Paramagnetic NMR spectroscopy and iron-sulfur (Fe–S) proteins have maintained a synergic relationship for decades. Indeed, the hyperfine shifts with their temperature dependencies and the relaxation rates of nuclei of cluster-bound residues have been extensively used as a fingerprint of the type and of the oxidation state of the Fe–S cluster within the protein frame. The identification of NMR signals from residues surrounding the metal cofactor is crucial for understanding the structure-function relationship in Fe–S proteins, but it is generally impaired in standard NMR experiments by paramagnetic relaxation enhancement due to the presence of the paramagnetic cluster(s). On the other hand, the availability of systems of different size and stability has, over the years, stimulated NMR spectroscopists to exploit iron-sulfur proteins as paradigmatic cases to develop experiments, models and protocols. Here, the cluster binding properties of human mitoNEET have been investigated by one-dimensional and two-dimensional 1H diamagnetic and paramagnetic NMR, in its oxidized and reduced states. The NMR spectra of both oxidation states of mitoNEET appeared to be significantly different from those reported for previously investigated [Fe2S2]2+/+ proteins. We show how the use of 1D NOE experiments, 13C direct-detected experiments, and the optimization of NMR experiments for paramagnetic systems significantly reduce the blind sphere of the protein around the paramagnetic cluster. The application of this approach provided a detailed description of the unique electronic properties of mitoNEET, that are responsible for its biological function. Indeed, the NMR properties suggested that the specific electronic structure of the cluster possibly drives the functional properties of different [Fe2S2] proteins.

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.

scholarly journals The NMR signature of gluconoylation: a frequent N-terminal modification of isotope-labeled proteins

2019 ◽  
Vol 73 (1-2) ◽  
pp. 71-79 ◽  
Author(s):  
David Schweida ◽  
Pierre Barraud ◽  
Christof Regl ◽  
Fionna E. Loughlin ◽  
Christian G. Huber ◽  
...  
Keyword(s):  
Recombinant Proteins ◽  
Chemical Shifts ◽  
Chemical Shift Assignment ◽  
Hnrnp A1 ◽  
Post Translational Modification ◽  
N Terminus ◽  
Shift Assignment ◽  
Nmr Signals ◽  
Histidine Tag ◽  
Selection Of

Abstract N-terminal gluconoylation is a moderately widespread modification in recombinant proteins expressed in Escherichia coli, in particular in proteins bearing an N-terminal histidine-tag. This post-translational modification has been investigated mainly by mass spectrometry. Although its NMR signals must have been observed earlier in spectra of 13C/15N labeled proteins, their chemical shifts were not yet reported. Here we present the complete 1H and 13C chemical shift assignment of the N-terminal gluconoyl post-translational modification, based on a selection of His-tagged protein constructs (CCL2, hnRNP A1 and Lin28) starting with Met-Gly-...-(His)6. In addition, we show that the modification can hydrolyze over time, resulting in a free N-terminus and gluconate. This leads to the disappearance of the gluconoyl signals and the appearance of gluconate signals during the NMR measurements. The chemical shifts presented here can now be used as a reference for the identification of gluconoylation in recombinant proteins, in particular when isotopically labeled.

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
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