Publication date: Available online 20 July 2013 Source:Progress in Nuclear Magnetic Resonance Spectroscopy
Author(s): Teodor Parella , Juan Félix Espinosa
A general review of novel NMR methods to measure heteronuclear long-range proton-carbon coupling constants ( n J CH ; n>1) in small molecules is made. NMR experiments are classified in terms of NMR pulse scheme and cross-peak nature. A discussion about simplicity, general applicability and accuracy for each particular NMR experiment is presented and exemplified. Important aspects such as the sign determination and measurement of very small coupling values involving protonated and non-protonated carbons as well as the complementarity between different experiments are also discussed. Finally, a compilation of applications in structural and conformational analysis of different types of molecules since 2000 is surveyed. Graphical abstract
[NMR paper] Unraveling long range residual dipolar coupling networks in strongly aligned proteins
Unraveling long range residual dipolar coupling networks in strongly aligned proteins
Publication date: Available online 10 July 2013
Source:Journal of Magnetic Resonance</br>
Author(s): Luke Arbogast , Ananya Majumdar , Joel R. Tolman</br>
Long-range residual dipolar couplings (lrRDCs) have the potential to serve as powerful structural restraints in protein NMR spectroscopy as they can provide both distance and orientation information about nuclei separate in sequence but close in space. Current nonselective methods for their measurement are limited to moderate...
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07-11-2013 12:07 PM
[Question from NMRWiki Q&A forum] Long-range 1H-{15N} coupling (HMBC)
Long-range 1H-{15N} coupling (HMBC)
Hello All
I have two examples of what appears to be 6J coupling between 1H and 15N using gradient HMBC experiments with 15N at natural abundance. For such an experiment, 2J and 3J correlations are typical, sometimes 4J (W-type) but I've never seen 6J before.
Has anyone else ever seen correlations over this distance? Any other comments?
Craig.
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10-29-2012 07:03 PM
[U. of Ottawa NMR Facility Blog] Measurement of Long Range C H Coupling Constants
Measurement of Long Range C H Coupling Constants
The stereochemistry of compounds is assigned very often with proton - proton NOE's by applying the 2D NOESY technique or the 1D selective gradient NOESY technique. These methods fail, however when the distance between protons is too large to measure an NOE. When faced with this situation, it may be possible to measure long range proton - carbon coupling constants which are able to provide the necessary information. Three-bond carbon - proton couplings follow a Karplus relationship where the magnitude of the coupling constant is related to...
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08-17-2012 10:44 PM
On the calculation of 3Jαβ-coupling constants for side chains in proteins
On the calculation of 3Jαβ-coupling constants for side chains in proteins
Abstract Structural knowledge about proteins is mainly derived from values of observables, measurable in NMR spectroscopic or X-ray diffraction experiments, i.e. absorbed or scattered intensities, through theoretically derived relationships between structural quantities such as atom positions or torsional angles on the one hand and observable quantities such as squared structure factor amplitudes, NOE intensities or 3 J-coupling constants on the other. The standardly used relation connecting 3 J-couplings...
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06-25-2012 04:41 AM
[Question from NMRWiki Q&A forum] How can I calculate a carbon-proton coupling constant for a molecule?
How can I calculate a carbon-proton coupling constant for a molecule?
I'm trying to explain a missing HMBC peak, and having a coupling constant less than 10 Hz would do that nicely. It's a formamidine derivative with a 3 bond correlation N=CHNC The C is a quaternary carbon in a benzene ring. Any help would be appreciated.
Check if somebody has answered this question on NMRWiki QA forum
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02-04-2011 07:12 PM
Conformational dependence of 13C shielding and coupling constants for methionine
Abstract Methionine residues fulfill a broad range of roles in protein function related to conformational plasticity, ligand binding, and sensing/mediating the effects of oxidative stress. A high degree of internal mobility, intrinsic detection sensitivity of the methyl group, and low copy number have made methionine labeling a popular approach for NMR investigation of selectively labeled protein macromolecules. However, selective labeling approaches are subject to more limited information content. In order to optimize the information available from such studies, we have performed DFT...
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08-25-2010 03:51 PM
[U. of Ottawa NMR Facility Blog] E.COSY and the Relative Signs of Coupling Constants
E.COSY and the Relative Signs of Coupling Constants
Spin-spin coupling constants can have values greater than or less than zero. The absolute sign of the coupling constants cannot be discerned from the simple examination of a 1H NMR spectrum. The E.COSY1 (Exclusive COrrelation SpectroscopY) technique is one method which can be used to determine the relative signs of coupling constants. E.COSY is a phase sensitive COSY variant which produces off-diagonal signals showing only the active coupling (i.e. the coupling directly responsible for the cross-peak) as 2x2 antiphase square tetrads...
Long-Range Proton-Carbon Coupling Constants: NMR methods and applications
Highlights
Linear Mode
