Determination of Isoleucine Side-Chain Conformations in Ground and Excited States of Proteins from Chemical Shifts

2010 ◽  
Vol 132 (22) ◽  
pp. 7589-7591 ◽  
Author(s):  
D. Flemming Hansen ◽  
Philipp Neudecker ◽  
Lewis E. Kay
Keyword(s):  
Excited States ◽  
Chemical Shifts ◽  
Side Chain ◽  
Chain Conformations

The Determination of Substituent Effects by 13C Nuclear Magnetic Resonance Spectrometry. The Effect of Solvent on CH2X Groups

1985 ◽  
Vol 38 (2) ◽  
pp. 337
Author(s):  
DAR Happer ◽  
BE Steenson
Keyword(s):  
Inductive Effect ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Side Chain ◽  
Polar Solvents ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic Resonance Spectrometry ◽  
Magnetic Resonance Spectrometry ◽  
Lines Of Force

A previous study of the effect of meta- and para-CH2X substituents on the 13C n.m.r. chemical shifts of the α and β side-chain carbons of β- methoxycarbonylstyrenes (methyl cinnamates ) in ethanol has been extended to cover five additional solvents (Me2SO, Me2CO, CDCl3, CCl4 and C6H6). The results support the earlier claim that, for most substituents , the magnitudes of the substituent -induced shifts are proportional to the inductive effect of X. The major contributor to the latter appears to be the field effect generated by the C-X dipole, with the lines of force passing mainly through the molecule. In non-polar solvents, however, there is evidence that lines of force passing directly through the solvent can also influence the shifts in both the meta and para series.

Analysis of 13C nuclear magnetic resonance chemical shifts of acyclic hydrocarbons

1980 ◽  
Vol 58 (12) ◽  
pp. 1258-1265 ◽  
Author(s):  
Helmut Beierbeck ◽  
John K. Saunders
Keyword(s):  
Chemical Shifts ◽  
Aliphatic Hydrocarbons ◽  
Bond Rotation ◽  
Molecular Asymmetry ◽  
13C Nuclear Magnetic Resonance ◽  
Cyclic Molecules ◽  
Chain Conformations ◽  
Acyclic Hydrocarbons ◽  
C Nmr

The 13C nmr chemical shifts of aliphatic hydrocarbons were derived from chemical shifts and probabilities of individual chain conformations. Conformer resonances were calculated with parameters developed for conformationally homogeneous cyclic molecules. Conformer populations were derived from bond rotation potentials and steric energy contributions, available from independent sources. This analysis contains non adjustable parameters. It represents a unified treatment of cyclic and acyclic hydrocarbon resonances, which is capable of dealing with molecular asymmetry and thus permits the determination of configuration in aliphatic hydrocarbons.

A New Approach to the Rapid Determination of Protein Side Chain Conformations

1991 ◽  
Vol 8 (6) ◽  
pp. 1267-1289 ◽  
Author(s):  
P. Tuffery ◽  
C. Etchebest ◽  
S. Hazout ◽  
R. Lavery
Keyword(s):  
Rapid Determination ◽  
Side Chain ◽  
New Approach ◽  
Chain Conformations

Determination of Leu Side-Chain Conformations in Excited Protein States by NMR Relaxation Dispersion

2010 ◽  
Vol 132 (1) ◽  
pp. 42-43 ◽  
Author(s):  
D. Flemming Hansen ◽  
Philipp Neudecker ◽  
Pramodh Vallurupalli ◽  
Frans A. A. Mulder ◽  
Lewis E. Kay
Keyword(s):  
Nmr Relaxation ◽  
Relaxation Dispersion ◽  
Side Chain ◽  
Excited Protein States ◽  
Chain Conformations

The effect of side chain conformation on the carbon-13 substituent chemical shifts of N-substituted benzamides

1981 ◽  
Vol 34 (6) ◽  
pp. 1205 ◽  
Author(s):  
CW Fong ◽  
HG Grant
Keyword(s):  
Chemical Shifts ◽  
Variable Temperature ◽  
Constant Term ◽  
Chain Conformation ◽  
Charge Ratio ◽  
Effective Dielectric Constant ◽  
Side Chain ◽  
Side Chain Conformation ◽  
Chain Conformations ◽  
Amide Side Chain

The carbon-13 substituent chemical shifts of the ipso and carbonyl atoms in the para-substituted series Z-C6H4CONY2 (where Y = Me, Pri, Ph) have been measured at low dilution in (D)chloroform, and dimethyl sulfoxide. The DSP equation has been shown to hold for varying side chain conformations with high precision when the same resonance substituent parameter is used. Analysis of these data by the DSP equation indicates that the 'reverse substituent chemical shift effect' for the carbonyl atom is substantially due to a localized polarization of the π-electron system of the amide side chain. The ratio of localized to extended π-polarization of the β position of the amide side chain has been estimated. It is suggested that the effective dielectric constant term for the transmission of field effects by the cavity model varies with side chain conformation. The Cl substituent shifts have been discussed in terms of the shift-charge ratio. A variable-temperature study of the DSP parameters indicates an insignificant temperature effect provided rotation around the benzene ring to amide side chain bond is rapid.

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