scholarly journals Accurate Measurement of Methyl13C Chemical Shifts by Solid-State NMR for the Determination of Protein Side Chain Conformation: The Influenza A M2 Transmembrane Peptide as an Example

2009 ◽  
Vol 131 (22) ◽  
pp. 7806-7816 ◽  
Author(s):  
Mei Hong ◽  
Tatiana V. Mishanina ◽  
Sarah D. Cady
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Influenza A ◽  
Chemical Shifts ◽  
Chain Conformation ◽  
Side Chain ◽  
Side Chain Conformation

The Use of Anisotropic 13C Chemical Shifts To Study the Side-Chain Conformation of Polycrystalline 2-Methoxydibenzofuran

1995 ◽  
Vol 117 (48) ◽  
pp. 11984-11988 ◽  
Author(s):  
Wei Wang ◽  
Cu G. Phung ◽  
D. W. Alderman ◽  
Ronald J. Pugmire ◽  
David M. Grant
Keyword(s):  
Chemical Shifts ◽  
Chain Conformation ◽  
Side Chain ◽  
13C Chemical Shifts ◽  
Side Chain Conformation

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.

A solid-state 133Cs nuclear magnetic resonance and X-ray crystallographic study of cesium complexes with macrocyclic ligands

2000 ◽  
Vol 78 (7) ◽  
pp. 975-985
Author(s):  
Alan Wong ◽  
Simon Sham ◽  
Suning Wang ◽  
Gang Wu
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Chemical Shifts ◽  
Macrocyclic Ligand ◽  
Chemical Shift Anisotropy ◽  
Macrocyclic Ligands ◽  
X Ray

We report solid-state NMR determination of the 133Cs chemical shift anisotropy (CSA) for a series of cesium complexes with macrocyclic ligands. It was found that the isotropic 133Cs chemical shifts are related to the number of oxygen atoms to which the Cs+ ion is coordinated. The 133Cs chemical shifts were found to correlate with average Cs-O distances. We also attempt to use the established correlation to deduce Cs+ coordination environment for compounds with unknown structures. We also report the X-ray determination of the crystal structure for Cs(DB18C6)2SCN•1/2CH3OH•1/2H2O. The compound crystallizes in monoclinic, a = 14.503(2), b = 15.152(3), c = 39.989(6) Å, β = 90.796(8)°, space group P21/c, Z = 8. There are two independent molecules in the asymmetric unit cell where each of the two Cs+ ions is coordinated to two DB18C6 ligand molecules forming a sandwich-type structure.Key words: solid state NMR, alkali metal, 133Cs chemical shift, macrocyclic ligand, crystal structure.

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