Studies on chloroplast membranes. III. 13C chemical shifts and longitudinal relaxation times of 1,2-Diacyl-3-(6-sulpho-α-quinovosyl)-sn-glycerol

1978 ◽  
Vol 31 (1) ◽  
pp. 65 ◽  
Author(s):  
SR Johns ◽  
DR Leslie ◽  
RI Willing ◽  
DG Bishop
Keyword(s):  
Chemical Shifts ◽  
Relaxation Times ◽  
Acid Group ◽  
Vesicular Structure ◽  
13C Chemical Shifts ◽  
Longitudinal Relaxation ◽  
Monomeric Structure ◽  
13C Chemical Shift ◽  
Nuclear Overhauser ◽  
The Individual

13C Chemical shifts, longitudinal relaxation times and some nuclear Overhauser enhancement factors of the individual carbon atoms in the chloroplast lipid, 1,2-diacyl-3-(6-sulpho-α-quinovosyl)-sn-glycerol (sl), have been measured in the three solvents: methanol[D4], chloroform[D] and water[D2]. Correlation times for the individual carbon atoms calculated from these results have been interpreted in terms of different secondary structures: a monomeric structure in methanol[D4], an inverted micellar structure in chloroform[D] and a bilayer vesicular structure in water[D2]. Substituent shift parameters have been determined for the sulphonic acid group from a series of alkanesulphonic acids and these have been used in the 13C chemical shift assignments in sl and a series of model compounds.

Studies on Chloroplast Membranes. II. 13C Chemical Shifts and Longitudinal Relaxation Times of 1,2-Di[(9Z,12Z,15Z)-octadeca-9,12,15-trienoyl]-3-galactosyl-sn-glycerol and 1,2-Di[(9Z,12Z,15Z)-octadeca-9,12,15-trienoyl]-3-digalactosyl-sn-glycerol

1977 ◽  
Vol 30 (4) ◽  
pp. 823 ◽  
Author(s):  
S Johns ◽  
D Leslie ◽  
R Willing ◽  
D Bishop
Keyword(s):  
Relaxation Time ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Longitudinal Relaxation Time ◽  
Time Data ◽  
Longitudinal Relaxation ◽  
Monomeric Structure ◽  
13C Chemical Shift ◽  
Nuclear Overhauser ◽  
The Individual

The 13C chemical shift and longitudinal relaxation time (T1) of the individual carbon atoms in the two major lipids of chloroplast thylakoids, 1,2-di[(9Z,12Z,15Z)-octadeca-9,12,15-trienoyl]-3- galactosyl-sn-glycerol and 1,2-di[(9Z,12Z,15Z)-octadeca-9,12,15- trienoyl]-3-digalactosyl-sn-glycerol, have been measured in the three solvents: methanol[D4], chloroform[D] and water[D2]. The longitudinal relaxation time data are interpreted in terms of different secondary structures in the different solvents, a monomeric structure in methanol[D4], an inverted micellar structure in chloroform[D] and a bilayer structure in water[D2]. Two possible correlations times can be obtained from the longitudinal relaxation times of the galactosyl and glyceryl carbon atoms in chloroform[D] and water[D2] and nuclear Overhauser enhancement values have been used to assign the correlation times to these carbon atoms.

Studies on chloroplast membranes. IV. 13C chemical shifts and longitudinal relaxation times of 3-sn-phosphatidylglycerol

1981 ◽  
Vol 34 (2) ◽  
pp. 357 ◽  
Author(s):  
JM Coddington ◽  
SR Johns ◽  
DR Leslie ◽  
RI Willing ◽  
DG Bishop
Keyword(s):  
Chemical Shifts ◽  
Relaxation Times ◽  
Secondary Structures ◽  
Chloroplast Membranes ◽  
13C Chemical Shifts ◽  
Nuclear Overhauser Enhancement ◽  
Enhancement Factors ◽  
Longitudinal Relaxation ◽  
Monomeric Structure ◽  
Nuclear Overhauser

13C chemical shifts, longitudinal relaxation times and some nuclear Overhauser enhancement factors of individual carbon atoms in the chloroplast lipid, 3-sn-phosphatidylglycerol (pg), have been measured in (D4)methanol and (D)chloroform. Correlation times for individual carbon atoms calculated from these results have been interpreted in terms of different secondary structures: a monomeric structure in (D4)methanol and an inverted micelle in (D)chloroform. Differences in structures between the four major lipid components of the chloroplast membrane are briefly discussed.

Studies on Chloroplast Membranes. I. 13C Chemical Shifts and Longitudinal Relaxation Times of Carboxylic Acids

1977 ◽  
Vol 30 (4) ◽  
pp. 813 ◽  
Author(s):  
S Johns ◽  
D Leslie ◽  
R Willing ◽  
D Bishop
Keyword(s):  
Carboxylic Acid ◽  
Chemical Shift ◽  
Carboxylic Acids ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Segmental Motion ◽  
Unsaturated Carboxylic Acids ◽  
Longitudinal Relaxation ◽  
13C Chemical Shift ◽  
The Individual

The 13C chemical shift and longitudinal relaxation time (T1) of the individual carbon atoms in a series of carboxylic acids in CDCl3 solution have been determined. Substituent shift parameters have been derived from the chemical shift data. The relaxation times have been interpreted in terms of increasing segmental motion along the methylene chains of the carboxylic acid molecules which are associated at the carboxylic acid groups in the form of inverted micelles. Differences in the segmental motion between saturated and unsaturated carboxylic acids are rationalized on the grounds of intermolecular interactions between adjacent molecules in the inverted micelle structures.

Cross-linked polydimethylsiloxane colloid as novel contrast agent for gastrointestinal magnetic resonance imaging: Transient nuclear Overhauser effect within the interface

2020 ◽  
Vol 35 (2) ◽  
pp. 264-273
Author(s):  
Fu-Hu Su ◽  
Wang-Chuan Xiao ◽  
Sheann-Huei Lin ◽  
Qiyong Li
Keyword(s):  
Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Relaxation Times ◽  
Resonance Imaging ◽  
Transverse Relaxation ◽  
Overhauser Effect ◽  
Nuclear Magnetic Resonance Spectra ◽  
Relaxation Experiments ◽  
Longitudinal Relaxation ◽  
Nuclear Overhauser

With good contrast in T1 and T2 weighted imaging as well as low toxicity in 3- (4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, this work proposes the cross-linked polydimethylsiloxane colloids as a novel non-ionic contrast agent for gastrointestinal magnetic resonance imaging. The experiments of nuclear magnetic resonance spectra and relaxation show that within the interface of the colloids, there are nuclear Overhauser effect and transient nuclear Overhauser effect (cross-relaxation). Regarding the longitudinal relaxation experiments of CH2CH2O segments of Tween 80, a two spins system is found and modeled well by the equation [Formula: see text] which is deduced based on the transient nuclear Overhauser effect proposed by Solomon. The arbitrary constant X is additionally added with the initial conditions ( Iz −  I0) t=0 = −2 XS0 and ( Sz −  S0) t=0 = −2 S0. For the two spins system, D1 and T1 are corresponding to longitudinal relaxation times of the bound water and the CH2CH2O respectively. Concerning the transverse relaxation experiments of the CH2CH2O, they agree with the equation with three exponential decays, defined by three relaxation times, likely corresponding to three mechanisms. These mechanisms possibly are intramolecular and intermolecular dipole–dipole (DD) interactions and scalar coupling. Within the interface, hydrogen bonding causes the positive nuclear Overhauser effect of the CH2CH2O’s nuclear magnetic resonance spectra, the transient nuclear Overhauser effect of the CH2CH2O’s longitudinal relaxation experiments and the intermolecular dipole–dipole interactions of the CH2CH2O’s transverse relaxation experiments.

The conformational equilibrium in [13C-1-methyl]-cis-1,4-dimethylcyclohexane

1980 ◽  
Vol 58 (23) ◽  
pp. 2709-2713 ◽  
Author(s):  
Harold Booth ◽  
Jeremy Ramsey Everett
Keyword(s):  
Conformational Equilibrium ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Nuclear Overhauser ◽  
In Cis ◽  
C Nmr

The conformational equilibrium in [13C-1-methyl]-cis-1,4-dimethylcyclohexane has been assessed by (a) direct integration of signals due to equatorial and axial methyl carbons in the 13C nmr spectrum at 172 K and (b) by measurement of the 13C chemical shifts of C-1 and C-4 in the spectrum at 300 K. It is concluded that a 13C isotope effect on the position of the degenerate equilibrium in cis-1,4-dimethylcyclohexane is either nonexistent, or is too small to be detected by methods of analyses employed. The 13C nmr data incidental to the study (chemical shifts, coupling constants, spin–lattice relaxation times, nuclear Overhauser enhancements, and 1-bond isotope shifts) are recorded for the title compound and its trans-isomer.

scholarly journals Detection of methylation, acetylation and glycosylation of protein residues by monitoring 13C chemical-shift changes

2016 ◽  
Author(s):  
Pablo G. Garay ◽  
Osvaldo A. Martin ◽  
Harold A. Scheraga ◽  
Jorge A. Vila
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Biological Processes ◽  
Proof Of Concept ◽  
Post Translational Modifications ◽  
13C Chemical Shifts ◽  
Protein Residues ◽  
Lysine Residues ◽  
13C Chemical Shift ◽  
Good Agreement

Post-translational modifications of proteins expand the diversity of the proteome by several orders of magnitude and have a profound effect on several biological processes. Their detection by experimental methods is not free of limitations such as the amount of sample needed or the use of destructive procedures to obtain the sample. Certainly, new approaches are needed and, therefore, we explore here, as a proof-of-concept, the feasibility of using 13C chemical shifts of different nuclei to detect methylation, acetylation and glycosylation of protein residues by monitoring the deviation of the 13C chemical shifts from the expected (mean) experimental value of the non-modified residue. As a validation test of this approach, we compare our theoretical computations of the 13Ce chemical-shift values against experimental data, obtained from NMR spectroscopy, for methylated and acetylated lysine residues with good agreement within ~1 ppm. Then, further use of this approach to select the most suitable 13C-nucleus, with which to determine other modifications commonly seen, such as methylation of arginine and glycosylation of serine, asparagine and threonine, shows encouraging results.

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