Determination of 13C? relaxation times in uniformly 13C/15N-enriched proteins

1995 ◽  
Vol 5 (2) ◽  
Author(s):  
Jan Engelke ◽  
Heinz R�terjans
Keyword(s):  
Relaxation Times ◽  
13C Relaxation Times ◽  
13C Relaxation

13C Relaxation Times Study of Liquid Crystalline p-Methoxybenzylidene-p-Butylaniline

1981 ◽  
Vol 78 (1) ◽  
pp. 227-236 ◽  
Author(s):  
S. Ochiai ◽  
K. Iimura ◽  
M. Takeda ◽  
M. Ohuchi ◽  
K. Matsushita
Keyword(s):  
Liquid Crystalline ◽  
Relaxation Times ◽  
13C Relaxation Times ◽  
13C Relaxation

A study of internal rotation in 2-furaldehyde through 13C relaxation times in the rotating frame

1987 ◽  
Vol 52 (2) ◽  
pp. 541-546 ◽  
Author(s):  
Vladimír Mlynárik
Keyword(s):  
Shape Analysis ◽  
Line Shape ◽  
Activation Enthalpy ◽  
Relaxation Times ◽  
Rotating Frame ◽  
Line Shape Analysis ◽  
13C Relaxation Times ◽  
Free Activation Energy ◽  
13C Relaxation ◽  
Good Agreement

Carbon-13 relaxation times in the rotating frame were used to study the exchange between unequally populated rotamers of 2-furaldehyde. Calculated free activation energy and activation enthalpy are in good agreement with the results of 1H line shape analysis. Accuracy and reliability of this method in comparison with the line shape analysis is discussed.

scholarly journals Studies of the conformation of bilirubin and its dimethyl ester in dimethyl sulphoxide solutions by nuclear magnetic resonance

1982 ◽  
Vol 201 (3) ◽  
pp. 605-613 ◽  
Author(s):  
D Kaplan ◽  
G Navon
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Shifts ◽  
Dimethyl Ester ◽  
Relaxation Times ◽  
Dimethyl Sulphoxide ◽  
13C Relaxation Times ◽  
Solvent Molecules ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
13C Relaxation

The conformation of bilirubin and its dimethyl ester in dimethyl sulphoxide (DMSO) was investigated by n.m.r. spectroscopy. The chemical shifts of the pyrrole NH and Lactam protons of bilirubin and its dimethyl ester in DMSO indicate a strong interaction with the solvent. Inter-proton distances were calculated from nuclear Overhauser effects (NOE), selective and non-selective relaxation times (T1) and rotational correlation times taken from 13C relaxation times. The interproton distances indicate that the conformation of the skeleton of bilirubin and its dimethyl ester in DMSO is similar to that of bilirubin and mesobilirubin in the crystalline state and in chloroform solutions, except for a possible slight twist of the pyrrolenone rings about the methine bonds, which may be a consequence of solvation of the NH groups by DMSO. Unlike in chloroform solutions, no direct hydrogen-bonding occurs between the carboxylic acid and the lactam groups of bilirubin in DMSO, as shown by the absence of an NOE between these groups. The fast exchange of the pyrrole NH protons with 2H shows that no hydrogen-bonding occurs between these protons and the propionic residues, in line with their solvation by DMSO. From the above results, and from the slowness of the internal motion of the propionic residues of bilirubin and its dimethyl ester, it is concluded that these residues are tied to the skeleton via bound solvent molecules.

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