A proton relaxation study of the conformations of some purine mononucleotides in aqueous solution

1982 ◽  
Vol 60 (23) ◽  
pp. 2976-2983 ◽  
Author(s):  
C. F. G. C. Geraldes ◽  
H. Santos ◽  
A. V. Xavier
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Proton Relaxation ◽  
Spin Lattice ◽  
Population Distributions ◽  
Anti Conformation ◽  
Relaxation Study ◽  
Interproton Distances

A method is described by which conformationally averaged interproton distances in mononucleotides are obtained from measured proton spin-lattice relaxation times and published crystal coordinates of selected mononucleotides. The glycosil conformations of adenosine in D2O and DMSO-d6 and of 5′-AMP, 5′-GMP, 3′-AMP, and 2′-AMP in D2O are examined by quantitative analysis of the conformationally averaged interproton distances in terms of population distributions obtained from potential energy calculations. 5′-AMP strongly prefers a single glycosyl conformation in the anti range. Besides the anti conformation, 5′-GMP has a secondary minimum in the syn region. 3′-AMP, 2′-AMP, and adenosine have more latitude in their glycosyl torsion angle values, with both the syn and anti regions highly populated.

A Proton Spin–Lattice Relaxation Study of Molecular Motion in Several Addition Complexes of Trimethylamine and Trimethylphosphine

1974 ◽  
Vol 52 (10) ◽  
pp. 1840-1847 ◽  
Author(s):  
T. T. Ang ◽  
B. A. Dunell
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Methyl Groups ◽  
Threefold Axis ◽  
Spin Lattice ◽  
Relaxation Study ◽  
Boron Tribromide ◽  
Thermal Stability Of

The spin–lattice relaxation times of the solid complexes of trimethylamine with I2, ICl, Br2, BCl3, and BBr3 and the relaxation null times of trimethylphosphine – boron trichloride and – boron tribromide have been measured over a range of temperature by pulsed proton magnetic resonance. A minimum in T1 corresponding to reorientation of the methyl groups about the C—N bonds is observed in each complex, although in the case of Me3, NBr2 the minimum corresponds to a combination of methyl group reorientation and reorientation of the whole Me3N moiety. The complexes with the boron trihalides show a second minimum in T1. These minima have been analyzed in terms of either of two possible motions, reorientation of NMe3 about its threefold axis, or that same motion combined with isotropic molecular tumbling. We favor the interpretation involving the simpler motion. Activation energies have been measured for all the motions. The barriers to reorientation of methyl groups about the C—N bond in the moiety Me3N appear to increase as the thermal stability of the complex decreases.

PROTON SPIN-LATTICE RELAXATION TIMES OF HUMIC ACIDS AS DETERMINED BY SOLUTION NMR

Soil Science ◽  
2003 ◽  
Vol 168 (2) ◽  
pp. 128-136 ◽  
Author(s):  
Kaijun Wang ◽  
L. Charles Dickinson ◽  
Elham A. Ghabbour ◽  
Geoffrey Davies ◽  
Baoshan Xing
Keyword(s):  
Humic Acids ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Solution Nmr ◽  
Spin Lattice

A133Cs NMR Spin-Lattice Relaxation Study in Incommensurate Cs2CdI4

2000 ◽  
Vol 55 (1-2) ◽  
pp. 339-342 ◽  
Author(s):  
Koh-ichi Suzuki ◽  
Shin'ichi Ishimaru ◽  
Ryuichi Ikeda
Keyword(s):  
Critical Exponent ◽  
Relaxation Times ◽  
Three Dimensional ◽  
Lattice Relaxation ◽  
Normal Phase ◽  
Incommensurate Phase ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Relaxation Study ◽  
Good Agreement

133Cs NMR spin-lattice relaxation times(T1) in crystalline Cs2CdI4 were measured at 225 - 373 K. The critical exponent ( of T\ observed near the normal-incommensurate transition in the normal phase was determined to be 0.62 ± 0.03, in good agreement with the predicted value for three-dimensional XK-model. The frequency dependent T1 in the incommensurate phase could be explained by the fluctuation of amplitudon and small gap phason.

Histopathological Evidence in Support of the Association of Elevated Proton Spin-lattice Relaxation Times with the Malignant State

1979 ◽  
Vol 65 (2) ◽  
pp. 157-162 ◽  
Author(s):  
S. S. Ranade ◽  
Smita Shah ◽  
G. V. Talwalkar
Keyword(s):  
Human Cancer ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Malignant Cell ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Histopathological Study ◽  
Spin Lattice ◽  
Malignant State ◽  
T Values

The pulsed nuclear magnetic resonance technique was explored for its potential diagnostic value in human cancer. Measurements of proton spin-lattice relaxation times (T1) of cellular water protons of normal and malignant esophageal tissues showed elevated T, values in the latter. In some cases, tissues which appeared normal on gross examination assumed as uninvolved tissues had T, values higher than the other grossly uninvolved tissues and often closer to the T, of the corresponding tumor tissue. A histopathological study of the assumed uninvolved areas also studied for the T, values was therefore undertaken. A preliminary study demonstrated the presence of malignant cell groups or clusters in some of the uninvolved samples with higher T1 compared to the true uninvolved tissues, which had a normal histological picture and low T, values. This observation has brought out the importance of histopathological studies in addition to relaxation studies to comprehend contributory factors to relaxation. Secondly, it lends support to the thesis of elevated T, values being characteristics of the malignant state.

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