Direct measurement of deuterium-deuterium dipolar coupling and analysis of the ordering of a specifically deuterated diunsaturated lipid

Baenziger, John E.; Smith, Ian C. P.; Hill, Robin J.; Jarrell, Harold C.

doi:10.1021/ja00232a042

Cited by 15 publications

(13 citation statements)

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“…For 16:0–18:2( n –9) PC bilayer we have carried out simulations in the range of temperatures from 283 to 313 K and compared computed order parameters with results of Baenziger et all. − Figure illustrates that simulations reproduce well the shape of the order parameter profile of the unsaturated tail with the fall in the area of double bonds and subsequent increase in the lower part of the tails, with the exception of carbons 9 and 10, for which simulations do not show the experimentally observed inversion, although they follow the right trend (increase for C9, decrease for C10 with increasing temperature). It is also worth noting that for this lipid the order parameters of the unsaturated tail are rather insensitive to the temperature in the considered range which is different from the temperature behavior in saturated lipids in which order parameters noticeably decrease with increase of the temperature …”

Section: Resultsmentioning

confidence: 86%

Extension of the Slipids Force Field to Polyunsaturated Lipids

Ermilova

Lyubartsev

2016

J. Phys. Chem. B

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The all-atomic force field Slipids (Stockholm Lipids) for lipid bilayers simulations has been extended to polyunsaturated lipids. Following the strategy adopted in the development of previous versions of the Slipids force field, the parametrization was essentially based on high-level ab initio calculations. Atomic charges and torsion angles related to polyunsaturated lipid tails were parametrized using structures of dienes molecules. The new parameters of the force field were validated in simulations of bilayers composed of seven polyunsaturated lipids. An overall good agreement was found with available experimental data on the areas per lipids, volumetric properties of bilayers, deuterium order parameters, and scattering form factors. Furthermore, simulations of bilayers consisting of highly polyunsaturated lipids and cholesterol molecules have been carried out. The majority of cholesterol molecules were found in a position parallel to bilayer normal with the hydroxyl group directed to the membrane surface, while a small fraction of cholesterol was found in the bilayer center parallel to the membrane plane. Furthermore, a tendency of cholesterol molecules to form chain-like clusters in polyunsaturated bilayers was qualitatively observed.

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Section: Resultsmentioning

confidence: 86%

Extension of the Slipids Force Field to Polyunsaturated Lipids

Ermilova

Lyubartsev

2016

J. Phys. Chem. B

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“…The insensitivity of the partially relaxed powder spectra to changes in the axial rotation rate is significant and justifies the use of oriented samples. It has been demonstrated recently (Pope et al, 1982;Baenziger et al, 1988;Auger et al, 1990;Bonmatin et al, 1990;Mayer et al, 1990) that oriented samples, as compared with powder samples, allow orientation-dependent effects to be detected unambiguously and are particularly effective for measuring anisotropic relaxation quantitatively. One reason for this difference is that the powder 2H spectrum is a superposition of spectra for which the order director is at random angles (e) to the applied magnetic field.…”

Section: Comments On Oriented Samples and The T1q Experimentsmentioning

confidence: 99%

Dynamics of glycolipids in the liquid-crystalline state. 2H NMR study

Winsborrow¹,

Smith²,

Jarrell³

1991

Biophysical Journal

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It has been shown previously that two types of motion are adequate to describe the partially relaxed 2H NMR line shapes (inversion recovery experiment) for the backbone portion of the glycolipid 1,2-di-O-tetradecyl-3-O-(beta-D-glucopyranosyl)-sn-glycerol (beta-DTGL) in the highly ordered gel phase (Auger, M.A., D. Carrier, I.C.P. Smith, and H. C. Jarrell. 1990. J. Am. Chem. Soc. 112:1373-1381). This study extends the latter investigation to the more fluid liquid-crystalline phase, where more complex motions are anticipated. Analyses of the powder line shapes and oriented sample relaxation data for both the glycerol backbone and head group regions of this lipid have been performed. The dynamics of glycerol at the C3 position in the gel state have been described by large angle jumps about the C2-C3 bond with a correlation time in the fast-limit motional regime (omega o tau c much less than 1) and site populations 0.46, 0.34, and 0.20. The present data show that in the liquid-crystalline phase the internal jump rate is maintained, and two additional motions are necessary to describe the dependence of the relaxation rate on the orientation of the director with respect to the magnetic field direction. These are rotation about the molecular long axis with a correlation time in the slow-limit motional regime very near to the T1 minimum (omega o tau c approximately 0.65), and molecular fluctuations about the order director (modeled by a Maier-Saupe restoration potential). This treatment was also extended to the glucose head group where additional segmental motion about the glycosidic bond has been reported previously. While the two motions dominating relaxation at the glycerol C3 segment reproduce the general relaxation features of the glucose head group, the results suggest that additional motion about the glycosidic linkage must be present. This study is a stringent test of the motional model chosen earlier because relaxation data were obtained at two 2H NMR frequencies using two relaxation experiments (T1Z and T1Q) and two types of sample preparation (oriented and dispersed multibilayers). The results strongly uphold the choice of model and indicate the utility of both oriented samples and the T1Q experiment.

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“…Their work has provided for many years a reference for orientation and dynamics of cholesterol and has been used for comparison with other techniques such as neutron scattering (Bloom and Bayerl, 1995;Douliez et al 1996), NMR relaxation times analysis (Dufourc et al, 1992;Bonmatin et al, 1990), and molecular dynamics simulations (Gabdoulline et al, 1996). Since then, significant methodological improvements in deuterium NMR of lipid bilayers have occurred, such as the use of oriented lipid bilayers (Jarrell et al, 1987) and proton decoupling (Jarrell et al, 1988). These methods allow the determination of quadrupolar splittings with a much higher resolution and accuracy than could be obtained using powder spectra.…”

Section: Introductionmentioning

confidence: 99%

Cholesterol Orientation and Dynamics in Dimyristoylphosphatidylcholine Bilayers: A Solid State Deuterium NMR Analysis

Marsan

Muller

Ramos

et al. 1999

Biophysical Journal

131

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Proton decoupled deuterium NMR spectra of oriented bilayers made of DMPC and 30 mol % deuterated cholesterol acquired at 76.8 MHz (30 degreesC) have provided a set of very accurate quadrupolar splitting for eight C-D bonds of cholesterol. Due to the new precision of the experimental data, the original analysis by. Biochemistry. 23:6062-6071) had to be reconsidered. We performed a systematic study of the influence on the precision and uniqueness of the data-fitting procedure of: (i) the coordinates derived from x-ray, neutron scattering, or force field-minimized structures, (ii) internal mobility, (iii) the axial symmetry hypothesis, and (iv) the knowledge of some quadrupolar splitting assignments. Good agreement between experiment and theory could be obtained only with the neutron scattering structure, for which both axial symmetry hypothesis and full order parameter matrix analysis gave satisfactory results. Finally, this work revealed an average orientation of cholesterol slightly different from those previously published and, most importantly, a molecular order parameter equal to 0.95 +/- 0.01, instead of 0.79 +/- 0.03 previously found for the same system at 30 degreesC. Temperature dependence in the 20-50 degreesC range shows a constant average orientation and a monotonous decrease of cholesterol Smol, with a slope of -0.0016 K-1. A molecular order parameter of 0.89 +/- 0.01 at 30 degreesC was determined for a DMPC/16 mol % of cholesterol.

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Direct measurement of deuterium-deuterium dipolar coupling and analysis of the ordering of a specifically deuterated diunsaturated lipid

Cited by 15 publications

References 0 publications

Extension of the Slipids Force Field to Polyunsaturated Lipids

Extension of the Slipids Force Field to Polyunsaturated Lipids

Dynamics of glycolipids in the liquid-crystalline state. 2H NMR study

Cholesterol Orientation and Dynamics in Dimyristoylphosphatidylcholine Bilayers: A Solid State Deuterium NMR Analysis

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