Molecular motion in the lyotropic liquid crystal system containing potassium palmitate: A study of proton spin-lattice relaxation times

Jeffrey, Kenneth R.; Wong, Tuck C.; Burnell, E. Elliott; Thompson, Mark; Higgs, T. P.; Chapman, N.R.

doi:10.1016/0022-2364(79)90090-8

Cited by 20 publications

(11 citation statements)

References 30 publications

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“…It should be stressed that only for an all-trans hydrocarbon chain undergoing rapid reorientation about the average long axis is it expected that all of the inter-and intrachain dipole-dipole interactions will be projected onto the reorientation axis. This has been shown to occur in aligned phospholipid systems in the La phase and in the L,B' phase of soaps (33). In the present study the observation of the orientation dependence of the dipolar splittings suggests that even in the Po phase (and possibly the higher temperatures of the LO' phase), sufficient motion is occurring to produce a similar effect in these crystalline systems.…”

Section: Discussionsupporting

confidence: 59%

NMR study of synthetic lecithin bilayers in the vicinity of the gel-liquid--crystal transition

Pope¹,

Walker²,

Cornell³

et al. 1981

Biophysical Journal

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1H, 2H, and 31P NMR methods have been employed in the study of dimyristoyl lecithin bilayers hydrated with D2O in the gel (L beta'), intermediate (P beta') and liquid-crystalline (L alpha) phases. For D2O/lipid molar ratios, n, in the range 7 less than or equal to n less than or equal to 11 discontinuities are observed in the deuterium NMR splittings at both main and pretransitions. A partial phase diagram based on NMR and differential scanning calorimetry data is presented. 1H NMR dipolar splittings are observed for macroscopically oriented samples in all three phases. Changes in the 1H splittings are correlated with 2H and 31P data and interpreted to show that the chain tilt in the gel phase undergoes a discontinuous change on transition to the intermediate phase, which brings the chain axes closer to the bilayer normal. An estimate of chain tilt in the gel phase is made on the basis of NMR data and found to be approximately 23 degrees for a sample with n = 11 at 18 degrees C.

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Section: Discussionsupporting

confidence: 59%

NMR study of synthetic lecithin bilayers in the vicinity of the gel-liquid--crystal transition

Pope¹,

Walker²,

Cornell³

et al. 1981

Biophysical Journal

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“…The basis of these observations, made by identification of the characteristic appearance of the lipid membrane in the liquid-crystalline or gel phase, was first identified in 1 H NMR experiments of the potassium laurate lyotropic mixture [160]. Additionally, 2 H quadrupolar spectra and relaxation times of perdeuterated fatty acids were recorded as a function of thermodynamic phase [158,161–165]. These studies, compared with studies of alkanes in solution, helped to establish the polarity (polar headgroup, non-polar acyl chains) of the molecule as an important factor in determining the orientational anisotropy and dynamics of the lyotropic phases.…”

Section: Analytical Theories Are Valuable Complements To Molecularmentioning

confidence: 99%

An NMR database for simulations of membrane dynamics

Leftin

Brown

2011

Biochimica et Biophysica Acta (BBA) - Biomembranes

102

119

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Computational methods are powerful in capturing the results of experimental studies in terms of force fields that both explain and predict biological structures. Validation of molecular simulations requires comparison with experimental data to test and confirm computational predictions. Here we report a comprehensive database of NMR results for membrane phospholipids with interpretations intended to be accessible by non-NMR specialists. Experimental 13C–1H and 2H NMR segmental order parameters (SCH or SCD) and spin-lattice (Zeeman) relaxation times (T1Z) are summarized in convenient tabular form for various saturated, unsaturated, and biological membrane phospholipids. Segmental order parameters give direct information about bilayer structural properties, including the area per lipid and volumetric hydrocarbon thickness. In addition, relaxation rates provide complementary information about molecular dynamics. Particular attention is paid to the magnetic field dependence (frequency dispersion) of the NMR relaxation rates in terms of various simplified power laws. Model-free reduction of the T1Z studies in terms of a power-law formalism shows that the relaxation rates for saturated phosphatidylcholines follow a single frequency-dispersive trend within the MHz regime. We show how analytical models can guide the continued development of atomistic and coarse-grained force fields. Our interpretation suggests that lipid diffusion and collective order fluctuations are implicitly governed by the viscoelastic nature of the liquid-crystalline ensemble. Collective bilayer excitations are emergent over mesoscopic length scales that fall between the molecular and bilayer dimensions, and are important for lipid organization and lipid-protein interactions. Future conceptual advances and theoretical reductions will foster understanding of biomembrane structural dynamics through a synergy of NMR measurements and molecular simulations.

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“…In particular,2H NMR results have shown that the incorporation of cholesterol causes an increase of the quadrupolar splitting of the fatty acyl chains, which can be explained by a decrease in the extent and rate of trans-gauche isomerization (Siminovitch et al, 1988). Because HT1 is thought to depend to a large extent on intrachain C-C bond rotation (Petersen and Chan, 1977;Jeffrey et al, 1979), we can conclude that the changes of HT, induced by the addition of cholesterol in DMPC bilayers come from a great attenuation of the rotation and kinks in the hydrocarbon chain and glycerol backbone bonds. This conclusion is different from that obtained by Cornell et al (1982) who had suggested that the presence of cholesterol induces only a small increase in HT, relaxation times of the methylene chain protons and concluded that cholesterol has little effect on the fast motions of the acyl chains.…”

Section: Spin-lattice Relaxation Times In the Laboratory Frame (Ht1)mentioning

confidence: 99%

New approach to study fast and slow motions in lipid bilayers: application to dimyristoylphosphatidylcholine-cholesterol interactions

Guernevé¹,

Auger²

1995

Biophysical Journal

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Natural abundance 13C solid-state nuclear magnetic resonance spectroscopy was used to investigate the effect of the incorporation of cholesterol on the dynamics of dimyristoylphosphatidylcholine (DMPC) bilayers in the liquid-crystalline phase. In particular, the use of a combination of the cross-polarization and magic angle spinning techniques allows one to obtain very high resolution spectra from which can be distinguished several resonances attributed to the polar head group, the glycerol backbone, and the acyl chains of the lipid molecule. To examine both the fast and slow motions of the lipid bilayers, 1H spin-lattice relaxation times as well as proton and carbon spin-lattice relaxation times in the rotating frame were measured for each resolved resonance of DMPC. The use of the newly developed ramped-amplitude cross-polarization technique results in a significant increase in the stability of the cross-polarization conditions, especially for molecular groups undergoing rapid motions. The combination of T1 and T1 rho measurements indicates that the presence of cholesterol significantly decreases the rate and/or amplitude of both the high and low frequency motions in the DMPC bilayers. This effect is particularly important for the lipid acyl chains and the glycerol backbone region.

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Molecular motion in the lyotropic liquid crystal system containing potassium palmitate: A study of proton spin-lattice relaxation times

Cited by 20 publications

References 30 publications

NMR study of synthetic lecithin bilayers in the vicinity of the gel-liquid--crystal transition

NMR study of synthetic lecithin bilayers in the vicinity of the gel-liquid--crystal transition

An NMR database for simulations of membrane dynamics

New approach to study fast and slow motions in lipid bilayers: application to dimyristoylphosphatidylcholine-cholesterol interactions

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