Deuterium nuclear magnetic resonance investigation of the dipalmitoyl lecithin-cholesterol-water system

Haberkorn, R. A.; Griffin, Robert G.; Meadows, Michael D.; Oldfield, Eric

doi:10.1021/ja00464a043

Cited by 103 publications

(68 citation statements)

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“…Early investigations [1,79,80] utilized site-specific labeling strategies, whereby synthetically accessible C–H sites along the acyl chain of the molecule, the glycerol backbone, and choline headgroup were replaced by C– 2 H bonds. These 2 H NMR studies revealed a systematic variation of the lineshapes as a function of segmental position, due to variations in the degree of motional averaging.…”

Section: Solid-state Nmr Spectra Exhibit Couplings That Allow Ordementioning

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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Section: Solid-state Nmr Spectra Exhibit Couplings That Allow Ordementioning

confidence: 99%

An NMR database for simulations of membrane dynamics

Leftin

Brown

2011

Biochimica et Biophysica Acta (BBA) - Biomembranes

102

119

View full text Add to dashboard Cite

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“…An important general observation is that under conditions for which a bilayer would be in the liquid crystalline phase, addition of cholesterol increases lipid chain orientational order and thus bilayer thickness. [1][2][3][4][5][6][7] Cholesterol also lowers the temperature below which rapid axially symmetric lipid reorientation freezes out. 5,7 NMR and other techniques such as neutron scattering and vibrational spectroscopy have also been used to examine cholesterol orientation, dynamics, and position within bilayers.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cholesterol on the Chain-Ordering Transition of 1-Palmitoyl-2-arachidonoyl Phosphatidylcholine

et al. 1999

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Deuterium nuclear magnetic resonance and differential scanning calorimetery were used to study the phase behavior, chain order, and dynamics of bilayers consisting of 1-palmitoyl-2-arachidonoyl phosphatidylcholine perdeuterated on the saturated acyl chain (16:0-20:4 PC-d 31 ) alone and in mixed bilayers containing 15 and 30 mol % cholesterol. In the liquid crystalline phase, saturated chain orientational order increases with increasing cholesterol concentration. The transition to a highly ordered phase is centered on -25°C regardless of cholesterol concentration. The observation of coexisting ordered and liquid crystalline phase spectral contributions near the transition in the absence of cholesterol implies a discontinuous transition. In the presence of cholesterol, the phase change is continuous and no evidence of coexisting domains of ordered and fluid phase lipid is observed. The observation of spectral intensity near (63 kHz in the ordered phase suggests near-immobilization of the methylene deuterons and is reminiscent of the subgel or L C phase of disaturated phospholipids. Cholesterol does not alter the apparent splitting of methylene deuterons in the ordered phase but does narrow the spectral contribution from methyl deuterons on the saturated chain. Quadrupole echo decay time measurements are used to gain some insight into long-range and more localized lipid motions that modulate the orientation-dependent quadrupole interaction on the time scale of the quadrupole echo experiment. The observed temperature dependence of the echo decay times suggests that echo decay in the ordered phase of 16:0-20:4 PC-d 31 bilayers is dominated by different motions than in disaturated phospholipids. These observations are compared with results from an earlier study on bilayers containing 16:0-18:2 PC-d 31 . While the difference in unsaturated chain has little effect on the chain-ordering transition temperature, small but potentially significant differences are observed in the response of the bilayer transition and dynamics to cholesterol.

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“…The method has been applied mainly to bilayers containing the phosphocholine head group, i.e. 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) [3,4], 1 -palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) [ 5,6], DPPC plus cholesterol [7], 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) [8] and egg-yolk lecithin [9]. In addition, a deuterium order profile has been published for Acholeplasma laidlawii membranes biosynthetically enriched with deuterated palmitate [lo].…”

Section: Introductionmentioning

confidence: 99%