Fatty acyl chain order in lecithin model membranes determined from proton magnetic resonance

Bloom, Myer; Burnell, E. Elliott; MacKay, Alexander L.; Nichol, Christine P.; Valic, M.I.

doi:10.1021/bi00619a024

Cited by 116 publications

(86 citation statements)

References 37 publications

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“…However, the results of various studies are not always consistent. Some groups have shown that curvature (vesicle size) does not influence the rates of lipid motions (26)(27)(28)(29) whereas others have provided evidence that there are significant changes with vesicle diameter (14)(15)(16). These are complex experiments, particularly when they recover information on ultrafast time scales that reflect structural fluctuations in contrast to slower processes of translational and orientational diffusion.…”

mentioning

confidence: 99%

Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D IR vibrational echoes

Kel

Tamimi

Fayer

2014

Proc. Natl. Acad. Sci. U.S.A.

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The ultrafast structural dynamics inside the bilayers of dilauroylphosphatidylcholine (DLPC) and dipalmitoylphosphatidylcholine vesicles with 70, 90, and 125 nm diameters were directly measured with 2D IR vibrational echo spectroscopy. The antisymmetric CO stretch of tungsten hexacarbonyl was used as a vibrational probe and provided information on spectral diffusion (structural dynamics) in the alkyl region of the bilayers. Although the CO stretch absorption spectra remain the same, the interior structural dynamics become faster as the size of the vesicles decrease, with the size dependence greater for dipalmitoylphosphatidylcholine than for DLPC. As DLPC vesicles become larger, the interior dynamics approach those of the planar bilayer.vesicle bilayer dynamics | vesicle size dependent dynamics | vesicles chainlength dependent dynamics T he plasma membrane provides a boundary between a living cell and its surroundings and between cellular compartments, providing organizational control of proteins and small molecules that are critical for achieving the complexity of biological systems. In addition to a permeability barrier, the second role of the plasma membrane is serving as the solvent for membrane proteins and other biomolecules. The lipid environment of membrane proteins can influence their function (1-5), and so impact cell signaling, metabolism, growth, defense, and a myriad of other biological functions.Membranes have a bilayer structure where the nonpolar chains of the lipids form the interior of bilayer, with zwitterionic or ionic head groups at the interfaces with water. Artificial lipid bilayers are frequently used as models of cell membranes for investigation of membrane properties and in studies of transmembrane proteins. Although a good deal is known about the structure of artificial membranes (6-12) and orientational and translational diffusion of lipids and other molecules (7, 13-16), much less is known about the fast interior structural dynamics of the bilayers, which serve as the dynamic bath modes that can impact membrane processes.Unilamellar vesicles (ULVs) of different sizes, as well as multilamellar vesicles (MLVs), are used as model membranes owing to their ease of preparation and handling. It has been shown that their properties depend on the curvature (size) (8,9,13,(17)(18)(19)(20). Aligned planar multi-bilayers (21) are membrane models that do not have curvature, yet they are less attractive for routine use because they are substantially more difficult to prepare than vesicles.Numerous experiments have been performed to determine which type of model bilayers most closely represents the properties of the plasma membrane. However, no consensus exists because the results obtained by different methods and groups are not in agreement. Some small-angle X-ray scattering and small-angle neutron scattering (SANS) experiments indicate that the structural properties of ULVs and MLVs are curvature independent, the overall bilayer thickness does not dependent on vesicle size, and the thicknesses of...

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mentioning

confidence: 99%

Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D IR vibrational echoes

Kel

Tamimi

Fayer

2014

Proc. Natl. Acad. Sci. U.S.A.

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“…MLVs have an extremely slow molecular tumbling and so an essentially infinite correlation time [21]. Therefore, in the case of these liposomes, the molecular tumbling does not interfere with the coherent perturbation applied by the MAS and gives rise to an efficient average of the inhomogeneous and anisotropic interactions contributing.…”

Section: Luvs and Mlvsmentioning

confidence: 99%

“…Therefore, in the case of these liposomes, the molecular tumbling does not interfere with the coherent perturbation applied by the MAS and gives rise to an efficient average of the inhomogeneous and anisotropic interactions contributing. A sample of MLVs was analyzed using the HR-MAS technique at different spinning speeds, see which have an extremely slow molecular tumbling [21], the gain in resolution obtained by raising the spinning speed, is more evident than in the case of LUVs which, in turn, have a molecular tumbling in an intermediate time scale regime [19]. Under the same spinning speed and temperature conditions, the 1 H HR-MAS spectrum of MLVs showed a better resolution than the HR-MAS spectrum of LUVs; in fact, the line widths of the resonances in the spectra of MLVs are always smaller than the corresponding resonances in the spectra of LUVs, see Table 1.…”

Section: Luvs and Mlvsmentioning

confidence: 99%

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An Improved NMR Study of Liposomes Using 1-Palmitoyl-2-oleoyl-sn-glycero-3-phospatidylcholine as Model

et al. 2006

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Abstract:In this paper we report a comparative characterization of Small Unilamellar Vesicles (SUVs), Large Unilamellar Vesicles (LUVs) and Multilamellar Vesicles (MLVs) prepared from 1-palmitoyl-2-oleoyl-sn-glycero-3-phospatidylcholine (POPC), carried out using two NMR techniques, namely High Resolution NMR in solution and High Resolution-Magic Angle Spinning (HR-MAS). The size and size distributions of these vesicles were investigated using the dynamic light scattering technique. An improved assignment of the 1 H-NMR spectrum of MLVs is also reported.

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“…Perhaps the foremost progress in recent years has been made in applications of NMR lineshape analysis to studies of the molecular ordering and conformations of membranous lipids (3)(4)(5)(6)(7). Yet, in spite of early promise (8)(9)(10)(11), the interpretation of nuclear spin relaxation experiments has not progressed similarly and, in fact, has remained an outstanding problem in membrane biophysics for more than a decade (cf.…”

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confidence: 99%

New view of lipid bilayer dynamics from 2H and 13C NMR relaxation time measurements.

Brown¹,

Ribeiro²,

Williams³

1983

Proc. Natl. Acad. Sci. U.S.A.

148

118

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Natural abundance 13C spin-lattice (TI) relaxation time measurements are reported for unilamellar vesicles of 1,2-dipalmitoylphosphatidylcholine (1,2-dipalmitoyl-sn-glycero-3-phosphocholine), in the liquid crystalline phase, at magnetic field strengths of 1. 40, 1.87, 2.35, 4.23, 7.05, 8.45, and 11.7 tesla (resonance frequencies of 15.0, 20.0, 25.1, 45.3, 75.5, 90.5, and 126 MHz, respectively), and the results are compared to previous 2H T, studies of multilamellar dispersions. For both the 13C and 2H T, studies, a dramatic frequency dependence of the relaxation was observed. At superconducting magnetic field strengths (4.23-11.7 tesla), plots of the 13C TF1 relaxation rates as a function of acyl chain segment position clearly reveal the characteristic "plateau" signature of the liquid crystalline phase, as found previously from 2H NMR studies. The dependence of Tj ' on ordering, determined previously from 2H NMR, and the Tj' dependence on frequency, determined from both '3C and 2H NMR studies, suggest that a unified picture of the bilayer molecular dynamics can be provided by a simple relaxation law of the form T' l ATf + BS2 H W-'1/2. In the above expression, A and B are constants, SCH (=SC-D) is the bond segmental order parameter, and of is the nuclear Larmor frequency. The first (A) term includes contributions from fast, local segmental motions characterized by the effective correlation time Tf, whereas the second (B) term describes slower, collective fluctuations in the local ordering. The value of Tf 10-11 sec, obtained by extrapolating Tj' to infinite frequency, suggests that the segmental microviscosity of the bilayer hydrocarbon region does not differ appreciably from that of the equivalent n-paraffinic liquids of similar chain length.NMR techniques were among the first biophysical methods to be applied to lipid bilayers and biological membranes (1, 2). Perhaps the foremost progress in recent years has been made in applications of NMR lineshape analysis to studies of the molecular ordering and conformations of membranous lipids (3-7). Yet, in spite of early promise (8-11), the interpretation of nuclear spin relaxation experiments has not progressed similarly and, in fact, has remained an outstanding problem in membrane biophysics for more than a decade (cf. ref. 12). The bulk of previous work has involved spin-lattice (TI) relaxation time measurements, which are sensitive to details of the molecular motions in the MHz region. Perhaps the major justification for T, relaxation studies of membranes is their dual character as both solid-like and liquid-like materials. The analogies to simpler liquid crystals point to the necessity of obtaining both static and dynamic information in defining these systems and of distinguishing membranes from other classes of biological macromolecules, such as the globular and fibrous proteins and the nucleic acids. These latter biopolymers, while also rich in dvnamic behavior (13,14), appear to have fairly well-defined average structures that can be directly re...

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Fatty acyl chain order in lecithin model membranes determined from proton magnetic resonance

Cited by 116 publications

References 37 publications

Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D IR vibrational echoes

Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D IR vibrational echoes

An Improved NMR Study of Liposomes Using 1-Palmitoyl-2-oleoyl-sn-glycero-3-phospatidylcholine as Model

New view of lipid bilayer dynamics from 2H and 13C NMR relaxation time measurements.

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