Determination of DMPC hydration in the Lαand Lβ′phases by2H solid state NMR of D2O

Faure, Chrystel; Bonakdar, L.; Dufourc, Érick J.

doi:10.1016/s0014-5793(97)00201-9

Cited by 62 publications

(99 citation statements)

References 29 publications

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“…First, the dehydration of lipid bilayers is generally only observed at MAS rates well above 10 kHz, whereas all data in this study were obtained at 8.33 kHz or below. Second, dehydration favors the formation the gel phase, as it features fewer water molecules per lipid (57)(58)(59)(60)(61). Indeed, it is well known that dehydration of membranes (and cells) causes a dramatic increase in the lipids' T m , rather than a decrease.…”

Section: Lowering Of the Lipid Melting Temperaturesmentioning

confidence: 99%

MAS 1 H NMR Probes Freezing Point Depression of Water and Liquid-Gel Phase Transitions in Liposomes

Mandal

Wel

2016

Biophysical Journal

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The lipid bilayer typical of hydrated biological membranes is characterized by a liquid-crystalline, highly dynamic state. Upon cooling or dehydration, these membranes undergo a cooperative transition to a rigidified, more-ordered, gel phase. This characteristic phase transition is of significant biological and biophysical interest, for instance in studies of freezing-tolerant organisms. Magic-angle-spinning (MAS) solid-state NMR (ssNMR) spectroscopy allows for the detection and characterization of the phase transitions over a wide temperature range. In this study we employ MAS 1 H NMR to probe the phase transitions of both solvent molecules and different hydrated phospholipids, including tetraoleoyl cardiolipin (TOCL) and several phosphatidylcholine lipid species. The employed MAS NMR sample conditions cause a previously noted substantial reduction in the freezing point of the solvent phase. The effect on the solvent is caused by confinement of the aqueous solvent in the small and densely packed MAS NMR samples. In this study we report and examine how the freezing point depression also impacts the lipid phase transition, causing a ssNMR-observed reduction in the lipids' melting temperature (T m ). The molecular underpinnings of this phenomenon are discussed and compared with previous studies of membrane-associated water phases and the impact of membrane-protective cryoprotectants.

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Section: Lowering Of the Lipid Melting Temperaturesmentioning

confidence: 99%

MAS 1 H NMR Probes Freezing Point Depression of Water and Liquid-Gel Phase Transitions in Liposomes

Mandal

Wel

2016

Biophysical Journal

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“…Sample temperature control was achieved by 30 passing the spectrometer bearing gas through a liquid nitrogen chiller and then heater unit; NMR data was collected in the range 5 -60 °C.…”

Section: Nuclear Magnetic Resonance (Nmr) Experimentsmentioning

confidence: 99%

“…Sphingomyelin rich 25 lipid rafts have been suggested to act as "hotspots" or platforms which promote or enable trans-membrane proteins to aggregate so they may initiate cell signalling events. In addition to forming a major component of the membrane structural matrix, sphingomyelin and its metabolic products have been proposed as 30 important signalling molecules in several processes including cellular apoptosis. 2 Despite its significant biological importance, there is a relative dearth of published physicochemical data for sphingomyelin (SM) when compared to the structurally analogous 35 phosphocholine based phospholipids.…”

Section: Introductionmentioning

confidence: 99%

Pressure–temperature phase behaviour of natural sphingomyelin extracts

et al. 2012

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Sphingomyelin is the only sphingolipid occurring naturally in mammalian cells and can form up to 50% of the total phospholipid content of the myelin sheath which surrounds nerves. Having predominantly long, saturated acyl chains, it has a relatively high chain melting temperature and has been strongly associated with formation of lipid microdomains. Here, the lyotropic phase behaviour of sphingomyelin 10 from three different natural sources (bovine brain, egg yolk and milk) in excess water is studied as a function of temperature and pressure by small-and wide-angle X-ray scattering, and solid state NMR. The different hydrocarbon chain length distributions of the three lipid extracts results in significant differences in their gel phase structure; both the bovine brain and egg yolk sphingomyelins can form a ripple gel phase but milk sphingomyelin forms an interdigitated gel phase due to the high degree of chain 15 mismatch in its longer hydrocarbon chain components.

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“…Lipid: 2 H 2 O molar ratio of 1:6 for the prepared sample suggests a moderate level of hydration. We performed experiments at 38°C; at this temperature the membrane fragments are in the lamellar liquid phase (26,27).The spectral degeneracy of the sn-1 and sn-2 carbonyls was lifted, giving two broad vibrational bands at 1,740 and 1,697 cm Ϫ1 , respectively (see linear IR spectrum in Fig. 2A) for nonlinear spectral probing.…”

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confidence: 99%

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confidence: 99%

Electrostatic interactions in phospholipid membranes revealed by coherent 2D IR spectroscopy

Volkov¹,

Chelli

Zhuang

et al. 2007

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

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The inter-and intramolecular interactions of the carbonyl moieties at the polar interface of a phospholipid membrane are probed by using nonlinear femtosecond infrared spectroscopy. Twodimensional IR correlation spectra separate homogeneous and inhomogeneous broadenings and show a distinct cross-peak pattern controlled by electrostatic interactions. The inter-and intramolecular electrostatic interactions determine the inhomogeneous character of the optical response. Using molecular dynamics simulation and the nonlinear exciton equations approach, we extract from the spectra short-range structural correlations between carbonyls at the interface.carbonyl ͉ interface ͉ intermolecular ͉ nonlinear exciton equations ͉ molecular dynamics A s a constituent organelle in a cell, the membrane sets the information and energy gradients necessary for life. Carbonyl, phosphate, and choline are the common structural moieties in the polar surface of cellular membranes (1), mediating molecular recognition and signal transduction (1-4). Unfortunately, our knowledge on their arrangement and dynamics is rather limited due to experimental difficulties. In a lipid bilayer, lateral irregularity smears the diffraction pattern in neutron scattering measurements, and NMR resonances are broad because of the restricted motions that result in incomplete motional narrowing. IR spectroscopy, on the other hand, is known to be helpful in application to such systems. Since 1972, the IR resonance of carbonyl moieties in phospholipid membranes has attracted considerable attention (5-9). The absorption band shows a clear inhomogeneous character and can be described as a superposition of several substates (5-7). The carbonyl stretching line-shapes in membranes could yield direct information about molecular architecture and fluctuations in the membrane interface (10, 11), provided that the origin of the spectral inhomogeneity of the carbonyl IR response in phospholipid membranes is understood. The inhomogeneity was attributed to differences in the local environment of the sn-1 and sn-2 carbonyl moieties stemming from the packing arrangements (6, 8), the local chain conformations (8,9,(12)(13)(14), the relative positions of the two CAO groups with respect to the interface (9, 15), and the degree of hydration (16,17). In an elegant work, Blume et al. (16) ruled out all of the scenarios involving local structural differences except hydrogen bonding. In a recent study, we eliminated the variance in hydration as a possible source of inhomogeneity (18).Here we employ 2D IR spectroscopy (19,20) to explore whether and to what extent the inhomogeneities of the carbonyl absorption can be attributed to electric field fluctuations. 2D IR techniques are femtosecond optical analogues of 2D NMR that generate 2D correlation plots that can separate homogeneous and inhomogeneous broadenings along the diagonal and antidiagonal axis and provide a rich cross-peak pattern (21). Electrostatic interactions strongly contribute to the optical response of molecular crystals (2...

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Determination of DMPC hydration in the L_αand L_β′phases by²H solid state NMR of D₂O

Cited by 62 publications

References 29 publications

MAS 1 H NMR Probes Freezing Point Depression of Water and Liquid-Gel Phase Transitions in Liposomes

MAS 1 H NMR Probes Freezing Point Depression of Water and Liquid-Gel Phase Transitions in Liposomes

Pressure–temperature phase behaviour of natural sphingomyelin extracts

Electrostatic interactions in phospholipid membranes revealed by coherent 2D IR spectroscopy

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