High pressure cell for neutron reflectivity measurements up to 2500 bar

Jeworrek, Christoph; Steitz, Roland; Czeslik, Claus; Winter, Roland

doi:10.1063/1.3553392

Cited by 16 publications

(16 citation statements)

References 36 publications

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“…Our newly designed, home-built high-pressure cell for neutron reflectivity studies was utilized for the experiments. 22 The reflectometer was operated in the time-of-flight mode using neutron wavelengths in the range λ = 2− 20 Å. A reflectivity curve was measured at two angles of incidence (θ 1 = 0.64°;…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Physical Properties of Archaeal Tetraether Lipid Membranes As Revealed by Differential Scanning and Pressure Perturbation Calorimetry, Molecular Acoustics, and Neutron Reflectometry: Effects of Pressure and Cell Growth Temperature

et al. 2012

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The polar lipid fraction E (PLFE) is a major tetraether lipid component in the thermoacidophilic archaeon Sulfolobus acidocaldarius. Using differential scanning and pressure perturbation calorimetry as well as ultrasound velocity and density measurements, we have determined the compressibilities and volume fluctuations of PLFE liposomes derived from different cell growth temperatures (T(g) = 68, 76, and 81 °C). The compressibility and volume fluctuation values of PLFE liposomes, which are substantially less than those detected from diester lipid membranes (e.g., DPPC), exhibit small but significant differences with T(g). Among the three T(g)s employed, 76 °C leads to the least compressible and most tightly packed PLFE membranes. This temperature is within the range for optimal cell growth (75-80 °C). It is known that a decrease in T(g) decreases the number of cyclopentane rings in archael tetraether lipids. Thus, our data enable us to present the new view that membrane packing in PLFE liposomes varies with the number of cyclopentane rings in a nonlinear manner, reaching maximal tightness when the tetraether lipids are derived from cells grown at optimal T(g)s. In addition, we have studied the effects of pressure on total layer thickness, d, and neutron scattering length density, ρ(n), of a silicon-D(2)O interface that is covered with a PLFE membrane using neutron reflectometry (NR). At 55 °C, d and ρ(n) are found to be rather insensitive to pressure up to 1800 bar, suggesting minor changes of the thickness of the membrane's hydrophobic core and headgroup orientation upon compression only.

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Section: ■ Materials and Methodsmentioning

confidence: 99%

Physical Properties of Archaeal Tetraether Lipid Membranes As Revealed by Differential Scanning and Pressure Perturbation Calorimetry, Molecular Acoustics, and Neutron Reflectometry: Effects of Pressure and Cell Growth Temperature

et al. 2012

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“…The difficulties in designing a hydrostatic pressure sample environment for appropriate experimental means like neutron reflectivity of polymer films − were overcome just recently. − Pressure applications to isotropic bulk systems such as thermosensitive hydrogels, on the contrary, have a longer tradition. − The latter showed that, albeit different in their chemical composition, all systems significantly swelled at elevated pressure under poor to Θ-solvent conditions, in particular close to the LCST, and below a threshold pressure of about 1000 bar. In this regime, pressure ( P ) was found to act antagonistically to temperature ( T ), leading to an increase of the LCST with pressure in T ( P ) phase space. − How these observations transfer to the pressure-response of the anisotropic and spatially varying polymer film structure is not known.…”

Section: Introductionmentioning

confidence: 99%

Fine-Tuning the Structure of Stimuli-Responsive Polymer Films by Hydrostatic Pressure and Temperature

et al. 2013

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The response of stimuli-responsive polymer brushes to moderately elevated pressure is investigated by neutron reflectivity and a thermodynamically consistent density functional theory where pressure effects are included by a hydrophobic cavity model. Evidence is provided that temperature and pressure effects on the brush spatial structure are entirely antagonistic. A ∼100 bar/K cancellation effect is found, which we argue is a general feature for hydrophobically associating homopolymers and serves for experimental guidance and fine-control of polymer film structure. Our results also suggest that polymeric interfaces which do not show a marked temperature dependence are also rather insensitive to pressure effects for applied pressures below 1 kbar.

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“…High pressure sample cells for neutron reflectometry have been constructed recently [31,32]. Here, we will briefly outline the design of our own cell used in this study [31].…”

Section: High Pressure Nr Experimentsmentioning

confidence: 99%

Packing Effects of N-Ras Binding to a DOPC Membrane – a Neutron Reflectivity and TIRF Spectroscopy High-Pressure Study

Erlkamp

Moulin

Winter

et al. 2014

Zeitschrift Für Physikalische Chemie

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We have analyzed the structural changes of a 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) membrane upon insertion of the lipidated N-Ras protein as a function of pressure. N-Ras is a small GTPase that plays an important role for signal transduction and cell growth. After lipidation with hexadecyl (HD) and farnesyl (Far) residues, N-Ras HD-Far can insert into lipid membranes. In this study, we describe the concomitant changes of the DOPC membrane structure using neutron reflectometry (NR) and total internal reflection fluorescence (TIRF) spectroscopy. The data have been recorded as a function of pressure up to 2000 bar, because pressure can be used to explore low-volume states and high packing densities. The analysis of the NR data reveals that the DOPC membrane adopts a more ordered state with sharpened polar-apolar interfaces upon pressurization. After binding of N-Ras HD-Far via insertion of the two lipid anchors, this effect becomes even more pronounced. Complementary TIRF experiments corroborate these findings. Whereas pressure increases the generalized polarization (GP) value of the DOPC membrane indicating a pressure-induced dense packing of the lipid chains, the incorporation of the N-Ras HD-Far into the DOPC membrane is also found to enhance the GP value. Moreover, application of high pressure does not decrease the degree of N-Ras HD-Far binding to the DOPC membrane confirming the bound state to be a low-volume state. The results of this study shed some light on the effect of pressure on membrane-associated Ras-controlled signaling events in extreme environments, such as the deep sea, where pressures up to 1 kbar are reached.

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High pressure cell for neutron reflectivity measurements up to 2500 bar

Cited by 16 publications

References 36 publications

Physical Properties of Archaeal Tetraether Lipid Membranes As Revealed by Differential Scanning and Pressure Perturbation Calorimetry, Molecular Acoustics, and Neutron Reflectometry: Effects of Pressure and Cell Growth Temperature

Physical Properties of Archaeal Tetraether Lipid Membranes As Revealed by Differential Scanning and Pressure Perturbation Calorimetry, Molecular Acoustics, and Neutron Reflectometry: Effects of Pressure and Cell Growth Temperature

Fine-Tuning the Structure of Stimuli-Responsive Polymer Films by Hydrostatic Pressure and Temperature

Packing Effects of N-Ras Binding to a DOPC Membrane – a Neutron Reflectivity and TIRF Spectroscopy High-Pressure Study

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