Characterizing the Gel to Liquid Crystal Transition in Lipid-Bilayer Model Systems

Koyama, Tsutomu; Stevens, Cliff R.; Borda, E. J.; Grobe, K. J.; Cleary, David

doi:10.1007/s00897990273a

Cited by 21 publications

(12 citation statements)

References 4 publications

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“…These data are consistent with the insertion of indinavir in the lipid membrane. In addition, nanoparticles without indinavir in phospholipid bilayers showed the phase transition temperature ( T m ) of 53.4°C, which is similar to those reported elsewhere ( T m of DSPC, 54–56°C21, 22), while nanoparticles with indinavir had a lower T m , 51.9°C (Fig. 1).…”

Section: Resultssupporting

confidence: 89%

pH-Dependent Interactions of Indinavir and Lipids in Nanoparticles and Their Ability to Entrap a Solute

Choi

Bui

2008

Journal of Pharmaceutical Sciences

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Section: Resultssupporting

confidence: 89%

pH-Dependent Interactions of Indinavir and Lipids in Nanoparticles and Their Ability to Entrap a Solute

Choi

Bui

2008

Journal of Pharmaceutical Sciences

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“…The temperature of the system was kept around 310 K, by coupling to a Berendsen heat bath61 with a coupling constant of 0.1 ps, with separate coupling of solutes (protein, nucleotides, and lipids) and solvent. The chosen temperature for the simulations is well above the phase transition temperature for DMPC ( T m = 296−297 K) to ensure that the bilayer is in the liquid crystalline state 62. The pressure was coupled semi‐isotropically (coupling constant of 1.0 ps and compressibility of 4.5 × 10 −5 bar −1 ), resulting in independent coupling of the lateral P(x+y) and perpendicular (Pz) pressures.…”

Section: Methodsmentioning

confidence: 99%

“…The chosen temperature for the simulations is well above the phase transition temperature for DMPC (T m 5 2962297 K) to ensure that the bilayer is in the liquid crystalline state. 62 The pressure was coupled semi-isotropically (coupling constant of 1.0 ps and compressibility of 4.5 3 10 25 bar 21 ), resulting in independent coupling of the lateral P(x1y) and perpendicular (Pz) pressures. The values of the lateral and perpendicular pressures were chosen to correspond to a surface tension of 25 dynes/cm (which was shown to give the correct area per lipid using the 45A3 GROMOS force-field 63 ).…”

Section: Sav1866 and Lipid Bilayer Assemblymentioning

confidence: 99%

Conformational changes induced by ATP‐hydrolysis in an ABC transporter: A molecular dynamics study of the Sav1866 exporter

2011

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ATP-Binding Cassette (ABC) transporters are ubiquitous membrane proteins that use energy from ATP binding or/and hydrolysis to actively transport allocrites across membranes. In this study, we identify ATP-hydrolysis induced conformational changes in a complete ABC exporter (Sav1866) from Staphylococcus aureaus, using molecular dynamics (MD) simulations. By performing MD simulations on the ATP and ADP+IP bound states, we identify the conformational consequences of hydrolysis, showing that the major rearrangements are not restricted to the NBDs, but extend to the transmembrane domains (TMDs) external regions. For the first time, to our knowledge, we see, within the context of a complete transporter, NBD dimer opening in the ADP+IP state in contrast with all ATP-bound states. This opening results from the dissociation of the ABC signature motif from the nucleotide. In addition, in both states, we observe the opening of a gate entrance in the intracellular loop region leading to the exposure of the TMDs internal cavity to the cytoplasm. To see if this opening was large enough to allow allocrite transport, the adiabatic energy profile for doxorubicin passage was determined. For both states, this profile, although an approximation, is overall downhill from the cytoplasmatic to the extracellular side, and the local energy barriers along the TMDs are relatively small, evidencing the exporter nature of Sav1866. The major difference between states is an energy barrier located in the cytoplasmic gate region, which becomes reduced upon hydrolysis, suggesting that allocrite passage is facilitated, and evidencing a possible molecular mechanism for the active transport in these proteins.

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“…We consider such an intermediate structure as constituted by cooperative units, C.U. (Genova et al, 2018(Genova et al, , 2019Koyama et al, 1999, Nelson and Cox, 2000, Ohline et al, 2001, allowing a dramatic change of the order at T m . In the PL conformation sense, the "cooperativity" of the transition at the bilayer level indicates that in the lower temperature L β gel state, the PL are closely packed by strong van der Waals forces.…”

Section: Dsc Of Sopc/chol Mixture and Pure Sopcmentioning

confidence: 99%

Differential Scanning Calorimetric Study of the Effect of Cholesterol on the Thermotropic Phase Behavior of the Phospholipid 1‐Stearoyl‐2‐Oleoyl‐sn‐Glycero‐3‐Phosphocholine

Genova

Chamati

Slavkova

et al. 2019

J Surfact & Detergents

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Using the differential scanning calorimetric (DSC) technique, the thermal properties of 1‐stearoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (SOPC) phospholipid and its mixture with cholesterol (Chol), in the range between 10 and 50 mol.%, were investigated. A considerable modification of the structural conformation and the biophysical properties of the bilayer of the phospholipid system after the Chol incorporation were detected. Concentrations below 30 mol.%, and especially in the range 10–20 mol.%, were found to be optimal in the effective miscibility of SOPC and Chol components. The effective miscibility completeness, mainly in the gel and liquid crystal phases, was indicated. It was discovered that Chol mixed with SOPC slightly shifts its gel (L β) to liquid crystal (L α) phase transition temperature, decreases cooperativity, expressed by the van't Hoff enthalpy, and markedly and progressively reduces the transition enthalpy to almost zero at 50 mol.%. By deep incubation of the cholesteric phospholipid mixture, it was revealed that the endothermic peak associated with laminar crystal to gel phase transition does not exist in conventional pure SOPC bilayer systems.

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Characterizing the Gel to Liquid Crystal Transition in Lipid-Bilayer Model Systems

Cited by 21 publications

References 4 publications

pH-Dependent Interactions of Indinavir and Lipids in Nanoparticles and Their Ability to Entrap a Solute

pH-Dependent Interactions of Indinavir and Lipids in Nanoparticles and Their Ability to Entrap a Solute

Conformational changes induced by ATP‐hydrolysis in an ABC transporter: A molecular dynamics study of the Sav1866 exporter

Differential Scanning Calorimetric Study of the Effect of Cholesterol on the Thermotropic Phase Behavior of the Phospholipid 1‐Stearoyl‐2‐Oleoyl‐sn‐Glycero‐3‐Phosphocholine

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