scholarly journals Effects of Isoflurane, Halothane, and Chloroform on the Interactions and Lateral Organization of Lipids in the Liquid-Ordered Phase

Langmuir ◽  
2011 ◽  
Vol 27 (23) ◽  
pp. 14380-14385 ◽  
Author(s):  
Serhan Turkyilmaz ◽  
Paulo F. Almeida ◽  
Steven L. Regen
Keyword(s):  
Liquid Ordered ◽  
Lateral Organization

scholarly journals Cholesterol Oxidation Modulates the Formation of Liquid-Ordered Domains in Model Membranes

2021 ◽  
Author(s):  
Paul Smith ◽  
Peter G Petrov ◽  
Christian D Lorenz
Keyword(s):  
Lipid Membranes ◽  
Coarse Grained ◽  
Cholesterol Oxidation ◽  
Phosphatidylinositol 3 Kinase ◽  
Single Chemical ◽  
Liquid Ordered ◽  
Dynamics Simulations ◽  
Lateral Organization ◽  
Molecular Description ◽  
Liquid Liquid Phase Separation

7-ketocholesterol (KChol) is one of the most cytotoxic oxysterols found in the plasma membrane, and increased levels of KChol are associated with numerous pathologies. It is thought to induce apoptosis via inactivation of the phosphatidylinositol 3-kinase/Akt signaling pathway - a pathway that depends on lipid-rafts as signaling platforms. By means of coarse-grained molecular dynamics simulations, we demonstrate that KChol disrupts the liquid-liquid phase separation seen in an equimolar mixture of (dipalmitoylphosphatidylcholine) DPPC, (dioleoylphosphatidylcholine) DOPC, and Cholesterol (Chol). This disruption occurs via two mechanisms: i) KChol adopts a wider range of orientations with the membrane, which disrupts the packing of neighboring lipids and ii) KChol has no preference for DPPC over DOPC, which is the main driving force for lateral demixing in DPPC/DOPC/Chol membranes. This provides a molecular description of the means by which KChol induces apoptosis, and illustrates that a single chemical substitution to cholesterol can have a profound impact on the lateral organization of lipid membranes.

scholarly journals Can macular xanthophylls replace cholesterol in formation of the liquid-ordered phase in lipid-bilayer membranes?

2012 ◽  
Vol 59 (1) ◽  
Author(s):  
Witold K Subczynski ◽  
Anna Wisniewska-Becker ◽  
Justyna Widomska
Keyword(s):  
Oxygen Transport ◽  
Fluid Phase ◽  
Transport Parameter ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Structural Functions ◽  
Liquid Ordered ◽  
Gel Phase ◽  
Lateral Organization

Lateral organization of membranes made from binary mixtures of dimyristoylphosphatidylcholine (DMPC) or dipalmitoylphosphatidylcholine (DPPC) and macular xanthophylls (lutein or zeaxanthin) was investigated using the saturation-recovery (SR) EPR spin-labeling discrimination by oxygen transport (DOT) method in which the bimolecular collision rate of molecular oxygen with the nitroxide spin label is measured. This work was undertaken to examine whether or not lutein and zeaxanthin, macular xanthophylls that parallel cholesterol in its function as a regulator of both membrane fluidity and hydrophobicity, can parallel other structural functions of cholesterol, including formation of the liquid-ordered phase in membranes. The DOT method permits discrimination of different membrane phases when the collision rates (oxygen transport parameter) differ in these phases. Additionally, membrane phases can be characterized by the oxygen transport parameter in situ without the need for separation, which provides information about the dynamics of each phase. In gel-phase membranes, two coexisting phases were discriminated in the presence of macular xanthophylls - namely, the liquid-ordered-like and solid-ordered-like phases. However, in fluid-phase membranes, xanthophylls only induce the solitary liquid-ordered-like phase, while at similar concentrations, cholesterol induces coexisting liquid-ordered and liquid-disordered phases. No significant differences between the effects of lutein and zeaxanthin were found.

scholarly journals Shiga Toxin (Stx)-Binding Glycosphingolipids of Primary Human Renal Cortical Epithelial Cells (pHRCEpiCs) and Stx-Mediated Cytotoxicity

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 139
Author(s):  
Johanna Detzner ◽  
Elisabeth Krojnewski ◽  
Gottfried Pohlentz ◽  
Daniel Steil ◽  
Hans-Ulrich Humpf ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Epithelial Cells ◽  
Shiga Toxin ◽  
Saturated Fatty Acids ◽  
Human Kidney ◽  
Enterohemorrhagic Escherichia Coli ◽  
Highly Sensitive ◽  
Liquid Ordered ◽  
Uremic Syndrome

Human kidney epithelial cells are supposed to be directly involved in the pathogenesis of the hemolytic–uremic syndrome (HUS) caused by Shiga toxin (Stx)-producing enterohemorrhagic Escherichia coli (EHEC). The characterization of the major and minor Stx-binding glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer), respectively, of primary human renal cortical epithelial cells (pHRCEpiCs) revealed GSLs with Cer (d18:1, C16:0), Cer (d18:1, C22:0), and Cer (d18:1, C24:1/C24:0) as the dominant lipoforms. Using detergent-resistant membranes (DRMs) and non-DRMs, Gb3Cer and Gb4Cer prevailed in the DRM fractions, suggesting their association with microdomains in the liquid-ordered membrane phase. A preference of Gb3Cer and Gb4Cer endowed with C24:0 fatty acid accompanied by minor monounsaturated C24:1-harboring counterparts was observed in DRMs, whereas the C24:1 fatty acid increased in relation to the saturated equivalents in non-DRMs. A shift of the dominant phospholipid phosphatidylcholine with saturated fatty acids in the DRM to unsaturated species in the non-DRM fractions correlated with the GSL distribution. Cytotoxicity assays gave a moderate susceptibility of pHRCEpiCs to the Stx1a and Stx2a subtypes when compared to highly sensitive Vero-B4 cells. The results indicate that presence of Stx-binding GSLs per se and preferred occurrence in microdomains do not necessarily lead to a high cellular susceptibility towards Stx.

scholarly journals Pictures of the Substructure of Liquid-Ordered Domains

2015 ◽  
Vol 109 (5) ◽  
pp. 854-855 ◽  
Author(s):  
Gerald W. Feigenson
Keyword(s):  
Liquid Ordered

scholarly journals Cholesterol provides nonsacrificial protection of membrane lipids from chemical damage at air–water interface

2018 ◽  
Vol 115 (13) ◽  
pp. 3255-3260 ◽  
Author(s):  
Xinxing Zhang ◽  
Kevin M. Barraza ◽  
J. L. Beauchamp
Keyword(s):  
Lipid Membranes ◽  
Membrane Lipids ◽  
Oh Radicals ◽  
Significant Finding ◽  
Water Interface ◽  
Unsaturated Lipids ◽  
Air Water Interface ◽  
Liquid Ordered ◽  
Ester Linkage

The role of cholesterol in bilayer and monolayer lipid membranes has been of great interest. On the biophysical front, cholesterol significantly increases the order of the lipid packing, lowers the membrane permeability, and maintains membrane fluidity by forming liquid-ordered–phase lipid rafts. However, direct observation of any influence on membrane chemistry related to these cholesterol-induced physical properties has been absent. Here we report that the addition of 30 mol % cholesterol to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (POPG) monolayers at the air–water interface greatly reduces the oxidation and ester linkage cleavage chemistries initiated by potent chemicals such as OH radicals and HCl vapor, respectively. These results shed light on the indispensable chemoprotective function of cholesterol in lipid membranes. Another significant finding is that OH oxidation of unsaturated lipids generates Criegee intermediate, which is an important radical involved in many atmospheric processes.

Sign in / Sign up

Export Citation Format

Share Document