Browse
Submit Data
Databases
API
Help

Dataset Information

16 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Phospholipid complexation of general anesthetics in fluid bilayers.

ABSTRACT: A nearest-neighbor recognition analysis has been performed in cholesterol-rich and cholesterol-poor liposomes derived from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in the presence of varying concentrations of chloroform. This analysis has yielded a fundamentally new, molecular-level view of the interaction of general anesthetics with lipid bilayers, which may be relevant to their biological action; that is, DPPC forms 1:1 complexes with CHCl(3) in both membranes in the fluid bilayer state.

SUBMITTER: Turkyilmaz S

PROVIDER: S-EPMC2856843 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Phospholipid complexation of general anesthetics in fluid bilayers.

Turkyilmaz Serhan S Mitomo Hideyuki H Chen Wen-Hua WH Regen Steven L SL

Langmuir : the ACS journal of surfaces and colloids 20100401 8

A nearest-neighbor recognition analysis has been performed in cholesterol-rich and cholesterol-poor liposomes derived from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in the presence of varying concentrations of chloroform. This analysis has yielded a fundamentally new, molecular-level view of the interaction of general anesthetics with lipid bilayers, which may be relevant to their biological action; that is, DPPC forms 1:1 complexes with CHCl(3) in both membranes in the fluid bilayer st ...[more]

PMID: 20297778

Similar Datasets

Cholesterol-phospholipid complexation in fluid bilayers as evidenced by nearest-neighbor recognition measurements.

Project description:Nearest-neighbor recognition experiments have been carried out using varying ratios of exchangeable dimer analogs of 1,2-dimyristoyl-sn-glycero-3-phosphatidylglycerol and 1,2-distearoyl-sn-glycero-3-phosphatidylglycerol in cholesterol-rich unilamellar vesicles at 60 degrees C. Equilibrium dimer distributions that were obtained support a structural model of the liquid-ordered bilayer in which free cholesterol and the longer-chain phospholipid homodimer are in equilibrium with a complex of unique stoichiometry, where one cholesterol molecule combines with two of the long-chain phospholipid homodimers. In this model, the mixing of the short-chain phospholipids with the uncomplexed long-chain phospholipids is ideal, and the complexed dimers are shielded from the disulfide exchange reaction.

| S-EPMC2517633 | biostudies-literature

Reduced sterol-phospholipid recognition in curved fluid bilayers.

Project description:Nearest-neighbor recognition experiments have been carried out in fluid liposomal membranes made from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cholesterol using exchangeable dimers derived from 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine and cholesterol. In cholesterol-rich bilayers, the association between these two exchangeable lipids was reduced as the curvature of the membrane increases; that is, when the diameter of the liposomes was below ca. 200 nm. In sharp contrast, the mixing of these exchangeable lipids was close to random in the cholesterol-poor membranes, regardless of their curvature. The biological implications of these findings are briefly discussed.

| S-EPMC2674620 | biostudies-literature

Loosening and reorganization of fluid phospholipid bilayers by chloroform.

Project description:The mixing behavior of an exchangeable phospholipid (A) with an exchangeable sterol (B) in host bilayers made from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) containing varying concentrations of cholesterol has been examined via the nearest-neighbor recognition method. At low sterol concentrations (i.e., 2.5 mol %), the mixing between A and B is close to ideal. Incremental increases in the sterol concentration to 40 mol % led to net increases in the affinity between A and B. Similar mixing experiments that were carried out in the presence of chloroform showed a leveling effect, where moderate sterol-phospholipid affinity was observed in all cases. These results, together with the fact that the number of chloroform molecules that are absorbed per phospholipid is essentially constant and independent of the sterol content, support a model in which chloroform favors solvation of the phospholipids and a common membrane state is produced. Fluorescence measurements and Raman spectra have also shown that chloroform significantly loosens both cholesterol-poor and cholesterol-rich membranes made from DPPC. In a broader context, these results suggest a fundamentally new mechanism of anesthesia, where the anesthetic, by solvating the lipid components, profoundly changes the lateral organization of the lipid framework.

| S-EPMC2753596 | biostudies-literature

1H NMR Shows Slow Phospholipid Flip-Flop in Gel and Fluid Bilayers.

Project description:We measured the transbilayer diffusion of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in large unilamellar vesicles, in both the gel (L?') and fluid (L?) phases. The choline resonance of headgroup-protiated DPPC exchanged into the outer leaflet of headgroup-deuterated DPPC-d13 vesicles was monitored using 1H NMR spectroscopy, coupled with the addition of a paramagnetic shift reagent. This allowed us to distinguish between the inner and outer bilayer leaflet of DPPC, to determine the flip-flop rate as a function of temperature. Flip-flop of fluid-phase DPPC exhibited Arrhenius kinetics, from which we determined an activation energy of 122 kJ mol-1. In gel-phase DPPC vesicles, flip-flop was not observed over the course of 250 h. Our findings are in contrast to previous studies of solid-supported bilayers, where the reported DPPC translocation rates are at least several orders of magnitude faster than those in vesicles at corresponding temperatures. We reconcile these differences by proposing a defect-mediated acceleration of lipid translocation in supported bilayers, where long-lived, submicron-sized holes resulting from incomplete surface coverage are the sites of rapid transbilayer movement.

| S-EPMC5397887 | biostudies-literature

Evidence for leaflet-dependent redistribution of charged molecules in fluid supported phospholipid bilayers.

Project description:The asymmetric distribution of charged molecules between the leaflets of solid-substrate-supported phospholipid bilayers is studied using imaging ellipsometry, fluorescence microscopy, and numerical solutions of the Poisson-Boltzmann equation. Experiments are facilitated by the use of patterned substrates that allow for side-by-side comparison of lipid monolayers and supported bilayers. On silica surfaces, negatively charged lipid components are shown to be enriched in the outer leaflet of a supported bilayer system at modest salt concentrations. The approaches developed provide a general means for determining asymmetries of charged components in supported lipid bilayers.

| S-EPMC2670441 | biostudies-literature

Phospholipid bilayers are viscoelastic.

Project description:Lipid bilayers provide the structural framework for cellular membranes, and their character as two-dimensional fluids enables the mobility of membrane macromolecules. Though the existence of membrane fluidity is well established, the nature of this fluidity remains poorly characterized. Three-dimensional fluids as diverse as chocolates and cytoskeletal networks show a rich variety of Newtonian and non-Newtonian dynamics that have been illuminated by contemporary rheological techniques. Applying particle-tracking microrheology to freestanding phospholipid bilayers, we find that the membranes are not simply viscous but rather exhibit viscoelasticity, with an elastic modulus that dominates the response above a characteristic frequency that diverges at the fluid-gel (L(α) - L(β)) phase-transition temperature. These findings fundamentally alter our picture of the nature of lipid bilayers and the mechanics of membrane environments.

| S-EPMC2984223 | biostudies-literature

Assembly of ?-synuclein aggregates on phospholipid bilayers.

Project description:The spontaneous self-assembly of ?-synuclein (?-syn) into aggregates of different morphologies is associated with the development of Parkinson's disease. However, the mechanism behind the spontaneous assembly remains elusive. The current study shows a novel effect of phospholipid bilayers on the assembly of the ?-syn aggregates. Using time-lapse atomic force microscopy, it was discovered that ?-syn assembles into aggregates on bilayer surfaces, even at the nanomolar concentration range. The efficiency of the aggregation process depends on the membrane composition, with the greatest efficiency observed for of 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine (POPS). Importantly, assembled aggregates can dissociate from the surface, suggesting that on-surface aggregation is a mechanism by which pathological aggregates may be produced. Computational modeling revealed that dimers of ?-syn assembled rapidly, through the membrane-bound monomer on POPS bilayer, due to an aggregation-prone orientation of ?-syn. Interaction of ?-syn with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) leads to a binding mode that does not induce a fast assembly of the dimer. Based on these findings, we propose a model in which the interaction of ?-syn with membranes plays a critical role initiating the formation of ?-syn aggregates and the overall aggregation process.

| S-EPMC6661114 | biostudies-literature

Blood clotting reactions on nanoscale phospholipid bilayers.

Project description:Blood clotting reactions, such as those catalyzed by the tissue factor:factor VIIa complex (TF:FVIIa), assemble on membrane surfaces containing anionic phospholipids such as phosphatidylserine (PS). In fact, membrane binding is critical for the function of most of the steps in the blood clotting cascade. In spite of this, our understanding of how the membrane contributes to catalysis, or even how these proteins interact with phospholipids, is incomplete. Making matters more complicated, membranes containing mixtures of PS and neutral phospholipids are known to spontaneously form PS-rich membrane microdomains in the presence of plasma concentrations of calcium ions, and it is likely that blood-clotting proteases such as TF:FVIIa partition into these PS-rich microdomains. Unfortunately, little is known about how membrane microdomain composition influences the activity of blood-clotting proteases, which is typically not under experimental control even in "simple" model membranes. Our laboratories have developed and applied new technologies for studying membrane proteins to gain insights into how blood-clotting protease-cofactor pairs assemble and function on membrane surfaces. This includes using a novel, nanoscale bilayer system (Nanodiscs) that permits assembling blood-clotting protease-cofactor pairs on stable bilayers containing from 65 to 250 phospholipid molecules per leaflet. We have used this system to investigate how local (nanometer-scale) changes in phospholipid bilayer composition modulate TF:FVIIa activity. We have also used detailed molecular-dynamics simulations of nanoscale bilayers to provide atomic-scale predictions of how the membrane-binding domain of factor VIIa interacts with PS in membranes.

| S-EPMC2836762 | biostudies-literature

Nanoscale patterning in mixed fluorocarbon-hydrocarbon phospholipid bilayers.

Project description:A growing body of literature suggests that fluorocarbons can direct self-assembly within hydrocarbon environments. We report here the fabrication and characterization of supported lipid bilayers (SLBs) composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and a synthetic, fluorocarbon-functionalized analogue, 1. AFM investigation of these model membranes reveals an intricate, composition-dependent domain structure consisting of approximately 50 nm stripes interspersed between approximately 1 microm sized domains. Although DSC of 1 showed a phase transition near room temperature, DSC of DPPC:1 mixtures exhibited complex phase behavior suggesting domain segregation. Finally, temperature-dependent AFM of DPPC:1 bilayers shows that, while the stripe structures can be melted above the Tm of 1, the stripes and domains result from immiscibility of the hydrocarbon and fluorocarbon lipid gel phases. Fluorination appears to be a promising strategy for chemical self-assembly in two dimensions. In particular, because no modification is made to the lipid headgroups, it may be useful for nanopatterning biologically relevant ligands on bilayers in vitro or in living cells.

| S-EPMC2507729 | biostudies-literature

Interleaflet mixing and coupling in liquid-disordered phospholipid bilayers.

Project description:Organized as bilayers, phospholipids are the fundamental building blocks of cellular membranes and determine many of their biological functions. Interactions between the two leaflets of the bilayer (interleaflet coupling) have been implicated in the passage of information through membranes. However, physically, the meaning of interleaflet coupling is ill defined and lacks a structural basis. Using all-atom molecular dynamics simulations of fluid phospholipid bilayers of five different lipids with differing degrees of acyl-chain asymmetry, we have examined interleaflet mixing to gain insights into coupling. Reasoning that the transbilayer distribution of terminal methyl groups is an appropriate measure of interleaflet mixing, we calculated the transbilayer distributions of the acyl chain terminal methyl groups for five lipids: dioleoylphosphatidylcholine (DOPC), palmitoyloleoylphosphatidylcholine (POPC), stearoyloleoylphosphatidylcholine (SOPC), oleoylmyristoylphosphatidylcholine (OMPC), and dimyristoylphosphatidylcholine (DMPC). We observed in all cases very strong mixing across the bilayer midplane that diminished somewhat with increasing acyl-chain ordering defined by methylene order parameters. A hallmark of the interleaflet coupling idea is complementarity, which postulates that lipids with short alkyl chains in one leaflet will preferentially associate with lipids with long alkyl chains in the other leaflet. Our results suggest a much more complicated picture for thermally disordered bilayers that we call distributed complementarity, as measured by the difference in the peak positions of the sn-1 and sn-2 methyl distributions in the same leaflet.

| S-EPMC4703536 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data