Search results for " Fluidity"

Vascular atherosclerotic disease: Behaviour of the polymorphonuclear leukocyte (PMN) filtration parameters, PMN membrane fluidity and PMN cytosolic C…

1996

The membrane environment modulates self-association of the human GpA TM domain--implications for membrane protein folding and transmembrane signaling.

2010

Abstract The influence of lipid bilayer properties on a defined and sequence-specific transmembrane helix–helix interaction is not well characterized yet. To study the potential impact of changing bilayer properties on a sequence-specific transmembrane helix–helix interaction, we have traced the association of fluorescent-labeled glycophorin A transmembrane peptides by fluorescence spectroscopy in model membranes with varying lipid compositions. The observed changes of the glycophorin A dimerization propensities in different lipid bilayers suggest that the lipid bilayer thickness severely influences the monomer–dimer equilibrium of this transmembrane domain, and dimerization was most effici…

Generation of proteoliposomes from subcellular fractions.

1998

Intracellular membranes are highly dynamic, yet they retain their identity and functional characteristics. Integral membrane proteins, which must confer this specific membrane identity, remain poorly characterized at the biochemical level, largely because detergent-mediated solubilization is required for purification and analysis, and several properties of integral membrane proteins can only be investigated when the molecule is properly embedded in a lipid bilayer. We present a method for the efficient reconstitution into proteoliposomes of integral membrane proteins from subcellular fractions. Integral membrane proteins were identified on high-resolution two-dimensional gels after selectiv…

Polymorphonuclear leukocyte membrane fluidity and cytosolic Ca2+ content at baseline and after activation in essential hypertension

2004

Obiective: To examine in essential hypertension (EH) the polymorphonuclear leukocyte (PMN) membrane fluidity and cytosolic Ca2+ content at baseline and after in vitro activation. Subjects and methods: In 45 hypertensive subjects (27 men and 18 women; mean age 45.8 +/- 11.3 years) we evaluated the PMN membrane fluidity, obtained by labeling PMNs with 1-[4-(trimethyImino)phenyl]-6phenyl-1,3,5-hexatriene (TMA-DPH) and considering the TMA-DPH polarization degree, inversely related to the membrane fluidity, and the PMN cytosolic Ca2+ content, obtained by marking PMNs with Fura 2-AM. These PMN parameters were examined at baseline and after in vitro activation (prolonged for 5 min) with two agents…

Electrostatic Contribution to the Surface Pressure of Charged Monolayers Containing Polyphosphoinositides

2008

Structural and functional studies of lateral heterogeneity in biological membranes have underlined the importance of membrane organization in biological function. Most inquiries have focused on steric determinants of membrane organization, such as headgroup size and acyl-chain saturation. This manuscript reports a combination of theory and experiment that shows significant electrostatic contributions to surface pressures in monolayers of phospholipids where the charge spacing is smaller than the Bjerrum length. For molecules with steric cross sections typical of phospholipids in the cell membrane (approximately 50 A(2)), only polyphosphoinositides achieve this threshold. The most abundant s…

Membrane fluidity of stressed cells of Oenococcus oeni

2000

International audience; The determination of membrane fluidity in whole cells of Oenococcus oeni was achieved by membrane probe 1,6-diphenyl-1,3,5-hexatriene fluorescence anisotropy measurements. The results demonstrated instantaneous fluidity variations with cells directly stressed during the measure. Heat (42°C) or acid (pH 3.2) shocks decreased the anisotropy values (fluidising effects), whereas an ethanol shock (10% ethanol, v/v) increased the membrane rigidity. The velocities of fluidity variation with non-adapted or adapted cells (incubation in inhibitory growth conditions) were compared. The adaptation of the cells to acid conditions had no effect on the membrane fluidity variation a…

Interaction of an odorant lactone with model phospholipid bilayers and its strong fluidizing action in yeast membrane

2003

International audience; Some odorant lactones are naturally present in fruits or in fermented products; they can also be used as food additives and can be produced by microorganisms at the industrial scale by biotechnological processes. Gamma-decalactone was previously shown to have antimicrobial properties. We determined by infrared spectroscopy measurements that this compound rapidly diffused into model phospholipid bilayers (within 2 min), modifying the general physical state of a dimyristoyl-L-alpha-phosphatidylcholine (DMPC) film. In vivo, the lactone strongly increased membrane fluidity in the model yeast Yarrowia lipolytica, as evaluated by fluorescence anisotropy measurements. This …

Lipid and fatty acid variations inCiona intestinalis ovary after tri-n-butyltin(IV)chloride exposure

2005

Reduction of total lipids (TL) content and significant variations of triglyceride (TG) and phospholipid (PL) fractions were observed as a consequence of exposure of Ciona intestinalis ovaries to tributyltin chloride (TBTCL) solutions. In particular, an evident TG decrease and a PL increase were observed, which probably provoked an increment in membrane fluidity, because of the high concentration of long chain fatty acids and, as a consequence, PL. This could be a cell adaptive standing mechanism towards the pollutants, as observed in Saccharomyces cerevisiae. Also the increase in the content of the polyunsaturated fatty acids (PUFA), important in the synthesis of compounds such as prostagla…

Lipids of the Plant Plasma Membrane

2010

The plasma membrane (PM) is arguably the most diverse membrane of the plant cell. Furthermore, the protein and lipid composition of the PM varies with cell type, developmental stage, and environment. Physical properties of lipids and associate proteins allow the formation of a barrier that is selectively permeable to macromolecules and solutes. As the plasma membrane delineates the interface between the cell and the environment, it is the primary part of signal recognition and transduction into intracellular responses for nutritional uptake/distribution, environmental responses, and developmental signaling. Many essential PM functions are carried out by proteinaceous components. However, PM…

Polymorphonuclear leukocyte membrane fluidity and cytosolic Ca2+ concentration in subjects with vascular atherosclerotic disease subdivided according…

2006

An abnormal activation state of polymorphonuclear leukocytes (PMN) plays a key role in organ injury induced by vascular atherosclerotic disease (VAD) and diabetes mellitus (DM). PMN membrane fluidity and cytosolic Ca2+ content can be considered markers of PMN activation. In this research we evaluated the PMN membrane fluidity and cytosolic Ca2+ content in VAD subjects with and without type 2 DM and examined the association between these parameters and the mono- or polyvascular localization. We enrolled 155 VAD subjects, including 92 non-diabetic (group A: mean age 63.6 +/- 9.2 years) and 63 diabetic patients (group B: mean age 65.4 +/- 7.8 years). Among group A 63 patients had monovascular …